| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Ian Hutchinson,John Goetz |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Unknown |
| Engineering Operator Run Comment |
| MP# 019 - Ip control. Also 013,010 |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:08:507PM |
| Author: To Be Determined |
| Physics operator summary for 930813. EO: PO: Granetz SL: Goetz, Hutchinson This run was based on the discharge development mini-proposal. There were two goals: 1) Explore Ip feedback, and 2) get true single null diverted plasmas. Due to a faulty heater thermocouple, there was about an hour delay in beginning the run. We started off trying Ip feedback, with the initial shot being 930811014, since Ian had calculated single-null x-point control based upon this shot (to be used later in the run). The outer limiter was pulled back to 0.95 m. The Ip controller we began with included OH1, OH2U & L, and EF3. The coefficients were calculated using one of S. Wolfe's routines, which try to form orthogonal controllers (i.e. create an Ip controller which has minimal effect on the R-centroid). However, this algorithm is based on vacuum magnetic fields, and today we confirmed that it is not satisfactory for plasma shots. Attempting to control Ip caused problems with the R-centroid position. The hybrid error signal and M-matrix feedback voltages were proper, as brilliantly proven on shot #001, for which the Ip demand had been loaded from a scope that displayed Ip in MA, resulting in an Ip demand of only 0.5 amps. Both the first and second shots had very hard disruptions, with #002 having a dI/dt=-0.9 MA! This may have caused a wall conditioning problem for the remainder of the run, and also re-killed one of the Bp coils. After shot #007, we decided to abandon the Ip feedback part of the run and switch to the single-null task. Here we had more success, although we were frequently plagued by the "shark fin" phenomenon, which may have been causing most of the shots to end in disruptions. Through a series of tweaks to OH2, EF1, EF2, and especially to R-centroid and Z-centroid, we achieved an excellent single-null configuration by late in the run. Shots #023, 024, and 025 (the best one) had several centimeter separations between the plasma edge and the inboard and outboard limiters, and the upper x-point was very far away from the plasma. The inner strike point was just on the nose of the divertor, not quite low enough to get to the low-impact angle section. Throughout the day we had to tweak the gas puffing in a feable attempt to avoid hard x-rays, which were generally high for much of the run. Scorecard: 25 shots --- 21 plasmas + 3 fizzles + 1 dud (EF3 failed to fire) |
| Physics Operator Summaries |
| Session Leader Comments | |||
| Aug 13 1993 09:16:46:540AM | John Goetz | Run 930813 follows MP019 and MP013. Both these mini-proposals are discharge
development tasks. MP019 covers plasma current control and MP013 covers true single null (SN) diverted discharges. The plasma current controllers from run 930630 will be reinvestigated. A controller consisting of OH1, OH2U, OH2L, and EF3 will be the first one tried. As time permits more controllers will be tries. Calculations have been performed using 930811014 as a baseline to determine the coil current changes needed to achieve true SN discharges. These changes will be applied and then tweaked up. | |
| Aug 13 1993 09:22:33:800AM | John Goetz | The run will start from shot 930811014. Changes made include:
-ZCUR controller consists of EFC, EF1U, EF1L, EF2U, EF2L, OH2U, and OH2L D_ZCUR=0.5; P_ZCUR=5.0 -IP and RCUR controllers consist of OH1, OH2U, OH2L, and EF3; the relative weights are calculated to keep the controllers orthogonal. P_IP=2.0 and turns on @.15sec. D_RCUR increased to 2.0 -IP current trace copied in to S_IP and smoothed to give 500kA from 0.2 to 0.4 Changes for SN operation will be detailed when they occur. | |
| Aug 13 1993 10:14:56:560AM | 930813001 | John Goetz | Plasma goes bad at .15sec when the IP controller is switched in. Problem traced to
drawing S_IP @ 0.5A not 0.5MA. Controller did work; it tried to lower the current but radial position control was lost. For shot 002: draw S_IP to 500000A. |
| Physics Operator Comments | |||
| Aug 13 1993 09:56:04:780AM | 930813001 | Robert Granetz | Pre-fill for shot 001 was 1.2e-5
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| Aug 13 1993 10:25:45:870AM | 930813002 | Robert Granetz | Disrupted at 0.268 s. dI/dt=-0.9 MA/ms ! Vertical position went to hell.
The Ip controller seemed to work well. Error was only about 30 kA. There seemed to be a growing vertical instability starting at 0.15, which is when we demand a rapid drop in Z from 0 to -2 cm. |
| Aug 13 1993 10:33:22:080AM | 930813002 | Robert Granetz | For the next shot (003) the Z-cur demand was changed from an instantaneous
lowering of the plasma, to a slower ramp down in the position. Start with z=0 at 0.15 s and linearly move to z=-2 cm at t=0.2 s. |
| Aug 13 1993 10:41:37:130AM | 930813003 | Robert Granetz | Fizzle. Forgot to lower the gas. For the next shot the pre-fill will be
lowered from 1.2 to 1.1e-5. (Does it really matter?) |
| Aug 13 1993 11:06:29:220AM | 930813004 | Robert Granetz | Ipmax=0.494 MA, duration=0.4 s, terminated by a major disruption. Vertically
unstable. Z-cur goes to -4 cm even before the instability starts in. Examination of the magnetics shows that BP17_BC broke again right at the big disruption of shot 002. |
| Aug 13 1993 11:12:08:150AM | 930813004 | Robert Granetz | We are going to break now for 45 minutes so I can get into the cell and change
BP17_BC to BP17_DE into the hybrid. |
| Aug 13 1993 11:53:40:140AM | 930813005 | Robert Granetz | Ipmax=0.46 MA, duration=0.45 s. Current feedback down to 0.4 MA started
to work at 0.15 s, but then at 0.18 s it lost out in competition to the R-cur controller. Apparently the two controllers are not orthogonal when there is plasma current (Wolfe's algorithm does a vacuum calculation). The plasma still terminated in a vertical disruption, and Z-cur had some small oscillations. Horne made some tweaks to the EFC voltage programming, and I tweaked the OH1 voltage to help keep the current from getting too high early on. |
| Aug 13 1993 12:07:19:660PM | 930813006 | Robert Granetz | Disrupted at 0.28 s. The chopper did not run because of an overcurrent
fault from the previous shot. Given that the elongation is 1.6, it's not surprising that we got a vertical instability. Also, there was not much of an indication of Ip feedback. For the next shot: Lower EF3 coefficient in the M-controller for Ip to reduce cross-talk with the R-CUR controller. Lower EF1 demand currents from 3300 to 3000 to reduce the elongation a little. Lower OH1 voltage from -160 to -150 to keep Ip from going to high. |
| Aug 13 1993 12:38:38:870PM | 930813007 | Robert Granetz | Bad shot. Disrupted at 0.33 s. The plasma started out 5 cm high for no
known reason. We've decided that we can't simultaneously feedback on Ip and R-cur, so we are abandoning that part of today's run. For the next shot, start the 2nd part of the run, i.e. attaining a true single-null diverted plasma. Re-load 930811014. EFC will be disabled, since it was not working for the reloaded shot. |
| Aug 13 1993 12:40:34:540PM | 930813008 | Robert Granetz | Still a bad shot. Ipmax=0.40 MA, disrupted at 0.29 s. Z-position was
good, but R is not good. There were also some hard x-rays. |
| Aug 13 1993 12:44:06:140PM | 930813008 | Robert Granetz | For the next shot, re-enable the EFC chopper supply.
|
| Aug 13 1993 12:51:03:750PM | 930813009 | Robert Granetz | Fizzle. Prior to this shot we had increased pulse-gas2 a little bit. Might
have been a mistake. |
| Aug 13 1993 12:54:29:830PM | 930813009 | Robert Granetz | For the next shot, reduce the gas puffing a little bit.
|
| Aug 13 1993 12:59:18:700PM | 930813009 | Robert Granetz | Also for the next shot:
Substantially reduce the derivative gain on Z-cur from 10.0 to 0.5, since EFC has now been enable, and Raise EF4 current from 1050 to 1070 amps at commutation. |
| Aug 13 1993 01:07:18:520PM | 930813010 | Robert Granetz | Getting there. Ipmax=0.39 MA, shot terminates with a major disruption at
0.39 s. Lots of hard x-rays. For the next shot, add back a little puffed gas. |
| Aug 13 1993 01:26:07:910PM | 930813011 | Robert Granetz | Another disruptive shot. Ipmax=0.42 MA, terminates with a major disruption
at 0.36 s. Hard x-rays are greatly reduced, but still finite. The current rise has been ratty all day. For the next shot, raise the pre-fill from 1.2 to 1.3e-5 torr, and also tweak the EF4 programming to remove a dip that Ian put in earlier today. |
| Aug 13 1993 01:28:09:530PM | 930813011 | Robert Granetz | Correction: the pre-fill is being changed from 1.3 to 1.4e-5 torr for the
next shot. |
| Aug 13 1993 01:40:54:340PM | 930813012 | Robert Granetz | Fizzle. For next shot reduce the pre-fill from 1.4 to 1.3e-5 torr. Also
I lowered some of the later gas puff spikes a little. |
| Aug 13 1993 01:55:21:870PM | 930813013 | Robert Granetz | Finally, a good shot. Ipmax=0.52 MA, duration=0.51 s. Position control
is okay. There was a small amount of hard x-rays. Shark fin started at 0.46 s and may have had something to do with terminating the shot. |
| Aug 13 1993 02:16:15:290PM | 930813014 | Robert Granetz | Not as good as the last one. Ipmax=0.44 MA, terminated by a disruption
at 0.395 s. The plasma position before 0.15 s was about 3 cm high, for some unknown reason. Changes for next shot: EF4 current tweaked by Ian, and PID on Z-cur EFC increased from 6 to 8. |
| Aug 13 1993 02:28:39:940PM | 930813015 | Robert Granetz | Ipmax=0.40 MA, duration=0.42 s. Diverted at 0.17 s and stays that way for the
rest of the shot. Another shark fin starting at 0.32 s. There was a minor disruption at 0.1 s, possibly due to too much density. For the next shot: Lower EF1U current by 1500 amps (from 1600 to 100), Raise EF2U current from 1700 to 2400 amps Remove and lower some of the gas puff spikes on pulse_gas3. |
| Aug 13 1993 02:45:56:380PM | 930813016 | Robert Granetz | Nice shot. Ipmax=0.52 MA, duration=0.66 s. There was a natural injection
at 0.470 s. A bit of hard x-rays, and they rise precipitously after 0.6 s. The position control was okay. The density was a little low, so we're going to add a little bit to pulse-gas3 for the next shot. |
| Aug 13 1993 03:02:33:670PM | 930813017 | Robert Granetz | Good shot. Ipmax=0.53 MA, duration=0.64 s. No natural injection this
time. Hard x-rays were high. For the next shot: Increase pulse-gas3 during the first half of the shot, and Decrease OH2U and L voltage preprogramming (from -30 to -10 volts). |
| Aug 13 1993 03:25:41:780PM | 930813018 | Robert Granetz | Ipmax=0.51 MA, terminates with a disruption at 0.44 s. Radiated power starts
to climb after 0.32 s. Lower x-point, but still not well separated from the inner wall. Therefore, for the next shot: Change R-CUR demand from 0.69 to 0.70 m (required scale-bit change), and Reduce one of the pulse-gas3 spikes a teeny bit. |
| Aug 13 1993 03:47:45:960PM | 930813019 | Robert Granetz | Bad shot. Short and disruptive. Lots of hard x-rays starting at 0.1 s.
For the next shot: Don't change anything to do with the gas. In fact, no changes were made. |
| Aug 13 1993 03:50:43:130PM | 930813020 | Robert Granetz | Not bad. Ipmax=0.50 MA, duration=0.50 s. Moderate hard x-rays, but much
better than the last shot, with no changes made to anything. A shark fin starts at 0.4 s. For the next shot: Increase pulse-gas2 a little, and Increase EF2L from 775 to 1200 amps. |
| Aug 13 1993 04:00:16:540PM | 930813021 | Robert Granetz | No breakdown, due to no EF3
|
| Aug 13 1993 04:29:59:060PM | 930813022 | Robert Granetz | Ipmax=0.51 MA, terminated by a disruption at 0.415 s. Moderate hard x-rays
again, as well as a shark fin starting at 0.31 s. For the next shot, increase pulse-gas2 a little, and Decrease the OH1 and OH2's voltage preprogramming demand around 0.15 s in order to lower the plasma current a little and thereby give a more elongated plasma. The hope is that this will separate the LCFS from the inner wall a little more. |
| Aug 13 1993 04:47:38:390PM | 930813023 | Robert Granetz | Shorter shot. Ipmax=0.43 MA. Disrupted at 0.34 s. Elongation increased
slightly from 1.4 to 1.45, resulting in a little more clearance on the inboard wall. Shark fin again, starting at 0.26 s. Hard x-rays are nearly gone. For the next shot, change the Z-cur demand from -3 to -4 cm. This required a change of scale bit. |
| Aug 13 1993 05:01:31:420PM | 930813024 | Robert Granetz | Ipmax=0.41 MA, disrupted at 0.43 s, and there was a minor disruption at
about 0.275 s. Plasma position did indeed move down from -1.5 to -2.5 cm, resulting in strike points that are nearly where we want them to be. For the next shot: Lower the pulse-gas3 spikes during the 2nd half of the shot, and Move the plasma another 0.5 cm down. |
| Aug 13 1993 05:20:16:360PM | 930813025 | Robert Granetz | Ipmax=0.47 MA, terminated by a disruption at 0.36 s. Looks like a shark
fin began to start at 0.32 s. Plasma position moved down another 0.5 cm, as programmed, from -2.5 to -3.0 cm. The resulting diverted plasma was strongly single null, with good clearance to the inner wall and outer limiter. The strike point was nearly past the inner nose of the divertor. The same can be said for the previous shot also. This was the last shot of the day. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:53:38:210AM | Plasma | Ok | First shot at 0955. Delayed by heater problems. All systems ok -- plas |
| 2 | 10:14:30:030AM | Plasma | Ok | plasma |
| 3 | 10:35:33:930AM | Plasma | Ok | plasma |
| 4 | 10:49:45:390AM | Plasma | Ok | no faults |
| 5 | 11:32:57:570AM | Plasma | Ok | no faults |
| 6 | 11:51:08:030AM | Plasma | Ok | chopper did not run -- disruption |
| 7 | 12:08:18:400PM | Plasma | Ok | no faults -- chopper ok |
| 8 | 12:33:13:860PM | Plasma | Ok | no faults |
| 9 | 12:46:38:530PM | Plasma | Bad | |
| 10 | 01:00:47:980PM | Plasma | Ok | no faults |
| 11 | 01:16:44:380PM | Plasma | Ok | chopper ioc -- no faults on supplies |
| 12 | 01:31:25:230PM | Plasma | Ok | no faults - dud |
| 13 | 01:43:34:440PM | Plasma | Ok | no faults |
| 14 | 01:58:16:600PM | Plasma | Ok | chopper over current |
| 15 | 02:13:54:750PM | Plasma | Ok | no faults |
| 16 | 02:28:03:750PM | Plasma | Ok | no faults |
| 17 | 02:50:15:170PM | Plasma | Ok | no faults |
| 18 | 03:05:21:150PM | Plasma | Ok | chopper over current |
| 19 | 03:26:28:270PM | Plasma | Ok | no faults |
| 20 | 03:41:44:180PM | Plasma | Ok | no faults |
| 21 | 03:57:14:490PM | Plasma | Bad | ack failure on transition to init -- cleared on transition to check -- n |
| 22 | 04:15:23:330PM | Plasma | Ok | chopper over current |
| 23 | 04:31:03:430PM | Plasma | Ok | chopper over current |
| 24 | 04:47:38:420PM | Plasma | Ok | no faults |
| 25 | 05:02:28:610PM | Plasma | Ok | no faults |