| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Robert Granetz |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Vinny Bertolino,Joe Daigle |
| Engineering Operator Run Comment |
| impurity screening |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:11:367PM |
| Author: To Be Determined |
| Run summary for 941206 R. Granetz SL: R. Granetz PO: J. Snipes EO: V. Bertolino/J. Daigle This run was devoted to MP #056, a comparison of impurity screening efficiency between diverted and limited plasmas. The method is the same as that used previously for last summer's study of divertor screening, namely: puff in a known amount argon gas, (which is a `recycling' impurity), and measure the resulting number of argon nuclei in the plasma using data from the HIREX spectrometer. All shots had 0.8 MA of plasma current at 5.3 Tesla. We did the screening measurements at 3 different densities, using the calibrated fast piezo valve on B-side (lower) for puffing in argon (N_injected was 4.35e17 atoms). The preliminary results are summarized in the following table (thank you, Francesca): Shot 941206 10^20 m-3 puffed? config. mode argon in plasma -------------------------------------------------------------------------- 011 1.32 no limited (background) 012 1.35 yes limited 0.08 013 1.24 yes diverted L 0.04 " H About twice L-mode 015 1.3 ? no diverted H & L (background) -------------------------------------------------------------------------- 016 0.76 yes diverted L 0.03 017 0.9 ? no limited (background) 018 0.95 yes limited 0.06 -------------------------------------------------------------------------- 019 2.4 no limited (background) 024 2.2 yes limited 0.06 025 2.1 yes diverted L 0.03 The results show that for this recycling impurity, limited plasmas allow twice as many particles to get into the plasma (6-8%) compared to diverted plasmas in L-mode (3-4%) at all three densities, but in all cases this fraction is relatively low. There is very preliminary data on diverted H-modes which shows about a doubling of the L-mode penetration fraction. It was also clearly observed that at the low and medium densities, the limited plasmas had much higher levels of molybdenum...enough to increase Zeff noticeably. However, at the high densities, there was virtually no difference in molydenum radiation between the diverted and limited plasmas. There were several things that caused major problems during the run. We had originally planned to puff in argon from the divertor and the inboard midplane using the NINJA system, in addition to the B-side location, but problems with controlling the amount of argon (and the timing of the puff) proved insurmountable today, so only the B-side valve was used. We also got bitten (severely mauled) by PCS bugs. I thought I was being clever by having the startup programmed in segment 01, a diverted plasma programmed in segment 02, and a limited plasma programmed in segment 03. The idea was to simply turn on the desired segment and turn off the unwanted segment in order to toggle between diverted and limited configurations. But PCS couldn't seem to handle segment 03 properly. At least 5 bugs related to segment loading and usage were found, and we did not bother to check out all the supposed fixes, so beware in the future. The biggest problem, though, was that several upper horizontal TF arms were taking a long time to cool down, even after running all day. This severely reduced the shot rep rate. The problem might have been caused by the relatively warm temperature of the upper dome. The moral may be that cooling should start at least one day before plasma operation begins. We also had more problems with fizzles today, compared to recent runs, especially after upward going disruptions. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:52:300PM |
| Author: To Be Determined |
From: PHYSOP::SNIPES Date: 6-DEC-1994 17:25:23 Description: Physics Operator Run Summary 941206 Overall, the machine ran reasonably well. We attempted to toggle between limited and diverted plasmas at several densities with and without argon puffing to determine the fueling efficiency of argon under various conditions. The result was that the divertor works to reduce the argon in the main plasma by about a factor of two over limited plasmas. The run was slowed down considerably by a couple of problems. First, bugs in PCS regarding the use of segment 3 instead of segment 2 lost the run a fair amount of time. Then, the cooling of the TF magnet was quite slow all day long so that we were usually waiting for cooling between shots. Other than that, there was only one shot lost to power supply problems (EF3 failed). But, that was quickly fixed. The run summary follows: Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax 1 0.000 0.010 2 1.323 0.828 3 1.342 0.830 4 0.000 0.044 5 1.071 0.830 6 0.000 0.042 7 1.327 0.830 8 0.315 0.450 9 0.000 0.047 10 0.000 0.047 11 1.337 0.828 12 1.325 0.825 13 1.319 0.833 14 0.000 0.016 15 1.322 0.835 16 0.980 0.895 17 1.323 0.822 18 1.314 0.822 19 1.092 0.812 20 0.000 0.024 21 0.000 0.047 22 0.000 0.052 23 0.471 0.750 24 1.276 0.817 25 1.222 0.825 Finished summary for 941206 Total of 25 shots. 25 shots. 17 plasmas. 6 fizzles. 2 duds. |
| Session Leader Comments | |||
| Dec 6 1994 08:49:46:470AM | Robert Granetz | MP 056 Impurity Screening
Today's run is devoted to the comparison of impurity screening between diverted and limited plasma configurations. We will alternate between diverted and limited plasmas, use three different densities (0.5, 0.8, and 1.5 e20 m-2), and puffing argon from three different locations (Ninja divertor private flux, Ninja inboard midplane, and non-Ninja fast B-side). | |
| Dec 6 1994 10:13:36:380AM | Robert Granetz | The pre-fill was set at 1.4e-5 torr at the start of the run.
| |
| Dec 6 1994 01:05:57:210PM | Robert Granetz | Throughout the day, the TF cooling was taking a very long time, causing a
very low rep rate. In addition, the NINJA system was having problems with several flaky pressure gauges, and couldn't seem to regulate the plenum pressures. Also the injection time had to be moved incredibly early (-1.8 s). | |
| Dec 6 1994 08:50:30:540AM | 941206001 | Robert Granetz | Standard Tuesday morning OH test.
|
| Dec 6 1994 08:59:16:820AM | 941206002 | Robert Granetz | This shot will hopefully be a limited plasma at 0.8 MA and nl=0.8e20 with
no argon puffing. Since it's our first plasma attempt since last Thursday, and since we've had at least one accidental leak, I don't expect things to go smoothly. |
| Dec 6 1994 09:35:10:460AM | 941206002 | Robert Granetz | Plasma! Ip=0.82 MA, duration=1.32 s, nl=0.8e20, no disruption.
Unfortunately, this was a diverted plasma, even though we asked for a limited plasma. The PCS programming uses segment 02 for the diverted plasma and segment 03 for the limited plasma, and segment 03 was definitely the requested one. It looks like segment 02 was actually in control though (see for example the z-centroid) Also, there was a dithering transition to H-mode. Next shot, copy segment 03 into segment 02 and load-into-model. This should be a limited shot, nl=0.8e20, no argon puffing. |
| Dec 6 1994 10:02:14:960AM | 941206003 | Robert Granetz | Plasma. Ip=-0.82 MA, duration=1.34 s, nl=0.8e20. No disruption.
This plasma was indeed limited. Spectroscopists report that there's some residual argon leftover from last week. Also, there's more molybdenum on this 0.8 MA limited plasma than during last week's 0.6 MA plasmas. Next shot: Turn on argon puff at -0.1 s in the private flux zone, nl=0.8e20, limited. |
| Dec 6 1994 10:23:09:050AM | 941206004 | Robert Granetz | Fizzle. I think it almost made it. No obvious problems. Next shot, repeat.
|
| Dec 6 1994 10:47:51:230AM | 941206005 | Robert Granetz | Plasma. Ip=-0.82 MA, duration=1.07 s. Disrupted. Argon levels were
enormous, and undoubtedly caused the disruption. Next shot, repeat, except reduce argon pressure as much as possible (which is only a factor of 2 to 4). Maybe this is what caused the previous fizzle too. |
| Dec 6 1994 11:02:27:100AM | 941206006 | Robert Granetz | Fizzle. Almost made it. Next shot, repeat with no changes.
|
| Dec 6 1994 11:46:55:180AM | 941206007 | Robert Granetz | Plasma, limited, Ip=-0.82 MA, duration=1.33 s. Too little argon.
Next shot, repeat with more argon. Also, change RXL and RXU to pull EF2 supplies off of their rails. |
| Dec 6 1994 11:57:30:040AM | 941206007 | Robert Granetz | Also for the next shot: Josh claims to have fixed the PCS bug that bit us
earlier, concerning the lack of segment 03 functionality. So for the next shot, we'll have segment 02 programmed for diverted plasma (but turned OFF) and segment 03 programmed for limited plasma (and turned ON). |
| Dec 6 1994 12:01:05:590PM | 941206008 | Robert Granetz | Plasma, but something went wrong at the PCS segment switch time of 0.1 s, and
the current ramped down. Duration=0.31 s. Next shot, recall shot 7, redo changes to RXL and RXU, and use only segment 02 (which is programmed for a limiter shot.) |
| Dec 6 1994 12:15:55:720PM | 941206009 | Robert Granetz | Fizzle, but it almost went. Next shot, move argon injection earlier (move
from -0.1 s to -0.5 s) because the lower plenum pressure results in a slower outflow. No other changes. |
| Dec 6 1994 12:44:53:120PM | 941206009 | Robert Granetz | Correction: the argon puff was moved to -1.8 s for the next shot.
|
| Dec 6 1994 12:39:57:590PM | 941206010 | Robert Granetz | Fizzle. Almost went. Ip is rising a little faster than normal, so for the
next shot we'll increase derivative gain early on (in segment 01). Also, the NINJA will be turned off for the next shot. The base pressure prior to the next shot was 3.5e-7 torr. |
| Dec 6 1994 12:51:23:650PM | 941206011 | Robert Granetz | Plasma, limited, no argon puff. Ip=-0.82 MA, duration=1.34 s.
Next shot, argon puff through fast B-side lower piezo. Same plasma, i.e. limited, nl=0.8e20 m-2. |
| Dec 6 1994 01:24:15:110PM | 941206012 | Robert Granetz | Plasma, argon puffed through B-side, Ip=-0.82 MA, duration=1.32 s.
Good limited plasma. Good spectroscopic signals. Next shot, change to a diverted configuration, with argon puff through B-side. |
| Dec 6 1994 01:45:29:100PM | 941206013 | Robert Granetz | Plasma, diverted, argon puff from B-side. Ip=-0.83 MA, duration=1.32 s.
There were some molybdenum injections. Next shot, same except B-side valve is disabled...no argon puff. |
| Dec 6 1994 01:47:12:810PM | 941206014 | Robert Granetz | No plasma. No EF3.
|
| Dec 6 1994 01:52:55:820PM | 941206014 | Robert Granetz | Actually this was a fizzle with no EF3.
|
| Dec 6 1994 02:12:34:430PM | 941206014 | Robert Granetz | Francesca reports the following preliminary screening efficiencies:
Limited shots: 8% of argon gets in. Diverted L-modes: 4% of argon gets in. Diverted H-modes: about double the L-mode number Subtraction of residual argon levels has not been done yet, but the next shot will provide that baseline. |
| Dec 6 1994 02:08:51:320PM | 941206015 | Robert Granetz | Plasma, diverted, no argon puff. Ip=-0.82 MA, duration=1.32 s.
Some more moly injections. H-mode again (as on all diverted shots today.) Next shot, diverted, with argon puff from B-side, but at lower density: nl=0.5e20 m-2. |
| Dec 6 1994 02:59:48:660PM | 941206016 | Robert Granetz | Plasma. Disrupted at 0.98 s. Ihalo_L=-100 kA, dI/dt=0.4 MA/ms.
Diverted, argon puff from B-side, and lower density: nl=0.5e20 m-2. Next shot, (which will probably be a fizzle because of this disruption) will be a limited plasma, no argon, at nl=0.5e20 m-2. |
| Dec 6 1994 02:58:07:890PM | 941206017 | Robert Granetz | Plasma, limited, no argon puff. Ip=-0.82 MA, duration=1.32 s.
Moly background is high, as it was during previous limited shots today. nl=0.6e20, although we asked for 0.5e20 m-2. Next shot, turn on argon puff from B-side. Limited, nl=0.5e20 m-2. |
| Dec 6 1994 03:10:14:450PM | 941206018 | Robert Granetz | Plasma, limited, argon puff from B-side. Ip=-0.82 MA, duration=1.31 s.
Density was still nl=0.6e20 m-2. Next shot: same limited plasma configuration, but at high density of nl=1.5e20 m-2, and no argon puff. |
| Dec 6 1994 03:35:41:860PM | 941206019 | Robert Granetz | Plasma, limited, nl=1.5e20 m-2 !!. No argon. Disrupted upward at 1.09 s,
dI/dt=0.9 MA/ms, Ihalo_U=120 kA. Lots of spiky things on radiation signals and on density. Next shot, same thing except turn on argon puff. The base pressure is large (1.2e-6 ... 1.1e-6 ... 1.0e-6 ... 9.5e-7) Okay, go. |
| Dec 6 1994 03:45:28:860PM | 941206020 | Robert Granetz | Fizzle. Not surprising, given the previous disruption. Repeat.
|
| Dec 6 1994 03:59:45:160PM | 941206021 | Robert Granetz | Fizzle. Almost went. Try again.
|
| Dec 6 1994 04:16:45:690PM | 941206022 | Robert Granetz | Fizzle. Almost went. Null is acceptable. Tweak RCUR derivative
gain early in shot and try again. |
| Dec 6 1994 04:30:47:910PM | 941206023 | Robert Granetz | Plasma. Disrupted early. Next shot, reduce the density demand to
nl=1.3e20 m-2. |
| Dec 6 1994 04:45:19:330PM | 941206024 | Robert Granetz | Plasma. Limited, with argon puff from B-side, nl=1.3e20 m-2 (note, this is
slightly less than we planned, but we were having too many problems at 1.5e20). Ip=-0.81 MA, duration=1.27 s. Several moly injections. Next shot, diverted configuration, nl=1.3e20 m-2, argon puff from B-side. |
| Oct 2 1996 04:10:39:960PM | 941206024 | Robert Granetz | It is now 1 year and 10 months after this shot was taken. Analysis of the
argon puff on this shot strongly suggests that the pressure reading on the argon plenum (pulse gas valve 3) had an incorrect reading of 3.01 psi on this shot. The plenum pressure on shot 019 and on the following shot (025) was about 2.5 psi, and no change to the plenum pressure was mentioned in the logbook be- tween these shots. Both Francesca Bombarda and John Goetz have told me that this gauge was sometimes known to give false readings after a disruption due to B-field pickup. (This problem was later alleviated by adding magnetic shield- ing.) Shots 019 and 023 disrupted, with fizzles between those two shots. I have therefore decided to overwrite the relevant pressure gauge information in the tree, changing the appropriate value in the node: \engineering::top.torvac.gas:gasrep:analog from 3.01 to 2.48 psi. RSG |
| Dec 6 1994 05:39:02:800PM | 941206025 | Robert Granetz | Plasma, diverted, nl=1.3e20 m-2, argon puff from B-side. Smallish disruption
late in the current rampdown, due to too high a density at that low current. Comparison of this diverted shot with the previous limiter shot at this density (nl=1.3e20 m-2) also gives a factor of two difference in screening (3% for diverted and 6% for limited), and also shows that there is very little difference in the molybdenum radiation (unlike at the lower densities). End of run. |
| Dec 6 1994 06:16:20:760PM | 941206025 | Robert Granetz | This shot has the latest PCS programming for an 0.8 MA diverted plasma (with
argon puff and nl=1.3e20 m-2) in segment 02, and a similar limited plasma in segment 03. If we want to do this type of run again (for example, using a non-recycling impurity gas), start with this shot. Keywords: fiducial, template, segment 03 |
| Physics Operator Comments | |||
| Dec 6 1994 08:42:40:240AM | 941206001 | Joseph Snipes | Shot 1
OH2 test shot. |
| Dec 6 1994 08:45:52:880AM | 941206001 | Joseph Snipes | Shot 2
Copied 941201025 and changed the plasma current to 0.8 MA and NL to 0.8 x 10^20 m^-2. We will start with a standard limited plasma with no impurity puff. |
| Dec 6 1994 09:28:47:680AM | 941206002 | Joseph Snipes | Shot 2
Looked good! However, PCS did not use segment 3 as requested and instead ran a standard diverted discharge. We got a short H-mode from 0.92 to 1.02 sec, which is incredible after an air leak on Friday! |
| Dec 6 1994 09:53:08:420AM | 941206003 | Joseph Snipes | Shot 3
Copied the limited plasma that we wanted into segment 2 and turned off segment 3. Now trying the limited plasma. Very good! |
| Dec 6 1994 10:17:43:910AM | 941206004 | Joseph Snipes | Shot 4
Limited with Ar puff at -0.1 sec from lower divertor capillary system. No plasma! Dud! |
| Dec 6 1994 10:18:16:710AM | 941206004 | Joseph Snipes | Shot 4
Limited with Ar puff at -0.1 sec from lower divertor capillary system. No plasma! Fizzle! |
| Dec 6 1994 11:02:24:600AM | 941206004 | Joseph Snipes | Shot 5
Repeat. Too much Ar from the divertor. |
| Dec 6 1994 11:04:15:810AM | 941206006 | Joseph Snipes | Shot 6
Previous disruption corrupted the walls. No plasma. Fizzle! |
| Dec 6 1994 11:22:25:040AM | 941206007 | Joseph Snipes | Shot 7
Trying again to get a limited plasma with a small Ar puff from the divertor. Looked good. |
| Dec 6 1994 11:56:47:980AM | 941206008 | Joseph Snipes | Shot 8
Moved RXL and RXU in by 1 cm to -1.5 cm during the plasma to avoid saturation of the EF2 coils. Reloaded segment 3 hoping that PCS is now working correctly. Still limited with more Ar. Died early. Apparently, the PCS fix that should allow us to run segment 3 instead of segment 2 did not work. |
| Dec 6 1994 12:12:50:030PM | 941206008 | Joseph Snipes | Shot 9
Reloaded shot 941206007 and then moved RXL and RXU in by 1 cm to -1.5 cm during the plasma to avoid saturation of the EF2 coils. Still limited with more Ar. Fizzle! |
| Dec 6 1994 12:41:41:310PM | 941206010 | Joseph Snipes | Shot 10
Fizzle! |
| Dec 6 1994 12:42:57:410PM | 941206011 | Joseph Snipes | Shot 11
Raised derivative gain on RCUR at about 0.01 sec. Got plasma. |
| Dec 6 1994 01:03:29:360PM | 941206011 | Joseph Snipes | Shot 12
B side lower Ar puff from 0.5 to 0.52 sec at 90 V. Changed RXL to move in to -1.5 cm before t=0. |
| Dec 6 1994 01:22:25:790PM | 941206012 | Joseph Snipes | Shot 12
B side lower Ar puff from 0.5 to 0.52 sec at 90 V. Changed RXL to move in to -1.5 cm before t=0. Good shot! |
| Dec 6 1994 01:45:14:550PM | 941206012 | Joseph Snipes | Shot 14
Same shot with no Ar puff. |
| Dec 6 1994 04:14:36:930PM | 941206013 | Joseph Snipes | Shot 13
Diverted plasma. Density at 8 x 10^19 m^-2. |
| Dec 6 1994 02:06:11:100PM | 941206014 | Joseph Snipes | Shot 14
Same shot with no Ar puff. Fizzle. No EF3. Power supply failure. |
| Dec 6 1994 02:07:33:130PM | 941206015 | Joseph Snipes | Shot 15
Same shot as 941206013 with no Ar puff. Good shot! |
| Dec 6 1994 02:09:52:940PM | 941206015 | Joseph Snipes | Shot 15
Same shot as 941206013 with no Ar puff. Good shot! H-mode from 0.8 to 1 sec in this shot and shot 13. |
| Dec 6 1994 02:37:54:440PM | 941206016 | Joseph Snipes | Shot 16
Reduced density to 5 x 10^19 m^-2. Still diverted. Disrupted at 980 ms. No H-mode. Perhaps there is a low density limit to the H-mode. |
| Dec 6 1994 02:54:38:680PM | 941206017 | Joseph Snipes | Shot 17
Limited plasma at 5 x 10^19 m^-2. Ar puff on B side lower. Good shot! |
| Dec 6 1994 03:00:35:090PM | 941206017 | Joseph Snipes | Shot 17
Correction to last comment. Limited plasma at 5 x 10^19 m^-2 with no Ar puff. |
| Dec 6 1994 03:09:26:980PM | 941206018 | Joseph Snipes | Shot 18
Limited plasma at 5 x 10^19 m^-2 with Ar puff from B side lower. Good shot! |
| Dec 6 1994 03:35:12:440PM | 941206019 | Joseph Snipes | Shot 19
Limited plasma at 1.5 x 10^20 m^-2 with no Ar puff. Reached the requested density. Good density feedback! Disrupted at 1.1 sec. |
| Dec 6 1994 03:44:22:430PM | 941206020 | Joseph Snipes | Shot 20
Limited plasma at 1.5 x 10^20 m^-2 with Ar puff. Fizzle! |
| Dec 6 1994 04:11:46:030PM | 941206021 | Joseph Snipes | Shot 21
Try again. Limited plasma at 1.5 x 10^20 m^-2 with Ar puff. Fizzle! |
| Dec 6 1994 04:12:23:690PM | 941206022 | Joseph Snipes | Shot 22
Try again. Fizzle! |
| Dec 6 1994 04:24:19:680PM | 941206023 | Joseph Snipes | Shot 23
Raised derivative gain on RCUR from 0.01 to 0.04 sec from a value of 4 to 6. Disrupted at 0.462 sec. |
| Dec 6 1994 04:51:02:590PM | 941206023 | Joseph Snipes | Shot 24
Density lowered to 1.3 x 10^20 m^-2. Good shot! |
| Dec 6 1994 05:18:48:110PM | 941206025 | Joseph Snipes | Overall, things worked reasonably well. However, very slow cooling really
delayed the run considerably. Also, some bugs in PCS slowed us down at the beginning of the run. 25 shots, 17 plasmas, 6 fizzles, 2 duds |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:34:24:900AM | Test | Ok | oh coax instrumentation test |
| 2 | 09:08:58:340AM | Plasma | Ok | no faults |
| 3 | 09:45:59:710AM | Plasma | Ok | no faults |
| 4 | 10:14:00:160AM | Plasma | Ok | no faults |
| 5 | 10:32:07:600AM | Plasma | Ok | no faults |
| 6 | 10:57:01:660AM | Plasma | Ok | no faults |
| 7 | 11:14:58:870AM | Plasma | Ok | no faults |
| 8 | 11:46:25:840AM | Plasma | Ok | no faults |
| 9 | 12:07:04:260PM | Plasma | Ok | no faults |
| 10 | 12:23:42:680PM | Plasma | Ok | no faults |
| 11 | 12:41:07:030PM | Plasma | Ok | no faults |
| 12 | 01:05:18:140PM | Plasma | Ok | no faults |
| 13 | 01:26:36:370PM | Plasma | Ok | No faults. |
| 14 | 01:44:44:980PM | Plasma | Bad | EF3 Bad air flow switch |
| 15 | 02:00:07:810PM | Plasma | Ok | No faults |
| 16 | 02:22:34:480PM | Plasma | Ok | No faults. |
| 17 | 02:43:25:180PM | Plasma | Ok | No faults. |
| 18 | 03:02:48:970PM | Plasma | Ok | No faults |
| 19 | 03:18:45:210PM | Plasma | Ok | Comm fault EF1 U&L OH2L |
| 20 | 03:38:48:970PM | Plasma | Ok | No faults |
| 21 | 03:53:05:930PM | Plasma | Ok | No faults. |
| 22 | 04:06:41:810PM | Plasma | Ok | No faults |
| 23 | 04:20:28:570PM | Plasma | Ok | No faults. |
| 24 | 04:35:38:780PM | Plasma | Ok | No faults. |
| 25 | 04:59:43:490PM | Plasma | Ok | No faults |