Alcator C-Mod Run 1020930 Information

Back to runs

Miniproposals
Miniproposal:304
Date Filed: 6/19/2002
Title:H-Mode Regimes
First Author:Martin Greenwald
Session Leader:Martin Greenwald (shots 1-17)

Operators
Session leader(s):Martin Greenwald
Physics operator(s):Bill Rowan
Engineering operator(s):Bill Parkin,Ed Fitzgerald,Gary Dekow

Engineering Operator Run Comment
MP#312 or #304;SL:Lee or Greenwald; PO:Rowan; EO:Dekow/Fitz/Parkin

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:30:897PM
Author: To Be Determined
Run Summary for 1020930
mp 304 H-mode regimes

Session Leader - Greenwald
Phys Op - Rowan

============================

Plan:

Given machine constraints, Emphasis will be on the EDA/ELMfree
boundary as a function of delta. The hope is that the loose tile
will not cause too much trouble. Even this study will be constrained
because of limits on plasma current.

The overall strategy is to pick a triangularity, get an H-mode. If
it is EDA, we scan up in current (down in q) till the discharge goes
ELMfree. If it is ELMfree, we scan down in current till it goes
EDA. Then go to next value of triangularity.

- start at the highest triangularity, maybe delta_av = 0.7, then
scan to 0.55 and 0.35. If time permits (hah!) we'll try to fill in.
a possible shot to start with would be 1020625021, though we
probably need to back of slightly on the upper triangularity to
avoid double null.

- Bt = 5.3 or whatever value it is these days that puts the D&E
antennas squarely on the magnetic axis

- no power scans - steady power at about 2 MW

- start at 1 MA for the high triangularity. we can probably drop
the base current as the triangularity is lowered.


==============================

Results:

Less than exciting. The early part of the run was plagued by
fizzles, then on shot 17 we had a fault in a commutation capacitor
which ended the run.

We got the start of our scan on shots 11 and 15. These were EDA
(First data this campaign with the PCI) at q95 = 5.3 and delta_av =
0.56. This is entirely consistent with previous scans, but did not
expand our database.

================================


Physics Operator Summaries
Entered: Jul 7 2004 04:37:16:350PM
Author: To Be Determined

Engineering setup for Monday, September 30th, Run 1020930

Either MP#312 or #304 depending on the availability of PCI
If PCI is available, then MP 304.

MP#312 Toroidal Rotation Profiles in Ohmic H-modes
Session Leader: Mr. Lee
Physics Operator: Rowan

MP#304 H-mode regimes
Session leader: Greenwald
Physics Operator: Rowan
For the experiment, use segment 2 of 1020625021 and segment 1
of a more recent shot for breakdown.
The overall strategy is to pick a triangularity, get an H-mode. If
it is EDA, we scan up in current (down in q) till the discharge goes
ELMfree. If it is ELMfree, we scan down in current till it goes
EDA. Then choose a new value of triangularity.


ECDC overnight in D2 stopping by 07:00 on Monday morning..
Bake at 60C

Set up for possible ECDC in D2 between shots.

Power systems as on 1020925007

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
leave J-Bottom as is Hybrid DISABLED (PG5)

Enable the following gate valves:
ECE, VUV, DNB

-------------------------------------------------------------------------------
RF Setup: FMIT#1 and 2 transmitters in Run On by 08:00
-------------------------------------------------------------------------------

------------------------------------------------------------------------------
Results
------------------------------------------------------------------------------

Just one pump station was in operation for this run. Pumpdown after a
plasma shot and after between-shot-ECDC was slow.

The breakdown was taken from shot 1020927032. After 100 ms (segement 2),
the setup for shot 1020625021 was used at the suggestion of the SL.

Triangularity scan------------------------------------------------------------
ZXU was increased from the starting point of 0.015 m to avoid double null.
The last value used for a plasma shot was 0.030. That value is too high for
this experiment and had the run continued, it would have been reduced.
ZCUR was lowered to -0.015. In the reference shot, ZCUR was set for
approximately 0.

Breakdown and early current rise----------------------------------------------
There were significant problems here. Although the initial fields seemed
close enough, there were duds. The pressure was slightly high but within a
tolerable range. Careful matching of BR_0, BZ_0 and prefill pressure at 5 ms
to the shot 1020927032 did result in a breakdown, but a few more shots would
be needed before concluding that these settings would produce a stable
breakdown and current rise.

Engineering problems----------------------------------------------------------
Failure of a cap in OH2L resulted in the run ending early.



------------------------------------------------------------------------------
Copy of logbook entries
------------------------------------------------------------------------------

Engineering setup for Monday, September 30th, Run 1020930

Either MP#312 or #304 depending on the availability of PCI
If PCI is available, then MP 304.

MP#312 Toroidal Rotation Profiles in Ohmic H-modes
Session Leader: Mr. Lee
Physics Operator: Rowan

MP#304 H-mode regimes
Session leader: Greenwald
Physics Operator: Rowan
For the experiment, use segment 2 of 1020625021 and segment 1
of a more recent shot for breakdown.
The overall strategy is to pick a triangularity, get an H-mode. If
it is EDA, we scan up in current (down in q) till the discharge goes
ELMfree. If it is ELMfree, we scan down in current till it goes
EDA. Then choose a new value of triangularity.


ECDC overnight in D2 stopping by 07:00 on Monday morning..
Bake at 60C

Set up for possible ECDC in D2 between shots.

Power systems as on 1020925007

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
leave J-Bottom as is Hybrid DISABLED (PG5)

Enable the following gate valves:
ECE, VUV, DNB

-------------------------------------------------------------------------------
RF Setup: FMIT#1 and 2 transmitters in Run On by 08:00
-------------------------------------------------------------------------------

started pcs

loaded 1020927032. Will use this for the breakdown

imported segment 2 from 1020625021 to meet requirements for the run

Did a load/clean
Load at 30-Sep-2002 09:30:48.0

Did a cold start

rtnode -- data loaded, A matrix responds
rtnode -- data loaded, M matrix responds
rtnode -- data loaded, PID matrix responds
RT_NODE Done

30-SEP-2002 09:33:30.14 doing TCL command TYPE *************** END COLD
START ******************
*************** END COLDSTART ******************

001-004 engineering testss

005. Dud

Next shot. Raise BZ by approximately 1 mT. Increased IC_ef4 from -1330 to -1315
Lowered BR_0 by 0.5 mT. Offset changed from 0.002 to 0.0015
Added 1 ms of prefill. PG4. Makes it 29 ms.

006. Dud.

Next shot. Increased the gas fill again. PG$ is notw 30 ms.

007. Dud.

Nest shot. ECDC for 10 minutes before the next shot.

008. Plasma. Low density. Copied shot requested it.

Next shot. Increase NL_04 from 0.3e20 demand to 1.0e20 demand.

009. PlasmaN

Next shot. Moved zxu out by 1.5 cm to get rid of double null
Also moved zcur to -0.015 instead of the 0 in the last shot.

010. Fizzle

Next shot. Added 2 ms to the gas feed
Increase BZ_0 by 0.5 mT.

011. Plasma.
SL wants more triangularity

Next shot. Moved zxu back in by approximately 0.5 cm.

012. Fizzle

Next shot. ECDC before the next shot.

013. Fizzle.

Next shot.
Decrease BZ-) by 1 mT
Decreaed the prefill by 1 ms. This was actually high on shot 012 as well.

014. Fizzle

Next shot. Increase BR-0 by 0.5 mT to match the breakdown of the
last shots on Friday.

015. Plasma, finally.

Next shot. moved zxu from 0.03 tp 0.027. This is more sensitive than
I thought.

016. Fizzle.
The pressure on this shot is slightly higher on this shot than on
1020927032.

Next shot. Reduce the prefill by 2 ms. PG4 is now 29 ms.

017. Fizzle.
Commutation failure on OH2L

Engineers supect a blown switch SCR if that is the case. Delay for at least an hour.

Next shot: no changes

The run is ended. There is a short in one of the caps in OH2L.



Session Leader Comments
Sep 30 2002 09:59:45:170AMMartin GreenwaldBackground

The "baseline" operating regime for proposed burning plasma
experiments is an ELMy H-mode. Standard H-mode operation for most
tokamaks includes large type I ELMs which can cause unacceptably
high peak heat loads on the first wall. There is a need to identify
and characterize regimes without large ELMs but which do have good
H-mode confinement (that is with a large edge pedestal temperature
and pressure) On C-Mod, we have achieved such regimes with the EDA
and type II ELMy discharges. We now must understand the physics
of these regimes sufficiently to assess their potential for
extrapolation into the reactor regime.

The aim of the experimental proposal is to to identify the critical
physics parameters which define the various regimes. Data from
these experiments would be used for comparison with theoretical
models of micro and macro stability.

Plan
Given machine constraints, I think what we can do is to look for the
EDA/ELMfree boundary as a function of delta. The hope is that the
loose tile will not cause too much trouble. Even this study will be
constrained because of limits on plasma current.

The overall strategy is to pick a triangularity, get an H-mode. If
it is EDA, we scan up in current (down in q) till the discharge goes
ELMfree. If it is ELMfree, we scan down in current till it goes
EDA. Then go to next value of triangularity.

- start at the highest triangularity, maybe delta_av = 0.7, then
scan to 0.55 and 0.35. If time permits (hah!) we'll try to fill in.
a possible shot to start with would be 1020625021, though we
probably need to back of slightly on the upper triangularity to
avoid double null.

- Bt = 5.3 or whatever value it is these days that puts the D&E
antennas squarely on the magnetic axis

- no power scans - steady power at about 2 MW

- start at 1 MA for the high triangularity. we can probably drop
the base current as the triangularity is lowered.

Sep 30 2002 10:20:43:730AM1020930006Martin GreenwaldDud
Sep 30 2002 10:50:57:543AM1020930007Martin GreenwaldDud
Sep 30 2002 11:05:09:830AM1020930008Martin GreenwaldPlasma - very low density
below H-mode threshold
raise for next shot
Sep 30 2002 11:20:34:510AM1020930009Martin GreenwaldPlasma
RF power only 1 MW, no H-mode
Sep 30 2002 11:32:46:560AM1020930010Martin Greenwaldfizzle
Sep 30 2002 11:52:34:373AM1020930011Martin GreenwaldPlasma H-mode
QC mode seen on PCI

delta_av = 0.56
delta_l = 0.4
delta_u = 0.7
q95 = 5.3
Sep 30 2002 12:05:49:580PM1020930012Martin Greenwaldfizzle
Sep 30 2002 12:24:54:843PM1020930013Martin Greenwaldfizzle
Sep 30 2002 12:49:56:163PM1020930014Martin Greenwaldfizzle
Sep 30 2002 01:00:24:540PM1020930015Martin GreenwaldH-mode

QC mode seen on PCI

delta_av = 0.56
delta_u = 0.4
delta_l = 0.7
q95 = 5.3
Sep 30 2002 01:18:50:160PM1020930016Martin Greenwaldfizzle
Sep 30 2002 01:32:27:417PM1020930017Martin Greenwaldfizzle

Physics Operator Comments
Sep 30 2002 09:19:53:217AMBill Rowanngineering setup for Monday, September 30th, Run 1020930

Either MP#312 or #304 depending on the availability of PCI
If PCI is available, then MP 304.

MP#312 Toroidal Rotation Profiles in Ohmic H-modes
Session Leader: Mr. Lee
Physics Operator: Rowan

MP#304 H-mode regimes
Session leader: Greenwald
Physics Operator: Rowan
For the experiment, use segment 2 of 1020625021 and segment 1
of a more recent shot for breakdown.
The overall strategy is to pick a triangularity, get an H-mode. If
it is EDA, we scan up in current (down in q) till the discharge goes
ELMfree. If it is ELMfree, we scan down in current till it goes
EDA. Then choose a new value of triangularity.


ECDC overnight in D2 stopping by 07:00 on Monday morning..
Bake at 60C

Set up for possible ECDC in D2 between shots.

Power systems as on 1020925007

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC)
fill C-side with 30 psi D2 Hybrid enabled (PG3)
leave J-Bottom as is Hybrid DISABLED (PG5)

Enable the following gate valves:
ECE, VUV, DNB

-------------------------------------------------------------------------------
RF Setup: FMIT#1 and 2 transmitters in Run On by 08:00
-------------------------------------------------------------------------------
Sep 30 2002 09:38:32:043AMBill Rowanstarted pcs

loaded 1020927032. Will use this for the breakdown

imported segment 2 from 1020625021 to meet requirements for the run

Did a load/clean
Load at 30-Sep-2002 09:30:48.0

Did a cold start

rtnode -- data loaded, A matrix responds
rtnode -- data loaded, M matrix responds
rtnode -- data loaded, PID matrix responds
RT_NODE Done

30-SEP-2002 09:33:30.14 doing TCL command TYPE *************** END COLD
START ******************
*************** END COLDSTART ******************
Sep 30 2002 10:17:20:163AMBill Rowan005. Dud

Next shot. Raise BZ by approximately 1 mT. Increased IC_ef4 from -1330 to -1315
Lowered BR_0 by 0.5 mT. Offset changed from 0.002 to 0.0015
Added 1 ms of prefill. PG4. Makes it 29 ms.
Sep 30 2002 10:29:13:197AMBill Rowan006. Dud.

Next shot. Increased the gas fill again. PG$ is notw 30 ms.
Sep 30 2002 10:38:42:070AM1020930007Bill Rowan007. Dud.

Nest shot. ECDC for 10 minutes before the next shot.
Sep 30 2002 11:06:20:677AM1020930008Bill Rowan008. Plasma. Low density. Copied shot requested it.

Next shot. Increase NL_04 from 0.3e20 demand to 1.0e20 demand.
Sep 30 2002 11:26:15:833AM1020930009Bill Rowan009. PlasmaN

Next shot. Moved zxu out by 1.5 cm to get rid of double null
Also moved zcur to -0.015 instead of the 0 in the last shot.
Sep 30 2002 11:40:01:760AM1020930010Bill Rowan010. Fizzle

Next shot. Added 2 ms to the gas feed
Increase BZ_0 by 0.5 mT.
Sep 30 2002 11:53:30:937AM1020930011Bill Rowan011. Plasma.
SL wants more triangularity

Next shot. Moved zxu back in by approximately 0.5 cm.

Sep 30 2002 12:04:55:313PM1020930012Bill Rowan012. Fizzle

Next shot. ECDC before the next shot.
Sep 30 2002 12:31:51:493PM1020930013Bill Rowan013. Fizzle.

Next shot.
Decrease BZ-) by 1 mT
Decreaed the prefill by 1 ms. This was actually high on shot 012 as well.
Sep 30 2002 12:51:59:103PM1020930014Bill Rowan14. Fizzle

Next shot. Increase BR-0 by 0.5 mT to match the breakdown of the
last shots on Friday.
Sep 30 2002 01:01:53:027PM1020930015Bill Rowan015. Plasma, finally.

Next shot. moved zxu from 0.03 tp 0.027. This is more sensitive than
I thought.
Sep 30 2002 01:28:18:957PM1020930016Bill Rowan016. Fizzle.
The pressure on this shot is slightly higher on this shot than on
1020927032.

Next shot. Reduce the prefill by 2 ms. PG4 is now 29 ms.
Sep 30 2002 01:49:59:680PM1020930017Bill Rowan017. Fizzle.
Commutation failure on OH2L

Next shot: no changes
Sep 30 2002 02:01:45:057PM1020930017Bill RowanEngineers supect a blown switch SCR. Delay for at least an hour if that is the case
Sep 30 2002 02:49:56:003PM1020930017Bill RowanThe run is ended. There is a short in one of the caps in OH2L.

Engineering Operator Comments
ShotTimeTypeStatusComment
107:23:24:350AMTestOkData System Test: Some PS Camacs offline
207:57:10:120AMTestOkData System Test
308:12:55:583AMTestOkData System Test
408:49:29:480AMTestOkData System Test
510:02:09:203AMPlasmaOk
610:19:09:337AMPlasmaOk
710:32:19:077AMPlasmaOk
810:53:46:220AMPlasmaOk
911:08:37:853AMPlasmaOk
1011:28:16:460AMPlasmaOk
1111:42:13:293AMPlasmaOk
1211:56:18:223AMPlasmaOk
1312:22:50:467PMPlasmaOk
1412:39:38:100PMPlasmaOk
1512:53:59:797PMPlasmaOk
1601:14:16:873PMPlasmaOk
1701:30:34:947PMPlasmaOk