| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Amanda Hubbard |
| Physics operator(s): | Ron Parker |
| Engineering operator(s): | Bill Cochran |
| Engineering Operator Run Comment |
| MP #327 Developing Low ne EDA H-Mode Targets for LHCD. Hubbard/Parker/C |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:31:850PM |
| Author: To Be Determined |
| Run Summary for 1021106 MP 327 Low ne EDA H-mode targets for LHCD Physics Operator: Ron Parker Session Leader: Amanda Hubbard A good run in which we accomplished most of the Part A of MP 327 (the part requiring ~ 2 MW ICRF). This consisted of a current and density scan, towards lower than usual values. The aim was to find out how low in density we could make a steady EDA H-mode, for use in future LHCD scenarios. We started at 800 kA (Shots 1-4), confirming that, as in past runs, a moderately high target density nel=8e19 m-2, shot 1) gives an EDA H-mode with steady density and radiation. Reducing density leads progressively to increasing radiation, edge cooling, ELMs (likely Type III) and transient conditions. The reference shot (1021106001) had nebar=2.6e20 m-3. Shots 5-16 were at 700 kA. Here the same type of phenomena applied. We were able to get to somewhat lower densities, but as target density was lowered increasing radiation and cooling edge became a problem. The early part of some of these H-modes was quite promising, with nebar~2.2e20 and neped ~1.7e20 m-3. (Shot 12 is perhaps the best example). A reference higher density, steady EDA shot was 16. Shots 18-24 were at 580 kA. Here we were able to get significantly lower H-mode densities while keeping radiation low and constant. The RF seemed to like this condition as well (after a few tuning shots). Shots 21 - 23 were good examples, with 1.9-2.1 MW RF, nebar ~ 2.4e20 m-3 and neped ~1.7-1.8 e20 m-3. These will be good shots to try as inputs for ACCOME and other LHCD codes, to see what driven current would be expected. The DNB was firing into most shots in the afternoon, so we should also have data on beam penetration and diagnostic s/n in these AT-relevant discharges. Initial assessment was "Pretty good, beam went further than expected". Edge TS also got good pedestal data in this new parameter regime (except for a few shots following its window seal freeze-up ~ shot 10-11!). Unfortunately PCI was not working so we did not get QC-mode data from it; hopefully the reflectometer will say something. The main thing NOT accomplished was part B of the MP, which called for taking a few of the best targets and increasing RF power to 3.5-4 MW, to increase Te for better off-axis LH absorption. This will have to await the next campaign, and could be accomplished in 1/2 run day. In the meantime, we will simulate changing power with TRANSP, based on the lower power data. See the logbook for shot-by shot session leader comments. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:16:940PM |
| Author: To Be Determined |
RUN SUMMARY The purpose of the run was to establish low-density H-Modes that would be suitable as targets for Lower Hybrid experiments. The run closely followed the run plan (see below) and was moderately successful. H-Modes with steady densities of about 2.1e14 were produced at currents of 600 kA. H-Mode (EDA) densities tended to increase somewhat with current. Interestingly, the radiation level that approached 100% at 800 kA dropped as the current was decreased, improving discharge quality. The machine ran extremely well for this run with good shots having no disruption produced in 22 out of 23 shots (plus one shot to test the gas valve) The only non-performing shot was a dud that was due to an air leak caused by a problem with the LN2 sump. This caused a delay of about 1.5 hours, which accounts for the lower than normal number of shots. Engineering Setup and Run Plan for Wednesday, November 6, 2002 MP 327 Developing Low ne EDA H-Mode Targets for LHCD SL: Hubbard PO: Parker Overnight Bake @ 60 C, ECDC Overnight in D2 @ 2e-4 Torr until 07:00 Run Begins at 09:00 and ends at 17:00 Power systems setup the same as for Shot 1021022025 Gas setup: B-Top 6 psi D2 Hybrid Enabled (PG4) B-side lower 1 psi Ar Hybrid Enabled (PG1) B-side upper 10 psi D2 Hybrid DISABLED (PG2, for ECDC) C-Side 30 psi D2 Hybrid Enabled (PG3) J-Bottom leave as is, Hybrid DISABLED Enable the following gate valves, assuming no vacuum problems: ECE, VUV, DNB RF Setup: Transmitters 1,2&3 in Run On by 07:00 RUN PLAN: Start with standard 800 kA discharges and lower the target density to re-establish the low density limit. Lower the current to 700 and then 600 kA and repeat the density scan. There will be limited power scans at different densities to vary the parameters that might affect the EDA/ELM-free boundary. |
| Session Leader Comments | |||
| Nov 6 2002 09:17:42:110AM | 1021106001 | Amanda Hubbard | Got what we wanted - nice steady EDA, 5.35T, 800 kA nel 0.9 (target) 1.6 (H) Now start dropping nel 0.1 per shot, see how long we can keep it. |
| Nov 6 2002 09:30:13:407AM | 1021106002 | Amanda Hubbard | Lower target. Ne rising slightly during H-mode. ELMs come in late, once edge has cooled. Nice clean RF at 2 MW. Repeat, with slightly higher RF |
| Nov 6 2002 09:47:29:737AM | 1021106003 | Amanda Hubbard | Similar, slightly higher RF. Prad is still rising rather fast, cooling the edge (and reducing WMHD) until 0.98 secs when ELMs start. Probably the EDA/QC mode is getting less effective. Go down further in density, may get ELM-free. |
| Nov 6 2002 10:09:28:700AM | 1021106004 | Amanda Hubbard | Drop target density. Got nel 7e19 at L-H. 2 H-modes, first is rather transient, ne, Prad rising fast. 2nd is more like shots 2-3, EDAish until ELMs start. |
| Nov 6 2002 10:11:08:127AM | 1021106005 | Amanda Hubbard | Reduce Ip to 700 kA (as per run plan) Target 8e18m-2. Got Fairly steady H-mode with nel 1.4 x10^20, 2.45, but some ELMs, cooling. Repeat for more RF power. |
| Nov 6 2002 10:25:11:880AM | 1021106006 | Amanda Hubbard | Rather similar. E-port still tripping, Prad still rising to 1.7 MW. (Why so high, post-boron?) Repeat. without argon. |
| Nov 6 2002 10:43:26:643AM | 1021106007 | Amanda Hubbard | Unusual H-mode, Prad jumping up and down, Tedge responding. Some periods are steady, with lower density (neped~2e20, nebar~2.3e20) Repeat, reducing RF late to see if this helps or hinders EDA. |
| Nov 6 2002 10:59:06:637AM | 1021106008 | Amanda Hubbard | Better, no injections. Nice low ne EDA early, neped~2.0, nebar~ 2.3, But, Prad still rising, get into ELMy period. ne then rises. Later, with lower RF, long ELMy period with nebar~2.4, but low Te0(1.6 keV) and W 43 kJ. Reduce target ne for next shot. |
| Nov 6 2002 11:20:21:747AM | 1021106009 | Amanda Hubbard | Target 7e19. Quite similar shot. Nice low ne EDA early, neped~2.0, nebar~ 2.3, Lasts a bit longer. But Prad still rising, get into ELMy period. Later, with lower RF, long ELMy period Try for more power on next shot. |
| Nov 6 2002 12:43:19:920PM | 1021106012 | Amanda Hubbard | Pretty good shot. EDA first, then ELMy bursts once Prad rises. Maybe some early high P ELMs. RF up to 2.5 MW. However, Prad also goes up to 2.5 MW, eventually. nel~ 1.3e20 m-2 in best period. neped~1.7e20 m-3 , lowest to date! If we could keep Prad lower, this would be great! |
| Nov 6 2002 12:46:04:583PM | 1021106013 | Amanda Hubbard | Lowered target density to 6e19 (although RF outgassing raises it to 7.7e19 by L-H). Too low - first H-mode looks ELM-free, get multiple H-modes with progressively lower WMHD. Next shot (if and when we get it) : raise target to 9e19 to confirm that we get steadier EDA, lower Prad. |
| Nov 6 2002 01:55:46:110PM | 1021106014 | Amanda Hubbard | Raised target density to 9e19. Brief, decent EDA, then ELMs. Many RF trips. Repeat. |
| Nov 6 2002 02:22:46:560PM | 1021106015 | Amanda Hubbard | Similar. 1.8 MW, some trips, Steady nel, but Prad still increasing. Not clear why! Try raising nel target some more. |
| Nov 6 2002 02:36:13:207PM | 1021106016 | Amanda Hubbard | With higher nel, get back to steady radiation. Nel 1.09-1.58 e20 m-2 neped 2.3e20 m-3. But, RF still trips, goes ELMy later. Next shot: go to 600 kA. We will then step down in current. |
| Nov 6 2002 03:01:45:807PM | 1021106017 | Amanda Hubbard | 600 kA, target nel 10^20. RF didn't like this. L-mode. Retune and repeat. |
| Nov 6 2002 03:49:15:100PM | 1021106018 | Amanda Hubbard | 600 kA, target nel 10^20. L-mode. |
| Nov 6 2002 03:55:40:090PM | 1021106019 | Amanda Hubbard | 600 kA H-Mode, steady density. low, steady Prad. 1.5 MW RF. nped ~ 1.7e20 m-3, nel 1.4e20. |
| Nov 6 2002 03:58:38:707PM | 1021106020 | Amanda Hubbard | 600 kA H-Mode, steady density. low, steady Prad. 1.9 MW RF. nped ~ 1.8e20 m-3, nel 1.5e20. Not a bad LH target. DNB firing ~ 0.8 secs 'getting way in!' |
| Nov 6 2002 04:13:08:820PM | 1021106021 | Amanda Hubbard | 600 kA H-Mode, steady density. low, steady Prad. 1.8 MW RF, nice and clean. Target nel 0.8 e20 m-2, H-mode 1.35e20. nped ~ 1.8e20 m-3, nebar 2.4e20, Good shot! Try for more RF next time. |
| Nov 6 2002 05:00:09:473PM | 1021106022 | Amanda Hubbard | Similar, slightly more RF (1.9 MW) nebar ~ 2.25, nel 1.3. neped 1.8e20 m-3. Still quite steady EDA, getting ELMy later. Steady Prad 1.2 MW. |
| Nov 6 2002 05:10:35:270PM | 1021106023 | Amanda Hubbard | Lower nel target 0.75. 2.1 MW RF. Still pretty steady H-mode, nel 1.27e20 m-3. Prad rising, 1.7 MW Probably close to the lower limit for ne. |
| Nov 6 2002 05:22:50:367PM | 1021106024 | Amanda Hubbard | Lower nel target 067e20. 2.5 MW RF, nice and clean! Getting higher Prad (up to 2.5 MW), less steady H-mode (not unexpected). But, some fairly steady periods at nel~1.2e20 m-2, nebar 2.2-2.3 e20 m-3, ne,ped~1.56e20 This is significantly lower than our usual pedestal density. |
| Physics Operator Comments | |||
| Nov 6 2002 09:16:43:907AM | 1021106001 | Ron Parker | The first shot loaded was 1021105007. It ran perfectly with just under 2 MW of RF. The programmed density will be lowered by 0.1e14 for shot 2 |
| Nov 6 2002 09:22:04:890AM | 1021106002 | Ron Parker | Shot 002 ran well, but without the desired lower density. |
| Nov 6 2002 09:47:31:140AM | 1021106003 | Ron Parker | Shot 3 ran well, a little more power. EDA mode getting less stable. For shot 4 the starting density will be lowered again by 0.1e14. |
| Nov 6 2002 09:59:35:423AM | 1021106004 | Ron Parker | Shot 4 again ran well, lower inital density, but little or even negative effect on density during H-mode. Now we'll lower current to 700 kA, returning the inital density to 0.8e14 |
| Nov 6 2002 10:07:36:260AM | 1021106005 | Ron Parker | Shot 5 ran well, but RF tripped. We'll run again after retuning. The H-mode density decreased slightly. |
| Nov 6 2002 10:21:39:640AM | 1021106006 | Ron Parker | Shot 6 ran well, but RF still breaking up. Radiated power seems high -- too much Argon? To check, no Argon on next shot. Otherwise the same as shot 6. |
| Nov 6 2002 10:42:25:157AM | 1021106007 | Ron Parker | Shot 7 again ran well, RF still somewhat intermittent. Radiated power looks essentially unchanged without Argon. For next shot, RF power will be stepped down at 1.2 s to check power scaling. |
| Nov 6 2002 10:56:56:447AM | 1021106008 | Ron Parker | Shot 8 ran well, density was lower during EDA, but the EDA period did not last long. For next shot, inital density will be lowered by 0.1e14. |
| Nov 6 2002 11:12:41:690AM | 1021106009 | Ron Parker | Shot 9 ran well, still intermittent EDA. For next shot, the RF power will be increased. |
| Nov 6 2002 12:12:17:700PM | 1021106010 | Ron Parker | OK, shot 10 was a dud, but what was interesting is that the fill pressure rose to 0.5 mT at -4 s! After a cycle test, no pathology was found, so the next shot will run wthout changes. |
| Nov 6 2002 12:13:16:313PM | 1021106011 | Ron Parker | Shot 11 was a test of the pulse gas valve. It was normal. |
| Nov 6 2002 11:57:54:273AM | 1021106012 | Ron Parker | Shot 12 ran well, even after the unexplained gas excursion on shot 11. Actually, it was a good shot in that there were extended periods of EDA with reasonable density. For next shot, the inital density will be lowered by 0.1e14. |
| Nov 6 2002 12:15:31:707PM | 1021106013 | Ron Parker | Shot 13 ran well. For next shot, inital density will be increased to 0.9e14. |
| Nov 6 2002 01:57:11:987PM | 1021106014 | Ron Parker | A break in the action: The leak that occurred on shot 10 has become stationary and can be diagnosed. It turned out to be the lower Thomson window, caused by a problem with the N2 sump. Operation will resume when leak is repaired. The repair took ~ 1.5 hours. After fixing the leak, shot 14 was run. The shot ran well but the RF broke up several times. The shot will be repeated on the next shot. |
| Nov 6 2002 02:21:08:837PM | 1021106015 | Ron Parker | Shot 15 ran well, again with somewhat intermittent RF. For next shot, the initial density will be raised to 1e14. |
| Nov 6 2002 02:34:58:360PM | 1021106016 | Ron Parker | Shot 16 was a nice shot, with an EDA transitioning to something that looks ELMy. The radiation fraction may have come down somewhat. For the next shot, the current will be lowered to 600 kA. |
| Nov 6 2002 03:26:15:030PM | 1021106017 | Ron Parker | Shot 17 ran well, but no H-Mode. Try again next shot. |
| Nov 6 2002 03:24:17:577PM | 1021106018 | Ron Parker | Shot 18 ran well, but not much of an H-Mode. Next shot, lower the inital density to 0.9e14 |
| Nov 6 2002 03:43:20:230PM | 1021106019 | Ron Parker | Lowering the density seemed to help trigger an H-Mode. RF not quite there yet. WE'll repeat. |
| Nov 6 2002 03:59:47:833PM | 1021106020 | Ron Parker | Shot 20 succeeded in producing a good H-Mode and at reasonably low density ~ 2e14, still at 600 kA. For next shot we'll lower the initial density to 0.8e14. |
| Nov 6 2002 04:10:49:227PM | 1021106021 | Ron Parker | Shot 21 ran well, again with a steady H-Mode @ 600 kA and neo ~ 2.2e14. For next shot, we'll raise the power. |
| Nov 6 2002 04:36:13:450PM | 1021106022 | Ron Parker | Shot 22 ran well, EDA mode transitioning to some ELMier regime. Density in H-Mode held steady at ~ 2.1e14. For next shot, the initial density will be reduced to 0.7e14. |
| Nov 6 2002 05:14:41:073PM | 1021106023 | Ron Parker | Shot 23 ran well, similar to 22. For next shot, initial density will be reduced to 0.6e16 and RF power raised to ~2.5 MW. |
| Nov 6 2002 05:11:52:820PM | 1021106024 | Ron Parker | Shot 24 ran well with the RF power at ~2.5 MW. H-Mode seems to transition between EDA's and ELMy phases. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:59:32:550AM | Plasma | Ok | |
| 2 | 09:16:18:220AM | Plasma | Ok | |
| 3 | 09:29:41:470AM | Plasma | Ok | |
| 4 | 09:45:05:983AM | Plasma | Ok | |
| 5 | 09:58:37:720AM | Plasma | Ok | |
| 6 | 10:11:47:517AM | Plasma | Ok | |
| 7 | 10:26:04:493AM | Plasma | Ok | |
| 8 | 10:44:18:583AM | Plasma | Ok | |
| 9 | 10:57:50:667AM | Plasma | Ok | |
| 10 | 11:16:30:240AM | Plasma | Ok | |
| 11 | 11:33:29:970AM | Test | Ok | GAs test |
| 12 | 11:44:35:207AM | Plasma | Ok | |
| 13 | 12:00:24:043PM | Plasma | Ok | |
| 14 | 01:36:04:567PM | Plasma | Ok | |
| 15 | 01:54:05:343PM | Plasma | Ok | |
| 16 | 02:21:10:820PM | Plasma | Ok | |
| 17 | 02:46:43:110PM | Plasma | Ok | |
| 18 | 03:09:44:723PM | Plasma | Ok | |
| 19 | 03:30:49:460PM | Plasma | Ok | |
| 20 | 03:45:02:293PM | Plasma | Ok | |
| 21 | 04:02:18:150PM | Plasma | Ok | |
| 22 | 04:22:49:510PM | Plasma | Ok | |
| 23 | 04:41:16:660PM | Plasma | Ok | |
| 24 | 04:59:11:347PM | Plasma | Ok | |