Miniproposals

Miniproposal: 364 Date Filed: 11/14/2003 Title: Measurement of wall pumping on Alcator C-Mod First Author: Bruce Lipschultz Session Leader: Bruce Lipschultz (shots 1-34)

Engineering Operator Run Comment

Boronization Recovery PO: Irby; EO: Dekow/Fitz/Parkin

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:34:820PM

Author: Bruce Lipschultz

Conditioning and cleanup with piggyback of MP 364 - 'Measurement of wall pumping on Alcator C-Mod' This mini-proposal has a number of interconnected goals all having to do with the wall sources and sinks of neutrals. First we would like to determine the role of the wall/limiters as a source of neutrals during RF power injection. The role of boronization in affecting the wall pumping/sources will be addressed. Understanding the processes involved will help us better control the plasma density (better understand the utility of the cryopump) and perhaps the H/D ratio. A further goal is to understand the scaling of pumping processes to enable prediction of the T stored in a high-Z first-wall in a BPX w/B in the vessel. Summary of results: Between 1031106 and 1031107 the machine was boronized. On 1031107 we were back in piggyback mode on top of boronization recovery and conditioning. H/D was significantly lower (3-4%) and the walls were outgassing through almost the entire day (unusual). So we would have to say that boronization certainly loads up the walls with gas. And that gas is D which, when it comes out, lowers H/D. We also looked at all shots for a given day and integrated all gas in and gas out over the shots where it was measured. On 1031104 there was a surfeit of 9% of the gas puffed (26 torr-liters) of gas out over in. This changed to 9% of the 528 torr-liters puffed (49 torr-liters) being pumped on 1031106, the day with the most shots measured. Finally, on 1031107 (after boronization) there again was a surplus of gas out over in of 13% (17 torr-liters).

Physics Operator Summaries

Entered: Jul 7 2004 04:37:19:660PM

Author: Jim Irby

Run 1031107: Boronization Recovery Engineering setup for Friday, 07 Nov 2003 Purpose: Recovery from Boronization EO: Dekow, Fitzgerald, Parkin Physics operator: Irby The machine was boronized overnight with 140 psi of B2D6 resulting in an average deposition thickness of 2048A. Following boronization, approximately 90 minutes of ECDC in D2 was done. Run begins at 09:00 and ends at 17:00. Power systems the same as on 1031106008 (0.8 MA, 5.4 T, lower single null) A-coils should be hooked up as on 1030507012 (+Dtop -Dbot -Jtop +Jbot), but the power supply should NOT be enabled. 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) Enable the following gate valves: ECE, VUV, DNB --------------------------------------------------------------------- RF Setup: All 4 transmitters in Run On by 08:00. --------------------------------------------------------------------- Run Plan: Start with lower null plasmas and bring up machine and rf as possible. --------------------------------------------------------------------- Summary: We had many duds and fizzles today. I'm sure operation will be much better next week after a few days of ecdc. We devoted the first 5 shots to fixing a problem with the data system. It turned out to be a bad power supply in the bus HV camac crate. We got our first plasma on shot 7, with about 1.5 MW of rf, and a nice h-mode. Then we had a series of fizzles and duds until shot 14 which was another good plasma. The h/(h+d) was down to 3 or 4% for these shots and the carbon II light was down a factor of 3 or 4 indicating that the boronization did its job. The difficulty with recovery also indicated that we had covered surfaces well. Shot 16 was a good shot with the h-mode beginning very soon after application of rf (as opposed to 7 and 14 with a 200 ms delay). RF struggled to get going again after boronization. Unfortunately there were only a few plasmas for them to get going on. The prefill gas pressure varied wildly from shot to shot. So I spent a great deal of effort trimming the gas puff pulse width. It seemed that a +-5% change in prefill pressure could take you from dud to fizzle. We should think of a better way to control the gas. The ratiomatic gauge also misbehaved on several shots, making it particularly hard to figure out what was going on. Steve Wolfe noted a problem with the EF1L power supply similar to the problem we had in 1999. Since we had the problem all day yesterday, it probably is not affecting startup, but we should look at the problem on Monday. Things to fix on Monday: EF1L G-Side Ratiomatic RF may want to vacuum condition on Monday Score: Duds 11,12,13,16,18,23,24,28,32,33,34 Fizzles 06,08,09,10,15,21,26,27,30,31 Plasmas 07,14,17,19,20,22,25,29 Tests 01,02,03,04,05

Session Leader Comments

Physics Operator Comments
Nov 7 2003 07:59:16:737AM		Jim Irby	Engineering setup for Friday, 07 Nov 2003 Purpose: Recovery from Boronization EO: Physics operator: Irby The machine was boronized overnight with 140 psi of B2D6 resulting in an average deposition thickness of 2048A. Following boronization, approximately 90 minutes of ECDC in D2 was done. Run begins at 09:00 and ends at 17:00. Power systems the same as on 1031106008 (0.8 MA, 5.4 T, Lower single null) A-coils should be hooked up as on 1030507012 (+Dtop -Dbot -Jtop +Jbot), but the power supply should NOT be enabled. 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) Enable the following gate valves: ECE, VUV, DNB ------------------------------------------------------------------------------- RF Setup: All 4 transmitters in Run On by 08:00. ------------------------------------------------------------------------------- Run Plan: Start with lower null plasmas and bring up machine and rf as possible.
Nov 7 2003 08:40:16:813AM		Jim Irby	Loaded seg 2 with seg 2 from 1031106008 Initial EF4 setting from yesterday -1330. Dropped density request to 0.8e20 / m^2
Nov 7 2003 08:59:30:533AM	1031107001	Jim Irby	Cycle test to check gas and data system Note that gas was 0.04 mTorr vs 0.06 on the last shot from yesterday Had lots of data system errors: no magnetics, no power room data PO jumped the gun and started test shot before PCS was fully loaded. Reloaded PCS and then did Hybrid coldstart to get everything in sync again.
Nov 7 2003 09:08:10:277AM	1031107002	Jim Irby	Second test shot to make sure data system is back online Still have data system troubles! Gas puff still low (.04)
Nov 7 2003 09:37:25:020AM	1031107003	Jim Irby	Another cycle test --- cycled highway driver Somewhat better, but still having missing data. Will try taking some crates out of the loop for the next test.
Nov 7 2003 09:52:38:570AM	1031107004	Jim Irby	Data system looks much better, but still a missing signal or two gas puff has not changed during the four cycle tests --- will raise it for the first plasma attempt.
Nov 7 2003 10:09:47:370AM	1031107005	Jim Irby	changed bus HV camac crate power supply pre puff increased from 22 to 25 ms. data system is now operational --- next shot try for plasma little more gas, but will increase a little more for next shot.
Nov 7 2003 10:24:09:983AM	1031107006	Jim Irby	pre puff from 25 to 27 ms Try for plasma --- fizzle --- prepuff a little high --- CII much lower than yesterday
Nov 7 2003 10:47:52:060AM	1031107007	Jim Irby	pre puff back to 25 ms ef4 from -1330 to -1300. basepressure before shot 4.1e-7 Torr plasma into rampdown --- nice h-mode with 1.5 MW of rf takes 200 ms to get into h-mode about 70 kJ of stored energy BIII signal is actually lower than on shot 08 from yesterday! CII signal factor of 2 to 4 down H/(H+D) 3 to 4 %
Nov 7 2003 10:53:14:163AM	1031107008	Jim Irby	EF4 from -1300 to -1310 --- Bz0 a little high compared to yesterday, and may go higher still next this shot fizzle --- fields and gas looked okay
Nov 7 2003 11:06:01:733AM	1031107009	Jim Irby	fizzle
Nov 7 2003 11:23:15:737AM	1031107010	Jim Irby	EF4 to -1320 pre puff to 23 ms from 25 ms fizzle --- play with EF4 again next shot
Nov 7 2003 11:37:55:990AM	1031107011	Jim Irby	Bz0 looks high compared to shot 8 from yesterday, also last shot EF4 back to -1330 --- yesterday's setting Dud ----
Nov 7 2003 11:53:15:667AM	1031107012	Jim Irby	EF4 to -1300 --- back to what we had on shot 007 dud!
Nov 7 2003 12:16:03:257PM	1031107013	Jim Irby	try to match yesterday's shot 29 a little better: ef4 to -1310 pre puff from 23 to 24 ms data system problem --- no power shot
Nov 7 2003 12:34:50:760PM	1031107014	Jim Irby	plasma into rampdown --- rf power about 1.5 MW --- h-mode after 200 ms
Nov 7 2003 12:35:42:367PM	1031107015	Jim Irby	no pcs changes fizzle --- didn't drop prepuff --- pressure high compared to 14
Nov 7 2003 12:56:52:587PM	1031107016	Jim Irby	gas puff to 22 ms from 24. dud --- gas still higher than on 14
Nov 7 2003 01:11:29:357PM	1031107017	Jim Irby	gas to 21 ms from 22 ms plasma into rampdown --- current rise a little faster than on 14, pressure a little lower tci feedback hene counter driven to limit --- feedback signal too low early in shot h-mode started earlier than on 14, but lost most of rf and h-mode after 1.1 s 76 kJ
Nov 7 2003 01:19:21:943PM	1031107018	Jim Irby	no pcs changes dud --- gas too high again, should have dropped it a little before shot
Nov 7 2003 01:40:47:223PM	1031107019	Jim Irby	pre puff from 21 to 20 ms plasma into rampdown --- clean startup rf power down a little --- h-mode a little later than on 17
Nov 7 2003 01:52:35:260PM	1031107020	Jim Irby	no pcs changes plasma into rampdown ---- short h-mode, lots of rf interupts gas and fields very similar to 19
Nov 7 2003 01:58:00:710PM	1031107021	Jim Irby	no pcs changes fizzle --- pressure is up again!
Nov 7 2003 02:25:35:783PM	1031107022	Jim Irby	pre puff from 20 to 19 ms. plasma --- clean but short h-mode period starting at .77 s
Nov 7 2003 02:39:23:460PM	1031107023	Jim Irby	no pcs changes dud --- gas now too low --- this is fun
Nov 7 2003 02:46:44:250PM	1031107024	Jim Irby	gas from 20 to 21 ms dud --- gas still low!
Nov 7 2003 03:11:30:887PM	1031107025	Jim Irby	pre puff from 21 to 23 ms plasma into rampdown --- gas and current startup identical to shot 17
Nov 7 2003 03:12:56:963PM	1031107026	Jim Irby	fizzle --- gas now too high
Nov 7 2003 03:23:49:107PM	1031107027	Jim Irby	gas back to 21 ms fizzle --- gas very low
Nov 7 2003 03:35:39:810PM	1031107028	Jim Irby	pre puff to 22 ms dud --- gas a little low now but...
Nov 7 2003 03:59:08:747PM	1031107029	Jim Irby	pre puff back to 23 ms plasma --- short h-mode starting late prefill pressure an overlay of shot 17 h/(h+d) still 3 to 5%
Nov 7 2003 04:13:08:857PM	1031107030	Jim Irby	no pcs changes --- will probably regret it fizzle --- pressue down a factor of two! Gauge problem....
Nov 7 2003 04:19:32:903PM	1031107031	Jim Irby	no pcs changes fizzle --- gas 10% high again asked rf to turn off j-port since it seems to need vacuum conditioning anyway.
Nov 7 2003 04:32:15:370PM	1031107032	Jim Irby	pre puff to 21 ms DNB given up for the day --- gatevalve will be closed rest of run dud --- gauge out to lunch again
Nov 7 2003 04:42:39:387PM	1031107033	Jim Irby	import seg 1 from shot 1031107017 to seg 1 Steve Wolfe has noted a problem with the EF1L power supply --- probably not affecting our startup since we had the problem all day yesterday. dud --- no gauge
Nov 7 2003 04:54:22:760PM	1031107034	Jim Irby	prefill to 23 ms one last time --- this is the last try dud --- done

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:40:37:063AM	Test	Ok
2	09:03:46:000AM	Test	Bad	camac problems
3	09:28:36:840AM	Test	Bad	Nox error on camac
4	09:39:34:753AM	Test	Ok
5	10:01:08:580AM	Test	Ok
6	10:10:54:587AM	Plasma	Ok
7	10:31:33:010AM	Plasma	Ok
8	10:46:45:920AM	Plasma	Ok
9	10:59:33:943AM	Plasma	Ok
10	11:12:15:070AM	Plasma	Ok
11	11:24:44:720AM	Plasma	Ok
12	11:39:28:333AM	Plasma	Ok
13	11:55:00:150AM	Test	Bad	Data System Hung
14	12:17:27:083PM	Plasma	Ok
15	12:31:02:950PM	Plasma	Ok
16	12:43:35:377PM	Plasma	Ok
17	12:59:03:350PM	Plasma	Ok
18	01:12:15:667PM	Plasma	Ok
19	01:24:54:987PM	Plasma	Ok
20	01:37:21:900PM	Plasma	Ok
21	01:52:54:917PM	Plasma	Ok
22	02:09:51:967PM	Plasma	Ok
23	02:28:09:077PM	Plasma	Ok
24	02:40:36:397PM	Plasma	Ok
25	02:53:42:060PM	Plasma	Ok
26	03:06:36:440PM	Plasma	Ok
27	03:19:32:357PM	Plasma	Ok
28	03:32:18:917PM	Plasma	Ok
29	03:44:51:510PM	Plasma	Ok
30	03:59:40:310PM	Plasma	Ok
31	04:12:50:213PM	Plasma	Ok
32	04:25:18:480PM	Plasma	Ok
33	04:38:00:323PM	Plasma	Ok
34	04:52:02:417PM	Plasma	Ok