| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Vinny Bertolino |
| Physics operator(s): | Robert Granetz |
| Engineering operator(s): | Vinny Bertolino |
| Engineering Operator Run Comment |
| ohmic H mode |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:11:727PM |
| Author: To Be Determined |
| Overall, it was a pretty good run. We achieved the goals of the experiment which were to map out the density and to some extent the current dependence of the H-mode threshold and compare with the addition of lithium pellets. Ohmic H-modes occurred at 800 kA and 5.3 T for densities in the range of 5.5 x 10^19 m^-2 and 8 x 10^19 m^-2. At higher densities, H-modes were not found, apparently due to not enough power. The low density limit seems to be pretty solid and may be due to increases in molybdenum as the plasma edge gets hotter at the lower densities. Ramping the current from 750 to 900 kA during the shot helped to increase the length of some of the H-modes by increasing power while the density increases during the H-mode. However, the density range up to 900 kA was not significantly higher than at 800 kA, at least for ramping current. Perhaps, at constant current of 900 kA, higher density H-modes could be achieved. One shot with current ramping from 500 kA to 650 kA at low density (5.5 x 10^19 m^-2) showed no evidence of an H-mode. The addition of lithium pellets does not appear to affect the H-mode threshold nor the H-mode quality at low, intermediate, or high density. However, the density feedback did cause problems after the pellets since as the density dropped below the pre-pellet value, the gas turned on hard and these gas puffs increased the H alpha emission and may have prevented the plasma from going into H-mode after the pellet. Marmar suggests increasing the derivative gain on the feedback to try to prevent this problem. A run should be devoted to tuning up the density feedback with pellets. Then, the effects of lithium pellets on H-mode might be worth readdressing. Except for problems on the first shot with EFC that caused several blown fuses and an hour delay, the power supplies worked very well. Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax 1 0.250 0.579 2 0.419 0.864 3 1.471 0.838 4 0.967 0.830 5 1.469 0.833 6 1.469 0.835 7 1.468 0.833 8 1.484 0.833 9 1.478 0.830 10 1.130 0.835 11 1.470 0.835 12 1.054 0.864 13 0.983 0.897 14 0.000 0.024 15 1.064 0.864 16 1.090 0.835 17 1.088 0.825 18 1.070 0.840 19 1.099 0.835 20 0.000 0.026 21 1.429 0.913 22 1.413 0.915 23 1.086 0.913 24 1.433 0.910 25 1.418 0.915 26 1.425 0.835 27 1.225 0.830 28 1.453 0.675 29 1.430 0.828 30 0.000 0.047 Finished summary for 941221 Total of 30 shots. 27 plasmas. 3 fizzles. 0 duds. |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:36:52:550PM |
| Author: To Be Determined |
| Physics operator's summary for Run 941221, MP 038?, "Ohmic H-modes" SL: J. Snipes PO: R. Granetz EL: V. Bertolino Goal: vary density and plasma current (0.6-0.9 MA) to further map out ohmic H-mode thresholds. The reciprocating probe will also be firing, in order to get profiles in the SOL. Towards the end of the run, we will also inject lithium pellets. This run succeeded at mapping out the density threshold for ohmic H-modes at Ip=0.8 MA and 5.3 T. The result is nl=0.72-0.78 x 10**20 m-2, which results in a value of about 0.020 for the coefficient in the standard ASDEX/DIII-D/JET scaling. The H-modes today were all ELMy. A low density limit of nl=0.5-0.55 x 10**20 m-2 was also found for Ip=0.5 to 0.8 MA. Also, lithium pellets do not seem to affect the threshold for the L-H transition, at least not in a clean tokamak. Further details of the physics results can be found in Joe's session leader summary. The only interesting new stuff today, from an operator's viewpoint, is that running at low density (nl=0.5e20 m-2) resulted in many disruptions around the time when the current rampdown began (approx 1.0 s), and running at higher densities did not result in these disruptions. This is in spite of the fact that the magnetic configuration was identical (i.e. the only changes to PCS had to do with density feedback, and there were no detachments, or "sharkfins"). This problem has been plaguing us, and changes in configuration programming don't seem to consistently solve the problem. Steve Horne noted that the disruptions are occurring around the time when the plasma becomes limited again on the inboard wall. Perhaps there is a problem with a sudden influx of molybdenum at this time, which is exacerbated at low densities because the SOL is hotter than at high densities. We tried to overcome this on shots 027 (0.8 MA) and 028 (0.65 MA) by programming a 60 ms burst in density from t=0.94 to 1.00 s, the idea being that the resulting puff of gas would cool down the edge and reduce impurity generation. This seemed to be successful, and should be explored further. (Note: shot 027 eventually did disrupt at 1.2 s, but this was due to the injection of a large lithium pellet at that time.) The blow-by-blow description follows: Start with a shot comprised of segments 1 and 2 from 941219027, with mods to RCUR (actually for larger outer gap), and density (start at nl=0.6e20 m-2). Pre-fill at 1.4e-5 torr. ECDC in Helium was done for 2.5 hours prior to this run. Shot 001: Plasma, but EFC didn't go, so there were large vertical oscillations, followed by a terminating disruption at t=0.25 s, followed by crowbars on the TF and OH supplies. (P.S. There were no hard x-rays.) Next shot: repeat (hopefully with EFC). Shot 002: Plasma, disrupted at 0.42 s because elongation got too high. Next shot: change RCUR from 0.65 to 0.66 m, keeping CLEARIN the same. This should reduce the elongation. Shot 003: Plasma, nice shot. There was a 45 ms ELMy H-mode from 0.755 to 0.80. It may have been terminated by a moly injection. There was a noticeable rise in the density during the H-mode. Next shot: repeat, with argon enabled. Shot 004: Plasma, disrupted at 0.97 s due to loss of vertical stability. No H-modes. Next shot: change RCUR again from 0.66 to 0.665 m, in order to further reduce kappa. Shot 005: Plasma, nice shot. H-mode from 0.85 to 1.0 s. Density was at nl=0.6e20 m-2. Next shot: increase density to nl=0.7e20 m-2. Looking for density threshold for ohmic H-mode. Shot 006: Plasma, nice shot. H-mode starts at 0.85 s. Next shot: increase density to nl=0.8e20 m-2, and move the time of gas turn-off earlier (from 0.85 s to 0.80 s.) Shot 007: Plasma, nice shot. H-mode starts at 0.95 s, when the density has decayed down to nl=0.72e20 m-2. Next shot: repeat at same density, except put the time of density turn-off back out to 0.85 s, in order keep the density from drooping prior to H-mode. Shot 008: Plasma, nice shot. H-mode starts at 1.0 s, when the density has decayed to nl=0.72e20 m-2 again. That must be the threshold! Next shot: increase density to 0.9e20 m-2. Shot 009: Plasma, nice shot. No H-mode, although there is still some dithering. So we've found the density threshold at Ip=0.8 MA. Next shot: decrease the density back down to what we started at on shot 003 (nl=0.6e20 m-2). This will begin a series of shots in which the density will be lowered, in an attempt to find a low density limit. We are repeating this density because the scanning probe missed it last time (on shot 003). Shot 010: Plasma, lots of big moly injections, terminated by a disruption at 1.13 s. No H-mode, no dithering. Don't know why. Next shot: repeat. Shot 011: Plasma, nice shot. H-mode starts at 0.75 s (same as on shot 003). Wp increases by 20%. X-ray emission rises sharply during the H-mode, and drops sharply at H-L transition. No moly injections... maybe that's the difference between this shot and the previous one. Next shot: lower density to nl=0.5e20 m-2. Shot 012: Plasma. No H-mode or dithering. Terminated by a disruption at 1.05 s. No moly injections. Reason for lack of H-mode: low density limit? Reason for disruption: ? Next shot: repeat, with a slight tweak on the early density programming, but nl=0.5e20 m-2 still. Shot 013: Plasma. No H-mode or dithering. Terminated by a disruption at 0.98 s. No moly injections. Next shot: raise density slightly from nl=0.5 to 0.55e20 m-2. Shot 014: Fizzle. No obvious reason. Next shot: repeat. Shot 015: Plasma. No H-mode or dithering. Terminated by a disruption at 1.06 s. There was a large molybdenum injection at 0.48 s. Density feedback control leaves something to be desired. Next shot: repeat one last time. Argon puff will NOT be enabled on the next shot. Shot 016: Plasma. Had H-mode this time! Terminated by a disruption at 1.09 s. Noticeable density rise and x-ray rise during the H-mode periods. Next shot: lower the density back down to nl=0.5e20 m-2, and keep the argon OFF. Shot 017: Plasma. No H-mode or dithering. Terminated by a disruption at 1.08 s. No moly injections. Next shot: raise pre-fill to 1.6e-5 (from 1.4e-5 torr), and increase gains of ZXL and ZXU from 2 to 4 after 1.0 s in order to try to do something about these disruptions around 1 second. Shot 018: Plasma. No H-mode or dithering. Terminated by a disruption at 1.07 s. Big moly injection at around 0.6 s. Next shot: raise density to nl=8.0e20 m-2. Shot 019: Plasma. H-mode at 0.83 s, preceded by lots of dithering. Density was nl=0.78e20 m-2 at the L-H transition which is close to the result we found earlier in the run. There was also a large moly injection at 0.91 s, which was probably due to the scanning probe. The plasma still terminated in a disruption at 1.1 s. Next shot: ramp plasma current from 0.75 MA at t=0.3 s up to 0.90 MA at t=1.0 s. Shot 020: Fizzle. Next shot: lower pre-fill back to 1.4e-5 torr and repeat. Shot 021: Plasma, good shot. H-mode at 0.84 s, Ip=0.88 MA, nl=0.76e20 m-2. Good Ip feedback control. No disruption. Next shot: same current ramp, and raise density to nl=0.9e20 m-2. Shot 022: Plasma, good shot. H-mode at 0.97 s, Ip=0.90 MA, nl=0.80e20 m-2. Next shot: lower density to nl=0.7e20 m-2. Shot 023: Plasma. H-mode starts at 0.63 s, Ip=0.84 MA, nl=0.71e20 m-2. Terminated by a disruption at 1.08 s. Next shot: raise density to nl=0.9e20 m-2, AND enable the lithium pellet injector at 0.505 s. Shot 024: Plasma, good shot. Lithium pellet did not seem to make any difference to getting an H-mode at this density (compare to shot 941221022). The interferometer data was screwed up on this shot. Next shot: repeat (to get the interferometer data), including lithium pellet injection at 0.505 s. Shot 025: Plasma, good shot. Again, lithium did not seem to make any difference to getting an H-mode at this density (compare to shot 941221022). Interferometer data is okay on this shot. Next shot: decrease density to nl=0.8e20 m-2, and program Ip to be a constant 0.8 MA (i.e. no current rampup). The lithium pellet at 0.505 s will be increased from medium to large size. There is also a lithium pellet being injected at 1.2 s for Peter O'Shea to study cold pulse propagation. Shot 026: Plasma, good shot. Again, lithium did not seem to make any difference to getting an H-mode at this density and current (compare to 941221007). Next shot: lower density to nl=0.55e20 m-2, and add a density puff around 1 s to try and avoid the disruption. Lithium still being injected. Shot 027: Plasma. Again lithium did not make a difference at this low density. There were several moly injections. Plasma terminated in a disruption at 1.2 s, which may have been due to the second lithium pellet. Next shot: Low current rampup experiment...ramp Ip from 0.5 to 0.65 MA, at the same density (nl=0.55e20 m-2). No lithium injection on this shot. Shot 028: Plasma, nice shot. No H-mode. Low current does not help get into H-mode at low density. Next shot: Density at nl=0.7e20 m-2 (puff around 1 s is removed), and current at a constant 0.8 MA. Lithium injection at 0.505 and 1.2 s. Shot 029: Plasma, good shot. No H-mode with the lithium pellet injection, even though the density (nl=0.7e20 m-2) and current (0.8 MA) are within the parameter range where we previously had H-modes without lithium injection (shot 941221006). Next shot: repeat without lithium pellet injection. Shot 030: Fizzle. Polychromator data indicates the protoplasma shot to the outside, which means the current ramped up too fast. This typically happens when the machine is very clean. End of run. |
| Session Leader Comments | |||
| Dec 21 1994 08:53:58:950AM | 941221001 | Joseph Snipes | The purpose of this run is to map out the ohmic H-mode threshold in plasma
current and electron density space. The starting point was a combination of shots 941130032 and 941219027, where we used the waveforms from the latter slightly modified in segment 2 to more reflect the former. Shot 1 EFC failed to chop causing early loss of control of the vertical position and a disruption at 0.25 sec and many blown fuses on TF, OH2, and EFC power supplies. |
| Dec 21 1994 09:45:43:200AM | 941221002 | Joseph Snipes | Shot 2
Power supplies worked, but the changes made in the RCUR apparently increased the elongation too much and railed the EF2 supplies as well as EFC. The plasma disrupted at 0.4 sec. So, for shot 3 we moved RCUR out to 0.66 m from 0.4 sec to try to reduce the elongation. |
| Dec 21 1994 09:57:14:730AM | 941221003 | Joseph Snipes | Shot 3
Good plasma. Short H-mode from 0.75 to 0.8 sec |
| Dec 21 1994 10:15:17:650AM | 941221004 | Joseph Snipes | Shot 4
Violent disruption at 0.96 sec. It seems kappa is still too high. So, for shot 5, we will move RCUR out another 5 mm to 0.665 m at 0.45 sec. Also, we are having many Moly injections. |
| Dec 21 1994 10:30:16:180AM | 941221005 | Joseph Snipes | Shot 5
Good shot! H-mode from 0.85 - 1.0 sec and another short one to 1.1 sec. |
| Dec 21 1994 10:38:14:250AM | 941221006 | Joseph Snipes | Shot 6
Good shot! Density was set to 7 x 10^19 m^-2. H-mode from 0.85 - 1.05 sec. |
| Dec 21 1994 11:03:13:720AM | 941221007 | Joseph Snipes | Shot 7
Density set to 8 x 10^19 m^-2. Very short H-mode as the density comes down at 0.95 sec to 1.05 sec. |
| Dec 21 1994 11:16:25:970AM | 941221008 | Joseph Snipes | Shot 8
Repeat keeping the density programming up to 0.85 sec. Good shot. Short H-mode as the density comes down and passes 7.2 x 10^19 m^-2 from 0.97 sec to 1.08 sec. |
| Dec 21 1994 11:40:54:950AM | 941221009 | Joseph Snipes | Shot 9
Good shot. Raise density to 9 x 10^19 m^-2. Got some "dithering" from 0.9 to 1 sec. |
| Dec 21 1994 12:06:17:330PM | 941221010 | Joseph Snipes | Shot 10
Returning to 6 x 10^19 m^-2. Plasma, but no H-mode. Perhaps, the moly injections made it too dirty to go into H-mode. |
| Dec 21 1994 12:07:10:700PM | 941221011 | Joseph Snipes | Shot 11
Repeat. Good shot! H-mode from 0.759 to 1 sec. |
| Dec 21 1994 12:25:30:670PM | 941221012 | Joseph Snipes | Shot 12
Density down to 5 x 10^19 m^-2. Disrupted at 1.05 sec. No H-mode |
| Dec 21 1994 12:36:19:280PM | 941221013 | Joseph Snipes | Shot 13
Good shot. No H-mode. May have reached the low density limit. |
| Dec 21 1994 12:37:38:730PM | 941221013 | Joseph Snipes | Shot 13
Good shot. No H-mode. Reached the low density limit. |
| Dec 21 1994 12:59:03:380PM | 941221014 | Joseph Snipes | Shot 14
Raising the density to 5.5 x 10^19 m^-2. Fizzle! |
| Dec 21 1994 01:05:34:040PM | 941221015 | Joseph Snipes | Shot 15
Good shot. No H-mode. |
| Dec 21 1994 01:41:13:140PM | 941221016 | Joseph Snipes | Shot 16
Repeat with no Argon puff. Short H-mode from 0.67 to 0.68 sec and from 0.76 to 0.83 sec. |
| Dec 21 1994 01:43:49:330PM | 941221017 | Joseph Snipes | Shot 17
Good shot but with some hard x rays. No H-mode. |
| Dec 21 1994 01:44:52:320PM | 941221018 | Joseph Snipes | Shot 18
Good shot but with some hard x rays and moly injections. No H-mode. |
| Dec 21 1994 02:09:23:250PM | 941221019 | Joseph Snipes | Shot 19
Raising the density to 8 x 10^19 m^-2 to recheck upper density limit for this current. Good shot. Disrupted late at 1.1 sec. H-mode from 0.83 to 0.91 sec. Looks like the fast scanning probe injected moly into the plasma at 0.91 sec. |
| Dec 21 1994 02:24:59:430PM | 941221020 | Joseph Snipes | Shot 20
Ramping the plasma current from 750 to 900 ka from 0.4 sec to 1 sec. Fizzle! |
| Dec 21 1994 02:36:01:990PM | 941221021 | Joseph Snipes | Shot 21
Ramping the plasma current from 750 to 900 ka from 0.4 sec to 1 sec. Good shot. H-mode from 0.84 to 1.1 sec. Dithering between 0.56 and 0.83 sec. |
| Dec 21 1994 03:04:27:240PM | 941221022 | Joseph Snipes | Shot 22
Another current ramp shot with higher density at 9 x 10^19 m^-2. H-mode from 0.97 to 1.05 sec. |
| Dec 21 1994 03:05:39:360PM | 941221023 | Joseph Snipes | Shot 23
H-mode from 0.6 2 to 0.88 sec. |
| Dec 21 1994 03:06:14:910PM | 941221023 | Joseph Snipes | Shot 23
Density set to 7 x 10^19 m^-2. H-mode from 0.6 2 to 0.88 sec. |
| Dec 21 1994 03:24:03:800PM | 941221024 | Joseph Snipes | Shot 24
Density set to 9 x 10^19 m^-2. Medium sized lithium pellet at 0.5 sec. Good shot! No density measurements. Dithering from 0.77 to 1.05 sec. Very short H-mode from 1.06 to 1.08 sec. |
| Dec 21 1994 03:46:21:550PM | 941221025 | Joseph Snipes | Shot 25
Density set to 9 x 10^19 m^-2. Medium sized lithium pellet at 0.5 sec and a small Li pellet at 1.2 sec. Good shot! Dithering from 0.72 to 0.96 sec. H-mode from 0.97 to 1.07 sec. |
| Dec 21 1994 04:01:10:930PM | 941221026 | Joseph Snipes | Shot 26
Density set to 8 x 10^19 m^-2. Big sized lithium pellet at 0.5 sec and a big Li pellet at 1.2 sec. Good shot! Dithering from 0.75 to 0.89 sec. H-mode from 0.89 to 1.07 sec. |
| Dec 21 1994 04:12:00:720PM | 941221027 | Joseph Snipes | Shot 27
Density set to 5.5 x 10^19 m^-2. Medium sized lithium pellet at 0.5 sec and a big Li pellet at 1.2 sec. Disrupted at second pellet. No H-mode. |
| Dec 21 1994 04:26:38:770PM | 941221028 | Joseph Snipes | Shot 28
Trying to get low power H-mode at 5.5 x 10^19 m^-2 with a current ramp from 0.5 to 0.65 MA from 0.17 sec to 1 sec. Good shot! No H-mode. |
| Dec 21 1994 04:46:57:000PM | 941221028 | Joseph Snipes | Shot 29
Returning to 800 kA flattop at 7 x 10^19 m^-2. Big Li pellets at 0.5 sec and 1.2 sec. No H-mode. |
| Dec 21 1994 05:01:28:610PM | 941221030 | Joseph Snipes | Shot 30
Repeat without Li pellet at 0.5 sec but with a small pellet at 1.2 sec. Fizzle! |
| Dec 21 1994 05:13:24:910PM | 941221030 | Joseph Snipes | Overall, it was a pretty good run. We achieved the goals of the experiment
which were to map out the density and to some extent the current dependence of the H-mode threshold and compare with the addition of lithium pellets. Ohmic H-modes occurred at 800 kA and 5.3 T for densities in the range of 5.5 x 10^19 m^-2 and 7.8 x 10^19 m^-2. At higher densities, H-modes were not found, apparently due to not enough power. The low density limit seems to be pretty solid and may be due to increases in molybdenum as the plasma edge gets hotter at the lower densities. |
| Dec 21 1994 05:18:19:820PM | 941221030 | Joseph Snipes | The addition of lithium pellets does not appear to affect the H-mode threshold
nor the H-mode quality at low, intermediate, or high density. However, the density feedback did cause problems after the pellets since as the density dropped below the pre-pellet value, the gas turned on hard and these gas puffs increased the H alpha emission and may have prevented the plasma from going into H-mode after the pellet. Marmar suggests increasing the derivative gain on the feedback to try to prevent this problem. |
| Physics Operator Comments | |||
| Dec 21 1994 08:27:41:180AM | Robert Granetz | Physics operator's summary for Run 941221, MP 038?, "Ohmic H-modes"
SL: J. Snipes PO: R. Granetz EL: V. Bertolino Goal: vary density and plasma current (0.6-0.9 MA) to further map out ohmic H-mode thresholds. The reciprocating probe will also be firing, in order to get profiles in the SOL. Towards the end of the run, we may also inject lithium pellets. Start with a shot comprised of segments 1 and 2 from 941219027, with mods to RCUR (actually for larger outer gap), and density (start at nl=0.6e20 m-2). Pre-fill at 1.4e-5 torr. ECDC in Helium was done for 2.5 hours prior to this run. | |
| Dec 21 1994 08:48:33:560AM | 941221001 | Robert Granetz | Shot 001: Plasma, but EFC didn't go, so there were large vertical
oscillations, followed by a terminating disruption at t=0.25 s, followed by crowbars on the TF and OH supplies. (P.S. There were no hard x-rays.) Next shot: repeat (hopefully with EFC) |
| Dec 21 1994 09:45:00:850AM | 941221002 | Robert Granetz | Shot 002: Plasma, disrupted at 0.42 s because elongation got too high.
Next shot: change RCUR from 0.65 to 0.66 m, keeping CLEARIN the same. This should reduce the elongation. |
| Dec 21 1994 09:57:57:190AM | 941221003 | Robert Granetz | Shot 003: Plasma, nice shot. There was a 45 ms ELMy H-mode from 0.755 to
0.80. It may have been terminated by a moly injection. There was a noticeable rise in the density during the H-mode. Next shot: repeat, with argon enabled. |
| Dec 21 1994 10:15:12:470AM | 941221004 | Robert Granetz | Shot 004: Plasma, disrupted at 0.97 s due to loss of vertical stability.
No H-modes. Next shot: change RCUR again from 0.66 to 0.665 m, in order to further reduce kappa. |
| Dec 21 1994 10:27:29:270AM | 941221005 | Robert Granetz | Shot 005: Plasma, nice shot. H-mode from 0.85 to 1.0 s. Density was
at nl=0.6e20 m-2. Next shot: increase density to nl=0.7e20 m-2. Looking for density threshold for ohmic H-mode. |
| Dec 21 1994 10:38:44:830AM | 941221006 | Robert Granetz | Shot 006: Plasma, nice shot. H-mode starts at 0.85 s.
Next shot: increase density to nl=0.8e20 m-2. |
| Dec 21 1994 10:56:47:830AM | 941221007 | Robert Granetz | Shot 007: Plasma, nice shot. H-mode starts at 0.95 s, when the density
has decayed down to nl=0.72e20 m-2. Next shot: repeat at same density, except put the time of density turn-off back out to 0.85 s, in order keep the density from drooping prior to H-mode. |
| Dec 21 1994 11:14:06:420AM | 941221008 | Robert Granetz | Shot 008: Plasma, nice shot. H-mode starts at 1.0 s, when the density has
decayed to nl=0.72e20 m-2 again. That must be the threshold! Next shot: increase density to 0.9e20 m-2. |
| Dec 21 1994 11:37:13:560AM | 941221009 | Robert Granetz | Shot 009: Plasma, nice shot. No H-mode, although there is still some
dithering. So we've found the density threshold at Ip=0.8 MA. Next shot: decrease the density back down to what we started at on shot 003 (nl=0.6e20 m-2). This will begin a series of shots in which the density will be lowered, in an attempt to find a low density limit. We are repeating this density because the scanning probe missed it last time (on shot 003). |
| Dec 21 1994 11:53:09:310AM | 941221010 | Robert Granetz | Shot 010: Plasma, lots of big moly injections, terminated by a disruption at
1.13 s. No H-mode, no dithering. Don't know why. Next shot: repeat. |
| Dec 21 1994 12:06:44:530PM | 941221011 | Robert Granetz | Shot 011: Plasma, nice shot. H-mode starts at 0.75 s (same as on shot 003).
Wp increases by 20%. X-ray emission rises sharply during the H-mode, and drops sharply at H-L transition. Next shot: lower density to nl=0.5e20 m-2. |
| Dec 21 1994 12:23:29:940PM | 941221012 | Robert Granetz | Shot 012: Plasma. No H-mode or dithering. Terminated by a disruption
at 1.05 s. No moly injections. Reason for lack of H-mode: low density limit? Reason for disruption: ? Next shot: repeat, with a slight tweak on the early density programming, but nl=0.5e20 m-2 still. |
| Dec 21 1994 12:37:12:210PM | 941221013 | Robert Granetz | Shot 013: Plasma. No H-mode or dithering. Terminated by a disruption
at 0.98 s. No moly injections. Next shot: raise density slightly from nl=0.5 to 0.55e20 m-2. |
| Dec 21 1994 12:44:00:900PM | 941221014 | Robert Granetz | Shot 014: Fizzle. No obvious reason.
Next shot: repeat. |
| Dec 21 1994 01:01:29:290PM | 941221015 | Robert Granetz | Shot 015: Plasma. No H-mode or dithering. Terminated by a disruption
at 1.06 s. There was a large molybdenum injection at 0.48 s. Density feedback control leaves something to be desired. Next shot: repeat one last time. |
| Dec 21 1994 01:06:49:090PM | 941221015 | Robert Granetz | Argon puff will NOT be enabled on the next shot.
|
| Dec 21 1994 01:21:19:270PM | 941221016 | Robert Granetz | Shot 016: Plasma. Had H-mode this time! Terminated by a disruption
at 1.09 s. Noticeable density rise and x-ray rise during the H-mode periods. Next shot: lower the density back down to nl=0.5e20 m-2, and keep the argon OFF. |
| Dec 21 1994 01:38:15:150PM | 941221017 | Robert Granetz | Shot 017: Plasma. No H-mode or dithering. Terminated by a disruption
at 1.08 s. No moly injections. Next shot: raise pre-fill to 1.6e-5 (from 1.4e-5 torr), and increase gains of ZXL and ZXU from 2 to 4 after 1.0 s in order to try to do something about these disruptions around 1 second. |
| Dec 21 1994 01:47:37:810PM | 941221018 | Robert Granetz | Shot 018: Plasma. No H-mode or dithering. Terminated by a disruption
at 1.07 s. Big moly injection at around 0.6 s. Next shot: raise density to nl=8.0e20 m-2. |
| Dec 21 1994 02:10:40:490PM | 941221019 | Robert Granetz | Shot 019: Plasma. H-mode at 0.83 s, preceded by lots of dithering. Density
was nl=0.78e20 m-2 at the L-H transition which is close to the result we found earlier in the run. There was also a large moly injection at 0.91 s, which was probably due to the scanning probe. The plasma still terminated in a disruption at 1.1 s. Next shot: ramp plasma current from 0.75 MA at t=0.3 s up to 0.90 MA at t=1.0 s. |
| Dec 21 1994 02:16:05:590PM | 941221020 | Robert Granetz | Shot 020: Fizzle.
Next shot: lower pre-fill back to 1.4e-5 torr and repeat. |
| Dec 21 1994 02:37:00:110PM | 941221021 | Robert Granetz | Shot 021: Plasma, good shot. H-mode at 0.84 s, Ip=0.88 MA, nl=0.76e20 m-2.
Good Ip feedback control. No disruption. Next shot: same current ramp, and raise density to nl=0.9e20 m-2. |
| Dec 21 1994 02:48:41:740PM | 941221022 | Robert Granetz | Shot 022: Plasma, good shot. H-mode at 0.97 s, Ip=0.90 MA, nl=0.80e20 m-2.
Next shot: lower density to nl=0.7e20 m-2. |
| Dec 21 1994 03:03:48:730PM | 941221023 | Robert Granetz | Shot 023: Plasma. H-mode starts at 0.63 s, Ip=0.84 MA, nl=0.71e20 m-2.
Terminated by a disruption at 1.08 s. Next shot: raise density to nl=0.9e20 m-2, AND enable the lithium pellet injector at 0.505 s. |
| Dec 21 1994 03:22:27:870PM | 941221024 | Robert Granetz | Shot 024: Plasma, good shot. Lithium pellet did not seem to make any
difference to getting an H-mode at this density (compare to shot 941221022). The interferometer data was screwed up on this shot. Next shot: repeat (to get the interferometer data), including lithium pellet injection at 0.505 s. |
| Dec 21 1994 03:40:38:320PM | 941221025 | Robert Granetz | Shot 025: Plasma, good shot. Again, lithium did not seem to make any
difference to getting an H-mode at this density (compare to shot 941221022). Interferometer data is okay on this shot. Next shot: decrease density to nl=0.8e20 m-2, and program Ip to be a constant 0.8 MA (i.e. no current rampup). The lithium pellet at 0.505 s will be increased from medium to large size. There is also a lithium pellet being injected at 1.2 s for Peter O'Shea to study cold pulse propagation. |
| Dec 21 1994 03:59:25:240PM | 941221026 | Robert Granetz | Shot 026: Plasma, good shot. Again, lithium did not seem to make any
difference to getting an H-mode at this density and current (compare to 941221007). Next shot: lower density to nl=0.55e20 m-2, and add a density puff around 1 s to try and avoid the disruption. Lithium still being injected. |
| Dec 21 1994 04:12:14:220PM | 941221027 | Robert Granetz | Shot 027: Plasma. Again lithium did not make a difference at this low
density. There were several moly injections. Plasma terminated in a disruption at 1.2 s, which may have been due to the second lithium pellet. Next shot: Low current rampup experiment...ramp Ip from 0.5 to 0.65 MA, at the same density (nl=0.55e20 m-2). No lithium injection on this shot. |
| Dec 21 1994 04:28:09:930PM | 941221028 | Robert Granetz | Shot 028: Plasma, nice shot. No H-mode. Current rampup does not help get
into H-mode at low density. Next shot: Density at nl=0.7e20 m-2 (puff around 1 s is removed), and current at a constant 0.8 MA. Lithium injection at 0.505 and 1.2 s. |
| Dec 21 1994 04:46:02:790PM | 941221029 | Robert Granetz | Shot 029: Plasma, good shot. No H-mode with the lithium pellet injection,
even though the density (nl=0.7e20 m-2) and current (0.8 MA) are within the parameter range where we previously had H-modes without lithium injection (shot 941221006). Next shot: repeat without lithium pellet injection. |
| Dec 21 1994 04:53:56:070PM | 941221030 | Robert Granetz | Shot 030: Fizzle. Don't know why
End of run. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:33:46:620AM | Plasma | Bad | chopper IOC, disruption, oh2u comm fault, tf IOC: in that order! |
| 2 | 09:27:30:180AM | Plasma | Ok | no faults |
| 3 | 09:45:24:840AM | Plasma | Ok | no faults |
| 4 | 09:57:20:940AM | Plasma | Ok | no faults |
| 5 | 10:16:12:760AM | Plasma | Ok | no faults |
| 6 | 10:30:27:580AM | Plasma | Ok | no faults |
| 7 | 10:48:10:180AM | Plasma | Ok | No faults |
| 8 | 11:04:55:530AM | Plasma | Ok | No faults |
| 9 | 11:22:18:400AM | Plasma | Ok | No faults. |
| 10 | 11:40:53:170AM | Plasma | Ok | No Faults. |
| 11 | 11:53:33:410AM | Plasma | Ok | No Faults |
| 12 | 12:09:39:480PM | Plasma | Ok | No faults. |
| 13 | 12:23:06:860PM | Plasma | Ok | No faults. |
| 14 | 12:38:36:780PM | Plasma | Ok | No Faults. |
| 15 | 12:51:18:770PM | Plasma | Ok | no faults |
| 16 | 01:07:53:010PM | Plasma | Ok | No Faults. |
| 17 | 01:23:25:100PM | Plasma | Ok | No Faults |
| 18 | 01:38:10:230PM | Plasma | Ok | NO faults |
| 19 | 01:51:47:390PM | Plasma | Ok | No Faults |
| 20 | 02:12:56:220PM | Plasma | Ok | No Faults. |
| 21 | 02:23:22:530PM | Plasma | Ok | Comm fault OH2 L |
| 22 | 02:39:45:370PM | Plasma | Ok | no faults |
| 23 | 02:51:54:170PM | Plasma | Ok | no faults |
| 24 | 03:07:32:090PM | Plasma | Ok | no faults |
| 25 | 03:22:24:330PM | Plasma | Ok | oh2u comm fault after disruption |
| 26 | 03:41:06:910PM | Plasma | Ok | no faults |
| 27 | 03:58:58:120PM | Plasma | Ok | no faults |
| 28 | 04:14:52:540PM | Plasma | Ok | no faults |
| 29 | 04:30:39:950PM | Plasma | Ok | oh1, oh2l comm faults after disruption |
| 30 | 04:48:06:130PM | Plasma | Ok | no faults |
| 31 | 05:32:06:660PM | Test | Ok | Data system test |
| 32 | 05:44:49:900PM | Test | Ok | Data system test |