| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Martin Greenwald |
| Physics operator(s): | Dmitri Mossessian |
| Engineering operator(s): | Gary Dekow |
| Engineering Operator Run Comment |
| temporary comment (jas) |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:23:350PM |
| Author: To Be Determined |
| Run Plan for 1000518 mp 232 EDA/ELMfree Session Leader - Greenwald Phys Op - Mossessian ============================ Plan: ---------------------------------------------------------------------------- 1000518xxx G SESSION_LEADER May 18 2000 9:16:44:000AM . . . . . . . . . . . . . . . . . . . . MP 253 Very Low Power EDA Session Leader - M. Greenwald Phys Op - D. Mossessian With its good energy confinement, moderate particle confinement and lack of large ELMs, the EDA H-mode could be a highly favorable regime for a tokamak reactor - if we can understand the underlying physics sufficiently to extrapolate into new regimes. The key to understanding EDA seems to be in the quasi-coherent fluctuations which have been observered by the reflectometer, PCI, and probes. These fluctuations seem always to accompany EDA and have been shown to drive significant particle flux. We want to understand the relationship between the mode and the local pedestal profiles allowing us to evaluate the micro and macro-stability. The first step will be to localize the mode relative to the density and temperature pedestals. We will try to correlate both mode amplitude and convected flux with the local gradients. Because the range of the scanning probe is limited by incident heat flux, we will attempt to run EDA H-modes at the lowest possible powers. Following the recipe that was successful on 990831, we will begin with discharges at relatively low q and then scan Bt and Ip to raise q allowing access to the EDA regime. Since q(t) must be similar from shot to shot, lowering the power will necessarily mean running at both lower field and current. Possible scenarios are shown in the attached figure, where shot 1 corresponds roughly to 990831015. There are 3 probe configurations that we would like to try. The A-side scanning probe will be used for all experiments. {1}N-S floating, E-W sweeping ion saturation curves: This configuration can give $\tilde \phi$, $\tilde n_e$, and $\tilde T_e$ as well as the convected particle and energy flux. {2}N-E floating: This gives the best k resolution. {3}Same as 1 but with very small sweeps about the floating potential on E-W. This maximizes the amount of T_e data and gives the best chance to measure E_r. - Special attention should be paid to pedestal and fluctuation diagnostics. ============================== Results: A good day. After the first shot, we had 24 plasmas in a row. It took longer than expected to get the right conditions for the probe measurements. Ohmic H-modes are, as always, marginal beasts. It looks like we were near the low density limit, even at 3T, which suggests that limit is not a function of Bt. Ip however was in our normal range (as was Ip/a^2). We had EDA's at very low power, down to maybe 0.6 MW. The run was made more difficult by the steady rain of particles from the top of the vessel. By fine tuning the Bt and Ip ramps, we were able to get shots with an L/H transition followed by ELMfree/EDA transition. On several shots, we had probe plunges into the EDA phase - at least 2 were quite deep. With PCI and the reflectometer, the fluctuations were similar to those seen before. PCI saw k_R ~ 5-6 cm^-1. The scanning probe saw considerably lower k_theta ~ 2-3 cm^-1. The previous data from 990831 was from the f-bottom probe and saw k_theta ~ 5 cm^-1. We may have A-side data from that day and could determine if this difference was due to the measurement locations. The quasi-coherent fluctuations were seen over a distance of ~7.5 but we never saw the inner edge of the mode. ================================ Shots suitable for further analysis include: All shots if you're interested in low field, low current ohmic discharges - most with h-mode. for the probe analysis 1000518009 1000518022 1000518023 1000518024 1000518025 |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:10:800PM |
| Author: To Be Determined |
| Physop summary for 1000518: _________________________ Run plan: SL M.Greenwald PO D.Mossessian EO G.Dekow Engineering setup: Overnight ECDC in D2, stopping 1-2 hours prior to the run. Run begins at 9:00 and ends at 17:00. Power system setup as on 1000517001 Gas setup - fill B-top 6 psi of D2 Hybrid enabled fill B-side lower 1 psi of Ar Hybrid enabled leave B-side upper as is Hybrid DISABLED fill C-side 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED The following gate valves should be enabled, assuming there are no vacuum problems: VUV ECE DNB We want to run ohmic EDA H-modes at the lowest possible power. Load segment 4 from 1000419021 - line integral density .6e20, ip=.8MA, Bt starts from 5.4 and ramps down to 3 T to get H-mode, then ramps back up to obtain EDA. Use segment 1 from last good shot on 1000517. _____________________________________________ Summary: Nice day from physop point of view. 1 fizzle out of 25 plasmas. I used segment 1 of shot 1000517022, which I had to modify only once, after the first fizle (shot 1). Bz was a bit low, and gas pressure looked low too. These two things were fixed and I haven't touched segment 1 since. Segment 4 was imported from 1000419021 into segment 2 for low power ohmic EDA shots. Multiple tweeks of nl, ip and Bt were performed at the SL request (see details). Starting from shot 10, current was programed to ramp down around .8 sec. During the rampdown, left and right gaps were increasing to up to 3 cm, causing vertical instability disruptions. We tryed to control the gaps by ramping CLEARIN down (decreasing gaps) first by 5 mm, and then by 10 mm and increasing integral gain on CLEARIN. That helped somewhat, but some of the shots still disrupted. Note that integral gain on CLEARIN is set to 8 on the last shot, as opposed to "standard" 4. Scorecard: 25 shots 24 plasmas 1 fizzle Details: 1000518001 Fizzle. Bz seems to be too low (-0.0045 as opposed to -0.001 on good shot) Low G-side pressure For next shot: IC_EF4 -1280 A -> -1265 A (Bz up 1 mT), pulse_gas4 20 msec -> 22 msec. ----------------------------------------------------------------------------- 1000518002 Plazma. Nice startup. 2 ohmic H-modes, 1 EDA. Strong peaking of density profile after EDA, as on 990831. For next shot: lower target nl to 5.5e19 ----------------------------------------------------------------------------- 1000518003 Plazma, same as previous shot For next shot: program target density to decrease linearly from 5.5e19 @.45 sec to 4.e19 @ 1.18 sec ----------------------------------------------------------------------------- 1000518004 Plasma, H-modes. For next shot: change TF waveform somewhat. ----------------------------------------------------------------------------- 1000518005 Plasma, no H-modes. For next shot: increases nl target 5.5e20->6.2e20 ----------------------------------------------------------------------------- 1000518006 Plasma, H-modes. For next shot: no changes ----------------------------------------------------------------------------- 1000518007 Plasma, H-mode. For next shot: no changes ----------------------------------------------------------------------------- 1000518008 Plasma, H-mode. Very large injection around .14 sec that reduces Ip to .4 from .6. For next shot: no changes ----------------------------------------------------------------------------- 1000518009 Plasma, H-mode. For next shot: decrease min Bt to 2.4 T, keeping const ramping rate. Add current rampdown at .75 sec to .55MA at 1.5MA/sec. Copyed TF trace from segment2 into segment 1. ----------------------------------------------------------------------------- 1000518010 Plasma, H-mode. Disrupted at .98 sec (end of current rampdown). Left and right gaps increase during current ramp. For next shot: Drop CLEARIN at current ramp by 5 mm ----------------------------------------------------------------------------- 1000518011 Plasma, H-mode.Stabilized gaps somewhat. Left gap is still increasing considerably at current rampdown, but then comes back to normal. Right gap has a lot of jitter. For next shot: Move current rampdown 50 msec forward and extended it by 50 msec. ----------------------------------------------------------------------------- 1000518012 Plasma, H-mode.Disrupted @ 1sec. Hard to say whether it's vertical instability or an injection. For next shot: Try to stabilize gaps more by doubling integral gain in CLEARIN from .70 secm. ----------------------------------------------------------------------------- 1000518013 Plasma , H-mode, disrupted at 1.15 sec. Vertical instability. Integral gain on CLEARIN didn't do much. For next shot: Drop CLEARIN by 5 mm, Extend curent rampdown by 100 msec ----------------------------------------------------------------------------- 1000518014 Plasma to 1.83 sec, no H-mode For next shot: Extend curent rampdown by 50 msec ----------------------------------------------------------------------------- 1000518015 Plasma , very similar to shot 14. No H-mode For next shot: delay Ip rampdown by 100 msec, delay CLEARIN drop by the same amount. ----------------------------------------------------------------------------- 1000518016 Plasma , very similar to shot 15. No H-mode For next shot: INcrease density 15% to 7e19 ----------------------------------------------------------------------------- 1000518017 Plasma , H-mode, disrupted at 1.27 sec For next shot: Shift the ip rampdown back 50 msec, increase its rate by 50 msec. Shift CLEARIN trace accordingly. ----------------------------------------------------------------------------- 1000518018 Plasma , no H-mode For next shot: Delay the ip and CLEARIN rampdown by 50 msec. ----------------------------------------------------------------------------- 1000518019 Plasma , H-mode For next shot: no changes ----------------------------------------------------------------------------- 1000518020 Plasma , ELM-free H-mode For next shot: no changes ----------------------------------------------------------------------------- 1000518021 Plasma , H-modes For next shot: speed up current ramp after .95 sec. ----------------------------------------------------------------------------- 1000518022 Plasma , H-modes For next shot: no PCS changes ----------------------------------------------------------------------------- 1000518023 Plasma , H-modes For next shot: no PCS changes ----------------------------------------------------------------------------- 1000518024 Plasma , H-modes For next shot: no PCS changes ----------------------------------------------------------------------------- 1000518025 Plasma , H-modes |
| Session Leader Comments | |||
| May 18 2000 09:16:44:000AM | Martin Greenwald | MP 253 Very Low Power EDA Session Leader - M. Greenwald Phys Op - D. Mossessian With its good energy confinement, moderate particle confinement and lack of large ELMs, the EDA H-mode could be a highly favorable regime for a tokamak reactor - if we can understand the underlying physics sufficiently to extrapolate into new regimes. The key to understanding EDA seems to be in the quasi-coherent fluctuations which have been observered by the reflectometer, PCI, and probes. These fluctuations seem always to accompany EDA and have been shown to drive significant particle flux. We want to understand the relationship between the mode and the local pedestal profiles allowing us to evaluate the micro and macro-stability. The first step will be to localize the mode relative to the density and temperature pedestals. We will try to correlate both mode amplitude and convected flux with the local gradients. Because the range of the scanning probe is limited by incident heat flux, we will attempt to run EDA H-modes at the lowest possible powers. Following the recipe that was successful on 990831, we will begin with discharges at relatively low q and then scan Bt and Ip to raise q allowing access to the EDA regime. Since q(t) must be similar from shot to shot, lowering the power will necessarily mean running at both lower field and current. Possible scenarios are shown in the attached figure, where shot 1 corresponds roughly to 990831015. There are 3 probe configurations that we would like to try. {1}N-S floating, E-W sweeping ion saturation curves: This configuration can give $\tilde \phi$, $\tilde n_e$, and $\tilde T_e$ as well as the convected particle and energy flux. {2}N-E floating: This gives the best k resolution. {3}Same as 1 but with very small sweeps about the floating potential on E-W. This maximizes the amount of T_e data and gives the best chance to measure E_r. | |
| May 18 2000 09:44:37:060AM | 1000518002 | Martin Greenwald | Good shot Ohmic H-modes, EDA Density peaking toward end of shot - like 990831 |
| May 18 2000 10:02:31:763AM | 1000518003 | Martin Greenwald | Good Shot Ohmic H-mode - mostly ELMfree might be EDA period later - no diagnostics to tell |
| May 18 2000 10:27:47:373AM | 1000518004 | Martin Greenwald | Good shot ohmic H-modes - mostly ELMfree 2 probe plunges |
| May 18 2000 10:51:38:577AM | 1000518005 | Martin Greenwald | Didn't scan the field down as far - no h-mode |
| May 18 2000 10:56:56:343AM | 1000518006 | Martin Greenwald | Raised density - Good shot - ohmic h-modes Looks like some eda periods - multiple small injections - traq_2 failure so no efit |
| May 18 2000 11:34:09:857AM | 1000518007 | Martin Greenwald | Good shot Ohmic H-mode, brief eda period first probe plunge may see a bit H-modes are interupted by injections (Moly?) |
| May 18 2000 11:51:01:687AM | 1000518008 | Martin Greenwald | Similar to shot 007 again, the injections interupt the h-mode |
| May 18 2000 12:12:51:450PM | 1000518009 | Martin Greenwald | Good shot ohmic h-modes - longer eda period probe sees a bit of this next shot lowering field and current farther |
| May 18 2000 12:35:01:217PM | 1000518010 | Martin Greenwald | Got an H-mode at 2.9T, 0.6 MA disrupts shortly after |
| May 18 2000 01:19:12:140PM | 1000518012 | Martin Greenwald | We tweaked the current got an earlier H-mode but disrupted after 100 msec into the H-mode OH power gets as low as 0.83 MW |
| May 18 2000 01:31:44:437PM | 1000518013 | Martin Greenwald | Lasts a little longer - disrupts vertically - maybe triggered by injection Ohmic EDA obtained with only 0.6 MW |
| May 18 2000 01:57:20:793PM | 1000518014 | Martin Greenwald | No H-mode there were two big injections at the time of minimum q (max power) |
| May 18 2000 02:20:40:937PM | 1000518015 | Martin Greenwald | No H-mode |
| May 18 2000 02:29:48:983PM | 1000518016 | Martin Greenwald | Delayed the current down ramp No H-Mode again despite plenty of power Next shot we'll raise the density in case we're below the low density limit |
| May 18 2000 02:50:45:153PM | 1000518017 | Martin Greenwald | Raising the density recovered the H-mode Two h-mode periods, the second was EDA with clear fluctuations on the PCI and Reflectometer |
| May 18 2000 03:03:15:030PM | 1000518018 | Martin Greenwald | Moved the current ramp earlier and lost the H-mode |
| May 18 2000 03:21:28:343PM | 1000518019 | Martin Greenwald | Got the H-mode again with clear EDA |
| May 18 2000 03:40:21:920PM | 1000518020 | Martin Greenwald | ELMfree H-mode probe when in after H/L transition |
| May 18 2000 03:58:51:297PM | 1000518021 | Martin Greenwald | Two h-mode phases, second one eda probe fired during L-mode in between |
| May 18 2000 04:17:42:640PM | 1000518022 | Martin Greenwald | Success EDA h-mode and probe at same time fluctuations are clear and last for about 1.5 mm of travel |
| May 18 2000 04:28:16:530PM | 1000518023 | Martin Greenwald | Even better clear EF/EDA transition probes hits EDA phase |
| May 18 2000 05:04:32:187PM | 1000518024 | Martin Greenwald | Pretty good shot We only get half of the probe scan we lose the h-mode at the time of maximum insertion |
| May 18 2000 06:07:29:687PM | 1000518025 | Martin Greenwald | Also a good shot probe catches EF/EDA transition |
| Physics Operator Comments | |||
| May 18 2000 09:10:51:747AM | Dmitri Mossessian | SL M.Greenwald PO D.Mossessian MP253 Very low power EDA H-modes Engineering setup: Overnight ECDC in D2, stopping 1-2 hours prior to the run. Run begins at 9:00 and ends at 17:00. Power system setup as on 1000517001 Gas setup - fill B-top 6 psi of D2 Hybrid enabled fill B-side lower 1 psi of Ar Hybrid enabled leave B-side upper as is Hybrid DISABLED fill C-side 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED Run plan: We want to run ohmic EDA H-modes at the lowest possible power. Load segment 4 from 1000419021 - line integral density .6e20, ip=.8MA, Bt starts from 5.4 and ramps down to 3 T to get H-mode, then ramps back up to obtain EDA. Use segment 1 from last good shot on 1000517. _________________________________________ Loaded shot 1000517022. Imported segment 4 from 1000419021 into segment 2. Load/clean. 9:05 Coldstart OK. | |
| May 18 2000 09:29:50:560AM | 1000518001 | Dmitri Mossessian | Fizzle. Bz seems to be too low (-0.0045 as opposed to -0.001 on good shot) Low G-side pressure For next shot: IC_EF4 -1280 A -> -1265 A (Bz up 1 mT), pulse_gas4 20 msec -> 22 msec. |
| May 18 2000 09:45:40:483AM | 1000518002 | Dmitri Mossessian | Plazma. Nice startup. 2 ohmic H-modes, 1 EDA. Strong peaking of density profile after EDA, as on 990831. For next shot: lower target nl to 5.5e19 |
| May 18 2000 10:03:08:340AM | 1000518003 | Dmitri Mossessian | Plazma, same as previous shot For next shot: program target density to decrease linearly from 5.5e19 @.45 sec to 4.e19 @ 1.18 sec |
| May 18 2000 10:19:59:030AM | 1000518004 | Dmitri Mossessian | Plasma, H-modes. For next shot: change TF waveform somewhat. |
| May 18 2000 10:46:21:357AM | 1000518005 | Dmitri Mossessian | Plasma, no H-modes. For next shot: increases nl target 5.5e20->6.2e20 |
| May 18 2000 11:08:31:360AM | 1000518006 | Dmitri Mossessian | Plasma, H-modes. For next shot: no changes |
| May 18 2000 11:34:06:873AM | 1000518007 | Dmitri Mossessian | Plasma, H-mode. For next shot: no changes |
| May 18 2000 12:14:51:293PM | 1000518008 | Dmitri Mossessian | Plasma, H-mode. Very large injection around .14 sec that reduces Ip to .4 from .6. For next shot: no changes |
| May 18 2000 12:18:23:280PM | 1000518009 | Dmitri Mossessian | Plasma, H-mode. For next shot: decrease min Bt to 2.4 T, keeping const ramping rate. Add current rampdown at .75 sec to .55Ma at 1.5MA/sec. Copyed TF trace from segment2 into segment 1. |
| May 18 2000 12:38:40:280PM | 1000518010 | Dmitri Mossessian | Plasma, H-mode. Disrupted at .98 sec (end of current rampdown). Left and right gaps increase during current ramp. For next shot: Drop CLEARIN at current ramp by 5 mm |
| May 18 2000 12:51:10:700PM | 1000518011 | Dmitri Mossessian | Plasma, H-mode.Stabilized gaps somewhat. Left gap is still increasing considerably at current rampdown, but then comes back to normal. Right gap has a lot of jitter. For next shot: Move current rampdown 50 msec forward and extended it by 50 msec. |
| May 18 2000 01:19:13:343PM | 1000518012 | Dmitri Mossessian | Plasma, H-mode.Disrupted @ 1sec. Hard to say whether it's vertical instability or an injection. For next shot: Try to stabilize gaps more by doubling integral gain in CLEARIN from .70 secm. |
| May 18 2000 01:59:13:357PM | 1000518013 | Dmitri Mossessian | Plasma , H-mode, disrupted at 1.15 sec. Vertical instability. Integral gain on CLEARIN didn't do much. For next shot: Drop CLEARIN by 5 mm, Extend curent rampdown by 100 msec |
| May 18 2000 01:55:34:483PM | 1000518014 | Dmitri Mossessian | Plasma to 1.83 sec, no H-mode For next shot: Extend curent rampdown by 50 msec |
| May 18 2000 02:15:35:310PM | 1000518015 | Dmitri Mossessian | Plasma , very similar to shot 14. No H-mode For next shot: delay Ip rampdown by 100 msec, delay CLEARIN drop by the same amount. |
| May 18 2000 02:29:26:343PM | 1000518016 | Dmitri Mossessian | Plasma , very similar to shot 15. No H-mode For next shot: INcrease density 15% to 7e19 |
| May 18 2000 02:52:32:123PM | 1000518017 | Dmitri Mossessian | Plasma , H-mode, disrupted at 1.27 sec For next shot: Shift the ip rampdown back 50 msec, increase its rate by 50 msec. Shift CLEARIN trace accordingly. |
| May 18 2000 03:03:01:577PM | 1000518018 | Dmitri Mossessian | Plasma , no H-mode For next shot: Delay the ip and CLEARIN rampdown by 50 msec. |
| May 18 2000 03:20:58:153PM | 1000518019 | Dmitri Mossessian | Plasma , H-mode For next shot: no changes |
| May 18 2000 03:38:50:467PM | 1000518020 | Dmitri Mossessian | Plasma , ELM-free H-mode For next shot: no changes |
| May 18 2000 03:57:37:030PM | 1000518021 | Dmitri Mossessian | Plasma , H-modes For next shot: speed up current ramp after .95 sec. |
| May 18 2000 04:41:17:983PM | 1000518022 | Dmitri Mossessian | Plasma , H-modes For next shot: no PCS changes |
| May 18 2000 04:41:51:233PM | 1000518023 | Dmitri Mossessian | Plasma , H-modes For next shot: no PCS changes |
| May 18 2000 04:41:56:700PM | 1000518024 | Dmitri Mossessian | Plasma , H-modes For next shot: no PCS changes |
| May 18 2000 05:02:18:547PM | 1000518025 | Dmitri Mossessian | Plasma , H-modes |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:13:03:890AM | Plasma | Ok | |
| 2 | 09:29:35:280AM | Plasma | Ok | |
| 3 | 09:47:33:153AM | Plasma | Ok | |
| 4 | 10:05:59:920AM | Plasma | Ok | |
| 5 | 10:29:37:873AM | Plasma | Ok | |
| 6 | 10:48:56:670AM | Plasma | Ok | |
| 7 | 11:09:30:717AM | Plasma | Ok | |
| 8 | 11:34:36:780AM | Plasma | Ok | |
| 9 | 11:53:11:747AM | Plasma | Ok | |
| 10 | 12:15:43:263PM | Plasma | Ok | |
| 11 | 12:38:56:200PM | Plasma | Ok | |
| 12 | 12:55:56:513PM | Plasma | Ok | |
| 13 | 01:21:24:700PM | Plasma | Ok | |
| 14 | 01:42:12:123PM | Plasma | Ok | |
| 15 | 02:02:11:403PM | Plasma | Ok | |
| 16 | 02:19:59:687PM | Plasma | Ok | |
| 17 | 02:37:11:123PM | Plasma | Ok | |
| 18 | 02:53:12:700PM | Plasma | Ok | |
| 19 | 03:10:07:153PM | Plasma | Ok | |
| 20 | 03:26:20:390PM | Plasma | Ok | |
| 21 | 03:45:34:623PM | Plasma | Ok | |
| 22 | 04:01:16:890PM | Plasma | Ok | |
| 23 | 04:18:39:873PM | Plasma | Ok | |
| 24 | 04:39:35:420PM | Plasma | Ok | |
| 25 | 04:56:55:763PM | Plasma | Ok | |