Miniproposals

Miniproposal: 440 Date Filed: 11/17/2005 Title: Erosion of boronization under different conditions First Author: Bruce Lipschultz Session Leader: Bruce Lipschultz (shots 1-23)

Engineering Operator Run Comment

MP# : Erosion of boronization Session leader: B. Lipschultz Physics oper

Session Leader Plans

Entered: Nov 18 2005 01:43:09:397PM

Author: Bruce Lipschultz

Toroidal Field: 5.3 Tesla (normal direction) ramping down to 4T for Ohmic H-modes Plasma Current: 1.2 MA (normal direction) Working Gas Species: D2 Density: NL04 ~ 1.0 x 1020 m-2 Equilibrium configuration: start from 1050810014 but with 1.2 MA and field ramped down to 4T RF Power, pulse length, phasing: none Impurity gas injection NONE - that means no Ar or Ne Pellet Injection (species): none Impurity blow-off injection: none Diagnostic Neutral Beam: not required Special gas puffing: Non-axisymmetric Coils (Connections, Current); compensation if needed to avoid locked-modes Run plan a) - 2-4 shots with Ohmic H-modes to develop them and determine the proper field to ramp down to. b) ECDC boronization w/resonance at R=90 cm (field sweep range 10 cm total) for 20 minutes (if using 10% diborane). The RF should not be pulsed (100% duty cycle). Follow this with as many shots as needed to evaluate effect and wear it off. c) Step resonance location inward in major radius to locations at 80, 75, 70, 65, 60 cm. After each boronization evaluate the effect on Mo source rates, IR camera images, Mo levels in core and rise with H-modes. d) If there is a minimum return to it and reevaluate that spot.

Physics Operators Plans

Entered: Nov 21 2005 08:56:43:447AM

Author: Earl Marmar

Engineering setup for Monday 21 Nov 2005 MP#440 : Erosion of boronization Session leader: B. Lipschultz Physics operator: E. Marmar Weekend ECDC in D2 and bake at 60 C. Run begins at 09:00 and ends at 17:00. Power systems as on 1050810014. We will be increasing Ip to 1.2 MA, and ramping the TF down during the pulse to 4T to obtain ohmic H-modes 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 + 2 psi Ne Hybrid DISABLED (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) fill NINJA with 10 psi D2 Leave DISABLED Enable the following gate valves and shutters, assuming no vacuum problems: ECE, VUV, Z-bolo shutters Torvac setup: Gate valves open NOTE: This run requires that both TMP1 and TMP2 be operational and pumping the torus We will use between-shot boronization during this run. We should start the day with the diborane bottle closed, until we get our target plasma. *******After the diborane bottle is opened, the cell and power room will be off-limits, except for SCBA equipped personnel********** ------------------------------------------------------------------------------- ICRF Setup: No RF required for the run today.

Session Leader Summaries

Entered: Nov 22 2005 06:37:00:133PM

Author: Bruce Lipschultz

A small fraction of the run plan was accomplished today: - We developed the 1.2 MA Ohmic H-mode shot that would be used. - One boronization was done and the first full-length discharge following was much improved. However, we were not able to determine how long the boronization lasted. Nor were we able to vary the resonance. There were various problems that kept us from accomplishing our goals - see the PO log. Results: - Shots 5,11,14, 15 were useful pre-boronization cases. - Shot 20 was the first post boronization shot (scan of 75-85 cm, 100% duty cycle, 10% diborane, 20 minutes). The d(prad)/dt was down by a factor of ~ 3 . The H-mode lasted much longer until the radiated power reached the usual value (~ 2MW from the 2 Pi foil) before L-H transition. There was also an ITB during rampdown. Note that the McPherson measurement of the Mo in the plasma shows essentially zero Mo during the H-mode. There were Mo and Fe injections prior to the H-mode that delayed its start. - Shot 22 started out well but killed by, it seemed. a 'brick'. - The molybdenum source rate (MoI) was undetectable at the inner wall and outer limiter during the limiter phase of shot 20. There was some MoI signal on shot 22 during this part of the discharge but it was still down by a factor of 10 from pre-boronization. This is a bit puzzling given the boronization range. - The general radiated power during the first 300-400 msec of the discharge was knocked down a factor of 2 or so by the boronization. We should consider shortening the boronization time if we do this again.

Physics Operator Summaries

Entered: Nov 22 2005 10:15:58:923AM

Author: Earl Marmar

This was a difficult day. There were a number of power supply problems. Work on a faulty OH2_L board required about 2 hours to fix (after shot 7). We also had a lot of startup difficulties, with a ~50% fizzle rate, even before the boronization. However, we did manage to get several pre-boronization shots with ohmic h-modes, and 1 good shot (020) after a 20 minute boronization (75, 80, 85 cm, 10%diborane, 100% duty factor). Shot 20 had clearly improved H-mode over the pre-boronization shots (lower dPrad/dt, higher stored energy, EDA-ish). Spectroscopy also showed reduced Mo sources (see session leader summary for details). Shot 22 suffered an early disruption, before any h-mode transition. The OH2_L instrumentation problem was manifested by a factor of ~2 discrepancy between the shunt and rogowski measures of the current, with the shunt being low. As a result, post disruption on shot 7, the current went to 40 kA; the PLC limit was set at 30 kA, but this uses the shunt signal for control. Finding the right conditions to avoid fizzles after the 20 minute boronization was difficult. Using the prescription from August, 2005, gave a dud (shot 16), with very low fill pressure. Scorecard: Plasmas 10 Fizzles 9 No power 2 Dud 1 Test 1 ____________ Total Cycles 23

Session Leader Comments
Nov 21 2005 09:52:12:837AM	1051121001	Bruce Lipschultz	fizzle?
Nov 21 2005 10:06:30:757AM	1051121002	Bruce Lipschultz	1.2 MA, nl04=1., disrupts at 1.5s H/(H+D) ~ 2% before H-modes, rising to 4% H-modes start at 0.77s dprad/dt ~ 7 (prad_diodex3) H-factors peaking around 1.5, dropping to 1.4 on last one. prad_foil reaching levels of 1.8 MW.
Nov 21 2005 10:15:50:587AM	1051121003	Bruce Lipschultz	fizzle
Nov 21 2005 10:41:45:600AM	1051121004	Bruce Lipschultz	1.2 MA, nl04=1., disrupts at 1.3s ramping the field back up at the end of the shot to get rid of the disruption (shot 2) did not seem to help H/(H+D) ~ 2% before H-modes, rising to 4% H-modes start at 0.52s with most being later dprad/dt ~ 6 (prad_diodex3) H-factors peaking around 1.5, dropping to 1.2 on last one. prad_foil reaching levels of 2.0 MW.
Nov 21 2005 11:01:16:070AM	1051121005	Bruce Lipschultz	1.2 MA, nl04=0.9, ramped down the current early to try and avoid disruptions - worked. H-modes start at 0.5s H/(H+D) starting at 10% and then rising. dprad/dt ~ 9 and dropping as the H-modes reoccur (prad_diodex3) H-factors peaking around 1.5, dropping with each H-mode. prad_foil reaching levels of 1.9 MW.
Nov 21 2005 11:06:37:680AM	1051121006	Bruce Lipschultz	fizzle
Nov 21 2005 12:04:31:693PM	1051121007	Bruce Lipschultz	disruption at 0.5s. Stop to investigate power supply problem.
Nov 21 2005 01:49:44:053PM	1051121009	Bruce Lipschultz	disruption before 0.5s.
Nov 21 2005 02:05:26:147PM	1051121011	Bruce Lipschultz	1.2 MA, nl04=0.9, H-modes start at 0.72s H/(H+D) starting at 7% and then rising. dprad/dt ~ 7 and dropping as the H-modes reoccur (prad_diodex3) H-factors peaking around 1.4, dropping with each H-mode. prad_foil reaching levels of 1.8 MW.
Nov 21 2005 02:15:54:367PM	1051121012	Bruce Lipschultz	fizzle
Nov 21 2005 02:46:47:897PM	1051121014	Bruce Lipschultz	1.2 MA, nl04=0.9 H-modes start at 0.72s H/(H+D) starting at 6% and then rising. dprad/dt ~ 6.5 and dropping as the H-modes reoccur (prad_diodex3) H-factors peaking around 1.2, dropping with each H-mode. prad_foil reaching levels of 1.6 MW.
Nov 21 2005 03:20:27:350PM	1051121015	Bruce Lipschultz	1.2 MA, nl04=0.9 H-modes start at 0.65s H/(H+D) starting at 6% and then rising. dprad/dt ~ 7.5 and dropping as the H-modes reoccur (prad_diodex3) H-factors peaking around 1.4, dropping with each H-mode. prad_foil reaching levels of 1.9 MW.
Nov 21 2005 04:54:57:203PM	1051121020	Bruce Lipschultz	First full plasma discharge post boronization (20 minutes 100% duty cycle, 75,80,85 scan) 1.2 MA, nl04=1.0 H-mode start at 0.95s, drops into L but immediately back into H-mode at 1.27s. The first H-mode is very long. The second H-mode seems to be an ITB (during current rampdown). H/(H+D) starting at 4.5-5% and then rising to 7% but lower than pre-boronization. dprad/dt ~ 2.7 and dropping as the H-modes reoccur (prad_diodex3) H-factors peaking around 1.4, dropping with each H-mode. prad_foil reaching levels of 1.9 MW, similar to pre-boronization before dropping out of H-mode.
Nov 21 2005 05:17:15:280PM	1051121022	Bruce Lipschultz	Second plasma discharge post boronization (20 minutes 100% duty cycle, 75,80,85 scan) - disrupted, likely due to something dropping in the plasma. 1.2 MA, nl04=1.0

Physics Operator Comments
Nov 21 2005 09:36:45:490AM	1051121001	Earl Marmar	load from 1051118005 (for the startup) load segment 2 from 1050810014 recalculate magnetics predictors in segment 2 (now using BP16_JK instead of BP16_DE) import a-coil feedback into segment 2, wire 9 turn on segment 2; turn off segment 3 Ip to 1.2 MA I_TF ramping to -111 kA (~4 Tesla @ 66 cm) fizzle, very late breakdown (after 20 msec)
Nov 21 2005 10:04:33:383AM	1051121002	Earl Marmar	EF4 10 amp less negative before t=0 B_R offset from -.0003 to +.0002 tesla plasma startup looks ok got ohmic H-modes disrupt near end of flattop OH1 hits PLC limit
Nov 21 2005 10:14:51:897AM	1051121003	Earl Marmar	raise PLC limits OH1 [-30kA,27kA] OH2_L [-30kA, 30kA] OH2_U [-30kA, 30kA] nl_04 target to .9e20 ramp TF back up starting at 1.2 seconds fizzle fields look ok (B_Z still a bit negative)
Nov 21 2005 10:44:17:443AM	1051121004	Earl Marmar	I_EF4 5 amp less negative (now -1320 A before t=0) B_R offset to 0 from +.0002 tesla plasma several h-modes disrupt at 1.3 seconds (near q_95 = 3)
Nov 21 2005 11:02:59:710AM	1051121005	Earl Marmar	start Ip rampdown at 1.2 seconds plasma h-modes bouncy startup, hards ramped all the way down
Nov 21 2005 11:04:24:367AM	1051121006	Earl Marmar	no pcs changes fizzle
Nov 21 2005 11:37:36:693AM	1051121007	Earl Marmar	add 1 msec to prefill puff plasma bounce on startup, lots of hards disrupt at .478 s OH2-L may have some issue (went to 40 kA on the rogowski after the disruption); engineers are investigating there will be a delay in the run (currently estimated at 45 minutes to 1 hour)
Nov 21 2005 01:19:21:257PM	1051121008	Earl Marmar	OH test; plc control
Nov 21 2005 01:31:49:897PM	1051121009	Earl Marmar	lower OH1 voltage to 170 (from 200) just after t=0 increase prefill puff by 2 msec plasma early disruption
Nov 21 2005 01:40:05:430PM	1051121009	Steve Wolfe	Shot#10: Wolfe taking over as physop while Earl goes to a meeting. Shot#9 still had early runaways, though not as bad as 7, and disrupted at 0.45 sec. next shot: slow down current rise to 1.2MA, density rise, increase PG4 again.
Nov 21 2005 01:49:18:523PM	1051121010	Steve Wolfe	Shot#10: slow down current rise to 1.2MA, density rise, increase PG4 from 35ms to 37ms fizzle. breakdown slightly late,7ms, goes in. Probably shouldn't have raised the fill on that one. Br a little negative. Leave it alone and see if it comes back.
Nov 21 2005 01:59:13:053PM	1051121011	Steve Wolfe	Shot#11: slow down current rise to 1.2MA, density rise from 9; PG4 still at 37ms Plasma, full length. Breakdown still around 7ms, runaways a lot lower, lots of short hmodes. Earl is back.
Nov 21 2005 02:18:20:587PM	1051121012	Earl Marmar	increase TF to 4.25 tesla during flattop fizzle fields look ok; breakdown is a touch late
Nov 21 2005 02:30:27:710PM	1051121013	Earl Marmar	reduce prefill puff by 2 msec (now 35 msec) no power; problems with state communications (Pat went silent)
Nov 21 2005 02:43:58:850PM	1051121014	Earl Marmar	no additional PCS changes plasma bounce to the outside on startup; hards h-modes
Nov 21 2005 03:05:34:147PM	1051121015	Earl Marmar	add 1 msec to prefill puff plasma late breakdown, no bounce, plenty of hards h-modes
Nov 21 2005 03:41:36:257PM	1051121016	Earl Marmar	Prior to this shot boronization, 10% deuterated diborane, 90% helium 20 minutes, 100% duty factor scan 75, 80 dwell, 85 cm prepuff to 9 msec (following the Auguest, 2005 experience) enter INIT at P-torus = 3e-6T gauge dud; fill pressure very low (.023 mTorr F-side)
Nov 21 2005 03:51:53:790PM	1051121017	Earl Marmar	prefill puff to 25 fizzle, very late breakdown
Nov 21 2005 04:06:08:257PM	1051121018	Earl Marmar	prefill puff to 30 msec fizzle breakdown looks better B_z is a bit high
Nov 21 2005 04:16:00:477PM	1051121019	Earl Marmar	ef4 10 a more negative before t=0 reduce prefill puff by 1 msec (to 29 msec) action monitor failure just before pulse no power
Nov 21 2005 04:36:22:257PM	1051121020	Earl Marmar	try again plasma h-mode is longer lasting confinement also improved dPrad/dt is decreased
Nov 21 2005 04:46:17:367PM	1051121021	Earl Marmar	increase prefill puff 2 msec (to 31 msec) fizzle very little current rise
Nov 21 2005 05:00:33:090PM	1051121022	Earl Marmar	reduce prepuff 2 msec (to 29 msec) plasma early disruption (~.7 s), something fell in?
Nov 21 2005 05:10:04:140PM	1051121023	Earl Marmar	one more time, with feeling no pcs changes fizzle

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:27:17:430AM	Plasma	Ok
2	09:40:30:540AM	Plasma	Bad	OH2 Lower IOC breaker opened
3	10:09:03:617AM	Plasma	Ok
4	10:26:33:040AM	Plasma	Bad	IOC OH2 Lower
5	10:45:33:587AM	Plasma	Ok
6	11:01:06:913AM	Plasma	Ok
7	11:15:16:650AM	Plasma	Ok
8	01:17:35:070PM	Test	Ok	OH2L PLC 10kA Test
9	01:30:19:053PM	Test	Ok
10	01:43:01:397PM	Test	Ok
11	01:55:50:990PM	Test	Ok
12	02:08:25:990PM	Test	Ok
13	02:21:13:850PM	Plasma	Bad	No Pat No Power Shot
14	02:34:43:367PM	Plasma	Ok
15	02:48:12:477PM	Plasma	Ok
16	03:34:55:507PM	Plasma	Ok
17	03:47:32:430PM	Plasma	Ok
18	04:00:16:163PM	Plasma	Ok
19	04:12:54:290PM	Plasma	Ok
20	04:24:34:960PM	Plasma	Ok
21	04:38:22:587PM	Plasma	Ok
22	04:52:46:147PM	Plasma	Ok
23	05:06:09:140PM	Plasma	Ok