Alcator C-Mod Run 1040416 Information

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Miniproposals
Miniproposal:397
Date Filed: 4/9/2004
Title:Comparison of C-Mod EDA regime with JFT2-M HRS regime
First Author:Amanda Hubbard
Session Leader:Amanda Hubbard (shots 1-35)

Operators
Session leader(s):Amanda Hubbard
Physics operator(s):Robert Granetz
Engineering operator(s):Gary Dekow

Engineering Operator Run Comment
MP 397 Compare CMOD EDA & JFT-2M; SL:Hubbard; PO:Granetz; EO:Dekow/Parki

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:04:880PM
Author: Amanda Hubbard




Run Summary for 1040128: MP 397 Comparison of C-Mod EDA regime with
JFT2M HRS regime

Session Leader: Amanda Hubbard
Physics Operator: Bob Granetz

Purpose: To assess the similarities and differences of the C-Mod EDA
regime with JFT2M HRS regime, in particular the fluctuation
properties and access regime.


Results:

This run was quite successful and accomplished some, though not all,
of the proposed scans. Since the run was immediately
post-boronization, shots 1-6 were spent in shot recovery and fizzles.
There was some tweaking of Ip to get the correct q95.

Most of the run was spent scanning power (upwards) and density
(downwards) at q95=3.5. (Shots 11-26). There were many unusual
obervations. At most densities, a steady EDA regime was seen.
However, fluctuation properties on PCI and magnetics (using probe in
dwell mode) showed two distinct frequency peaks (harmonics?). At the
lowest densities, the discharges entered what appears to be a regime
with large distinct ELMs and no QC mode (eg shots 24,25,26).
This is quite unusual for C-mod, and warrants some stability
assessment
to determine whether they may be Type I ELMS.

We then decided to go to q95=2.9, for which JFT2M was recently able
to access HRS regime at higher collisionality. Shots 28-35 had the
desired q, and the shape did not change noticably. As is
typical for C-mod at this q, H-modes were no longer steady but
consisted of several short H-modes with back-transitions. There were
some edge fluctuations, which need to be examined, but they were rather
erratic and incoherent. We used the last few shots to scan up in
density (causing some frustration for RF tuning). The H-modes did
appear to get longer and steadier with increasing ne; shot 34, with
target ~10^20 m-2, was the best example. There is more room to
explore this operating space. As noted by the physop,
we were close to several power supply limits so caution is needed.

An interesting feature was that this shape tended to produce ohmic
H-modes much more easily than our standard shape. Many of the
discharges, at both q values, had their first L-H transitions well before the
RF turned on. This in fact occurred more at the higher densities,
contrary to usual expectations. A particularly interesting example
was shot 35, where the density and neutral pressure ended up higher
than expected causing RF to trip out. This shot had a late, very
steady, H-mode visible in density signals, but little or no
Temp pedestal . There were very broad, incoherent, magnetic
fluctuations. The threshold conditions for these discharges will be
interesting to study.

Overall, after the post-boron recovery, the machine ran very well.
We obtained a range of plasma conditions at
medium q which will be worthwhile to evaluate collisionality etc and
compare with JFT2M. We expect another run will be necessary to fill
in gaps and to explore the high q95 part of the proposal, as well as
a wider range at low q95. The run did produce some fluctuations
which were different than have been seen before and at least
qualitatively similar to those on JFT2M. Given that the plasma
parameters were fairly typical for C-Mod, this presumably was due to
the non-standard shape.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:49:910PM
Author: Robert Granetz
Physics operator summary for run 1040416 (Friday):

MP 397: Comparison of C-Mod EDA regime with JFT-2M HRS regime

Session leader: A. Hubbard
Physics operator: R. Granetz

Summary: After a half-dozen shots of post-boronization recovery, a pre-fill
gas puff of just 10 ms resulted in very reliable plasma startup.
The tokamak ran well with the JFT-2M shape. We ran down to very
low density, eventually getting a locked mode disruption, but then
the A-coils were turned on and fixed that problem. During the
latter portion of the run, we ran a lot of shots at q95=2.9, with
the JFT-2M shape. Many of these ran fine, but a number disrupted
because the unusual shape resulted in many of the EF coil supplies
bumping into their current limits. We were able to delineate the
EDA H-mode over some parameters. See the session leader's report
for details. We had no computer problems today, and no breaker
problems.

Scorecard: 31 plasmas
4 fizzles
0 duds
0 tests or no-power shot cycles
0 aborted and/or screwed up by computer problems
0 beam-into-gas calibration shots with B-field(s)
----------
35 total

-------------------------------------------------------------------------------
Engineering setup for Friday, 16 Apr 2004

MP 397: Comparison of C-Mod EDA regime with JFT-2M HRS regime

Session leader: A. Hubbard
Physics operator: R. Granetz

No ECDC overnight, since we're boronizing.

Run begins at 09:00 and ends at 17:00.

Power systems the same as 1040128009 (previously developed JFT-2M shape)

A-coils should be disabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Disable NINJA

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics:
Edge TS, PCI, reflectometry, fast magnetics. Scanning Langmuir probe(s),
ideally with a magnetic head, is desirable but not essential.

-------------------------------------------------------------------------------
RF Setup: All four transmitters in RUN-ON by 08:00, all at 80 MHz. This
miniproposal calls for 1.0-3.5 MW at 80 MHz.

-------------------------------------------------------------------------------
Run Plan: Start with shape from 1040128009, but raise Bt to 5.4 T and lower
Ip to 840 kA in order to match the JFT-2M q95 value of 3.5. If
needed, tweak Ip and shape to get good match to JFT-2M. From
this starting point, we will run several values of density, RF
power, and Ip to scan T_ped, nu_star, and beta_p parameter space,
observing the H-mode and pedestal characteristics.

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

Boronization was done last night, followed by 4 hours of He ECDC.

Hybrid coldstart done by the engineering group; no errors found

Loaded PCS segments 2,3,4 from shot 1040128009
set Bt to 5.4 T
set Ip to 840 kA
disabled A-coils
PCS segment 1 from shot 1040415014
set the pre-fill gas puff at 14 ms.

Possible RF fiducial shot for boronization recovery: 1040218003

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

Shot 01 -- Plasma. Good full-length shot. Ip=0.80 MA, Bt=5.5 T, q95=3.8.
nl_04=1.0-1.1e20 m-2. No RF. Ip has a big dip around t=0.1 s.

Next shot: tweak Ip and Bt to get closer to the q95 we want. Also
tweak early Zcur, early gas puffing, and pre-fill.

Shot 02 -- Fizzle.

Next shot: untweak the pre-fill.

Shot 03 -- Fizzle. Post-boronization blues.

Next shot: reduce pre-fill another 1 ms. It will now be down
to 12 ms.

Shot 04 -- Fizzle.

Next shot: add 0.2 mT to Br0, reduce pre-fill another 1 ms to 11 ms.

Shot 05 -- Plasma. Good shot. No RF. Ip still has dip at t=0.1 s.

Next shot: increase outer gap during early part of shot (for
scanning probe) and decrease nl_04 to 0.9e20 m-2. Tweak Ip just
after t=0.1 s.

Shot 06 -- Fizzle. Fields look good.

Next shot: reduce pre-fill another 1 ms to just 10 ms

Shot 07 -- Plasma. Disrupted at t=1.4 s due to a big injection. Good outer
gap for the scanning probe. Strange increase in density
occurred at t=0.72 s for no explicable reason. D-port antenna
came on briefly at low power.

Next shot: no changes.

Shot 08 -- Plasma. Good shot. Prf=0.6 MW from D. J-port is also just
starting to come to life. The density rise from t=0.7-1.5 s is
apparently an H-mode. Ip=0.83-0.84 MA, Bt=5.4 T, but q95=3.9.

Next shot: raise Ip by 50 kA to get closer to q95=3.5. More RF
power.

Shot 09 -- Plasma. Good shot. Prf=1.3 MW (D+E). H-mode (weak). q95=3.5-3.7

Next shot: adjust Zcur during first part of shot. Adjust Ip
late in shot to keep q95 close to 3.5.

Shot 10 -- Plasma. Good shot. Prf=2.0 MW from D+E. H-mode. Z-position
is steady now. q95=3.7 (we want 3.5).

Next shot: undo the change to Zcur by re-loading wire 2 from
shot 09. Also increase Ip by another 30 kA.

Shot 11 -- Plasma. Good shot. Prf=2.0 MW (D+E). H-mode. q95=3.5 for
nearly all of flattop.

Next shot: no PCS changes.

Shot 12 -- Plasma. Good shot. Prf=2.0 MW (D+E). H-mode. q95=3.4-3.5.

Next shot: flatten Zcur at the value it has at t=1.0 s.

Shot 13 -- Plasma. Good shot. Prf=2.6 -> 1.5 MW (D+E). q95=3.4-3.5.
Magnetic axis height is now very steady at the desired value.

Next shot: no PCS changes. RF tuning, more power

Shot 14 -- Plasma. Good shot. Prf=1.5 MW (E). q95=3.4-3.5.

Next shot: reduce nl_04 to 0.7e20 m-2 (from 0.9e20 m-2)

Shot 15 -- Plasma. Good shot. Prf=1.6 -> 2.5 MW (D+E). q95=3.4. Got the
lower target density.

Next shot: reduce Ip by 10 kA.

Shot 16 -- Plasma. Good shot. Prf=2.0 -> 2.8 MW (D+E). q95=3.5.

Next shot: no PCS changes. Try for more RF power.

Shot 17 -- Plasma. Good shot. Prf=1.8 MW, with some excursions to 3 MW.
There was some power from J-port antenna late in the flattop.
q95=3.4-3.5.

Next shot: reduce nl_04 to 0.5e20 m-2. Also reduce Ip by
another 10 kA.

Shot 18 -- Plasma. Good shot. Prf=2.3 -> 4.3 MW (D+E+J). q95=3.5. Got a
little lower density, but not as low as we wanted.

Next shot: no PCS changes.

Shot 19 -- Plasma. Good shot. Prf=4.3 -> 2.3 MW (D+E+J). q95=3.5. Got
the lower density. Huge radiated power.

Next shot: no PCS changes...more RF power for longer

Shot 20 -- Plasma. Good shot. Prf=4 -> 2 MW (D+E+J). q95=3.5. Target
density is climbing.

Next shot: no PCS changes...more RF power for longer

Shot 21 -- Plasma. Good shot. Prf=3.5 MW (D+E+J). q95=3.5.

Next shot: reduce gas puffing in segment 1 in order to try and
get lower target density.

Shot 22 -- Plasma. Good shot. Prf=3.5-5.1 MW (D+E+J). q95=3.5. Stored
energy reaches 150 kJ. Target density was 0.6e20 m-2.

Next shot: reduce nl_04 and early gas puffing even more.

Shot 23 -- Plasma. Good shot. Prf=3.5-5.1 MW (D+E+J). q95=3.5. Target
density was 0.4e20 m-2. The current rise dip has returned.

Next shot: no PCS changes

Shot 24 -- Plasma. Good shot. Target density is down to nl_04=0.35e20
m-2. This finally switched us from EDA to ELMy H-modes.
Prf=2.5-3.8 MW (D+E+J). q95=3.4

Next shot: no PCS changes. Lower the RF power

Shot 25 -- Plasma. Disrupted at t=0.92 s. Looks like a locked mode.
Prf=2.2 MW (D+E+J), and NO H-MODE.

Next shot: same, except enable the A-coils and program 2000 A
for the entire flattop. Also increase the early gas.

Shot 26 -- Plasma. Good shot. No locked mode. Prf=3.8 MW. ELMfree,
followed my ELMy, followed by L-mode. No EDA. So this is the
lower density limit for the JFT-2M shape.

Next shot: raise Ip to 1.1 MA (q95=2.9) and nl_04 to 0.6e20 m-2.

Shot 27 -- Plasma. Good shot. Many short H-modes. q95=3.05. Target
nl_04=0.6e20 m-2. Prf=2 -> 4.2 MW.

Next shot: tweak Ip up a bit to get q95=2.9.

Shot 28 -- Plasma. Good shot. Many short H-modes again. q95=2.9, as
desired. Prf=2.2+ MW. RF is faulting a lot.

Next shot: no PCS changes. Tune up the RF.

Shot 29 -- Plasma. Disrupted at t=1.46 s because EF2L and EF3's are at
their current limits. Prf=2.3 -> 4.3 MW. q95=2.9.

Next shot: increase nl_04 to 0.8e20 m-2. Increase EF3 PLC
current limit to 14 kA (from 12)

Shot 30 -- Plasma. Early disruption (t=0.18 s). Presumably an injection.

Next shot: try again, no changes

Shot 31 -- Plasma. Good shot. Lots of short H-modes. Prf=2.3 -> 3.7 MW.
q95=2.9.

Next shot: raise nl_04 to 1.0e20 m-2

Shot 32 -- Plasma. Disrupted at t=0.84 s. EF2L hit zero, which led to
loss of control. The big dip during the early current rise has
become very pronounced again.

Next shot: try this one once more

Shot 33 -- Plasma. Good shot. q95=2.9. Prf=2.3 -> 3.7 MW. We're just
barely squeeking by on several of the EF coil current limits.

Next shot: raise nl_04 to 1.1e20 m-2

Shot 34 -- Plasma. Good shot. q95=2.9. H-modes got a little
longer. Prf=2.3 -> 3.8 MW.

Next shot: raise nl_04 to 1.25e20 m-2 and put some finite
programming on the gas valve in segment 2.

Shot 35 -- Plasma. Good shot. No RF. Still got a weak ohmic H-mode.
Several EF supplies hit their rails.

End of run

Session Leader Comments
Apr 16 2004 09:13:18:453AM1040416001Amanda HubbardGood plasma - note we are postboronization. 5.49 T, 0.8 MA, nominally JFT2M shape.

RF had trouble coupling; essentially ohmic.

Apr 16 2004 10:48:47:200AM1040416007Amanda HubbardBrief RF, followed by unexpected ne rise. Possibly H mode? Jerry reports an ne pedestal. Poor ETS coverage.



Apr 16 2004 10:54:42:110AM1040416008Amanda HubbardSteady RF at 0.6 MW, Apparent H mode, steady.

Weak mode, apparent QC mode, seen on PCI.





Apr 16 2004 11:27:57:920AM1040416010Amanda HubbardGood shot. q95=3.7 ( a bit high still).

2 MW RF, nice H-mode.




Apr 16 2004 11:28:50:967AM1040416010Amanda HubbardGood shot. q95=3.7 ( a bit high still). nel 0.9-1.4e20 m-2.

2 MW RF, nice H-mode.




Apr 16 2004 11:57:24:660AM1040416011Amanda HubbardGood shot. q95=3.5 (just right).

2 MW RF, nice H-mode.




Apr 16 2004 11:57:55:410AM1040416012Amanda HubbardGood shot. q95=3.44

2 MW RF, nice H-mode. Start going up in power.




Apr 16 2004 12:23:47:347PM1040416013Amanda HubbardGood shot. q95=3.44 Shape is steadier.

Brief 2.5 MW, then 1.5 MW (getting our power scans....)

ne rises late in H-mode again...

Note H-mode is starting at 0.52 secs, well BEFORE RF (ie ohmic H-mode).

Also, PCI is reporting an unusual QC mode with two frequencies/harmonics,
quite broadband.



Apr 16 2004 12:24:44:863PM1040416014Amanda HubbardRF tripped earlier; doesn't seem happy with high power in these conditions.

Start ne scan, going down to target 7e19 m-2. H-mode starts ohmic (0.6 s) again.





Apr 16 2004 12:42:45:280PM1040416015Amanda Hubbard
Good. nel 7e19 target, 1.3e20 m-2 in H-mode.

RF steps at 2 MW, 2.6 MW. Raise 2nd step next shot.






Apr 16 2004 01:00:37:290PM1040416016Amanda Hubbard
Good. nel 7e19 target, 1.3e20 m-2 in H-mode. Again, rises late in shot.

RF steps at 2 MW, 2.8 MW.

H-mode starts ohmic again. Dalpha looks different; less fluctaions early, then more spikes (ELMS) esp in higher
power phase.

Apr 16 2004 01:20:16:320PM1040416017Amanda Hubbard
nel 7e19 target, 1.3e20 m-2 in H-mode. no ohmic transition this shot.

Brief 3.1 MW RF, then drops to 2 MW. Got some J-port power late.

Step down in nel for next shot.
Apr 16 2004 01:32:22:533PM1040416018Amanda Hubbard
nel 6.7e19 target, still 1.3e20 m-2 in H-mode. L-H transition at start of RF

Nice RF, steps from 2 MW to 4 MW (neutral pressure getting low enough for J)

H-mode looks like EDA with ELMs.
Apr 16 2004 01:36:40:560PM1040416019Amanda Hubbard
nel 6.6e19 target, Starting with 4.2 MW RF, then trips to 2 MW.

Different H-mode character this time, ne rises faster. Ends up at nel 1.43e20 m-2.

Edge Te higher, up to 600 eV Te6, Te95 ~ 700 eV. ne_95 2.1 e19 m-3
Apr 16 2004 01:43:57:250PM1040416019Amanda Hubbardnel 7.2 e19 target, Ends up at nel 1.5e20 m-2.

RF starts at 4 MW, but trips. Sveral injections.
Apr 16 2004 02:02:51:120PM1040416021Amanda Hubbardnel 7.4 e19 target, Ends up at nel 1.4e20 m-2.

RF starts at 3.5 MW, only a few trips. Later period with 5.1 MW, but many trips.

Try to lower ne to request (5e19 m-2) for next shot.
Te95 770 eV early Still looks like EDA with high beta ELMy spikes.
Apr 16 2004 03:28:12:630PM1040416023Amanda HubbardBrief 'quiet' (ELM-free?) period, then continuous, hashy spikes on Dalpha.
PCI, magnetics fluctns getting very incoherent.
Apr 16 2004 02:43:30:340PM1040416024Amanda Hubbardnel down to 4.2 e19 target,

This shot looks like classic 'large' ELMs. With ELM-free period preceding and between. We seem to have lost the
EDA regime. Very hot edge. Te6 900 eV, te95 900 eV. ne95 1.6e20 m-3.
This will be an interesting point on the operating diagram.
RF 3.5-3.7 MW, many trips (maybe due to ELMs).
Next shot, same plasma, lower RF power.
Apr 16 2004 02:59:22:143PM1040416025Amanda Hubbardnel down to 3.5 e19 target,

Reduced RF requst to 2.5 MW. L-mode, locked mode, and disruption.
Apr 16 2004 03:10:16:793PM1040416026Amanda Hubbardnel 3.9 e19 target,

Got a brief H-mode, with ELM-free periods and several quite large, distinct, ELMs. 3.3-3.9 MW.
L-mode for later period.
NO QC mode on PCI; we seem to have found the lower limit at this q95=3.5

Next skip to step 4 of MP, q95=2.9

start with moderate target nel ~ 7e19
Apr 16 2004 03:20:59:893PM1040416027Amanda HubbardWent to 1.07 MA, q95=3.0 (aiming for 2.9)

target ~ 5e19 m-2. Series of H-mode periods, type unclear. Many RF trips.
Retune, retry.
Apr 16 2004 03:36:39:593PM1040416028Amanda HubbardGot q95=2.9 Target nel 6e19.

RF tripping a lot, an d H-modes very unsteady. No modes on PCI, Magnetics early, then very broad fluctns later.
Apr 16 2004 03:48:57:183PM1040416029Amanda Hubbard q95=2.9 , 1.11 MA Target nel 6e19. Disrupts ~ 1.4 secs

H-modes still unsteady, nel rising with intermittend back transitions.
Got a fairly clean 2.3 MW period early. A lot of trips in later, high P phase.

raise target nel to 8e19 to next shot, see if we get back EDA.
Apr 16 2004 04:18:54:330PM1040416031Amanda Hubbard q95=2.9 , 1.11 MA Target nel 8e19. Series of brief H-modes. Again 2.3 MW period quite clean, high P phase has
trips. Interestingly, Edge Te is progressively
higher on each, giving a scan. Te6 0.5 to 0.9 keV. Nel dropping to ~ 10 20 in later H-modes; nu* must be
low. May be a few ELMs late, or just transtions?
Aug 20 2004 10:38:12:717AM1040416032Amanda Hubbard
q95=2.9 , 1.11 MA Target nel 10e20 m02. Disrupts ~0.9 s.

Series of 2-4 H-modes -first two are ohmic! 1st one looks quite ELM-free, later ones, including RF heated (2.3 MW)
phase, have more fluctuations. PCI, magnetics see weak QC mode ~0.65 s, stronger one in RF.

But, not strong enough for steady density.
-
Aug 18 2004 01:46:16:307PM1040416033Amanda HubbardThis one didn't disrupt. Still a series of H-Modes, but longer, weaker ne rise. RF 2.3 to 3.8 MW, some trips.
Apr 16 2004 05:04:41:370PM1040416034Amanda Hubbard q95=2.9 , 1.11 MA Target nel 1.0 10e20 m-2.

This one actually had target nearly 10^20. Longer, though not quite steady, H-modes. 1st is ohmic again.
RF happier.
Te95 ~ 400 eV, ne95 2.7 e20
Go up more in nel for last shot.
Apr 16 2004 05:09:13:957PM1040416035Amanda HubbardGot target nel ~ 1.4e20 m-2 (more than we asked for). This led to zero RF.

But, we did get what appears to be a long, steady H-mode from 1.1-1.4ish seconds.
A hint of a mode on PCI, but mostly outside the window. Interesting place to revisit.

Physics Operator Comments
Apr 15 2004 01:23:12:360PMRobert GranetzEngineering setup for Friday, 16 Apr 2004

MP 397: Comparison of C-Mod EDA regime with JFT-2M HRS regime

Session leader: A. Hubbard
Physics operator: R. Granetz

No ECDC overnight, since we're boronizing.

Run begins at 09:00 and ends at 17:00.

Power systems the same as 1040128009 (previously developed JFT-2M shape)

A-coils should be disabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Disable NINJA

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics:
Edge TS, PCI, reflectometry, fast magnetics. Scanning Langmuir probe(s),
ideally with a magnetic head, is desirable but not essential.

-------------------------------------------------------------------------------
RF Setup: All four transmitters in RUN-ON by 08:00, all at 80 MHz. This
miniproposal calls for 1.0-3.5 MW at 80 MHz.

-------------------------------------------------------------------------------
Run Plan: Start with shape from 1040128009, but raise Bt to 5.4 T and lower
Ip to 840 kA in order to match the JFT-2M q95 value of 3.5. If
needed, tweak Ip and shape to get good match to JFT-2M. From
this starting point, we will run several values of density, RF
power, and Ip to scan T_ped, nu_star, and beta_p parameter space,
observing the H-mode and pedestal characteristics.
Apr 16 2004 08:17:49:913AMRobert Granetz Boronization was done last night, followed by 4 hours of He ECDC.

Hybrid coldstart done by the engineering group; no errors found

Loaded PCS segments 2,3,4 from shot 1040128009
set Bt to 5.4 T
set Ip to 840 kA
disabled A-coils
PCS segment 1 from shot 1040415014
set the pre-fill gas puff at 14 ms.
Apr 16 2004 09:15:51:677AM1040416001Robert GranetzShot 01 -- Plasma. Good full-length shot. Ip=0.80 MA, Bt=5.5 T, q95=3.8.
nl_04=1.0-1.1e20 m-2. No RF. Ip has a big dip around t=0.1 s.

Next shot: tweak Ip and Bt to get closer to the q95 we want. Also
tweak early Zcur, early gas puffing, and pre-fill.
Apr 16 2004 09:21:49:557AM1040416002Robert GranetzShot 02 -- Fizzle.

Next shot: untweak the pre-fill.
Apr 16 2004 09:38:57:757AM1040416003Robert GranetzShot 03 -- Fizzle. Post-boronization blues.

Next shot: reduce pre-fill another 1 ms. It will now be down
to 12 ms.
Apr 16 2004 09:48:48:200AM1040416004Robert GranetzShot 04 -- Fizzle.

Next shot: add 0.2 mT to Br0, reduce pre-fill another 1 ms to 11 ms.
Apr 16 2004 10:23:09:680AM1040416005Robert GranetzShot 05 -- Plasma. Good shot. No RF. Ip still has dip at t=0.1 s.

Next shot: increase outer gap during early part of shot (for
scanning probe) and decrease nl_04 to 0.9e20 m-2. Tweak Ip just
after t=0.1 s.
Apr 16 2004 10:18:24:177AM1040416006Robert GranetzShot 06 -- Fizzle. Fields look good.

Next shot: reduce pre-fill another 1 ms to just 10 ms
Apr 16 2004 10:38:51:113AM1040416007Robert GranetzShot 07 -- Plasma. Disrupted at t=1.4 s due to a big injection. Good outer
gap for the scanning probe. Strange increase in density
occurred at t=0.72 s for no explicable reason. D-port antenna
came on briefly at low power.

Next shot: no changes.
Apr 16 2004 10:49:33:577AM1040416008Robert GranetzShot 08 -- Plasma. Good shot. Prf=0.6 MW from D. J-port is also just
starting to come to life. The density rise from t=0.7-1.5 s is
apparently an H-mode. Ip=0.83-0.84 MA, Bt=5.4 T, but q95=3.9.

Next shot: raise Ip by 50 kA to get closer to q95=3.5. More RF
power.
Apr 16 2004 11:06:06:133AM1040416009Robert GranetzShot 09 -- Plasma. Good shot. Prf=1.3 MW (D+E). H-mode (weak). q95=3.5-3.7

Next shot: adjust Zcur during first part of shot. Adjust Ip
late in shot to keep q95 close to 3.5.
Apr 16 2004 11:25:49:760AM1040416010Robert GranetzShot 10 -- Plasma. Good shot. Prf=2.0 MW from D+E. H-mode. Z-position
is steady now. q95=3.7 (we want 3.5).

Next shot: undo the change to Zcur by re-loading wire 2 from
shot 09. Also increase Ip by another 30 kA.
Apr 16 2004 11:51:16:043AM1040416012Robert GranetzShot 12 -- Plasma. Good shot. Prf=2.0 MW (D+E). H-mode. q95=3.4-3.5.

Next shot: flatten Zcur at the value it has at t=1.0 s.
Apr 16 2004 12:06:46:243PM1040416013Robert GranetzShot 13 -- Plasma. Good shot. Prf=2.6 -> 1.5 MW (D+E). q95=3.4-3.5.
Magnetic axis height is now very steady at the desired value.

Next shot: no PCS changes. RF tuning, more power
Apr 16 2004 12:17:40:643PM1040416014Robert GranetzShot 14 -- Plasma. Good shot. Prf=1.5 MW (E). q95=3.4-3.5.

Next shot: reduce nl_04 to 0.7e20 m-2 (from 0.9e20 m-2)
Apr 16 2004 12:44:42:610PM1040416015Robert GranetzShot 15 -- Plasma. Good shot. Prf=1.6 -> 2.5 MW (D+E). q95=3.4. Got the
lower target density.

Next shot: reduce Ip by 10 kA.
Apr 16 2004 12:53:13:147PM1040416016Robert GranetzShot 16 -- Plasma. Good shot. Prf=2.0 -> 2.8 MW (D+E). q95=3.5.

Next shot: no PCS changes. Try for more RF power.
Apr 16 2004 01:02:42:687PM1040416017Robert GranetzShot 17 -- Plasma. Good shot. Prf=1.8 MW, with some excursions to 3 MW.
There was some power from J-port antenna late in the flattop.
q95=3.4-3.5.

Next shot: reduce nl_04 to 0.5e20 m-2. Also reduce Ip by
another 10 kA.
Apr 16 2004 01:27:57:803PM1040416018Robert GranetzShot 18 -- Plasma. Good shot. Prf=2.3 -> 4.3 MW (D+E+J). q95=3.5. Got a
little lower density, but not as low as we wanted.

Next shot: no PCS changes.
Apr 16 2004 01:35:00:337PM1040416019Robert GranetzShot 19 -- Plasma. Good shot. Prf=4.3 -> 2.3 MW (D+E+J). q95=3.5. Got
the lower density. Huge radiated power.

Next shot: no PCS changes...more RF power for longer
Apr 16 2004 01:45:29:563PM1040416020Robert GranetzShot 20 -- Plasma. Good shot. Prf=4 -> 2 MW (D+E+J). q95=3.5. Target
density is climbing.

Next shot: no PCS changes...more RF power for longer
Apr 16 2004 02:01:15:523PM1040416021Robert GranetzShot 21 -- Plasma. Good shot. Prf=3.5 MW (D+E+J). q95=3.5.

Next shot: reduce gas puffing in segment 1 in order to try and
get lower target density.
Apr 16 2004 02:14:19:007PM1040416022Robert GranetzShot 22 -- Plasma. Good shot. Prf=3.5-5.1 MW (D+E+J). q95=3.5. Stored
energy reaches 150 kJ. Target density was 0.6e20 m-2.

Next shot: reduce nl_04 and early gas puffing even more.
Apr 16 2004 02:29:48:083PM1040416023Robert GranetzShot 23 -- Plasma. Good shot. Prf=3.5-5.1 MW (D+E+J). q95=3.5. Target
density was 0.4e20 m-2. The current rise dip has returned.

Next shot: no PCS changes
Apr 16 2004 02:37:36:900PM1040416024Robert GranetzShot 24 -- Plasma. Good shot. Target density is down to nl_04=0.35e20
m-2. This finally switched us from EDA to ELMy H-modes.
Prf=2.5-3.8 MW (D+E+J). q95=3.4

Next shot: no PCS changes. Lower the RF power
Apr 16 2004 02:57:11:750PM1040416025Robert GranetzShot 25 -- Plasma. Disrupted at t=0.92 s. Looks like a locked mode.
Prf=2.2 MW (D+E+J), and NO H-MODE.

Next shot: same, except enable the A-coils and program 2000 A
for the entire flattop. Also increase the early gas.
Apr 16 2004 03:07:54:443PM1040416026Robert GranetzShot 26 -- Plasma. Good shot. No locked mode. Prf=3.8 MW. ELMfree,
followed my ELMy, followed by L-mode. No EDA. So this is the
lower density limit for the JFT-2M shape.

Next shot: raise Ip to 1.1 MA (q95=2.9) and nl_04 to 0.6e20 m-2.
Apr 16 2004 03:17:25:047PM1040416027Robert GranetzShot 27 -- Plasma. Good shot. Many short H-modes. q95=3.05. Target
nl_04=0.6e20 m-2. Prf=2 -> 4.2 MW.

Next shot: tweak Ip up a bit to get q95=2.9.
Apr 16 2004 03:33:09:903PM1040416028Robert GranetzShot 28 -- Plasma. Good shot. Many short H-modes again. q95=2.9, as
desired. Prf=2.2+ MW. RF is faulting a lot.

Next shot: no PCS changes. Tune up the RF.
Apr 16 2004 03:51:14:913PM1040416029Robert GranetzShot 29 -- Plasma. Disrupted at t=1.46 s because EF2L and EF3's are at
their current limits. Prf=2.3 -> 4.3 MW. q95=2.9.

Next shot: increase nl_04 to 0.8e20 m-2. Increase EF3 PLC
current limit to 14 kA (from 12)
Apr 16 2004 04:07:01:927PM1040416030Robert GranetzShot 30 -- Plasma. Early disruption (t=0.18 s). Presumably an injection.

Next shot: try again, no changes
Apr 16 2004 04:19:05:470PM1040416031Robert GranetzShot 31 -- Plasma. Good shot. Lots of short H-modes. Prf=2.3 -> 3.7 MW.
q95=2.9.

Next shot: raise nl_04 to 1.0e20 m-2
Apr 16 2004 04:30:46:440PM1040416032Robert GranetzShot 32 -- Plasma. Disrupted at t=0.84 s. EF2L hit zero, which led to
loss of control. The big dip during the early current rise has
become very pronounced again.

Next shot: try this one once more
Apr 16 2004 04:41:24:510PM1040416033Robert GranetzShot 33 -- Plasma. Good shot. q95=2.9. Prf=2.3 -> 3.7 MW. We're just
barely squeeking by on several of the EF coil current limits.

Next shot: raise nl_04 to 1.1e20 m-2
Apr 16 2004 04:57:03:617PM1040416034Robert GranetzShot 34 -- Plasma. Good shot. q95=2.9. H-modes got a little
longer. Prf=2.3 -> 3.8 MW.

Next shot: raise nl_04 to 1.25e20 m-2 and put some finite
programming on the gas valve in segment 2.
Apr 16 2004 05:08:28:133PM1040416035Robert GranetzShot 35 -- Plasma. Good shot. No RF. Still got a weak ohmic H-mode.
Several EF supplies hit their rails.

End of run

Engineering Operator Comments
ShotTimeTypeStatusComment
109:02:45:587AMPlasmaOk
209:17:50:973AMPlasmaOk
309:31:31:530AMPlasmaOk
409:44:20:417AMPlasmaOk
509:56:49:080AMPlasmaOk
610:12:11:453AMPlasmaOk
710:24:45:930AMPlasmaOk
810:37:38:097AMPlasmaOk
910:52:35:000AMPlasmaOk
1011:14:12:890AMPlasmaOk
1111:30:37:607AMPlasmaOk
1211:43:37:617AMPlasmaOk
1311:56:11:563AMPlasmaOk
1412:09:14:047PMPlasmaOk
1512:28:57:450PMPlasmaOk
1612:42:25:653PMPlasmaOk
1712:55:33:277PMPlasmaOk
1801:08:40:200PMPlasmaOk
1901:22:37:980PMPlasmaOk
2001:35:14:180PMPlasmaOk
2101:48:16:370PMPlasmaOk
2202:03:56:967PMPlasmaOk
2302:16:57:043PMPlasmaOk
2402:30:48:507PMPlasmaOk
2502:43:26:073PMPlasmaOk
2602:57:37:343PMPlasmaOk
2703:11:31:827PMPlasmaOk
2803:24:15:977PMPlasmaOk
2903:39:04:433PMPlasmaOk
3003:52:12:017PMPlasmaOk
3104:04:54:443PMPlasmaOk
3204:20:10:633PMPlasmaOk
3304:33:58:430PMPlasmaOk
3404:46:24:173PMPlasmaOk
3504:59:06:633PMPlasmaOk