Alcator C-Mod Run 960226 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Jeff Schachter (shots 1-35)

Operators
Session leader(s):	Jeff Schachter
Physics operator(s):	Steve Wolfe
Engineering operator(s):	Joe Daigle,Frank Silva,Vinny Bertolino

Engineering Operator Run Comment
wolfeman

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:15:553PM

Author: To Be Determined

Run Summary for MP 122A - Rho-Star Scaling - 96.02.26 - Jeff Schachter
======================================================================

This run was a continuation from 95.12.18 and 96.02.01. Today we concentrated
on H-mode rhostar scaling.

I have identified three different parameter ranges (H-A, H-B, H-C) potentially
useful for H-mode scaling:

H-A
---
betat=0.87, nustare=0.17, q_eng=4.0. The parameters required at each field are:

3.5 T: Ip=630 kA, nebar=1.6, Te0=1.9 keV
5.7 T: Ip=1.0 MA, nebar=3.0, Te0=2.5 keV

H-B
---
betat=1.3, nustare=5 (my units), q_eng=3.7

2.75 T: Ip=550 kA, nebar=1.6, Te0=1.5 keV
5.3 T: Ip=1.05 MA, nebar=3.8, Te0=2.4 keV

H-C
---
scaling from 3.5 T (shot 960226018):
betat=0.56, nustare=22 (my units), q_eng=3.7

3.5 T: Ip=720 kA, nebar=1.4, Te0=1.4 keV
5.7 T: Ip=1.2 kA, nebar=2.6, Te0=1.9 keV

scaling from 5.7 T (shot 960206015):
betat: 1.0, nustare=10 (my units), q_eng=3.7

3.5 T: Ip=720 kA, nebar=1.6, Te0=1.9 keV
5.7 T: Ip=1.2 kA, nebar=3.1, Te0=2.6 keV

-------------------------------------------------------------------------------

I will detail the attempts we made to get shots for each group:

H-A Shots: 3-17 Useful: none
---

The 5.3 T shots already exist (see 960206007 or a host of others). A 3.5 T
shot from last year - 950214014 - matched the required parameters except for Ip
(720 kA versus 630 kA required). We tried to reproduce 950214014 at the lower
current first. After lots of problems, we were able to get H-modes in shots 15
and 17. The temperature, and therefore beta, was too low in both shots to be
scalable to any of the existing 5.3 T H-modes. This is the same problem that
plagued us 960201 with the low field H-modes.

H-C Shots: 18-25 Useful: none
---

We went back to 720 kA in an attempt to duplicate the result from 950214014,
hoping that the higher current would give us a higher temperature (and
therefore match other shots in the H-mode database, like 960206015). We were
able to get an H-mode in shot 18, but it was too cold. I think the ECE
temperature measurement in 950214014 is suspect (it read 2.0 keV). The YAG
reads about 500 eV lower, and closer to the temperatures we got today (1.5
keV). Shots 19 & 20 didn't go, and 21 didn't give us an H-mode. We punted the
3.5 T attempts, believing that we couldn't get them any hotter, and instead
decided to tweak the 5.7 T counterpart shot: 960206015 - one of the high
performance H-modes - attempting to lower its temperature to match 960226018.
This didn't work (see PHYSOP summary as to why). The one H-mode we were able
to get was too hot.

H-B Shots: 26-34 Useful: 27,30,34,35
---

Finally, some success! In these shots we attempted to get a hot 2.75 T H-mode.
Our starting point was 960223022, a "good" ohmic H-mode from last week.
Hitting it with as much RF as possible gave peak Te0's of 1.5 keV and higher,
high enough to scale against the bulk of the H-modes obtained at 5.3 T. The
problem here was the density - since ne scales as such a strong function of B
(B^4/3), the densities we reached in these shots were at the upper edge, if not
beyond, what was obtained at 5.3 T. Still, the shots I mention should be
scalable. In particular, shot 35 should work. For this shot we cut the RF
power down by ~ 0.6 MW (transmitted, not absorbed) and kept the density lower.

These H-modes had beta_normal's of 1.4. H-factors have yet to be determined,
as we need to get a better idea of what the absorbed RF power was for these
shots. Steps put into the RF pulse should be able to allow calculation of the
absorbed power (analysis TBA).

Physics Operator Summaries

Entered: Jul 7 2004 04:36:56:270PM

Author: To Be Determined

Physics Operator Summary for 960226

MP#122A
SL Schachter
PO wolfe
EO silva,bertolino,daigle,bertolino

The plan for todays run was to produce shots at several fields (3.5,5.3,2.7T)
which would satisfy a constant nustar, constant beta condition, i.e. a
rhostar scan, in H-mode. Shots at 3.5T were to be ohmic, while the 5.3T would
be standard D(H) heating, and the 2.7 would be 2nd harmonic H in D. Shots were
obtained at all three fields, but only those at the low field end are likely
to be useful for the rho-star scan.

ECDC was performed in He for 48hours over the weekend.

Shot 1 was the usual Tuesday test, and shot 2 was a fiducial. The fiducial had
numerous injections, and some runaways. I did not load the fiducial database;
someone should look at the data and decide if this is a suitable shot.

Shot 3 was the start of the main program. We started with a 3.5T shot, trying
to reproduce the conditions of 950214014, but with a high field startup. The
starting point was a 700kA shot, although we wanted to move to a 620kA shot
for this field. Shots 3-11 all had problems with vertical instability and
early disruptions. They also mostly suffered from current rise disruptions and
moderate runaways, which tended to dump at the CR disruption. Lots of tweaks
in this group, many in the wrong direction. See logbook for details (note that
all logbook entries before 26 include a brief summary of the run plan; it was
offscreen and I didmn't notice it.) A common feature was that the density would
drop before the disruption, possibly leading to higher li and greater
susceptibility to vertical problems.

Shot 12 made it into rampdown, but had no h-mode. 13 was an unsuccessful
attempt to drop the density, 14 was another early disruption.

Shot 15 was the first "good" shot, with NL04 demand increased to 0.8e20, and a
good solid h-mode. Unfortunately, the Te0 and betat ewere too low to match
existing 5T shots. On shot 16 the density was down again, and the h-mode was
in-and-out. Shot 17 was another good h-mode with a higher target density, and
again the beta and Te were too low.

Shot 18 went back to 700kA and got repetitive h-modes, still too cold and low
beta. Tried dropping density again on shot 19 (power supply dud-EF2) and 20,
which disrupted early.

Shot 21 had no h-mode, but was a full length shot at 6e19 after making some
more changes to the equilibrium. This may be near the low density limit?

After it had become apparent that we would not be getting high enough beta or
te0 at 3.5 to match the existing 5T cases, we moved on to try some 5T cases
that might be "pulled down" by reducing the input power. The starting point
was 960206015, a 1.2MA 5.8T high performance shot. Shots 22-25 were attempts
to tweak this shot. All had disruptions except 25, which fizzled. None of the
disruptions produced a halo warning, but 24 generated our first coil stress
alarm (EF2U above 50% allowable). Some but not all the problems could be
attributed to EF3 hitting its current rail (nominally 12kA, but actually
encountered at 10.5kA). The falling density syndrome was still present. We
punted after shot 25 and moved on to the 2.7T sequence.

We started the 2.7T sequence by loading 960223022, with 1.5psi H2 added to the
a-side plenum to give the same minority fraction as 960223, and tried to hit
it with lots of RF. Shots 27-35 were all variations on this theme, the idea
being to get the right temperature and density to match the high performance
5T h-modes. The temperatures were acceptable, but there was some difficulty
getting the density down enough to match nustar. beta_normals around 1.5 were
obtained. The best density match was probably shot 35, at reduced RF power.
Shot 35 unfortunately caused a TF crowbar after it disrupted (and after a PF
crowbar), and that ended the run.

Today's run had lots of difficulties with disruptions, both in current rise
and in flattop. In addition, there were some mild runaway shots, which gave
large signals on the high-gain "\neuts_hards" signal, but just thickened the
bit noise on the regular "\hards_rate" diode. I may have spent too much
effort trying to get rid of these. The current rise disruption/locked mode
could be reduced by a 100V/20V drop in the OH1/OH2 voltage waveforms. The
flattop disruptions were mostly associated with dropping density. These should
be looked at for possible locked modes. In retrospect, 48hours of He ECDC may
have unloaded the walls too much.

There were two EF2L faults in charge-up today, one causing a dud and the other
a fizzle. The problem seems to be that one of the supplies pops its breaker
and the other can't deal with the full demand.

Scorecard:
----------

Tests 1
Duds 1
Fizzles 3
Plasmas 30
------- --
Total 35

Session Leader Comments

Feb 26 1996 08:30:14:350AM Jeff Schachter Today's run plan:

1) H-Mode Stuff
===============

group H-A:
----------

Already have a 5.3 T H-mode: 960206007 (one of the really high beta and
H-factor shots). The goal here is to tweak an existing H-Mode at 3.5 T. The
shot we will be tweaking is 950214014 - the "best" 3.5 T ohmic H-mode.

Rerun 950214014 as is to make sure that we still get H-mode, and to see effects
of boronization. Then try to get the parameters at 3.5 T into the right
range.

Ip: Lower to 620 kA (q95 should be 3.8 not 3.3)
nebar: ok as is - want 1.69e20
Te0: want 1960 eV - ensure Te diags all in sync; may need to RF heat
Zeff: 1.4
Upper triangularity: 0.33

Here are nustar's and beta's we want:

betat: 0.87
betap: 0.49 - this is high, may be tough!
nustare: 0.15
nustari: 0.15
(ie. Ti/Te ~ 1.0)

If we can't get the temperature high enough at 620 kA, we may need to tweak the
5.3 T shot as well (lower its temperature). But I will definitely start off
with 950214014.

group H-B:
----------

Shot 960201030 -- a 2.6 T H-mode -- is not scalable to 5.3 T. Its density is
too high. We need a lower density, higher temperature H-mode at 2.6 T. We
should start with one of the ohmic H-modes from last week - 960223022 - and
heat it as much as possible. Ideally, we should get:

Ip: 530-560 kA
Te0: 1.2 keV
nebar: 1.2

This will require lots of heating and luck with the density.

2) L-Mode stuff
===============

Plan is to try to run g

Feb 26 1996 08:53:29:720AM Jeff Schachter oops... continuation of run plan

2) L-Mode stuff
===============

Plan is to try to run groups B & C at 5.3 T. Hopefully these won't go into
H-Mode. We know we can't do group D because of H-modes. If any of these do
H-mode, I will ask Martin to try them during his reversed field run.

group L-B: Ip=710 kA, NL04=1.37e20, Te=1.5 keV (need to scan RF power)
other params (kappa, a, delta's) the same as 951218010:
kappa=1.6, delta_u=.25, delta_l=0.52, a=22 cm
left_gap=1.7 cm, right_gap=1.3 cm

group L-C: Ip=808 kA, NL04=1.6e20, Te=1.4 keV (also need RF scan)
other params same as 951218017:
kappa=1.6, delta_u=.25, delta_l=0.52, a=22 cm
left_gap=1.4 cm, right_gap=0.7 cm

We will try to squeeze in some 5.3 T L-mode shots between groups H-A and H-B.
H-B should be done last, as it is going to require lots of H minority.

Feb 26 1996 08:30:49:870AM 960226001 Jeff Schachter OH power supply test

Feb 26 1996 08:31:02:960AM 960226002 Jeff Schachter Fiducial

Feb 26 1996 08:33:29:430AM 960226003 Jeff Schachter First shot of run: attempt to duplicate 950214014

Result: disruption (before reaching 720 kA)

Next: go to 620 kA, other params the same

Feb 26 1996 08:51:26:500AM 960226004 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption before reaching H-mode

Next: try again

Feb 26 1996 09:11:39:750AM 960226005 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption

Next: try again

Feb 26 1996 09:20:46:510AM 960226006 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption

Next: try again

Feb 26 1996 09:52:31:940AM 960226007 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption

Next: try again

Feb 26 1996 09:53:05:050AM 960226008 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: better plasma, but no h-mode

Next: try again

Feb 26 1996 10:06:42:100AM 960226009 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: no sign of H-mode. Disruption.

on 950214014, the preH-mode NL04 was ~ 0.6e20, and the Ohmic power
was ~ 0.8 MW. Here, NL04 ~ 0.70 and Poh ~ 0.9 MW. Why no H-mode?

Next: try again

Feb 26 1996 10:25:21:430AM 960226010 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: No H-mode. Density bouncing up and down. Rise after 0.63 s,
but no indications in Halpha or the 2pi that there is an H-mode.

Next: keep trying

Feb 26 1996 10:26:58:360AM 960226011 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption

Next: try again

Feb 26 1996 10:46:49:870AM 960226012 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: Good plasma, but no H-mode. NL04 is high compared to 950214014
(0.8-0.9). No EFIT - magnetics problem.

Next: try again

Feb 26 1996 11:04:04:610AM 960226013 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: No H-mode. NL04 didn't come down (still ~ 0.9). Poh is nearly
1 MW. If P/S = 0.022 (nebar)(Bt), then P/S = 0.022*(1.3)*(3.55)=0.1.
If S=7 m^2, then P~0.7 MW. So we should be in H-mode. Why aren't we???

Next: try again

Feb 26 1996 11:17:33:590AM 960226014 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: disruption. Steve tried to bring the density down again. It
went up to ~ 0.7, started coming down, and then disrupted

Next: try again

Feb 26 1996 11:52:12:660AM 960226015 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: Nice H-mode! Te, nebar too low (so betat low: 0.5, need 0.75)

Next: try lowering density

Feb 26 1996 12:05:13:560PM 960226016 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: No H-mode.

Next: Lower to intermediate density

Feb 26 1996 12:19:08:180PM 960226017 Jeff Schachter This shot: 950214014 with -

Ip = 620 kA (lowered from 720)
Te0 ~ 2 keV (probably as hot as we can get)
nebar ~ 1.7 (ok as is)

Result: H-mode. Too cold! Te ~ 1.1 keV. Can't scale to 5.3 T (get
1.8 keV).

Next: give up on this one, because can't heat. Go back to 720 kA - try
to reproduce 950214014 as is - this one may be comparable to 960206015.
(They have the same qeng).

Feb 26 1996 12:47:26:380PM 960226018 Jeff Schachter This shot: 950214014 "as is" - actually, same setup as 960226017, with
Ip=700 kA.

Ip = 700 kA
Te0 ~ 1.8 keV
nebar ~ 1.6
betat ~ 0.75

Result: Te ~ 1.5 - too cold. Must recheck scalings, as I was using
Martin's (read: incorrect) field.

Next:

Feb 26 1996 12:47:56:420PM 960226019 Jeff Schachter This shot: 950214014 "as is" - actually, same setup as 960226017, with
Ip=700 kA.

Ip = 700 kA
Te0 ~ 1.8 keV
nebar ~ 1.6
betat ~ 0.75

Result: Dud.

Next: try 018 with lower density

Feb 26 1996 01:07:11:550PM 960226020 Jeff Schachter This shot: 950214014 "as is" - actually, same setup as 960226017, with
Ip=700 kA.

Ip = 700 kA
Te0 ~ 1.8 keV
nebar ~ 1.6
betat ~ 0.75

Result: disruption

Next: try again

Feb 26 1996 01:04:57:850PM 960226021 Jeff Schachter This shot: 950214014 "as is" - actually, same setup as 960226017, with
Ip=700 kA.

Ip = 700 kA
Te0 ~ 1.8 keV
nebar ~ 1.6
betat ~ 0.75

Result: No H-mode

Next: Try to tweak 960206015 to lower Te and Ne and therefore betat and
nustar - to match 960226018

Feb 26 1996 01:07:03:320PM 960226021 Jeff Schachter This shot: 950214014 "as is" - actually, same setup as 960226017, with
Ip=700 kA.

Ip = 700 kA
Te0 ~ 1.8 keV
nebar ~ 1.6
betat ~ 0.75

Result: disruption

Next: try again

Feb 26 1996 01:16:04:250PM 960226022 Jeff Schachter This shot: try 960206015 - as is.

Want to scale from 960226018:

Ip = 1.1 MA
nebar = 2.80
Te0 = 2.0 keV
betat = 0.56
qeng = 3.7
my nustar = 13

Result: boom! disruption

Next: try again

Feb 26 1996 01:58:25:550PM 960226023 Jeff Schachter Trying 960206015 again.

Result: Small H-mode 0.86-0.90 s. Te too high, and nebar too low.

Next: try again

Feb 26 1996 01:53:44:070PM 960226024 Jeff Schachter Trying again... No H-mode.

Feb 26 1996 02:16:30:890PM 960226025 Jeff Schachter Fizzle. TCI problems.

Feb 26 1996 03:01:12:470PM 960226026 Jeff Schachter This shot: went to 2.6 T.

Disruption

Feb 26 1996 03:05:02:620PM 960226027 Jeff Schachter This shot: another attempt at 960223022, with lots of RF (?)

Result: some H-modes - RF tripping out so it doesn't stay in H-mode.
Te0_YAG looks high enough!

Next: try again, with RF feedback.

Feb 26 1996 03:10:07:840PM 960226027 Jeff Schachter Numbers for this shot:

Shot: 960226027 Time: 0.685000 Window: 0.0100000
Bt = 2.79 T Ip = 0.55 MA Te = 1.57 keV Pin = 2.08 MW
NL04 = 0.88 Nebar = 1.46
a = 21.9376 Zeff = 1.54

FIELD (T) IP (MA) NL04(e20/m3) TE (keV) PINPUT (MW)
--------- -------- ------------ -------- -----------
2.60000 0.515161 0.801274 1.49583 1.80184
3.50000 0.693486 1.19099 1.82366 3.26516
5.30000 1.05014 2.07102 2.40482 7.48722
8.00000 1.58511 3.58594 3.16441 17.0588

RHOSTAR: 0.0204565 NUSTAR: 12.0930 BETAT: 1.00988

Feb 26 1996 03:30:39:290PM 960226028 Jeff Schachter This shot: try 960226027 again, with RF feedback

Result: disruption. No useful H-mode before it.

Next: try again

Feb 26 1996 03:30:00:400PM 960226029 Jeff Schachter This shot: try 960226027 again, with RF feedback

Result: fizzle

Next: try again

Feb 26 1996 03:52:19:880PM 960226030 Jeff Schachter This shot: try 960226027 again, with RF feedback

Result: RF better. Asked for higher density and got it - but shouldn't
have asked. YAG timebase is funny - it is missing data, but it catches
the H-mode and shows Te reaching 2.0 keV!

Numbers:
Shot: 960226030 Time: 0.685000 Window: 0.0100000
Bt = 2.79 T Ip = 0.55 MA Te = 1.29 keV Pin = 2.41 MW
NL04 = 1.07 Nebar = 1.63
a = 22.1799 Zeff = 1.33

FIELD (T) IP (MA) NL04(e20/m3) TE (keV) PINPUT (MW)
--------- -------- ------------ -------- -----------
2.60000 0.516032 0.975968 1.23117 2.09506
3.50000 0.694658 1.45065 1.50100 3.79652
5.30000 1.05191 2.52254 1.97934 8.70566
8.00000 1.58779 4.36775 2.60453 19.8349

RHOSTAR: 0.0183568 NUSTAR: 18.9595 BETAT: 1.01614

Next: try again with density back down to what it was on 960226027

Feb 26 1996 03:53:00:420PM 960226031 Jeff Schachter This shot: try again with lower density (back to 960226027)

Result: fizzle

Next: try again

Feb 26 1996 04:02:19:130PM 960226032 Jeff Schachter This shot: trying again

Result: fizzle

Next: another fizzle

Feb 26 1996 04:36:17:710PM 960226033 Jeff Schachter This shot: try again, lower ne?

Result: disruption

Next: again

Feb 26 1996 05:07:02:980PM 960226034 Jeff Schachter This shot: try again

Result: H-mode! Density really high - scales too high for 5.3. Te0_YAG
is nice and hot.

Next: try again, cut the RF power in one transmitter at 0.8 s - hopefully
will give lower density

Feb 26 1996 05:08:33:580PM 960226035 Jeff Schachter This shot: try again, with RF power step at 0.8 s

Result: H-mode! Density down by 20% - may be usable in scaling. Te0
good.

Next: Nothing - TF crowbar fault and blown fuses. Will need time to fix.

**** THAT'S ALL FOLKS! ****

Physics Operator Comments

Feb 26 1996 07:02:42:950AM Steve Wolfe Run 960226
MP 122A
SL Schachter
PO Wolfe
EO Silva...

Fiducial setup from 960213011, reduce BR0 t0 .0054, increase prepulse to
13msec
Coldstart at 26-FEB-1996 06:59:47.55

Feb 26 1996 07:17:32:250AM Steve Wolfe Run 960226
MP 122A
SL Schachter
PO Wolfe
EO Silva...

For the 3.5T case to start the experiment, start from 960223020 and
copy waveforms from 950214014 (yes, that's 95....) for Ip,RCUR,ZCUR,
RXL,ZXL,RXU,ZXU; change TF prog to step to -100000; setup rampdown
RCUR predictor but leave at 3.0sec.

This was done Saturday and stored as 960226991 in my area.
Ramp ZXU down instead of up at rampdown, and ZXL up instead of down.
Tweak rampdown on CLEARIN,RCUR

Feb 26 1996 07:55:01:680AM Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

What to do next we can discuss tomorrow morning hopefully before the run starts
or between shots if there is time. The basic plan should be to pick an H-mode
at 2.6 T that is reproducible and RF heat it as much as possible, while
keeping the density low enough. 960223022 is a better starting point than
960201030 in that the density is lower, but we'd have to get the RF up (and
this may raise the density?).

If we can fit in the 5.3 T L-mode stuff, then great, but its not a big deal.

Feb 26 1996 08:05:15:270AM 960226001 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226001 - Tuesday OH test - ok

Feb 26 1996 08:20:05:110AM 960226002 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226002 - fiducial: ok - 2h-modes, lots of injections.
Ohmic is ok, I'm not sure of the RF times. Had some runaways too. oh well,
let's get on with the run; we'll come back to it later.

Feb 26 1996 08:41:32:760AM 960226003 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226003 - First shot of the run = 3.5T 700kA shot
Disruption at .54sec.

Feb 26 1996 08:55:32:760AM 960226004 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226004 - Drop TF demand to -94000. Drop IP demand to 600000.
Raise early PG3 gas puff in seg1.
Disruption at similar time. What are we doing wrong?
Still some early runaways - need to up the prepuff. The disruption is a
vertical problem.

Feb 26 1996 09:12:18:360AM 960226005 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226005 -
up the prepuff to 16msec. Raise ZCUR demand to -.02. Change RXL to -.005
change RXU to -.02
Same thing. Need to reduce that elongation!
This one died earlier, around .45

Feb 26 1996 09:24:21:470AM 960226006 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226006 -
copy in RCUR and CLEARIN from fiducial!
Increase prepuff by another msec
Even earlier disruption !

The disruptions are happening when the density drops..

Feb 26 1996 09:40:15:520AM 960226007 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226007 -
Raise Br0 to 0.006
Raise nl4 demand to .7e20

Same thing. Every change has been in the wrong direction.
Still getting runaways too. and breakdown is worse.

Feb 26 1996 09:53:05:510AM 960226008 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226008 -
Br0 back to to 0.0055
Raise nl4 demand to .8e20
Drop clearin to -.005 early

Better, still disrupts at about 1sec, still vertically unstable. And no
h-mode in sight. both gaps are big: 2cm and 2.5. Still getting runaways early.

Feb 26 1996 10:07:53:990AM 960226009 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226009 -
Raise early pg3 in seg 1. Move CLEARIN to -.005 for whole flattop.
MOve RCUR out 1mm to .667
Another late disruption, a little earlier this time.
Density is down to .7 or so, no H-mode. No runaways this time.
This one doesn't look like a vertical problem. Maybe an injection .838,
disrupts at .84
Inner gap stable at 1.9cm, outer around 2.5.

Feb 26 1996 10:20:30:280AM 960226010 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226010 -
Repeat. I think last disruption was a brick.
Looking more closely, it already had a problem. This one will probably
do the same thing.

Makes it into rampdown, but still has a problem.

Feb 26 1996 10:30:47:570AM 960226011 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226011-
Move RCUR out to .669, slow down ramp in at end.
Start RXL already at -.005
Early disruption.

Feb 26 1996 10:40:35:130AM 960226012 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226012-
Put OH crowbars back to .2sec
MOve RXL at t=0 back to 0.

PLasma ran into rampdown, no h-mode. Density is at .9e20,
MAGTRAQ2 corrupted.

Feb 26 1996 10:54:29:650AM 960226013 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226013-

Drop density after .5sec to 6e19.
Disrupted in rampdown, no h-mode. density did not come down.
Breaker pulled - blown fuse in OH1.

Feb 26 1996 11:22:38:200AM 960226014 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226014-

Reduce NL04 demand to .6e20
slow down ZXU rampdown.
Early disruption again! Density starts dropping at .26, then we get a
disruption at crossover.

Feb 26 1996 11:41:44:310AM 960226015 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226015-

Bring up early nl04 demand to .8e20, drop Ar puff to 14msec.
Plasmas H-mode. NL04 during H-mode is about .9e20. Te and betat look low
compared to Jeff's target shot.

Feb 26 1996 11:59:53:690AM 960226016 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226016-

Move EF1 crowbars to .12 (why were they moved?)
Increase seg1 PG3 puff again.
Drop seg2 PG3 after .4sec

No h-mode or maybe going in and out very fast?
density at .5e20. Still getting current rise disruptions.

Feb 26 1996 12:15:47:100PM 960226017 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226017-

Drop voltage on OH1 and OH2's as I did Friday night.
Raise nl04 demand to 7e19

Good h-mode from about .7sec, nl4 at .9e19.
Seem to have got rid of the CR disruption.
Te still too cold according to Jeff.

Feb 26 1996 12:32:19:190PM 960226018 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226018-

Raise current to 700kA sort of as on 950214014
Four little h-modes and maybe one on ramp-down
qpsib = 3.35, I could push the current a bit further id Jeff wants.

Feb 26 1996 12:41:42:270PM 960226019 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226019-

Drop nl4 demand to .6e20.
dud? EF2L is having a problem in charging.

Feb 26 1996 12:53:26:460PM 960226020 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226020-

Try again with nl4 demand to .6e20.
Disrupted early. density dropped again?
Had some runaways again, there were some there on 18 as well.
Maybe push some more early gas?

Feb 26 1996 01:04:35:920PM 960226021 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226021-
Raise pre-puff to 18msec.
Raise 300msec nl4 point from .8 to .9e20
Copy ZCUR program from fiducial (early drop)
Good plasma - no h-mode

Feb 26 1996 01:23:28:110PM 960226022 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226022-
Start on the 5T case, load seg2 from 960206015 a 1.2MA 5.8T shot.
Yuichi is setting up for "Teo=2keV"
Early disruption. Falling density again!
Also, I told Joe to use PLC control on TF and the shot was under hybrid
control, so we ended up at too high a field.

Feb 26 1996 01:40:29:960PM 960226023 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226023-
Back to hybrid control on TF : -158700
Raise NL04 demand to .8e20 (was .7)
Reduce initial clearin to -.005.

Disrupted in rampdown.
Short h-mode gets to 132kJ, RF=1.8MW, injection? at .886

Feb 26 1996 01:55:50:810PM 960226024 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226024-
Drop pg3 after .5sec
Speed up Ip rise to get to 1.2 at .6sec

Still disrupting at .86 this time. pulled a breaker this time.
We cannot continue this.
Got a coil stress warning! EF2U over 50%.
EF3 is on its current rail (at 10.6kA instead of 12)
Got a glitch on the TF at the disruption.
Density dropped leading to the disruption.

Feb 26 1996 02:19:38:350PM 960226025 Steve Wolfe 960226- Run plan summary

We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014
suitably tweaked (Ip 720->630, delta_u 0.33->0.25).

Shot 960226025-
Up the EF3 current limit to 15kA
Drop the current to 1.1MA
PUt back the pg3 voltage
Raise ZXL to -.015
TF on PLC control at 164kA
Damn - I started typing with focus on the PCS and now it is reloading
multiple times!

fizzle.
Irby reports CO2 is gone, so its just as well.

Feb 26 1996 02:48:12:500PM 960226026 Steve Wolfe 960226026 -
GO to 2.7T cases = load 960223022
Add 1.5psi of H2 to a-side plenum (was 19.5psi D2)
INcrease prepuff to 14msec.
Hybrid control on TF

Disrupted at .668? I don't know why.

Feb 26 1996 03:08:14:140PM 960226027 Steve Wolfe 960226027 -
No changes, see if it does it again. On the original shot, the density
was overshooting, on this one it gave what I asked for.

plasma to 1.37sec, lots of H-modes. RF is modulated, shifted from H-modes.

Feb 26 1996 03:14:49:960PM 960226028 Steve Wolfe 960226028 -
Repeat - Try RF feedback this time.
Note for next time - Had runaways again, and CR disruption.

Disruption at .58. Early injection following the CR disruption

Feb 26 1996 03:21:50:120PM 960226029 Steve Wolfe Shot 960226029 -
Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3
Ask for 8e19 density, adjust some rampdown waveforms

Fizzle&^(&)( ^@E^(^#$E@

Feb 26 1996 03:23:27:530PM 960226029 Steve Wolfe Shot 960226029 -
Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3
Ask for 8e19 density, adjust some rampdown waveforms

Fizzle&^(&)( ^@E^(^#$E@
EF2L did its thing again.

Feb 26 1996 03:44:24:850PM 960226030 Steve Wolfe Shot 960226030 -
Try again with:
Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3
Ask for 8e19 density, adjust some rampdown waveforms

Disrupts at 1.2. RF off at 1.05, and density drops as it comes out
of H-mode. beta gets to 1.3%, maybe too high for him.

Feb 26 1996 03:55:57:360PM 960226031 Steve Wolfe Shot 960226031 -

Reduce NL4 demand to 6e19, keeping pre-0.5sec level at 8e19
Drop Br0 to .005

Fizzle. 50kA fizzle, bounces outside.

Feb 26 1996 04:30:10:790PM 960226033 Steve Wolfe Shot 960226033 -

Reload seg1 from 28 It doesn't look to me like I did anything that early
but try it anyway. The pre-puff and early gas wil be different.

EARLY DISRUPTION. .6sec, Falling density.
Back to the runaways and CR disruptions.

Feb 26 1996 04:43:44:990PM 960226034 Steve Wolfe Shot 960226034 -
Raise seg1 pg3 after 50msec
NL04 to 7e19

Plasma, disrupts at 1.2sec h-modes.
RF feedback was only on for first RF pulse, RF didn't come back on
beta is 1.3 again, density is too high.

Feb 26 1996 05:16:33:920PM 960226034 Steve Wolfe Shot 960226035-
Try less RF power, see if the density stays low.

PLasma disrupts late, around 1.3sec
TF Crowbar. Fuses blown, no more time.
NL04 got to 1.15-1.2e20, may be low enough. beta around 1.1%

Engineering Operator Comments

Shot Time Type Status Comment

1 08:03:14:620AM Test Ok

2 08:13:19:490AM Plasma Ok

3 08:27:20:010AM Plasma Ok

4 08:45:38:470AM Plasma Ok

5 09:01:42:710AM Plasma Ok

6 09:18:07:830AM Plasma Ok

7 09:33:24:230AM Plasma Ok

8 09:45:14:910AM Plasma Ok

9 09:59:46:700AM Plasma Ok

10 10:12:47:370AM Plasma Ok

11 10:24:48:980AM Plasma Ok

12 10:34:41:940AM Plasma Ok

13 10:45:30:400AM Plasma Ok

14 11:14:13:450AM Plasma Ok

15 11:29:29:940AM Plasma Ok

16 11:49:05:830AM Plasma Ok

17 12:03:39:930PM Plasma Ok

18 12:20:30:480PM Plasma Ok

19 12:34:14:200PM Plasma Bad EF2LB breaker pulled before pulse state.

20 12:44:42:540PM Plasma Ok IOC OH2L & OH1 Bypass comm fault OH2U.

21 01:00:26:840PM Plasma Ok

22 01:13:56:970PM Plasma Ok

23 01:28:52:920PM Plasma Ok

24 01:45:25:800PM Plasma Ok Comm Fault OH2L & OH1.

25 02:10:24:850PM Plasma Ok

26 02:38:10:650PM Plasma Ok

27 02:56:39:270PM Plasma Ok OH1 Comm fault OH2 Bypass comm fault.

28 03:10:05:720PM Plasma Ok

29 03:20:12:260PM Plasma Ok

30 03:31:18:260PM Plasma Ok

31 03:50:21:960PM Plasma Ok

32 03:59:56:980PM Plasma Ok

33 04:19:47:210PM Plasma Ok

34 04:32:27:730PM Plasma Ok

35 04:46:24:750PM Plasma Ok

Session Leader Comments
Feb 26 1996 08:30:14:350AM		Jeff Schachter	Today's run plan: 1) H-Mode Stuff =============== group H-A: ---------- Already have a 5.3 T H-mode: 960206007 (one of the really high beta and H-factor shots). The goal here is to tweak an existing H-Mode at 3.5 T. The shot we will be tweaking is 950214014 - the "best" 3.5 T ohmic H-mode. Rerun 950214014 as is to make sure that we still get H-mode, and to see effects of boronization. Then try to get the parameters at 3.5 T into the right range. Ip: Lower to 620 kA (q95 should be 3.8 not 3.3) nebar: ok as is - want 1.69e20 Te0: want 1960 eV - ensure Te diags all in sync; may need to RF heat Zeff: 1.4 Upper triangularity: 0.33 Here are nustar's and beta's we want: betat: 0.87 betap: 0.49 - this is high, may be tough! nustare: 0.15 nustari: 0.15 (ie. Ti/Te ~ 1.0) If we can't get the temperature high enough at 620 kA, we may need to tweak the 5.3 T shot as well (lower its temperature). But I will definitely start off with 950214014. group H-B: ---------- Shot 960201030 -- a 2.6 T H-mode -- is not scalable to 5.3 T. Its density is too high. We need a lower density, higher temperature H-mode at 2.6 T. We should start with one of the ohmic H-modes from last week - 960223022 - and heat it as much as possible. Ideally, we should get: Ip: 530-560 kA Te0: 1.2 keV nebar: 1.2 This will require lots of heating and luck with the density. 2) L-Mode stuff =============== Plan is to try to run g
Feb 26 1996 08:53:29:720AM		Jeff Schachter	oops... continuation of run plan 2) L-Mode stuff =============== Plan is to try to run groups B & C at 5.3 T. Hopefully these won't go into H-Mode. We know we can't do group D because of H-modes. If any of these do H-mode, I will ask Martin to try them during his reversed field run. group L-B: Ip=710 kA, NL04=1.37e20, Te=1.5 keV (need to scan RF power) other params (kappa, a, delta's) the same as 951218010: kappa=1.6, delta_u=.25, delta_l=0.52, a=22 cm left_gap=1.7 cm, right_gap=1.3 cm group L-C: Ip=808 kA, NL04=1.6e20, Te=1.4 keV (also need RF scan) other params same as 951218017: kappa=1.6, delta_u=.25, delta_l=0.52, a=22 cm left_gap=1.4 cm, right_gap=0.7 cm We will try to squeeze in some 5.3 T L-mode shots between groups H-A and H-B. H-B should be done last, as it is going to require lots of H minority.
Feb 26 1996 08:30:49:870AM	960226001	Jeff Schachter	OH power supply test
Feb 26 1996 08:31:02:960AM	960226002	Jeff Schachter	Fiducial
Feb 26 1996 08:33:29:430AM	960226003	Jeff Schachter	First shot of run: attempt to duplicate 950214014 Result: disruption (before reaching 720 kA) Next: go to 620 kA, other params the same
Feb 26 1996 08:51:26:500AM	960226004	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption before reaching H-mode Next: try again
Feb 26 1996 09:11:39:750AM	960226005	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption Next: try again
Feb 26 1996 09:20:46:510AM	960226006	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption Next: try again
Feb 26 1996 09:52:31:940AM	960226007	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption Next: try again
Feb 26 1996 09:53:05:050AM	960226008	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: better plasma, but no h-mode Next: try again
Feb 26 1996 10:06:42:100AM	960226009	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: no sign of H-mode. Disruption. on 950214014, the preH-mode NL04 was ~ 0.6e20, and the Ohmic power was ~ 0.8 MW. Here, NL04 ~ 0.70 and Poh ~ 0.9 MW. Why no H-mode? Next: try again
Feb 26 1996 10:25:21:430AM	960226010	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: No H-mode. Density bouncing up and down. Rise after 0.63 s, but no indications in Halpha or the 2pi that there is an H-mode. Next: keep trying
Feb 26 1996 10:26:58:360AM	960226011	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption Next: try again
Feb 26 1996 10:46:49:870AM	960226012	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: Good plasma, but no H-mode. NL04 is high compared to 950214014 (0.8-0.9). No EFIT - magnetics problem. Next: try again
Feb 26 1996 11:04:04:610AM	960226013	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: No H-mode. NL04 didn't come down (still ~ 0.9). Poh is nearly 1 MW. If P/S = 0.022 (nebar)(Bt), then P/S = 0.022(1.3)(3.55)=0.1. If S=7 m^2, then P~0.7 MW. So we should be in H-mode. Why aren't we??? Next: try again
Feb 26 1996 11:17:33:590AM	960226014	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: disruption. Steve tried to bring the density down again. It went up to ~ 0.7, started coming down, and then disrupted Next: try again
Feb 26 1996 11:52:12:660AM	960226015	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: Nice H-mode! Te, nebar too low (so betat low: 0.5, need 0.75) Next: try lowering density
Feb 26 1996 12:05:13:560PM	960226016	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: No H-mode. Next: Lower to intermediate density
Feb 26 1996 12:19:08:180PM	960226017	Jeff Schachter	This shot: 950214014 with - Ip = 620 kA (lowered from 720) Te0 ~ 2 keV (probably as hot as we can get) nebar ~ 1.7 (ok as is) Result: H-mode. Too cold! Te ~ 1.1 keV. Can't scale to 5.3 T (get 1.8 keV). Next: give up on this one, because can't heat. Go back to 720 kA - try to reproduce 950214014 as is - this one may be comparable to 960206015. (They have the same qeng).
Feb 26 1996 12:47:26:380PM	960226018	Jeff Schachter	This shot: 950214014 "as is" - actually, same setup as 960226017, with Ip=700 kA. Ip = 700 kA Te0 ~ 1.8 keV nebar ~ 1.6 betat ~ 0.75 Result: Te ~ 1.5 - too cold. Must recheck scalings, as I was using Martin's (read: incorrect) field. Next:
Feb 26 1996 12:47:56:420PM	960226019	Jeff Schachter	This shot: 950214014 "as is" - actually, same setup as 960226017, with Ip=700 kA. Ip = 700 kA Te0 ~ 1.8 keV nebar ~ 1.6 betat ~ 0.75 Result: Dud. Next: try 018 with lower density
Feb 26 1996 01:07:11:550PM	960226020	Jeff Schachter	This shot: 950214014 "as is" - actually, same setup as 960226017, with Ip=700 kA. Ip = 700 kA Te0 ~ 1.8 keV nebar ~ 1.6 betat ~ 0.75 Result: disruption Next: try again
Feb 26 1996 01:04:57:850PM	960226021	Jeff Schachter	This shot: 950214014 "as is" - actually, same setup as 960226017, with Ip=700 kA. Ip = 700 kA Te0 ~ 1.8 keV nebar ~ 1.6 betat ~ 0.75 Result: No H-mode Next: Try to tweak 960206015 to lower Te and Ne and therefore betat and nustar - to match 960226018
Feb 26 1996 01:07:03:320PM	960226021	Jeff Schachter	This shot: 950214014 "as is" - actually, same setup as 960226017, with Ip=700 kA. Ip = 700 kA Te0 ~ 1.8 keV nebar ~ 1.6 betat ~ 0.75 Result: disruption Next: try again
Feb 26 1996 01:16:04:250PM	960226022	Jeff Schachter	This shot: try 960206015 - as is. Want to scale from 960226018: Ip = 1.1 MA nebar = 2.80 Te0 = 2.0 keV betat = 0.56 qeng = 3.7 my nustar = 13 Result: boom! disruption Next: try again
Feb 26 1996 01:58:25:550PM	960226023	Jeff Schachter	Trying 960206015 again. Result: Small H-mode 0.86-0.90 s. Te too high, and nebar too low. Next: try again
Feb 26 1996 01:53:44:070PM	960226024	Jeff Schachter	Trying again... No H-mode.
Feb 26 1996 02:16:30:890PM	960226025	Jeff Schachter	Fizzle. TCI problems.
Feb 26 1996 03:01:12:470PM	960226026	Jeff Schachter	This shot: went to 2.6 T. Disruption
Feb 26 1996 03:05:02:620PM	960226027	Jeff Schachter	This shot: another attempt at 960223022, with lots of RF (?) Result: some H-modes - RF tripping out so it doesn't stay in H-mode. Te0_YAG looks high enough! Next: try again, with RF feedback.
Feb 26 1996 03:10:07:840PM	960226027	Jeff Schachter	Numbers for this shot: Shot: 960226027 Time: 0.685000 Window: 0.0100000 Bt = 2.79 T Ip = 0.55 MA Te = 1.57 keV Pin = 2.08 MW NL04 = 0.88 Nebar = 1.46 a = 21.9376 Zeff = 1.54 FIELD (T) IP (MA) NL04(e20/m3) TE (keV) PINPUT (MW) --------- -------- ------------ -------- ----------- 2.60000 0.515161 0.801274 1.49583 1.80184 3.50000 0.693486 1.19099 1.82366 3.26516 5.30000 1.05014 2.07102 2.40482 7.48722 8.00000 1.58511 3.58594 3.16441 17.0588 RHOSTAR: 0.0204565 NUSTAR: 12.0930 BETAT: 1.00988
Feb 26 1996 03:30:39:290PM	960226028	Jeff Schachter	This shot: try 960226027 again, with RF feedback Result: disruption. No useful H-mode before it. Next: try again
Feb 26 1996 03:30:00:400PM	960226029	Jeff Schachter	This shot: try 960226027 again, with RF feedback Result: fizzle Next: try again
Feb 26 1996 03:52:19:880PM	960226030	Jeff Schachter	This shot: try 960226027 again, with RF feedback Result: RF better. Asked for higher density and got it - but shouldn't have asked. YAG timebase is funny - it is missing data, but it catches the H-mode and shows Te reaching 2.0 keV! Numbers: Shot: 960226030 Time: 0.685000 Window: 0.0100000 Bt = 2.79 T Ip = 0.55 MA Te = 1.29 keV Pin = 2.41 MW NL04 = 1.07 Nebar = 1.63 a = 22.1799 Zeff = 1.33 FIELD (T) IP (MA) NL04(e20/m3) TE (keV) PINPUT (MW) --------- -------- ------------ -------- ----------- 2.60000 0.516032 0.975968 1.23117 2.09506 3.50000 0.694658 1.45065 1.50100 3.79652 5.30000 1.05191 2.52254 1.97934 8.70566 8.00000 1.58779 4.36775 2.60453 19.8349 RHOSTAR: 0.0183568 NUSTAR: 18.9595 BETAT: 1.01614 Next: try again with density back down to what it was on 960226027
Feb 26 1996 03:53:00:420PM	960226031	Jeff Schachter	This shot: try again with lower density (back to 960226027) Result: fizzle Next: try again
Feb 26 1996 04:02:19:130PM	960226032	Jeff Schachter	This shot: trying again Result: fizzle Next: another fizzle
Feb 26 1996 04:36:17:710PM	960226033	Jeff Schachter	This shot: try again, lower ne? Result: disruption Next: again
Feb 26 1996 05:07:02:980PM	960226034	Jeff Schachter	This shot: try again Result: H-mode! Density really high - scales too high for 5.3. Te0_YAG is nice and hot. Next: try again, cut the RF power in one transmitter at 0.8 s - hopefully will give lower density
Feb 26 1996 05:08:33:580PM	960226035	Jeff Schachter	This shot: try again, with RF power step at 0.8 s Result: H-mode! Density down by 20% - may be usable in scaling. Te0 good. Next: Nothing - TF crowbar fault and blown fuses. Will need time to fix. ** THAT'S ALL FOLKS! **

Physics Operator Comments
Feb 26 1996 07:02:42:950AM		Steve Wolfe	Run 960226 MP 122A SL Schachter PO Wolfe EO Silva... Fiducial setup from 960213011, reduce BR0 t0 .0054, increase prepulse to 13msec Coldstart at 26-FEB-1996 06:59:47.55
Feb 26 1996 07:17:32:250AM		Steve Wolfe	Run 960226 MP 122A SL Schachter PO Wolfe EO Silva... For the 3.5T case to start the experiment, start from 960223020 and copy waveforms from 950214014 (yes, that's 95....) for Ip,RCUR,ZCUR, RXL,ZXL,RXU,ZXU; change TF prog to step to -100000; setup rampdown RCUR predictor but leave at 3.0sec. This was done Saturday and stored as 960226991 in my area. Ramp ZXU down instead of up at rampdown, and ZXL up instead of down. Tweak rampdown on CLEARIN,RCUR
Feb 26 1996 07:55:01:680AM		Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). What to do next we can discuss tomorrow morning hopefully before the run starts or between shots if there is time. The basic plan should be to pick an H-mode at 2.6 T that is reproducible and RF heat it as much as possible, while keeping the density low enough. 960223022 is a better starting point than 960201030 in that the density is lower, but we'd have to get the RF up (and this may raise the density?). If we can fit in the 5.3 T L-mode stuff, then great, but its not a big deal.
Feb 26 1996 08:05:15:270AM	960226001	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226001 - Tuesday OH test - ok
Feb 26 1996 08:20:05:110AM	960226002	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226002 - fiducial: ok - 2h-modes, lots of injections. Ohmic is ok, I'm not sure of the RF times. Had some runaways too. oh well, let's get on with the run; we'll come back to it later.
Feb 26 1996 08:41:32:760AM	960226003	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226003 - First shot of the run = 3.5T 700kA shot Disruption at .54sec.
Feb 26 1996 08:55:32:760AM	960226004	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226004 - Drop TF demand to -94000. Drop IP demand to 600000. Raise early PG3 gas puff in seg1. Disruption at similar time. What are we doing wrong? Still some early runaways - need to up the prepuff. The disruption is a vertical problem.
Feb 26 1996 09:12:18:360AM	960226005	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226005 - up the prepuff to 16msec. Raise ZCUR demand to -.02. Change RXL to -.005 change RXU to -.02 Same thing. Need to reduce that elongation! This one died earlier, around .45
Feb 26 1996 09:24:21:470AM	960226006	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226006 - copy in RCUR and CLEARIN from fiducial! Increase prepuff by another msec Even earlier disruption ! The disruptions are happening when the density drops..
Feb 26 1996 09:40:15:520AM	960226007	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226007 - Raise Br0 to 0.006 Raise nl4 demand to .7e20 Same thing. Every change has been in the wrong direction. Still getting runaways too. and breakdown is worse.
Feb 26 1996 09:53:05:510AM	960226008	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226008 - Br0 back to to 0.0055 Raise nl4 demand to .8e20 Drop clearin to -.005 early Better, still disrupts at about 1sec, still vertically unstable. And no h-mode in sight. both gaps are big: 2cm and 2.5. Still getting runaways early.
Feb 26 1996 10:07:53:990AM	960226009	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226009 - Raise early pg3 in seg 1. Move CLEARIN to -.005 for whole flattop. MOve RCUR out 1mm to .667 Another late disruption, a little earlier this time. Density is down to .7 or so, no H-mode. No runaways this time. This one doesn't look like a vertical problem. Maybe an injection .838, disrupts at .84 Inner gap stable at 1.9cm, outer around 2.5.
Feb 26 1996 10:20:30:280AM	960226010	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226010 - Repeat. I think last disruption was a brick. Looking more closely, it already had a problem. This one will probably do the same thing. Makes it into rampdown, but still has a problem.
Feb 26 1996 10:30:47:570AM	960226011	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226011- Move RCUR out to .669, slow down ramp in at end. Start RXL already at -.005 Early disruption.
Feb 26 1996 10:40:35:130AM	960226012	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226012- Put OH crowbars back to .2sec MOve RXL at t=0 back to 0. PLasma ran into rampdown, no h-mode. Density is at .9e20, MAGTRAQ2 corrupted.
Feb 26 1996 10:54:29:650AM	960226013	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226013- Drop density after .5sec to 6e19. Disrupted in rampdown, no h-mode. density did not come down. Breaker pulled - blown fuse in OH1.
Feb 26 1996 11:22:38:200AM	960226014	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226014- Reduce NL04 demand to .6e20 slow down ZXU rampdown. Early disruption again! Density starts dropping at .26, then we get a disruption at crossover.
Feb 26 1996 11:41:44:310AM	960226015	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226015- Bring up early nl04 demand to .8e20, drop Ar puff to 14msec. Plasmas H-mode. NL04 during H-mode is about .9e20. Te and betat look low compared to Jeff's target shot.
Feb 26 1996 11:59:53:690AM	960226016	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226016- Move EF1 crowbars to .12 (why were they moved?) Increase seg1 PG3 puff again. Drop seg2 PG3 after .4sec No h-mode or maybe going in and out very fast? density at .5e20. Still getting current rise disruptions.
Feb 26 1996 12:15:47:100PM	960226017	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226017- Drop voltage on OH1 and OH2's as I did Friday night. Raise nl04 demand to 7e19 Good h-mode from about .7sec, nl4 at .9e19. Seem to have got rid of the CR disruption. Te still too cold according to Jeff.
Feb 26 1996 12:32:19:190PM	960226018	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226018- Raise current to 700kA sort of as on 950214014 Four little h-modes and maybe one on ramp-down qpsib = 3.35, I could push the current a bit further id Jeff wants.
Feb 26 1996 12:41:42:270PM	960226019	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226019- Drop nl4 demand to .6e20. dud? EF2L is having a problem in charging.
Feb 26 1996 12:53:26:460PM	960226020	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226020- Try again with nl4 demand to .6e20. Disrupted early. density dropped again? Had some runaways again, there were some there on 18 as well. Maybe push some more early gas?
Feb 26 1996 01:04:35:920PM	960226021	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226021- Raise pre-puff to 18msec. Raise 300msec nl4 point from .8 to .9e20 Copy ZCUR program from fiducial (early drop) Good plasma - no h-mode
Feb 26 1996 01:23:28:110PM	960226022	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226022- Start on the 5T case, load seg2 from 960206015 a 1.2MA 5.8T shot. Yuichi is setting up for "Teo=2keV" Early disruption. Falling density again! Also, I told Joe to use PLC control on TF and the shot was under hybrid control, so we ended up at too high a field.
Feb 26 1996 01:40:29:960PM	960226023	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226023- Back to hybrid control on TF : -158700 Raise NL04 demand to .8e20 (was .7) Reduce initial clearin to -.005. Disrupted in rampdown. Short h-mode gets to 132kJ, RF=1.8MW, injection? at .886
Feb 26 1996 01:55:50:810PM	960226024	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226024- Drop pg3 after .5sec Speed up Ip rise to get to 1.2 at .6sec Still disrupting at .86 this time. pulled a breaker this time. We cannot continue this. Got a coil stress warning! EF2U over 50%. EF3 is on its current rail (at 10.6kA instead of 12) Got a glitch on the TF at the disruption. Density dropped leading to the disruption.
Feb 26 1996 02:19:38:350PM	960226025	Steve Wolfe	960226- Run plan summary We can start off with group H-A: which is the 3.5 T ohmic H-mode 950214014 suitably tweaked (Ip 720->630, delta_u 0.33->0.25). Shot 960226025- Up the EF3 current limit to 15kA Drop the current to 1.1MA PUt back the pg3 voltage Raise ZXL to -.015 TF on PLC control at 164kA Damn - I started typing with focus on the PCS and now it is reloading multiple times! fizzle. Irby reports CO2 is gone, so its just as well.
Feb 26 1996 02:48:12:500PM	960226026	Steve Wolfe	960226026 - GO to 2.7T cases = load 960223022 Add 1.5psi of H2 to a-side plenum (was 19.5psi D2) INcrease prepuff to 14msec. Hybrid control on TF Disrupted at .668? I don't know why.
Feb 26 1996 03:08:14:140PM	960226027	Steve Wolfe	960226027 - No changes, see if it does it again. On the original shot, the density was overshooting, on this one it gave what I asked for. plasma to 1.37sec, lots of H-modes. RF is modulated, shifted from H-modes.
Feb 26 1996 03:14:49:960PM	960226028	Steve Wolfe	960226028 - Repeat - Try RF feedback this time. Note for next time - Had runaways again, and CR disruption. Disruption at .58. Early injection following the CR disruption
Feb 26 1996 03:21:50:120PM	960226029	Steve Wolfe	Shot 960226029 - Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3 Ask for 8e19 density, adjust some rampdown waveforms Fizzle&^(&)( ^@E^(^#$E@
Feb 26 1996 03:23:27:530PM	960226029	Steve Wolfe	Shot 960226029 - Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3 Ask for 8e19 density, adjust some rampdown waveforms Fizzle&^(&)( ^@E^(^#$E@ EF2L did its thing again.
Feb 26 1996 03:44:24:850PM	960226030	Steve Wolfe	Shot 960226030 - Try again with: Change current rise phase on OHvolts, prepuff to 16msec, increase seg1 pg3 Ask for 8e19 density, adjust some rampdown waveforms Disrupts at 1.2. RF off at 1.05, and density drops as it comes out of H-mode. beta gets to 1.3%, maybe too high for him.
Feb 26 1996 03:55:57:360PM	960226031	Steve Wolfe	Shot 960226031 - Reduce NL4 demand to 6e19, keeping pre-0.5sec level at 8e19 Drop Br0 to .005 Fizzle. 50kA fizzle, bounces outside.
Feb 26 1996 04:30:10:790PM	960226033	Steve Wolfe	Shot 960226033 - Reload seg1 from 28 It doesn't look to me like I did anything that early but try it anyway. The pre-puff and early gas wil be different. EARLY DISRUPTION. .6sec, Falling density. Back to the runaways and CR disruptions.
Feb 26 1996 04:43:44:990PM	960226034	Steve Wolfe	Shot 960226034 - Raise seg1 pg3 after 50msec NL04 to 7e19 Plasma, disrupts at 1.2sec h-modes. RF feedback was only on for first RF pulse, RF didn't come back on beta is 1.3 again, density is too high.
Feb 26 1996 05:16:33:920PM	960226034	Steve Wolfe	Shot 960226035- Try less RF power, see if the density stays low. PLasma disrupts late, around 1.3sec TF Crowbar. Fuses blown, no more time. NL04 got to 1.15-1.2e20, may be low enough. beta around 1.1%

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:03:14:620AM	Test	Ok
2	08:13:19:490AM	Plasma	Ok
3	08:27:20:010AM	Plasma	Ok
4	08:45:38:470AM	Plasma	Ok
5	09:01:42:710AM	Plasma	Ok
6	09:18:07:830AM	Plasma	Ok
7	09:33:24:230AM	Plasma	Ok
8	09:45:14:910AM	Plasma	Ok
9	09:59:46:700AM	Plasma	Ok
10	10:12:47:370AM	Plasma	Ok
11	10:24:48:980AM	Plasma	Ok
12	10:34:41:940AM	Plasma	Ok
13	10:45:30:400AM	Plasma	Ok
14	11:14:13:450AM	Plasma	Ok
15	11:29:29:940AM	Plasma	Ok
16	11:49:05:830AM	Plasma	Ok
17	12:03:39:930PM	Plasma	Ok
18	12:20:30:480PM	Plasma	Ok
19	12:34:14:200PM	Plasma	Bad	EF2LB breaker pulled before pulse state.
20	12:44:42:540PM	Plasma	Ok	IOC OH2L & OH1 Bypass comm fault OH2U.
21	01:00:26:840PM	Plasma	Ok
22	01:13:56:970PM	Plasma	Ok
23	01:28:52:920PM	Plasma	Ok
24	01:45:25:800PM	Plasma	Ok	Comm Fault OH2L & OH1.
25	02:10:24:850PM	Plasma	Ok
26	02:38:10:650PM	Plasma	Ok
27	02:56:39:270PM	Plasma	Ok	OH1 Comm fault OH2 Bypass comm fault.
28	03:10:05:720PM	Plasma	Ok
29	03:20:12:260PM	Plasma	Ok
30	03:31:18:260PM	Plasma	Ok
31	03:50:21:960PM	Plasma	Ok
32	03:59:56:980PM	Plasma	Ok
33	04:19:47:210PM	Plasma	Ok
34	04:32:27:730PM	Plasma	Ok
35	04:46:24:750PM	Plasma	Ok