| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Darren Garnier |
| Physics operator(s): | Earl Marmar |
| Engineering operator(s): | Vinny Bertolino,Joe Daigle |
| Engineering Operator Run Comment |
| pep mode |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:13:583PM |
| Author: To Be Determined |
From: ZENITH::GARNIER Date: 28-APR-1995 20:05:51 Description: Run Summary 950427 Run Summary 950427 (and 950426 part II) SL: Garnier PO: Marmar EO: Bertolino/Daigle MP081 Li PEP Mode studies This run was a continuation of MP081 which was begun in February. (Run 950210). Our goals today were the following: 0. Obtain highest reactivity plasmas. 1. Optimize pellet/RF timing for different conditions. 2. Attempt PEP modes at lower currents/continue current scan. 3. Based on the idea that PEP modes are caused by reverse shear, attempt to lengthen PEP mode by ramping current. 4. Attempt to diagnose causes of PEP mode. We began the run on shot 30 of 950426 and began optimizing the PEP mode at 800 kA. Our best neutron rate was obtained on shot 950426032 with 5.5e13/sec at 2.1MW. Attempts to optimize pellet/RF timing indicate that the RF should be turned on just before the time of maximum XRay peakedness. Shots 34-35 and 9504027001-2 where attempts to lengthen the PEP mode by ramping the current up. No significant improvements were seen. Next, we attempted to expand the density scan done previously. By raising the density we had several shots that showed very little or no enhancement. The pellet peaking would often crash before the RF and we had a return of the cannoli phenomena. Interestingly, although we had asked for higher density, we didn't get it, so perhaps it was just the puffing that caused the crash. We attempted to answer this later but found that the pellet would disrupt the plasma. With lower density, the neutron rate was lower for similar powers. Conclusion: Nel_4 of 1e20 is optimum. After shot 9 it was clear that the E port antenna was kaput, so we gave up on trying to get the highest neutron rate. Shots 12-17 were double pellet experiments to take cigar data of normal and pep-mode plasmas. This data will be fed into EFIT to determine whether the current profile is profoundly different during PEP mode. Shot 18-21 were a return to Bob's killer pellet run. One thing that wasn't tried then was to shoot the gold pellet into a non-VDE plasma. On one pellet, the plasma did disrupt, but not very quickly. The plasma survived the second pellet. My guess is that the 300ug of gold did not ablate into the plasma. The next thing to try would be a ~1mg piece of gold wire "sugar coated" to go in the injector better. Lowering the current to 600kA, we found that the PEP mode duration and the post pellet particle confinement time doubled. However, the peak neutron rate was less. An attempt was made to scan the density, but the pellet injector proved unreliable (small pellets). Finally, we attempted to ramp the current downward from 800 to 600 kA immediately after the pellet. This effectively gave us a pep mode with the 800kA neutron rate for the 600 kA duration. Although we did not reach our goal of surpassing the record neutron rate because of the antenna failure, and we were plagued by many disruptions, this run was very successful. We were able to optimize pellet timing and density and explore the effect of plasma current. The extensive cigar data should also yield information about the mode. LPI Summary: 49 Pellets requested. 13 missing. (this is abnormally bad.) |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:54:050PM |
| Author: To Be Determined |
From: PHYSOP::MARMAR Date: 27-APR-1995 18:14:37 Description: Physop summary 950427 Run 950427 In support of MP081 PEP mode studies PO Marmar SL Garnier EO Bertolino/Daigle The run was reasonably successful. We managed a rather complete density scan at 0.8 MA, scanned the delay time between pellet and RF turn-on, explored .6 and .8 MA flat current, as well as current ramp-up and -down after the pellet. See the session leader's summary for results. Engineering systems ran flawlessly, with 32 plasmas in a row. The E-Port antenna had problems, believed to be due to arcing in the transmission line. As a result, after shot 9 we could get little more than 1 MW of auxiliary power. This was enough to test certain aspects of the PEP modes, such as particle and energy confinement, but the MP should not be considered complete until we have a go with ~3MW available. In the middle of the run, we devoted 4 shots to gold doped "killer" pellets; in this case the pellets were injected into plasmas where the vertical feedback was not turned off. Of the two shots with pellets (20 and 21) the first disrupted, but not very quickly, and the second survived. The run was turned over to Steve Horne at 4:00 pm, for power supply tests. His summary can be found at the end of this bulletin. The shot by shot summary: 1 start from 950426035, with ZCUR to -.5cm and ZXL moved down by .5cm fill 2.1e-5 .8 MA ramp up to 1 MA after pellet; asked for and got 1 pellet; disrupt at .8 MA (halo warning) 2 fill 1.9e-5, argon on move rcur in 2 mm, .8MA to 1 MA to .7 MA , disrupt after 2'nd pellet, .7 MA 3 rcur in 2 more mm, .8 MA straight across, disrupt after 2'nd pellet, .8 MA 4 reload shot 950426035, .8 to 1 MA ramp, disrupt at .645 s, no pellet 5 reload shot 950426034, early disrupt, a few hards 6 fill 2.1e-5, no pellets, no RF, good plasma, many tiny moly injections 7 disrupt on second pellet, at .8 second, .8MA 8 nl_04 to 1.2e20, fiddle with RCUR, ZXL and RXL after 1 second, disrupt .8s, halo warning 9 reduce clearin 5mm, move rcur in 2 mm, fire only 1'st pellet, disrupt at 1.07 s, .75 MA, halo warning 10 one pellet, at .6s, D port antenna only, didn't get the pellet, ramped to .5 MA, a few hards early 11 fill 2.3e-5 try for 2 pellets closer together, D port antenna only, disrupt after 1'st pellet, plasma got unhappy at ~.5s 12 nl_04 to 8e19, got 2 pellets, second cigar at 76 cm, then disrupt 13 got no pellets, ramped down to .3MA 14 2 pellets, disrupt 15 no argon, lasted a little longer 16 add deriv gain to nl_04 feedback, only got first pellet 17 2 pellets, then disrupt 18 switch to gold doped pellet MP; first a no pellet ohmic, nl_04=6e19, good shot 19 300 microgram Au pellet at .6 seconds, didn't get the pellet 20 try again; got it this time, disrupt, but not terribly fast 21 try again, survived 22 2 Li pellets, disrupt after second, .8MA 23 repeat, first pellet delayed 30 msec, only got 1'st pellet, 24 raise nl_04 to 1.5e20, disrupt at first pellet 25 small pellet at .6s, got in, disrupt .97s, .8MA 26 nl_04 1.0e20, medium pellet at .6 s, disrupt at 1.03, .74MA 27 decrease clearin and rcur 4 mm, lower nl_04 after pellet, pellet 20ms earlier 28 Ip .6 MA, prompt disrupt after pellet 29 small pellet, survived 30 nl_04 8e20, pellet didn't go 31 retry, no pellet 32 ramp Ip down from .9 to .6 MA after medium pellet, good shot, long particle confinement after pellet, PEP mode lasts longer than at higher current Summary: 32 plasma attempts, 32 plasmas, 0 fizzles, 0 duds. ______________________________________________________________________________ Shots 34-38 were tests of the OH2 and EF1 supplies. There has been speculation in some quarters that the various improvements to the OH2 supplies have significantly degraded their dynamic response, thus enhancing their ability to produce vertical disruptions. These shots were based on one from MP#42 by Tinios; the OH2 and EF1 supplies were driven at various frequencies (50,80,100,140,180 Hz); the results will be compared to those obtained in April 1994. |
| Session Leader Comments |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:39:56:140AM | Plasma | Ok | |
| 2 | 08:56:29:210AM | Plasma | Ok | |
| 3 | 09:12:28:790AM | Plasma | Ok | |
| 4 | 09:28:53:050AM | Plasma | Ok | |
| 5 | 09:42:04:470AM | Plasma | Ok | |
| 6 | 09:56:15:390AM | Plasma | Ok | |
| 7 | 10:07:33:760AM | Plasma | Ok | |
| 8 | 10:20:33:560AM | Plasma | Ok | |
| 9 | 10:34:04:160AM | Plasma | Ok | |
| 10 | 10:49:01:870AM | Plasma | Ok | |
| 11 | 11:14:29:940AM | Plasma | Ok | |
| 12 | 11:26:44:730AM | Plasma | Ok | |
| 13 | 11:39:25:600AM | Plasma | Ok | |
| 14 | 11:52:01:940AM | Plasma | Ok | |
| 15 | 12:06:34:380PM | Plasma | Ok | |
| 16 | 12:19:55:060PM | Plasma | Ok | |
| 17 | 12:31:02:420PM | Plasma | Ok | |
| 18 | 12:42:43:940PM | Plasma | Ok | |
| 19 | 12:58:06:930PM | Plasma | Ok | |
| 20 | 01:12:18:810PM | Plasma | Ok | No Faults. |
| 21 | 01:26:16:900PM | Plasma | Ok | No faults. |
| 22 | 01:42:31:110PM | Plasma | Ok | No Faults. |
| 23 | 01:54:14:190PM | Plasma | Ok | No Faults. |
| 24 | 02:07:06:970PM | Plasma | Ok | No Faults. |
| 25 | 02:19:21:480PM | Plasma | Ok | No Faults. |
| 26 | 02:32:06:700PM | Plasma | Ok | No Faults. |
| 27 | 02:48:15:730PM | Plasma | Ok | No Faults. |
| 28 | 03:01:48:390PM | Plasma | Ok | No Faults. |
| 29 | 03:16:38:720PM | Plasma | Ok | No Faults. |
| 30 | 03:31:32:160PM | Plasma | Ok | No Faults |
| 31 | 03:45:58:780PM | Plasma | Ok | No Faults. |
| 32 | 04:02:22:150PM | Plasma | Ok | no faults. |
| 33 | 04:14:27:420PM | Test | Ok | baseline shot |
| 34 | 04:25:54:780PM | Test | Ok | no faults |
| 35 | 04:38:45:790PM | Test | Ok | no faults |
| 36 | 04:49:30:360PM | Test | Ok | no faults |
| 37 | 05:00:07:550PM | Test | Ok | no faults |
| 38 | 05:11:17:000PM | Plasma | Ok | no shot computer locked up |