Alcator C-Mod Run 1060707 Information

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Miniproposals
Miniproposal:445
Date Filed: 3/1/2006
Title: Ti measurements in ITB plasmas
First Author:Kirill Zhurovich
Session Leader:Kirill Zhurovich (shots 1-31)

Operators
Session leader(s):Kirill Zhurovich
Physics operator(s):Bill Rowan
Engineering operator(s):Andy Pfeiffer,Bill Parkin

Engineering Operator Run Comment
automatically entered by signon - please replace with real comment

Session Leader Plans
Entered: Jul 6 2006 11:05:07:163AM
Author: Kirill Zhurovich

MP #445 "Ti measurements in ITB plasmas"

The purpose of this experiment is to understand triggering mechanism for producing off-axis ICRF internal transport barriers. The question of whether ITB formation can be explained in the framework of suppressing ITG turbulence via increasing ion temperature scale length to the critical scale length is the target.
This idea will be tested by varying Bt and thus shifting the RF resonance location on shot-to-shot basis.

This is an extension and continuation of the MP 422 and run 1050707.

Required diagnostics: all standard core diagnostics, especially TS, ECE, HIREX, PCI, reflectometery +CHERS (if available)

Overnight boronization before this run.
Set up ECE diagnsotics for 5.4-6.45 T operation
ICRF - 80MHz, D&E only, 2-2.5MW. Be ready to switch to J antenna operation.

Proposed Bt, Ip scan:

Bt Ip
5.4 0.9
5.5 0.917
5.6 0.933
5.7 0.95
5.8 0.967
5.9 0.983
6.0 1.0
6.1 1.017
6.2 1.033
6.3 1.05
6.4 1.067
6.45 1.075

Note that these numbers are approximate and that the actual ones are a bit different. First, establish an ITB at higher field. 1050707019 is a good candidate.
Then start Bt scan with 0.2T increment/decrement, filling the gaps later in the day as time allows.
We may want to try small Bt sweeps during the shots to derive Te gradients better.

We should expect first plasma at around 10am, because RF group needs some time to fix D antenna problem.
-

Physics Operators Plans
Entered: Jul 6 2006 12:13:53:873PM
Author: Bill Rowan
Physop plan and engineering setup for Friday, 07-Jul-2006

MP #445 "Ti measurements in ITB plasmas"
SL: Zhurovich
PO: Rowan

Overnight boronization on Thursday 7/6/2006

Follow boronization with 4 hours ECDC in helium.

The run will start at 9:00 and end at 17:00.

Engineering setup:
-------------------
Power system setup as on 1050707019

A-coil configuration: normal [+Dtop -Dbot -Jtop +Jbot] and enabled.

Gas Setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
leave NINJA as is DISABLED

We will want to be ready to use between-shot boronization during the run,
but do not open the bottle until requested.

Enable the following gate valves and shutters: ECE,VUV,Z-bolo shutters;
these must be disabled for between-shot boronization
MSE shutter should be CLOSED before the run and remain closed.

Key diagnostics: TS, ECE, HIREX, PCI, reflectometery

FMIT#1,2 in Run-on by 8:30AM
Note that the SL wants the possibility of using J so FMIT #3,4 may be needed.

Session Leader Summaries
Entered: Jul 7 2006 06:14:02:140PM
Author: Kirill Zhurovich
MP #445 "Ti measurements in ITB plasmas"
SL: Kirill Zhurovich
PO: Bill Rowan

We started with D&E 80Mhz setup, 6.3T (ITB range) operation. The first plasma shot (3) had a weak ITB. After that we struggled with the machine performance, having trouble getting nice, long H-modes not to mention ITBs. Most of the shots had brief late or multiple H-modes where Molly injections were an issue. Tried to tweak plasma parameters (taget density, current, RF power) to ease an access to H-modes.
Finally (by ~2:30pm) we swithched to J-antenna 70Mhs lower field operation. Got some useful shots for Bt scan:
22-5.4T, long H-mode with weak ITB; no Ar puff this shot
23-5.4T, weak ITB
25-5.5T, long H-mode, weak ITB, but the best today
28-5.2T, multiple H-modes (not clear how useful this shot is)
29-5.0T, long H-mode
31-4.8T, long H-mode

Physics Operator Summaries
Entered: Jul 10 2006 01:15:07:603PM
Author: Bill Rowan
C-Mod and the RF ran reasonably well during this run. Boronization was completed on the evening before this run. A weak ITB was generated on the first plasma shot 003. Impurity injection was a problem throughout the run and caused disruptions on several shots. The impurity content may account for the lack of ITB's. Impurities were also a problem in the two previous attempts to generate ITB's at these conditions during this campaign (1060502 and 1060504). One source for the impurity problem for this run may have been that the ICRF resonance was very close to the tips of the RF antenna. This led to the decision to attempt the experiment at 70 MHz with J antenna and at lower TF. See SL comments for results and reasons for changing.

Since the target discharge for this run was from 2005, segment 1 was clearly to be taken from a more recent run. Attempted to use the last shot from 1060705. This resulted in a dud. It seemed simpler to select a different shot for segment 1 than to try to fix the one from 1060705. Segment 1 from 1060623017 proved to work just fine. One shot (002) was lost because the PhysOp missed predictor recalculation for one of the several wires for which it was required. A computer or triggering hardware problem caused loss of two shots (007 and 008).

Score Card

Plasma 24 (002,003,004,005,006,009,010,011,013,
014,015,016,017,018,019,020,021,022,
023,025,028,029,030,031)
Fizzles 4 (012,024,026,027)
Dud 1 (001)
No power shots 2 (007,008)

Total 31


Session Leader Comments
Jul 7 2006 09:12:46:810AM1060707001Kirill ZhurovichDud.
Enable Ar puff for the next shot
Jul 7 2006 09:27:00:423AM1060707002Kirill ZhurovichDisruption at ~0.19s
Bt is 5.4T instead of 6.3T ???
Jul 7 2006 09:45:11:387AM1060707003Kirill ZhurovichLooks like weak ITB.
No HIREX data.
Enable Ar puff for the next shot.
Jul 7 2006 10:00:52:953AM1060707004Kirill ZhurovichIf there si an ITB it's even weaker than the previous one, but RF drops to 1MW at the time of possible ITB formation (this is the reason?)
HIREX does not see Ar.
Next: increase RF to 2.5MW, increase Ar puff time to 50ms
Jul 7 2006 10:20:44:290AM1060707005Kirill ZhurovichH mode starts at ~1s when E antenna drops out completely - I don't get it...
No ITB, no HIREX data because voltage on the Ar puff was too low.
Jul 7 2006 10:55:03:350AM1060707006Kirill ZhurovichVery late H-mode, no ITB, of course.
H-modes are getting later and later every shot...
Next: cut the Ar puff down to 40ms (I guess), increase Ip by 100kA to have more ohmic power.
Jul 7 2006 11:32:49:723AM1060707009Kirill ZhurovichNo H-mode at all :(
Next: remove Ar puff, lower the target density
Jul 7 2006 12:14:42:317PM1060707010Kirill ZhurovichMultiple H-modes, no ITB.
Next: increase Bt to 6.4T, current by another 100kA, no Ar
Jul 7 2006 12:13:31:740PM1060707011Kirill ZhurovichDisruption at ~0.374s likely due to the injections
Jul 7 2006 12:41:46:890PM1060707013Kirill Zhurovich3 brief H-modes, no ITB.
Back transitions are likely due to RF trips
Jul 7 2006 12:46:18:703PM1060707014Kirill ZhurovichDisruption at ~0.33s, looks like an explosion on TV
Jul 7 2006 01:03:06:883PM1060707015Kirill ZhurovichMultiple H-modes, no ITB
Jul 7 2006 01:32:13:160PM1060707016Kirill ZhurovichMultiple H-modes with no ITBs
Jul 7 2006 01:52:13:963PM1060707017Kirill ZhurovichDisruption at ~.56s likely due to injection
Jul 7 2006 02:23:28:697PM1060707019Kirill Zhurovich3 H-modes, no ITBs.
Next: Go to 5.4T with J antenna (70Mhz) operation.
Jul 7 2006 02:32:57:523PM1060707020Kirill ZhurovichStrange H-mode with hardly any RF at all, no ITB
Jul 7 2006 02:44:05:107PM1060707021Kirill ZhurovichBrief H-mode, RF is tripping, no ITB
Jul 7 2006 03:06:51:083PM1060707022Kirill ZhurovichNice and long H-mode, hint of weak ITB.
Jul 7 2006 03:29:11:187PM1060707023Kirill ZhurovichI guess weak ITB again.
Next: increase Bt to 5.5T
Jul 7 2006 03:49:34:727PM1060707025Kirill Zhurovich5.5T, Long H-mode, ITB - not the great one, but the best so far today
Next: Bt scan, go to 5.2T
Jul 7 2006 04:24:50:287PM1060707028Kirill ZhurovichMultiple H-modes.
Jul 7 2006 04:42:24:887PM1060707029Kirill ZhurovichNice, long H-mode
next: go down to 4.8T
Jul 7 2006 04:51:20:110PM1060707030Kirill ZhurovichDisruption at ~.84s
Jul 7 2006 05:02:24:753PM1060707031Kirill Zhurovich4.8T , long H-mode

Physics Operator Comments
Jul 7 2006 08:16:31:740AMBill RowanOvernight boronization before this run.

Approximately 4.5 hours ECDC in helium before this run.

A-coils returned to their normal configuration by Ed and checked by Gary
(+Dtop -Dbot -Jtop +Jbot)

Jul 7 2006 08:53:32:397AMBill RowanLoaded 1050707019.
Recalculated predictors listed in Steve's e-mail of 5/19/06

Loaded segment 1 from 1060705024 for the startup
Did not use the startup from 1060706 because it was the startup for 8T

Jul 7 2006 08:54:49:897AMBill Rowan
The prepuff is 14 ms so leave it there.

Jul 7 2006 09:21:29:767AM1060707001Bill Rowan001. Dud
No data from sparker. Do not know whether it worked.
BZ0 very negative. Now unsure of this startup
Loaded a different startup: segment 1 from 1060623017

Jul 7 2006 09:33:11:770AM1060707002Bill Rowan002. Plasma. Disrupted at 0.228 s

Next shot
recalculated the RCUR predictor
my attempt before the run did not work for rcur
recalculations were taken for the other magnetics predictors

Jul 7 2006 09:48:07:980AM1060707003Bill Rowan003. Plasma. Full length.
ITB (?) at 1 s

Next shot.
enable argon. puff starts at 35 ms and continues for 40 ms

Jul 7 2006 09:55:51:500AM1060707004Bill Rowan004. Plasma.


Next shot
increase argon pulse by 10 ms to 50 ms (PG1)

Jul 7 2006 10:12:45:897AM1060707005Bill Rowan005. Plasma

Next shot.
Increase the pulse on PG1 fropm 10 to 100

Jul 7 2006 10:41:55:437AM1060707006Bill Rowan006. Plasma

Next shot.
Increase IP to 1.1 MA

Jul 7 2006 10:53:16:897AM1060707007Bill Rowan007. No plasma.
Probably no trigger.
Checking with Tom



Jul 7 2006 10:58:18:537AM1060707007Bill Rowaninit died in the middle of the last shot
Tom suggests a no power cycle

Jul 7 2006 10:58:33:007AM1060707007Bill RowanNext shot.
No power cycle.

Jul 7 2006 11:19:33:623AM1060707008Bill Rowan008. No power shot.

Next shot. Plasma attempt

Jul 7 2006 11:31:31:050AM1060707009Bill Rowan009. Plasma

Next shot.
Search for H-mode.
disable pg1 (turn off the argon)
lower nl04 to from a demand of 1.1e+20 to a demand of 0.9e+20

Jul 7 2006 11:47:44:650AM1060707010Bill Rowan010. Plasma
H-modes
No ITB

Next shot.
Increase the TF from 6.27 T (175368A) to 6.4 T (179000A)
Increase Ip from 1.1 MA to 1.2 MA

Jul 7 2006 12:08:15:643PM1060707011Bill Rowan011. Plasma.
Disrupted at 0.376 s
Probably an injection

Next shot.
IP from 1.2 MA back to 1.0 MA

Jul 7 2006 12:23:01:710PM1060707012Bill Rowan012. Post disruption fizzle

Next shot.
Reduced prefill from 21 ms to 20 ms

Jul 7 2006 12:41:42:123PM1060707013Bill Rowan013. Plasma
Intermittent H-modes
No ITB

Next shot.
No PCS changes
Retune RF

Jul 7 2006 12:53:12:973PM1060707014Bill Rowan014. Plasma
Early disruption due to injection

Next shot.
No PCS changes
Jul 7 2006 01:23:49:470PM1060707015Bill Rowan015, Plasma

Next shot.
Reduce the density demand from 0.9e+19 to 0.8e+19
Reduce the TF to 6.3 T
Jul 7 2006 01:49:13:213PM1060707017Bill Rowan017, Plasma
Disruption at 0.56 s
Injection

Next shot.
No PCS changes

Jul 7 2006 02:01:34:547PM1060707018Bill Rowan018. Plasma
Many injections as on previous shots

Next shot.
BT reduced to 6.0 T.
Preparing RF to change to 70 MHz

Jul 7 2006 02:29:35:883PM1060707019Bill Rowan019. Plasma

Next shot
BT reduced to 5.4 T
Ip = 0.8 MA
nl_04 = 1.0e+20
70 MHz RF

Jul 7 2006 02:53:39:580PM1060707021Bill Rowan021. Plasma

Next shot. No PCS changes

Jul 7 2006 03:16:04:823PM1060707022Bill Rowan022. Plasma
Long H-mode

Next shot.
Argon puff enabled

Jul 7 2006 03:28:23:013PM1060707023Bill Rowan023. Plasma

Next shot
BT increased to 5.5T (152800 A)

Jul 7 2006 03:35:21:080PM1060707024Bill Rowan024. Fizzle

Next shot.
Increase BZ0 by 1 mT. IC_EF4U changed from -1325 to -1310

Jul 7 2006 03:49:42:180PM1060707025Bill Rowan025. Plasma
BT=5.5 T

Next shot.
Reduce TF to 5.2 T (144400 A)

Jul 7 2006 04:02:16:887PM1060707026Bill Rowan026. Fizzle

Next shot.
IP reduced to 756 kA
No other PCS changes

Jul 7 2006 04:13:10:610PM1060707027Bill Rowan027. Fizzle

Next shot.
Reduce the prefill puff from 20 ms to 18 ms

Jul 7 2006 04:26:59:553PM1060707028Bill Rowan028. Plasma
BT=5.2 T
IP = 0.75 MA

Jul 7 2006 04:27:12:600PM1060707028Bill RowanNext shot
Reduce the prefill puff from 18 to 17 ms

Jul 7 2006 04:31:23:960PM1060707028Bill RowanNext shot
Reduce the prefill puff from 18 to 17 ms
Reduce BT to 5.0 T (138900 A)
Reduce IP to 727 kA

Jul 7 2006 04:44:37:857PM1060707029Bill Rowan029. Plasma
BT = 5.1 T
IP= 726 kA

Next shot
Reduced the prefill putt from 17 ms to 16 ms
ReducedBT to 4.8T (133300 A)
Reduce Ip to 698 kA

Jul 7 2006 04:53:47:297PM1060707030Bill Rowan030. Plasma
BT = 4.8 T
IP = 694 kA
disrupted at 0.85 s

Next shot.
No PCS changes

Jul 7 2006 05:01:30:440PM1060707031Bill Rowan031. Plasma
Last shot.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:02:24:460AMPlasmaOk
209:23:06:000AMPlasmaOk
309:36:00:833AMPlasmaOk
409:49:17:417AMPlasmaOk
510:07:28:893AMPlasmaOk
610:25:32:807AMPlasmaOk
710:43:12:440AMTestBad
811:00:18:180AMTestBadCYCLE TEST
911:22:29:187AMPlasmaOk
1011:35:09:363AMPlasmaOk
1111:55:08:920AMPlasmaOk
1212:16:36:410PMPlasmaOk
1312:29:04:980PMPlasmaOk
1412:43:17:453PMPlasmaOk
1512:58:53:380PMPlasmaOk
1601:27:11:390PMPlasmaOk
1701:39:51:443PMPlasmaOk
1801:52:41:387PMPlasmaOk
1902:05:23:877PMPlasmaOk
2002:24:45:133PMPlasmaOk
2102:37:53:637PMPlasmaOk
2203:01:11:350PMPlasmaOk
2303:13:55:587PMPlasmaOk
2403:28:58:373PMPlasmaOk
2503:41:48:723PMPlasmaOk
2603:54:33:040PMPlasmaOk
2704:08:24:090PMPlasmaOk
2804:20:52:330PMPlasmaOk
2904:33:26:040PMPlasmaOk
3004:46:14:530PMPlasmaOk
3104:58:47:580PMPlasmaOk