| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Joseph Snipes |
| Physics operator(s): | Earl Marmar |
| Engineering operator(s): | Gary Dekow |
| Engineering Operator Run Comment |
| MP# 254 Peaked Density H-modes SL:Snipes PO:Marmar EO:Dekow |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:24:100PM |
| Author: To Be Determined |
| Run Plan and Engineering Setup for MP254 Peaked Density H-modes 1000608 Engineering setup for Tuesday, 06 June 2000: 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 1000518002 Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid DISABLED leave B-side upper as is Hybrid DISABLED fill C-side with 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED The following gate valves should be enabled, assuming no vacuum problems: ECE, VUV, DNB ------------------------------------------------------------------------------- Run plan: MP# 254 Peaked Density H-modes SL: J. Snipes PO: E. Marmar This run will begin with Ohmic H-modes as on 1000518002 and vary the TF and Ip ramp timing and ramp rates to attempt to optimize the density peaking in H-mode. Visible bremsstrahlung and Thomson scattering are essential diagnostics to measure the density peaking. ICRF may be added late in the H-mode to attempt to heat an already peaked density profile to improve fusion performance. ECE measurements will be difficult for this run because of large variations in the TF during the discharge and from shot to shot. We will begin by copying shot 1000518002 but using the TF waveform from shot 990831015 and lengthen Ip flattop to 1.6 s. Shots 1-3: Reproduce peaking from 990831015 Shot 3: Move TF ramp up back to 1.1 s to attempt to improve peaking Shot 4: Move TF ramp up back to 1.0 s to attempt to improve peaking If peaking improves, Shot 5: Move TF ramp up back to 0.9 s to attempt to further improve peaking If peaking worsens or remains the same on shots 3 - 4, Shot 5: Return to TF timing of shot 3 and ramp the TF back up only to 4.5 T Shot 6: Repeat with TF ramp reaching 4.9 T and remain at 4.9 T to 1.6 s Choose the optimum TF waveform of these and begin Ip ramping experiments Shot 7: Ramp Ip up from 0.8 to 1.0 MA from 0.8 - 1.3 sec then held til 1.6 sec. If peaking improves, Shot 8: Increase Ip ramp rate to peak at 1.1 MA with same timing If peaking continues to improve, Shot 9: Increase Ip ramp rate to peak at 1.2 MA possibly changing TF timing to avoid going below q95 = 2.5. Adjust CLEARIN and RCUR to keep the inner and outer gaps at least 1 cm. If peaking continues to improve, Shot 10: Increase Ip ramp rate to peak at 1.3 MA changing TF timing to avoid going below q95 = 2.5 If the peaking worsens with increasing current, return to the optimum conditions and repeat as needed for diagnostics to obtain transport data and begin couping ICRF late in the H-mode. Some changes in TF may also be required when adding ICRF to determine the influence of the ICRF resonance location on the peaking. Summary: Overall, it was a good run, though the information learned was limited by numerous impurity injections that made it sometimes unclear whether the change we made had made things worse or whether it was just worse because of the injections. The most peaked shot was 1000608006 which had an ne0 = 6 x 10^20 m^-3 and an ne_ped = 2 x 10^20 m^-3. We tried adding RF and found that it did not improve the peaking, though it was not clear that it reduced the peaking either. Plasmas were obtained with moderate peaking also with RF. We also tried to determine if the TF ramp was essential for obtaining strong peaking. This was rather difficult to nail down completely given the irreproducibility of the plasmas. Nonetheless, shot 22 had a long EDA H-mode where we kept the field nearly constant and had only moderate peaking. Still, the best peaking occurred on shot 6 after the TF had been flat for 0.2 s, but after a rapid ramp up. Finally, late in the day, we tried increasing the current with the TF and adding RF. Shot 25 was the best example of RF + Ohmic peaked H-mode, but there was only 1.3 MW of RF at the peak time. There, ne0 reached 5 x 10^20 m^-3 and ne_ped = 2.8 x 10^20 m^-3 with some indication of a core barrier as well as an edge barrier. The strongest peaking occurred at 4.3 T, which is rather low field for good ICRF heating at 80 MHz with H minority. So, there is some incompatibility with obtaining peaked density H-modes in Ohmic plasmas and in ICRF heated plasmas. A couple of attempts to heat with ICRF at 4.5 T did not have very good peaking. Perhaps, more time should be spent on this scenario as well as on the last scenario that was tried, which included ramping the current up to increase the Ohmic heating while ramping the field up to stay in EDA H-mode up to 5.3 T and then get on-axis ICRF heating at 80 MHz. This should be tried with more RF power. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:11:300PM |
| Author: To Be Determined |
| Run plan: MP# 254 Peaked Density H-modes SL: J. Snipes PO: E. Marmar EO: G. Dekow The machine ran very reliably today. We started with a fizzle (no prepuff from the DNB) and then had 26 full current plasma shots. The run involved attempts to optimize the peaking of ohmic H-Mode discharges. Every shot had at least one H-mode phase. Many were hampered by radiated power increases, both transient and monotonically rising. Shots 6 and 25 appeared to come closest to the goals of the MP. There were attempts to heat with RF, ramping the field up after the transition at low field. Shot 25 is an example. Currents were explored in the range from 0.7 MA to 1.1 MA. Summary 26 plasmas 1 fizzle __________ 27 data system cycles |
| Session Leader Comments | |||
| Jun 8 2000 08:36:01:280AM | Joseph Snipes | Run Plan and Engineering Setup for MP254 Peaked Density H-modes 1000608 Engineering setup for Tuesday, 06 June 2000: 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 1000518002 Gas setup - fill B-top with 6 psi of D2 Hybrid enabled fill B-side lower with 1 psi of Ar Hybrid DISABLED leave B-side upper as is Hybrid DISABLED fill C-side with 30 psi of D2 Hybrid enabled leave J-bottom as is Hybrid DISABLED The following gate valves should be enabled, assuming no vacuum problems: ECE, VUV, DNB ------------------------------------------------------------------------------- Run plan: MP# 254 Peaked Density H-modes SL: J. Snipes PO: E. Marmar This run will begin with Ohmic H-modes as on 1000518002 and vary the TF and Ip ramp timing and ramp rates to attempt to optimize the density peaking in H-mode. Visible bremsstrahlung and Thomson scattering are essential diagnostics to measure the density peaking. ICRF may be added late in the H-mode to attempt to heat an already peaked density profile to improve fusion performance. ECE measurements will be difficult for this run because of large variations in the TF during the discharge and from shot to shot. We will begin by copying shot 1000518002 but using the TF waveform from shot 990831015 and lengthen Ip flattop to 1.6 s. Shots 1-3: Reproduce peaking from 990831015 Shot 3: Move TF ramp up back to 1.1 s to attempt to improve peaking Shot 4: Move TF ramp up back to 1.0 s to attempt to improve peaking If peaking improves, Shot 5: Move TF ramp up back to 0.9 s to attempt to further improve peaking If peaking worsens or remains the same on shots 3 - 4, Shot 5: Return to TF timing of shot 3 and ramp the TF back up only to 4.5 T Shot 6: Repeat with TF ramp reaching 4.9 T and remain at 4.9 T to 1.6 s Choose the optimum TF waveform of these and begin Ip ramping experiments Shot 7: Ramp Ip up from 0.8 to 1.0 MA from 0.8 - 1.3 sec then held til 1.6 sec. If peaking improves, Shot 8: Increase Ip ramp rate to peak at 1.1 MA with same timing If peaking continues to improve, Shot 9: Increase Ip ramp rate to peak at 1.2 MA possibly changing TF timing to avoid going below q95 = 2.5. Adjust CLEARIN and RCUR to keep the inner and outer gaps at least 1 cm. If peaking continues to improve, Shot 10: Increase Ip ramp rate to peak at 1.3 MA changing TF timing to avoid going below q95 = 2.5 If the peaking worsens with increasing current, return to the optimum conditions and repeat as needed for diagnostics to obtain transport data and begin couping ICRF late in the H-mode. Some changes in TF may also be required when adding ICRF to determine the influence of the ICRF resonance location on the peaking. | |
| Jun 8 2000 09:42:03:640AM | 1000608002 | Joseph Snipes | Shot 2: Good shot, but short H-mode. Some peaking during H-mode and more peaking after the H-L transition. |
| Jun 8 2000 09:51:13:543AM | 1000608003 | Joseph Snipes | Shot 3: Good shot, but with two H-modes interrupted by a large impurity injection. Some density peaking. |
| Jun 8 2000 10:32:27:967AM | 1000608004 | Joseph Snipes | Shot 4: Good shot. H-mode lasts longer, but the final density is lower and so is the peaking. |
| Jun 8 2000 10:37:12:840AM | 1000608005 | Joseph Snipes | Shot 5: Good shot. Less peaking though. |
| Jun 8 2000 01:07:42:360PM | 1000608006 | Joseph Snipes | Shot 6: Very good shot. H-mode lasts longer and peaks up very well to 6 x 10^20 m^-3. |
| Jun 8 2000 11:32:43:000AM | 1000608007 | Joseph Snipes | Shot 7: Decent shot, but with impurity injections. Moderate peaking. |
| Jun 8 2000 11:33:08:467AM | 1000608008 | Joseph Snipes | Shot 8: Decent shot, but with impurity injections. Moderate peaking. |
| Jun 8 2000 11:39:33:903AM | 1000608009 | Joseph Snipes | Shot 9: Adding RF power up to 2 MW. Nice long H-mode from 1.1 - 1.6 s. Reasonable peaking with ne0 up to 4 x 10^20 m^-3. |
| Jun 8 2000 12:04:14:420PM | 1000608010 | Joseph Snipes | Shot 10: RF only got 1 MW. ELM-free and EDA H-modes. Not as good peaking. |
| Jun 8 2000 12:37:11:263PM | 1000608011 | Joseph Snipes | Shot 11: Allow RF to tune first as we adjust the gaps. Decent shot but only moderate peaking. Still plagued by impurity injections. |
| Jun 8 2000 12:38:27:920PM | 1000608012 | Joseph Snipes | Shot 12: RF requested 2.5 MW and got about 1 MW with D port tripping. Decent H-mode but only moderate peaking. |
| Jun 8 2000 12:59:35:140PM | 1000608013 | Joseph Snipes | Shot 13: Two H-modes, one ELM-free the other EDA-like but with a lot of Prad. Not very much peaking. |
| Jun 8 2000 01:15:12:047PM | 1000608014 | Joseph Snipes | Shot 14: Tried a downward Ip ramp and as expected that was worse. RF got in 1.5 MW and there was a low density EDA H-mode, which might be a good lower hybrid target H-mode, but was not very high performance. Some peaking after the H-L transition but only moderate peaking during the H-mode. |
| Jun 8 2000 01:47:54:560PM | 1000608015 | Joseph Snipes | Shot 15: Return to 0.8 MA flattop and reduce the final field to 3.8 T straight across. Short H-mode. |
| Jun 8 2000 01:49:16:920PM | 1000608016 | Joseph Snipes | Shot 16: Allow Ip to droop by programming it straight across. Short ELM-free H-mode resulting in too much radiation. |
| Jun 8 2000 02:05:15:827PM | 1000608017 | Joseph Snipes | Shot 17: Try increasing nl04 to 7.5 x 10^19 m^-2 to get into EDA H-mode instead. Brief but more EDA-like H-mode. Possibly interrupted by an impurity injection but the injection also occurs right as the TF is reaching its flattop value. |
| Jun 8 2000 02:28:01:030PM | 1000608018 | Joseph Snipes | Shot 18: Try a slower TF ramp from 1 to 1.6 sec from 3.2 to 4.3 T. Split the difference on the density programmed to nl04 = 7 x 10^19 m^-2. Better EDA H-mode moderate peaking. |
| Jun 8 2000 02:52:42:187PM | 1000608019 | Joseph Snipes | Shot 19: Try 6.5 x 10^19 m^-2 programmed density. Got EDA but two H-modes rather than one long one. |
| Jun 8 2000 03:08:57:937PM | 1000608020 | Joseph Snipes | Shot 20: Repeat. Impurity injection killed the first H-mode. A bit more ELM-free like. EDA H-mode late. |
| Jun 8 2000 03:10:42:903PM | 1000608021 | Joseph Snipes | Shot 21: Reduce field to 3.5 T after the ramp down to 3.2 T. nl04 to 7.5 x 10^19 m^-2. Good shot. Long EDA but with only moderate peaking to ne0 = 3.5 x 10^20 m^-3. |
| Jun 8 2000 03:21:15:560PM | 1000608022 | Joseph Snipes | Shot 22: Reduce nl04 to 7 x 10^19 m^-2 and TF to 3.4 T. Got a long EDA H-mode but still with moderate peaking. Suggests that we need more of a TF ramp to get strong peaking. |
| Jun 8 2000 03:44:22:640PM | 1000608023 | Joseph Snipes | Shot 23: Ramp TF from 1 sec to 5.2 T as fast as possible. Dropped out of H-mode at 1.05 s. |
| Jun 8 2000 04:07:51:187PM | 1000608024 | Joseph Snipes | Shot 24: Add RF after 1.25 s at low power for tuning. Raise nl04 to 7.5 x 10^19 m^-2. Ramp Ip from 1 to 1.15 s to 1.0 MA then stay there until 1.6 s to attempt to stay in H-mode longer. Good shot. Density peaked up to ne0 = 5 x 10^20 m^-2. The plasma fell out of H-mode just before the ICRF turned on though. |
| Jun 8 2000 04:24:43:653PM | 1000608025 | Joseph Snipes | Shot 25: Move the TF and Ip ramps up to 0.89 s and turn on the RF at 1.14 sec. Good shot with substantial peaking. ne0 up to 5 x 10^20 m^-3. RF turns on during the peak density. First H-mode is a little too ELM-free. |
| Jun 8 2000 05:55:00:280PM | 1000608026 | Joseph Snipes | Shot 26: Asking RF for more power. Raise nl04 to 7.5 x 10^19 m^-3. Several H-modes with only moderate peaking. Up to 2 MW of ICRF. |
| Jun 8 2000 05:57:25:593PM | 1000608027 | Joseph Snipes | Shot 27: Increased Ip to 1.1 MA, decreased nl04 to 7 x 10^19 m^-2. Increased radiated power in H-mode. Two H-modes. One RF antenna tripped. Need more time for RF coupling to these plasmas. Not very good peaking. |
| Jun 8 2000 05:58:20:090PM | 1000608027 | Joseph Snipes | Summary: Overall, it was a good run, though the information learned was limited by numerous impurity injections that made it sometimes unclear whether the change we made had made things worse or whether it was just worse because of the injections. The most peaked shot was 1000608006 which had an ne0 = 6 x 10^20 m^-3 and an ne_ped = 2 x 10^20 m^-3. We tried adding RF and found that it did not improve the peaking, though it was not clear that it reduced the peaking either. Plasmas were obtained with moderate peaking also with RF. We also tried to determine if the TF ramp was essential for obtaining strong peaking. This was rather difficult to nail down completely given the irreproducibility of the plasmas. Nonetheless, shot 22 had a long EDA H-mode where we kept the field nearly constant and had only moderate peaking. Still, the best peaking occurred on shot 6 after the TF had been flat for 0.2 s, but after a rapid ramp up. Finally, late in the day, we tried increasing the current with the TF and adding RF. Shot 25 was the best example of RF + Ohmic peaked H-mode, but there was only 1.3 MW of RF at the peak time. There, ne0 reached 5 x 10^20 m^-3 and ne_ped = 2.8 x 10^20 m^-3 with some indication of a core barrier as well as an edge barrier. The strongest peaking occurred at 4.3 T, which is rather low field for good ICRF heating at 80 MHz with H minority. So, there is some incompatibility with obtaining peaked density H-modes in Ohmic plasmas and in ICRF heated plasmas. A couple of attempts to heat with ICRF at 4.5 T did not have very good peaking. Perhaps, more time should be spent on this scenario as well as on the last scenario that was tried, which included ramping the current up to increase the Ohmic heating while ramping the field up to stay in EDA H-mode up to 5.3 T and then get on-axis ICRF heating at 80 MHz. This should be tried with more RF power. |
| Physics Operator Comments | |||
| Jun 8 2000 09:06:23:780AM | 1000608001 | Earl Marmar | coldstart -- all matrices respond; no errors load from 1000607007, adjust TF to look like 990831015, keep I_p flattop to 1.6 nl_04 to 0.7e20 adjust various demands to account for I_p flat to 1.6 fizzle fill pressure too low; no DNB today |
| Jun 8 2000 09:33:13:670AM | 1000608002 | Earl Marmar | raise prefill (PG4) from 19 to 27 msec enable argon plasma into H-mode at 1.15 s |
| Jun 8 2000 09:51:19:577AM | 1000608003 | Earl Marmar | lower nl_04 prog to 6.5e19 plasma went into H-mode earlier, injection took it back to L, then H again. |
| Jun 8 2000 10:15:51:297AM | 1000608004 | Earl Marmar | tweak ZCUR slightly to keep the center of the plasma closer to -0.5 cm plasma still having increases in radiated power during H-Mode |
| Jun 8 2000 10:29:36:670AM | 1000608005 | Earl Marmar | change TF program to start ramping back up at 1.1 s plasma better H-Modes, but less peaking |
| Jun 8 2000 10:53:22:123AM | 1000608006 | Earl Marmar | reduce TF ramp rate and stop at lower field; start back up at 1.0 s plasma nicer H-Mode |
| Jun 8 2000 11:05:48:937AM | 1000608007 | Earl Marmar | ramp back up starting at 0.9; go up to 4.5 T plasma not as nice; 3 H-modes |
| Jun 8 2000 11:30:43:013AM | 1000608008 | Earl Marmar | turn on RF, .5 MW at 1.15 s plasma still in and out of H-mode |
| Jun 8 2000 12:03:59:310PM | 1000608009 | Earl Marmar | start TF rampdown at 0.05 s (in segment 1) plasma |
| Jun 8 2000 12:04:55:530PM | 1000608010 | Earl Marmar | Ip ramp up to 1 MA during B_T re-ramp plasma disrupt during I_p rampdown |
| Jun 8 2000 12:21:13:590PM | 1000608011 | Earl Marmar | increase gaps at high current plasma |
| Jun 8 2000 12:37:17:593PM | 1000608012 | Earl Marmar | no PCS changes plasma |
| Jun 8 2000 12:59:50:560PM | 1000608013 | Earl Marmar | reduce prepuff to 25 msec continue B_T re-ramp back to 150kA plasma |
| Jun 8 2000 01:19:47:123PM | 1000608014 | Earl Marmar | reload shot 6 (segment 2) match toroidal field across the segment switch I_p rampdown to 700kA between 1 and 1.2 seconds, then flat to 1.6 plasma |
| Jun 8 2000 01:52:55:780PM | 1000608015 | Earl Marmar | TF re-ramp not so far plasma |
| Jun 8 2000 01:53:30:343PM | 1000608016 | Earl Marmar | I_p tweak removed plasma |
| Jun 8 2000 02:01:09:170PM | 1000608017 | Earl Marmar | nl_04 demand to 7.5e19 plasma goes into H-mode about 100 ms later |
| Jun 8 2000 02:16:26:170PM | 1000608018 | Earl Marmar | modify TF re-ramp, to 4.3 T a 1.6 s nl_04 to 7e19 plasma |
| Jun 8 2000 02:52:08:500PM | 1000608019 | Earl Marmar | nl_04 to 6.5e19 plasma better H-Mode |
| Jun 8 2000 02:52:39:560PM | 1000608020 | Earl Marmar | repeat plasma more radiation during H-mode |
| Jun 8 2000 03:09:31:717PM | 1000608021 | Earl Marmar | nl_04 to 7.5e19 stop B_T reramp at 3.5 Tesla plasma decent H-mode |
| Jun 8 2000 03:26:21:607PM | 1000608022 | Earl Marmar | B_T reramp to 3.4T nl_04 to 7.0e19 plasma decent EDA-looking H-mode at quite low q disrupt at 1.47 seconds |
| Jun 8 2000 03:47:42:983PM | 1000608023 | Earl Marmar | T_F reramp back to 5.2 T starting at 1 s plasma |
| Jun 8 2000 04:07:02:827PM | 1000608024 | Earl Marmar | nl_04 to 7.5e20 I_p to 1 MA (from 0.8 at 1.0 s) plasma interesting EN-mode with 1 MW off-axis RF |
| Jun 8 2000 04:26:12:357PM | 1000608025 | Earl Marmar | move TF reramp to start 110 ms earlier RF likewise nl_04 to 7e19 plasma |
| Jun 8 2000 04:38:29:437PM | 1000608026 | Earl Marmar | nl_04 to 7.5e19 plasma |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:02:00:560AM | Plasma | Ok | |
| 2 | 09:20:19:013AM | Plasma | Ok | |
| 3 | 09:38:53:497AM | Plasma | Ok | |
| 4 | 09:57:35:280AM | Plasma | Ok | |
| 5 | 10:16:49:217AM | Plasma | Ok | |
| 6 | 10:35:41:873AM | Plasma | Ok | |
| 7 | 10:56:12:717AM | Plasma | Ok | |
| 8 | 11:12:51:373AM | Plasma | Ok | |
| 9 | 11:32:50:217AM | Plasma | Ok | |
| 10 | 11:51:51:217AM | Plasma | Ok | |
| 11 | 12:07:52:513PM | Plasma | Ok | |
| 12 | 12:25:36:530PM | Plasma | Ok | |
| 13 | 12:42:07:670PM | Plasma | Ok | |
| 14 | 01:00:53:140PM | Plasma | Ok | |
| 15 | 01:21:02:187PM | Plasma | Ok | |
| 16 | 01:36:59:543PM | Plasma | Ok | |
| 17 | 01:53:31:250PM | Plasma | Ok | |
| 18 | 02:09:15:297PM | Plasma | Ok | |
| 19 | 02:26:28:420PM | Plasma | Ok | |
| 20 | 02:43:42:560PM | Plasma | Ok | |
| 21 | 03:00:07:280PM | Plasma | Ok | |
| 22 | 03:15:12:700PM | Plasma | Ok | |
| 23 | 03:33:23:857PM | Plasma | Ok | |
| 24 | 03:51:33:483PM | Plasma | Ok | |
| 25 | 04:10:04:390PM | Plasma | Ok | |
| 26 | 04:30:34:110PM | Plasma | Ok | |
| 27 | 04:50:39:640PM | Plasma | Ok | |