Miniproposals

Miniproposal: 348a Date Filed: 6/27/2003 Title: Initial Tests of the Boron Injector First Author: Jim Irby Session Leader: Jim Irby (shots 11-35)

Miniproposal: 421 Date Filed: 4/8/2005 Title: Obtaining Steady, Low Density H-Modes First Author: Martin Greenwald Session Leader: Martin Greenwald (shots 1-10)

Engineering Operator Run Comment

MP #421 Steady low density H-modes

Session Leader Plans

Entered: Jun 29 2005 03:35:54:337PM

Author: Martin Greenwald

MP 421 - Obtain steady, low-density h-modes Purpose: 1. Develop a method to lower the density of steady H-modes at normal current 2. Provide data on the scaling of the low density limit for the L/H transition 3. Explore ELM behavior at low collisionality Background and approach: Obtaining H-mode operation at low density is difficult because of the low density limit in the L-H threshold. Because a minimum density is required to make the transition, more gas is puffed into the target plasma than is desirable for lower density H-mode operation. The approach of this run is to enter H-mode at low current and low density, then to ramp up the current to normal operating levels. The figure from the MP shows proposed Ip and Prf waveforms Plan: Normal Bt, 5.3T, Standard plasma shape 1. Ip = 0.4 MA ramping to 0.8 as shown in MP figure RF power as shown, flat-top at about 2.5 MW start at nebar ~ 0.8 e20 adjust waveforms to optimize H-mode drop density shot by shot until low density l/h limit is reached 2. Ip to 0.2 MA repeat above, starting at lower density 3. Ip to 0.3 if time allows 4. Ip to 0.6 if time allows

Entered: Jul 1 2005 09:19:01:700PM

Author: Jim Irby

The boron injector has been modified since the last injector run on 4/13/05 to allow larger pellets and about twice the amount of boron per pulse. The larger pellets should penetrate much better with about 8 times the mass of the pellets from the last run (4/13 run: 40-90 um, 6/30 run: 90-180 um). We will start with a fiducial shot with 2 MW of RF and judge the status of the boronization as determined by the radiated power, h-mode transitions, etc. Several shots will be taken with the boron injector to determine how much boron can be applied w/o disrupting or otherwise affecting the plasma. Several shots will be take with the plasma outboard limited to see if this allows better boron deposition.

Physics Operators Plans

Entered: Jun 30 2005 08:59:31:760AM

Author: Earl Marmar

Physop Plan 1050630 MP 421 - Steady, low density H-Modes SL: Greenwald PO: Marmar original plan: no overnight ECDC; bake at 60 C However, around 7:00 pm, a small room air leak was opened through the LPI gate-valve and pressure went up to about 3e-6 (from ~1e-6); the volume behind the valve was pumped out at about 10:00 pm, and then ECDC was run from 10:30 pm until 7:00 am, 2e-4 (gauge) deuterium. Mass 3/4 ratio did not seem out of the ordinary. We will stay the course. Engineering setup as on 1050602017 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 2 psi Ar Hybrid disabled (PG1) leave B-side upper alone fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) Enable the following: ECE and VUV gate valves, Z-bolo shutters ICRF Setup: All transmitters in run on at 8:30

Session Leader Summaries

Entered: Jul 1 2005 11:21:48:120PM

Author: Jim Irby

We started MP348A on shot 11 after it was clear the boronization was not good enough for MP421. Shot 11 was a fiducial shot with many h-mode periods with ICRF power around 1.5 MW and the radiated power about 800 kW. On shot 12 the boron injector was turned on early with a long pulse train so that boron could arrive in the plasma during startup and extend the full length of the discharge. Unlike the last injector run the boron was clearly seen on the BIII diode looking down from k-top, I assume because of the much larger pellets. However, the plasma only lasted 0.8 s before it disrupted. We tried again on shot 14 but got only a 0.5 s discharge. We then turned off the injector for several shots while the PO re-established plasma operation. It is not clear if it was general problems with startup or the boron that caused these problems. We had plasma again by shot 18, but kept the boron injector off until shot 20 when only one pulse was used. By shot 23 we were up to 7 pulses when a disruption on shot 24 caused us to drop back to one pulse. We did not really get back up to extended amounts of boron injection until shot 32 when the boron was timed to arrive at about 0.5 s and extend over the remaining discharge length. If the boron caused the disruptions it was probaby more to do with the timing of the boron injection rather than the amount. Starting on shot 26 we went outboard limited to see if this helped deposit the boron on more critical surfaces. The radiated power remained rather constant at the 2 MW level with 3 MW of ICRF power. The stored energy also remained at the 100 kJ level through most of the run. The boron injection clearly did not improve performance of the machine and may even have degraded it somewhat. The boron was again seen spectroscopically and it may have affected the moly radiation. This data is being analyzed. The boron also produced some diborane-like gas that was clearly seen on the RGA after the shot. The spectrum and amount seen was similar to what we see on the RGA following disruptions in a well boronized machine. Because we suspected the injector was causing the disrutions, we again operated with boron deposition rates much lower than available from the injector. It would be useful to try again with the arrival time of the boron from 0.4 to 0.5 s and extended over the rest of the discharge. 11 fiducial shot 12 disruption, boron injection 13 disruption, boron injection 14 disruption at 1.45 s, later and much reduced boron injection 15-17 fizzled, duds, short discharge, no injection 18 plasma, no injection, 1 MW radiation, 1.5 MW ICRF 19 plasma, no injection, 1.25 MW radiation, 2 MW ICRF 20 plasma, 1 pulse of boron, 1.5 MW rad, 2 MW ICRF 21 plasma, 3 pulses boron, 1.5 MW rad, 2 MW ICRF 22 no power shot but boron was dropped 23 plasma, l-mode, 7 pulses, 400 kW rad, 2 MW ICRF 24 disruption at .93 s, 7 pulses 25 plasma, 5 pulses,1.5 MW rad, 3 MW ICRF 26 plasma, outboard limited, 5 pulses, 1.5 MW rad, 3 MW ICRF 27-33 plasma, 3 MW ICRF, various amounts of boron 34-35 plasma, no boron

Entered: Jul 8 2005 05:51:45:127PM

Author: Martin Greenwald

For mp 421 We weren't successful in testing the low density limit. Radiation was a severe problem at the lower densities - may be the result of the incomplete boronization carried out 2 days ago. Interestingly, The first 8 shots went into H-mode at Pnet ~ 1 MW where Pnet = Ploss - Prad Shot 10 seemed to go into H-mode out of a poloidal detachment. If so, the edge Te was near 0!! Te95 at the threshold was uniformly high compared to our previously published results. At the L-H transition we have the following results: L-H PL/ Pnet/ Shot time nebar Ip PL nB Pnet nB Te95 01 0.76 1.5 0.57 2.0 0.21 1.0 0.10 180 02 0.49 1.0 0.49 1.4 0.30 1.1 0.24 190 03 0.46 1.0 0.46 1.3 0.28 1.1 0.24 180 04 1.05 1.2 0.82 2.7 0.47 1.1 0.19 250 05 1.02 1.3 0.81 2.5 0.39 1.2 0.19 200 06 1.00 1.2 0.80 2.5 0.43 1.1 0.19 200 07 0.90 1.1 0.75 2.6 0.48 1.0 0.18 220 08 1.04 0.74 0.88 1.8 0.50 1.1 0.30 300 09 none 0.7 0.42 1.6 0.45 0.6 0.17 110 none 0.75 0.42 3.4 0.70 1.4 0.29 0 (detached) 10 1.4? 1.0 0.42 2.5 0.67 0.5 0.13 0 (detached!)

Physics Operator Summaries

Entered: Jun 30 2005 05:43:51:743PM

Author: Earl Marmar

The machine ran reasonably well today. We started with MP 421, attempting to make low density H-modes. The idea is to get into H-mode at low current and density, and then ramp up the current. After 10 shots, the session leader concluded that machine conditions were not conducive to this MP: there was too much radiated power in the low density plasmas during RF pulses. The run was then switched to the backup, MP 348, tests of the boron injector. If MP421 is revisited, it should probably be right after boronization. The startup used today came from 1050602, which was a special low-current startup. After we moved to MP348, which called for 1 MA plasmas, the startup from 1050622014 was loaded. However, this appeared to be less robust, yielding a funny current rise shot (14) followed by a fizzle and a dud. So I went back to the 1050602 startup from the day, which worked well. Note that this has some unusual settings, and only gives 400 kA at segment switch. For details, see the physop notes from 1050602. In any event, the plasmas started up nicely for the rest of the day. The only significant startup tweak, other than prepuff adjustments, was to add a preprogrammed gas puff in segment 1 starting earlier than usual (20 msec), starting from shot 6. This may have helped with runaway suppression, even for startups that hesitated. As part of MP348, we ran the ohmic parts of shots from 0.5 to 1.0 s on the outboard limiters, returning to LSN after 1.0 s when the RF was turned on. The current for the outboard limiter phase was also reduced, ramping up to 1 MA after 1 second. This seemed to have no obvious ill effects. Boron was seen spectroscopically, but if it had any effects on wall conditioning, they were extremely subtle. Scorecard: plasmas 32 fizzles 1 duds 1 no power cycles 1 (loss of PLC communication in check) total cycles 35

Session Leader Comments
Jun 30 2005 09:08:41:243AM	1050630001	Martin Greenwald	Good shot Density a bit high....
Jun 30 2005 09:27:20:307AM	1050630002	Martin Greenwald	OK shot density rises when RF comes on - goes into H-mode at 1e20 - still higher than we want.
Jun 30 2005 09:39:41:923AM	1050630003	Martin Greenwald	similar to last shot
Jun 30 2005 09:56:38:617AM	1050630004	Martin Greenwald	For this shot we're going to put a small step in the RF early in the discharge. The aim is to degas the antennas. Also lowered the target density No H-mode until after 1 second when nebar is at 1e20 and RF power is at 2.7 MW That is - no H-mode for almost 0.6 seconds
Jun 30 2005 10:11:26:813AM	1050630005	Martin Greenwald	Similar to shot 4 Not early H-mode, despite P/nBS reaching 0.6 Radiated power is high during this early phase
Jun 30 2005 10:27:24:060AM	1050630006	Martin Greenwald	Similar to shot 5
Jun 30 2005 10:42:31:647AM	1050630007	Martin Greenwald	Raise Ip to 0.6 MA Otherwise similar to previous 2 shots Goes into H-mode at 0.87 seconds when Ip is at 0.74 MA and nebar is 1e20 No earlier H-mode despite P/nBS > 0.5 Edge temperatures are very cold Te95 no more than 150 eV
Jun 30 2005 10:58:35:780AM	1050630008	Martin Greenwald	Lower RF power Radiation is better but still no early H-mode Goes in at IP = 0.8 MA Te95 at transition is above 200 eV
Jun 30 2005 11:07:32:120AM	1050630009	Martin Greenwald	Ip dropped to 0.4 without ramp to 0.8 No H-mode edge temperature very low ~ 100eV
Jun 30 2005 11:51:06:713AM	1050630011	Jim Irby	Now moving to 348a --- Boron injector miniproposal will start with fiducial shot -- sln, 1 MA, 1e20/m^2, 2 MW of rf, no boron good shot --- lots of h-modes --- outer gap a little large
Jun 30 2005 12:08:34:893PM	1050630012	Jim Irby	set a12 timing start to -0.75 s boron gate [-0.7,10,.5,25] disruption at 0.83 s lots of flashes seen on BIII diode Matt sees lots of moly at .4 s or so
Jun 30 2005 12:16:20:737PM	1050630013	Jim Irby	boron gate [-.75,10,.5,25] --- not sure if Boron injector caused the last shot to disrupt, so just try it again disruption at 0.5 s --- probably boron injector
Jun 30 2005 12:36:45:883PM	1050630014	Jim Irby	boron gate [0.,10,.5,5] lasted 1.49 s --- better boron injector continued to inject past gate time (new mods to cylinder?) rga shows diborane like spectrum possibly from injector but possibly just from disruptions boron injector off for next shot
Jun 30 2005 12:44:21:570PM	1050630015	Jim Irby	boron gate off fizzle still see a few pulses of scattered light
Jun 30 2005 12:56:03:860PM	1050630016	Jim Irby	try again (Matt observed strong boron lines on shot 14) dud --- Earl is going back to shot 11 startup
Jun 30 2005 01:37:48:783PM	1050630017	Jim Irby	boron injector off NINJA puffing starts at 1 s
Jun 30 2005 01:51:21:090PM	1050630020	Jim Irby	boron gate [0,10,.5,1] --- work up from here should hit plasma around 0.7 s plasma into rampdown no boron effects in plasma except from BIII diode
Jun 30 2005 02:05:49:110PM	1050630021	Jim Irby	boron gate [0,10,.5,3] good shot very little seen again from boron
Jun 30 2005 02:17:07:443PM	1050630022	Jim Irby	boron gate [-.25,10,.5,7] no power shot --- but still plenty of boron fell
Jun 30 2005 02:34:31:843PM	1050630023	Jim Irby	try [-.25,10,.5,7] again "diborane" shows up on RGA again, but no disruption this time
Jun 30 2005 02:47:00:753PM	1050630024	Jim Irby	boron gate [.25,10,.5,7] disruption at 0.933 s --- back off boron next shot
Jun 30 2005 03:00:51:713PM	1050630025	Jim Irby	boron gate [-.25,10,.5,5] more boron on the RGA
Jun 30 2005 03:18:26:030PM	1050630026	Jim Irby	boron gate [-.25,10,.5,5] outboard limited, rf delayed to 1 s plasma into rampdown
Jun 30 2005 03:25:34:720PM	1050630027	Jim Irby	boron gate [-.25,10,.5,5] plasma into rampdown RGA up no clear effects on other diagnostics prad_main still high
Jun 30 2005 03:40:56:023PM	1050630028	Jim Irby	boron gate [-.4,10,.5,7] plasma into rampdown rga signal up over shot 26, 27
Jun 30 2005 03:58:36:830PM	1050630029	Jim Irby	boron gate [-.4,10,.5,7] plasma into rampdown
Jun 30 2005 04:09:32:863PM	1050630030	Jim Irby	gate [-.5,10,.5,10] plasma for 1.73 s
Jun 30 2005 04:18:58:913PM	1050630031	Jim Irby	gate [-.5,10,.5,10] very similar to last shot
Jun 30 2005 04:26:52:230PM	1050630032	Jim Irby	boron gate [-.5,20,.5,30] fewer back transitions, but radiation is still high
Jun 30 2005 04:39:31:593PM	1050630033	Jim Irby	gate [-.5,20,.5,30] argon disabled good shot

Physics Operator Comments
Jun 30 2005 09:11:27:213AM	1050630001	Earl Marmar	load from 1050602017 reduce prefill puff to 20 msec redraw current waveform to ramp up to 0.8 MA at 1.0s nl_04 target to .8e20 plasma density higher than SL wanted (nl vs n-bar) 3 H-modes 3'rd has lowest radiated power fraction, H_89=1.4 RF waveform is close to desired; a few trips
Jun 30 2005 09:28:53:760AM	1050630002	Earl Marmar	nl_04 target to .5e20 argon enabled (40 msec starting at 0.3) plasma multiple H-modes, look pretty ELM-free (from the density and Prad point of view)
Jun 30 2005 09:40:39:487AM	1050630003	Earl Marmar	no pcs changes plasma multiple H-modes density is rising a bit when the RF turns on, before the first H-mode
Jun 30 2005 09:55:29:557AM	1050630004	Earl Marmar	reduce prepuff by 1 msec, to 19 msec reduce argon puff by 5 msec, to 35 msec reduce nl_04 target to .4e20 from .5e20 plasma startup bounced, some early hards got lower L-mode density; no H-mode until after 1 second
Jun 30 2005 10:14:19:890AM	1050630005	Earl Marmar	add 2 msec to prepuff (now 21 msec) plasma bigger hesitation on startup; more hards
Jun 30 2005 10:30:41:777AM	1050630006	Earl Marmar	turn on segment 1 preprogram gas puff at 20 msec BR_0 offset to .3 mT (from 0) plasma no hesitation on current rise; early hards gone still not going into H-mode at 400 kA
Jun 30 2005 10:42:03:320AM	1050630007	Earl Marmar	first current flattop to 600 kA (from 400 kA) plasma still no early H-mode
Jun 30 2005 10:53:40:097AM	1050630008	Earl Marmar	no pcs changes lower the early RF power plasma no early h-mode
Jun 30 2005 11:09:46:527AM	1050630009	Earl Marmar	400 kA straight across plasma no H-mode; looks detached late, then disrupts at 1.5 seconds
Jun 30 2005 11:28:12:457AM	1050630010	Earl Marmar	nl_04 target to 5e19 plasma very small H-mode late, disrupt around 1.5 s again
Jun 30 2005 11:44:06:857AM	1050630011	Earl Marmar	switching to MP348, Tests of boron injector plan is to try to inject as much as the plasma can handle will also try double null and possibly outboard limited First shot should be without boron, 1 MA, LSN, nl_04 target 1e20 plasma multiple h-modes disrupt in rampdown (0.5 MA)
Jun 30 2005 12:10:31:490PM	1050630012	Earl Marmar	Increase RCUR about 3 mm (decrease outer gap) should be some boron shaking on this one plasma several injections (Matt says moly) disrupt shortly after RF turns on density was lurching around
Jun 30 2005 12:21:10:343PM	1050630013	Earl Marmar	bring nl_04 up to target value sooner plasma earlier disruption; boron might have caused some problems
Jun 30 2005 12:38:40:837PM	1050630014	Earl Marmar	load from 1050622014 (normal early current ramp) Engineering setup also changed to match that shot prefill puff to 21 msec (as on previous shots) BR_0 offset to +.3 mT (as on previous shots) boron shaking delayed to hit the plasma starting at ~0.7 s plasma current rise looks terrible disrupt at 1.48 s
Jun 30 2005 12:45:25:130PM	1050630015	Earl Marmar	no pcs changes boron shaker off fizzle
Jun 30 2005 01:00:28:280PM	1050630015	Earl Marmar	no pcs changes boron shaker off fizzle
Jun 30 2005 01:00:25:453PM	1050630016	Earl Marmar	reduce prepuff by 2 msec to 18 msec dud
Jun 30 2005 01:11:07:263PM	1050630017	Earl Marmar	back to 1050630011 engineering settings to match plasma startup looks good disrupt at .44 seconds
Jun 30 2005 01:33:06:533PM	1050630018	Earl Marmar	lower target nl_04 a bit delay a-coil turn-on by .2 s Ninja puffing at 1 sec plasma ramped all the way down
Jun 30 2005 01:35:34:690PM	1050630019	Earl Marmar	reduce outer gap 4 mm still no boron shaking plasma similar to 18; large number of h-modes
Jun 30 2005 01:47:24:730PM	1050630020	Earl Marmar	no pcs changes boron shaking - 1 pulse, should hit at about 0.7 s plasma looks a lot like 19 multiple short h-modes
Jun 30 2005 02:07:10:153PM	1050630021	Earl Marmar	no pcs changes more boron (Jim says factor ~3) plasma no obvious change
Jun 30 2005 02:14:21:300PM	1050630022	Earl Marmar	nl_04 target to 1.1e20 more boron plc problem; no power shot
Jun 30 2005 02:35:41:780PM	1050630023	Earl Marmar	try again, nl_04 target 1.1e20 plasma very steady at 1.0e20, 2 MW, L-mode boron was shaken
Jun 30 2005 02:47:52:753PM	1050630024	Earl Marmar	reduce prepuff by 1 msec to 20 msec plasma much better current rise than on 23 3 MW RF, some trips; got h-mode. big increase in Prad, then disrupt at .93 s boron was shaken
Jun 30 2005 02:56:43:900PM	1050630025	Earl Marmar	no pcs changes plasma into rampdown 3 MW RF, ragged H-modes, H89 < 1.2 less boron this shot
Jun 30 2005 05:08:44:810PM	1050630026	Earl Marmar	go outboard limited until 1 second (increase RCUR 7 mm) delay RF to start at 1 second plasma rode the outboard limiter from 0.5 to 1 sec significant injection(s) right around .5 seconds, Matt says first boron, then moly
Jun 30 2005 03:28:31:380PM	1050630027	Earl Marmar	no pcs changes plasma similar to 26, but no big injection near .5 sec
Jun 30 2005 03:35:22:053PM	1050630028	Earl Marmar	no pcs changes more boron requested plasma looks pretty similar
Jun 30 2005 03:54:04:857PM	1050630029	Earl Marmar	reduce Ip to .6 MA, then bring it up to 1 MA plasma similar during RF
Jun 30 2005 04:07:32:847PM	1050630030	Earl Marmar	ramp current up to 1.15 MA during RF more boron plasma similar; a little more stored energy at the higher current; H89 unchanged; Prad unchanged
Jun 30 2005 04:11:33:927PM	1050630031	Earl Marmar	no pcs changes repeat boron amount plasma; looks more or less the same.
Jun 30 2005 04:28:33:730PM	1050630032	Earl Marmar	back to 1 MA during RF more boron plasma similar, fewer back transitions, H89~1
Jun 30 2005 04:36:49:297PM	1050630033	Earl Marmar	no pcs changes argon disabled for this shot still shaking boron plasma similar to previous
Jun 30 2005 04:54:49:320PM	1050630034	Earl Marmar	no boron shaking for this shot plasma very similar
Jun 30 2005 05:03:47:527PM	1050630035	Earl Marmar	no pcs changes no boron shaking plasma similar, slightly higher peak stored energy

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:02:51:447AM	Plasma	Ok
2	09:16:39:057AM	Plasma	Ok
3	09:31:46:857AM	Plasma	Ok
4	09:48:09:527AM	Plasma	Ok
5	10:00:49:647AM	Plasma	Ok
6	10:17:02:330AM	Plasma	Ok
7	10:29:58:637AM	Plasma	Ok
8	10:47:21:503AM	Plasma	Ok
9	11:01:39:107AM	Plasma	Ok
10	11:16:45:070AM	Plasma	Ok
11	11:32:34:987AM	Plasma	Ok
12	11:56:25:710AM	Plasma	Ok
13	12:09:48:177PM	Plasma	Ok
14	12:23:40:437PM	Plasma	Ok
15	12:38:08:570PM	Plasma	Ok
16	12:50:38:333PM	Plasma	Ok
17	01:03:12:827PM	Plasma	Ok
18	01:18:21:837PM	Plasma	Ok
19	01:31:05:770PM	Plasma	Ok
20	01:43:40:467PM	Plasma	Ok
21	01:55:58:150PM	Plasma	Ok
22	02:08:21:817PM	Plasma	Bad	Ack Failure
23	02:22:41:353PM	Plasma	Ok
24	02:36:47:687PM	Plasma	Ok
25	02:49:38:693PM	Plasma	Ok
26	03:04:34:713PM	Plasma	Ok
27	03:17:09:123PM	Plasma	Ok
28	03:29:33:050PM	Plasma	Ok
29	03:42:03:213PM	Plasma	Ok
30	03:55:07:187PM	Plasma	Ok
31	04:07:38:567PM	Plasma	Ok
32	04:20:04:430PM	Plasma	Ok
33	04:32:39:030PM	Plasma	Ok
34	04:45:12:517PM	Plasma	Ok
35	04:57:26:400PM	Plasma	Ok