| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Martin Greenwald |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Gary Dekow |
| Engineering Operator Run Comment |
| MP#333 Density Limits and Turbulence; SL: Greenwald; PO: Snipes; EO:Deko |
| Session Leader Plans |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Jul 7 2004 03:49:32:430PM |
| Author: To Be Determined |
| Run Summary for 1030523 MP 333 Session Leader Greenwald Phys Op Snipes Plan: Investigate the role of turbulent transport at the plasma edge in determining the tokamak density limit. Emphasis will be on the evolution of the temperature and neutral source profiles as the limit is approached. These experiments will extend our previous work in several ways. First, we will run at slightly higher fields and lower currents in order to avoid ECE cutoff at the density limit. Simultaneously, measurements of the H$_\alpha$ emission profile at the outboard midplane will be made for comparison with 1D transport modeling. (The aim will be to calculate the components of neutral-related transport.) Finally, we want to look at the level and spectra of short wavelength magnetic fluctuations as the density is raised. These have already been shown to be large in standard L-mode discharges. Parameters which avoid the ECE cutoff at the plasma edge when operating near the density limit are 6T, giving a cutoff density at $4.1 \times 10^{20}$ and 0.5 MA, giving a density limit of $3.2 \times 10^{20}$. This should give a reasonable margin of error. The 2nd harmonic ECE will not be black throughout the whole edge profile, however we are mainly interested in the radial evolution rather than the absolute temperature. Results: We got the engineering parameters and diagnostic data that we wanted but the plasma was not cooperative. All shots had strong marfes and poloidal detachments at fairly low densities, 1-2 x 10^20. The combination of higher field and lower current did allow us to get good HECE temperature profiles all the way to the edge. The poloidal detachment can be clearly observed as shrinkage of the temperature profile. This can be as much as 4 or 5 cm and still be stable apparently There were also problems with fizzles, which tended to occur every other shot - probably due to heavy gas load.. For the first part of the run we struggled with radiated power. This was hard to explain given the low input powers per particle. There were indications that the source was a loss of gap control at crossover. Overshooting the plasma current to consume more flux moved the crossover earlier and decoupled the detachment which moved about .4 seconds later. Shots for further analysis: 1030523008 1030523010 1030523012 1030523013 1030523014 1030523015 1030523017 1030523022 1030523024 1030523026 1030523028 1030523030 |
| Physics Operator Summaries |
| Entered: Jul 7 2004 04:37:17:990PM |
| Author: To Be Determined |
| Engineering Setup and Run Plan for Thurs. 5/23/2003 MP#333 "Density Limits and Turbulence" SL: Greenwald PO: Snipes Overnight ECDC in D2 at 2e-4, bake at 60C Power Systems as on 1021107012 Gas setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid enabled (PG1) fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC) fill C-side with 30 psi D2 Hybrid enabled (PG3) fill Ninja with 40 psi D2 Hybrid enabled Enable the following gate valves, assuming no vacuum problems: ECE, DNB, VUV Run plan: We're going to start with shot 1021107012, but push the field to 6T and the current to 0.5 MA. Once the discharge is established we'll push the density to a disruption late in the flat-top. If we have enough time we'll try for more data at lower current. Summary: Running high density disruptions apparently overgasses the walls making breakdown unreliable so that almost every other shot was a fizzle. A few ms lower prepuff is insufficient to resolve this problem. Perhaps, a larger decrease in prepuff might help, but it was not attempted. A large MARFE was present on all discharges that we tried to get rid of but were only successful in delaying by going to higher current. The result was that very little of the miniproposal was accomplished. Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax 1 0.802 0.669 2 1.084 0.707 3 1.735 0.668 4 0.000 0.032 5 1.783 0.671 6 1.711 0.647 7 0.000 0.032 8 0.754 0.645 9 0.000 0.036 10 1.064 0.640 11 0.000 0.028 12 1.222 0.647 13 1.921 0.646 14 1.872 0.635 15 1.863 0.607 16 0.000 0.032 17 1.872 0.736 18 1.862 0.721 19 0.000 0.032 20 1.866 0.737 21 0.000 0.031 22 1.873 0.742 23 0.000 0.033 24 1.827 0.740 25 0.000 0.032 26 1.820 0.814 27 0.000 0.033 28 1.815 0.812 29 0.000 0.038 30 1.806 0.818 Finished summary for 1030523 Total of 30 shots. 30 shots. 19 plasmas. 11 fizzles. 0 duds. Shot 1: Copied shot 1021107012 but then modified it substantially by setting Ip to 0.5 MA, TF current to 167 kA corresponding to 6 T, reduced Pulse Gas 3 a factor of 2, edited bolofeed controller for historical reasons, reset the A-coil currents to zero in all segments. Ninja gas puffing from the inner wall to raise the density. Disrupted at 0.79 s. Ninja puff is apparently too strong. The plasma current also did not stay at 0.5 MA perhaps because of too much gas. Shot 2: Increased TF current to 170 kA. Modified the plasma current to program a small overshoot at segment switch. Reduced Ninja pressure to 30 psi. Still disrupted with too strong a density rise, but the disruption was a bit later at 1.07 s. Shot 3: Increased TF current to 173 kA. Modified the plasma current to make it flat at 0.5 MA programmed. Reduced Ninja pressure to 20 psi. Decreased SSEP from -0.005 to -0.01 to reduce the efficiency of the inner wall fueling. Decent shot. Disrupted late around 1.73 s. Large slow oscillations on the D alpha. Shot 4: Put a ramp in Ip from 0.6 s to 1.5 s from 0.5 MA to 0.57 MA to attempt to flatten out the current at 0.5 MA. Ninja programming changed. Fizzle! Shot 5: Br0 jumped up by 0.5 mT, so I've reduced it by that amout to 0. Good shot though it still had the large D alpha oscillations. Shot 6: Try decreasing SSEP to -0.02. This required changing the controller and resetting its time constant from 9.78 to 6. Good shot but again with the D alpha oscillations. Shot 7: Returned SSEP to -0.01 and doubled gas preprogramming and programmed nl04 feedback to go to 4 x 10^20 m^-2 after 0.5 s. Fizzle! Shot 8: Reduced EF4 current by 15 A to -1315 A. Disrupted at 0.6 s. It was clearly overgassed. Shot 9: Reduce the rate of rise of the density. Reduced the gas preprogramming from 90 to 60 before 0.2 s as well. Reduced prepuff to 24 ms to attempt to avoid a fizzle. Fizzle nonetheless. Shot 10: Increased prepuff back to 27 ms duration. Good shot. Disrupted at 1.05 s. Shot 11: Reduced the rate of rise of the density programming. Fizzle! Shot 12: Increased prepuff by 1 ms to 28 ms duration. Good shot. Disrupted at 1.22 s. Shot 13: Reduced the rate of rise of the density making a linear ramp from the very beginning of the shot. Also reduced the gas preprogramming by a factor of 2. Good shot. Backed off a bit too much on the density. Shot 14: Increase the rate of rise of the density to get past the Greenwald limit. Turned off the argon gas puff. Good shot. Shot 15: Reduced ZXU from 0.03 to 0.02 to reduce the elongation and raise q. Good shot. No effect on elongation. Plasma bumps against the inner wall at 0.78 s at OH1 crossover. Shot 16: Increased ZXU to 0.045 m. Added an overshoot in Ip to attempt to avoid the problem with the OH1 crossover. Fizzle. Shot 17: Increased EF4 current by 15 A to -1300 A. Increased prepuff by 1 ms to 29 ms duration. Good shot. Disrupted late in rampdown. Shot 18: Turned off SSEP control and increased gain on ZXU to 6 to have control over the elongation. Put a step in CLEARIN at OH1 crossover to try to eliminate the plasma touching the inner wall and outboard limiter. It worked! Still, there is an increase in density at that time as the plasma goes detached. Good shot. Shot 19: Increased RXL out to 1.5 cm from 0.6 s on to pull the strike point out of the slot and put it on the vertical plate. Raised Ip to 0.55 MA again maitaining a ramp to 0.61 MA to keep the current constant. Fizzle! Shot 20: Startup was nearly identical to shot 3 from today, which had a fine current rise. Wolfe suggests decreasing the prepuff, so I took 2 ms off of it to make it 27 ms duration. Try again. Good shot. Shot 21: Increased ZXU to 0.07 to reduce the elongation. Fizzle! Shot 22: Repeat. Good shot. Still getting density peak at crossover. Elongation did not go down much. Shot 23: Increase ZXU to 0.09 m and decrease ZCUR by 0.5 cm to -1.5 cm. Fizzle! Shot 24: Took out two early points in the gas preprogramming to reduce further the early density. Increased CLEARIN by 3 mm to 0.007 m between 0.6 and 0.9 s to attempt to keep the density bump down. Good shot. Shot 25: Lowered ZCUR by another 0.5 cm to -0.02 m. Increased early Ip to 0.8 MA ramping back down to 0.55 MA by 0.8 s. Fizzle! Shot 26: Repeat. Good shot. Shot 27: Increased CLEARIN to 0.007 m throughout the shot. Fizzle! Shot 28: Decreased prepuff by 2 ms to 25 ms duration. Changed CLEARIN from 0.35 to 0.6 to 0.007 m then returned it to 0.0035 m for the rest of the shot. Good shot. Shot 29: Decreased prepuff by 2 ms to 23 ms duration. Increased Ip to 0.65 MA after the initial rampdown. Ramped RXL inward by 1.5 cm to 0 between 0.735 s and 1 s. Fizzle! Shot 30: Repeat. Good shot. |
| Session Leader Comments | |||
| May 23 2003 08:47:35:933AM | Martin Greenwald | MP 333 - Density limits and turbulence Session leader - Greenwald Phys Op Snipes Plan Investigate the role of turbulent transport at the plasma edge in determining the tokamak density limit. Emphasis will be on the evolution of the temperature and neutral source profiles as the limit is approached. These experiments will extend our previous work in several ways. First, we will run at slightly higher fields and lower currents in order to avoid ECE cutoff at the density limit. Simultaneously, measurements of the H$_\alpha$ emission profile at the outboard midplane will be made for comparison with 1D transport modeling. (The aim will be to calculate the components of neutral-related transport.) Finally, we want to look at the level and spectra of short wavelength magnetic fluctuations as the density is raised. These have already been shown to be large in standard L-mode discharges. Parameters which avoid the ECE cutoff at the plasma edge when operating near the density limit are 6T, giving a cutoff density at $4.1 \times 10^{20}$ and 0.5 MA, giving a density limit of $3.2 \times 10^{20}$. This should give a reasonable margin of error. The 2nd harmonic ECE will not be black throughout the whole edge profile, however we are mainly interested in the radial evolution rather than the absolute temperature. | |
| May 23 2003 05:25:13:560PM | Martin Greenwald | Run Summary for 1030523 MP 333 Session Leader Greenwald Phys Op Snipes Plan: Investigate the role of turbulent transport at the plasma edge in determining the tokamak density limit. Emphasis will be on the evolution of the temperature and neutral source profiles as the limit is approached. These experiments will extend our previous work in several ways. First, we will run at slightly higher fields and lower currents in order to avoid ECE cutoff at the density limit. Simultaneously, measurements of the H$_\alpha$ emission profile at the outboard midplane will be made for comparison with 1D transport modeling. (The aim will be to calculate the components of neutral-related transport.) Finally, we want to look at the level and spectra of short wavelength magnetic fluctuations as the density is raised. These have already been shown to be large in standard L-mode discharges. Parameters which avoid the ECE cutoff at the plasma edge when operating near the density limit are 6T, giving a cutoff density at $4.1 \times 10^{20}$ and 0.5 MA, giving a density limit of $3.2 \times 10^{20}$. This should give a reasonable margin of error. The 2nd harmonic ECE will not be black throughout the whole edge profile, however we are mainly interested in the radial evolution rather than the absolute temperature. Results: We got the engineering parameters and diagnostic data that we wanted but the plasma was not cooperative. All shots had strong marfes and poloidal detachments at fairly low densities, 1-2 x 10^20. The combination of higher field and lower current did allow us to get good HECE temperature profiles all the way to the edge. The poloidal detachment can be clearly observed as shrinkage of the temperature profile. This can be as much as 4 or 5 cm and still be stable apparently There were also problems with fizzles, which tended to occur every other shot - probably due to heavy gas load.. For the first part of the run we struggled with radiated power. This was hard to explain given the low input powers per particle. There were indications that the source was a loss of gap control at crossover. Overshooting the plasma current to consume more flux moved the crossover earlier and decoupled the detachment which moved about .4 seconds later. Shots for further analysis: 1030523008 1030523010 1030523012 1030523013 1030523014 1030523015 1030523017 1030523022 1030523024 1030523026 1030523028 1030523030 | |
| May 23 2003 09:22:26:113AM | 1030523001 | Martin Greenwald | Shot disrupts earlier than expected probably too much gas puffing for this current reducing ninja pressure for next shot |
| May 23 2003 09:52:17:880AM | 1030523002 | Martin Greenwald | Disrupts at 1.05 seconds density rise from puff is still too fast increasing ssep for next shot and lowering ninja pressure to 20 psi aim is to slow down density rise |
| May 23 2003 10:26:02:500AM | 1030523003 | Martin Greenwald | Very high density - strong marfes but no density limit disruption probably poloidally detached radiation is still very high - close to 100% by .5 sec |
| May 23 2003 10:28:11:997AM | 1030523004 | Martin Greenwald | fizzle |
| May 23 2003 11:00:55:150AM | 1030523005 | Martin Greenwald | Similar to shot 3 disrupts during rampdown 100% radiation for much of the shot plasma is poloidally detached for much of the shot we're increasing ssep to see if we can slow down the density rise |
| May 23 2003 11:13:47:897AM | 1030523006 | Martin Greenwald | Same as shot 5 still lots radiation, etc. going to standard piezo valve and feedback for next shot |
| May 23 2003 11:23:17:303AM | 1030523007 | Martin Greenwald | fizzle |
| May 23 2003 11:40:41:090AM | 1030523008 | Martin Greenwald | We were too aggressive with the gas puff gets ugly at .5 sec disrupts at .76 |
| May 23 2003 11:50:28:433AM | 1030523009 | Martin Greenwald | fizzle |
| May 23 2003 12:09:33:543PM | 1030523010 | Martin Greenwald | Better than 8, but density rise is still too fast backing off on gas puff and density feedback |
| May 23 2003 12:18:08:437PM | 1030523011 | Martin Greenwald | fizzle |
| May 23 2003 12:39:00:693PM | 1030523012 | Martin Greenwald | Better, shot lasts til 1.2 sec Still a lot of radiation reaches 100% by .57 sec detaches afterward |
| May 23 2003 01:00:18:370PM | 1030523013 | Martin Greenwald | After lowering gas puff, the shot lasts through rampdown still 100% radiation at about 1 sec poloidally detached from that point on |
| May 23 2003 01:20:39:783PM | 1030523014 | Martin Greenwald | Similar to last shot |
| May 23 2003 01:22:04:250PM | 1030523015 | Martin Greenwald | similar to 13 Tried to decrease elongation to raise q we're having a problem at crossover plasma bangs into inner and outer limiters we'll put in an Ip overshoot to move the crossover earlier |
| May 23 2003 01:32:41:550PM | 1030523016 | Martin Greenwald | fizzle |
| May 23 2003 01:56:28:547PM | 1030523017 | Martin Greenwald | Similar to 15 |
| May 23 2003 02:17:14:803PM | 1030523019 | Martin Greenwald | fizzle |
| May 23 2003 02:47:18:050PM | 1030523021 | Martin Greenwald | fizzle |
| May 23 2003 03:01:54:493PM | 1030523022 | Martin Greenwald | similar to shot 20 |
| May 23 2003 03:14:11:820PM | 1030523023 | Martin Greenwald | fizzle |
| May 23 2003 03:44:01:300PM | 1030523025 | Martin Greenwald | Fizzle |
| May 23 2003 04:05:56:193PM | 1030523026 | Martin Greenwald | We put more overshoot on current to burn up flux and move crossover earlier that worked and decoupled detachment which now occurs at 1.03 seconds - though at higher densities. |
| May 23 2003 04:12:32:833PM | 1030523027 | Martin Greenwald | fizzle |
| May 23 2003 04:28:27:667PM | 1030523028 | Martin Greenwald | similar to 26, detaches at .95 sec |
| May 23 2003 04:58:29:960PM | 1030523030 | Martin Greenwald | Raising current to 0.65 MA delayed detachment til 1.2 second otherwise similar to previous shots |
| Physics Operator Comments | |||
| May 23 2003 08:46:40:107AM | Joseph Snipes | Engineering Setup and Run Plan for Thurs. 5/23/2003 MP#333 "Density Limits and Turbulence" SL: Greenwald PO: Snipes Overnight ECDC in D2 at 2e-4, bake at 60C Power Systems as on 1021107012 Gas setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid enabled (PG1) fill B-side upper with 10 psi D2 Hybrid DISABLED (PG2) (for ECDC) fill C-side with 30 psi D2 Hybrid enabled (PG3) fill Ninja with 40 psi D2 Hybrid enabled Enable the following gate valves, assuming no vacuum problems: ECE, DNB, VUV Run plan: We're going to start with shot 1021107012, but push the field to 6T and the current to 0.5 MA. Once the discharge is established we'll push the density to a disruption late in the flat-top. If we have enough time we'll try for more data at lower current. | |
| May 23 2003 09:20:04:163AM | 1030523001 | Joseph Snipes | Shot 1: Copied shot 1021107012 but then modified it substantially by setting Ip to 0.5 MA, TF current to 167 kA corresponding to 6 T, reduced Pulse Gas 3 a factor of 2, edited bolofeed controller for historical reasons, reset the A-coil currents to zero in all segments. Ninja gas puffing from the inner wall to raise the density. Disrupted at 0.79 s. Ninja puff is apparently too strong. The plasma current also did not stay at 0.5 MA perhaps because of too much gas. |
| May 23 2003 09:52:34:380AM | 1030523002 | Joseph Snipes | Shot 2: Increased TF current to 170 kA. Modified the plasma current to program a small overshoot at segment switch. Reduced Ninja pressure to 30 psi. Still disrupted with too strong a density rise, but the disruption was a bit later at 1.07 s. |
| May 23 2003 10:24:03:143AM | 1030523003 | Joseph Snipes | Shot 3: Increased TF current to 173 kA. Modified the plasma current to make it flat at 0.5 MA programmed. Reduced Ninja pressure to 20 psi. Decreased SSEP from -0.005 to -0.01 to reduce the efficiency of the inner wall fueling. Decent shot. Disrupted late around 1.73 s. Large slow oscillations on the D alpha. |
| May 23 2003 10:28:05:873AM | 1030523004 | Joseph Snipes | Shot 4: Put a ramp in Ip from 0.6 s to 1.5 s from 0.5 MA to 0.57 MA to attempt to flatten out the current at 0.5 MA. Ninja programming changed. Fizzle! |
| May 23 2003 11:10:53:947AM | 1030523005 | Joseph Snipes | Shot 5: Br0 jumped up by 0.5 mT, so I've reduced it by that amout to 0. Good shot though it still had the large D alpha oscillations. |
| May 23 2003 11:11:58:897AM | 1030523006 | Joseph Snipes | Shot 6: Try decreasing SSEP to -0.02. This required changing the controller and resetting its time constant from 9.78 to 6. Good shot but again with the D alpha oscillations. |
| May 23 2003 11:26:45:233AM | 1030523007 | Joseph Snipes | Shot 7: Returned SSEP to -0.01 and doubled gas preprogramming and programmed nl04 feedback to go to 4 x 10^20 m^-2 after 0.5 s. Fizzle! |
| May 23 2003 11:43:37:427AM | 1030523008 | Joseph Snipes | Shot 8: Reduced EF4 current by 15 A to -1315 A. Disrupted at 0.6 s. It was clearly overgassed. |
| May 23 2003 11:49:57:170AM | 1030523009 | Joseph Snipes | Shot 9: Reduce the rate of rise of the density. Reduced the gas preprogramming from 90 to 60 before 0.2 s as well. Reduced prepuff to 24 ms to attempt to avoid a fizzle. Fizzle nonetheless. |
| May 23 2003 12:04:57:880PM | 1030523010 | Joseph Snipes | Shot 10: Increased prepuff back to 27 ms duration. Good shot. Disrupted at 1.05 s. |
| May 23 2003 12:23:01:447PM | 1030523011 | Joseph Snipes | Shot 11: Reduced the rate of rise of the density programming. Fizzle! |
| May 23 2003 12:39:28:083PM | 1030523012 | Joseph Snipes | Shot 12: Increased prepuff by 1 ms to 28 ms duration. Good shot. Disrupted at 1.22 s. |
| May 23 2003 12:52:39:483PM | 1030523013 | Joseph Snipes | Shot 13: Reduced the rate of rise of the density making a linear ramp from the very beginning of the shot. Also reduced the gas preprogramming by a factor of 2. Good shot. Backed off a bit too much on the density. |
| May 23 2003 01:11:24:497PM | 1030523014 | Joseph Snipes | Shot 14: Increase the rate of rise of the density to get past the Greenwald limit. Turned off the argon gas puff. Good shot. |
| May 23 2003 01:29:39:667PM | 1030523015 | Joseph Snipes | Shot 15: Reduced ZXU from 0.03 to 0.02 to reduce the elongation and raise q. Good shot. No effect on elongation. Plasma bumps against the inner wall at 0.78 s at OH1 crossover. |
| May 23 2003 01:38:26:097PM | 1030523016 | Joseph Snipes | Shot 16: Increased ZXU to 0.045 m. Added an overshoot in Ip to attempt to avoid the problem with the OH1 crossover. Fizzle. |
| May 23 2003 01:59:28:477PM | 1030523017 | Joseph Snipes | Shot 17: Increased EF4 current by 15 A to -1300 A. Increased prepuff by 1 ms to 29 ms duration. Good shot. Disrupted late in rampdown. |
| May 23 2003 02:14:35:983PM | 1030523018 | Joseph Snipes | Shot 18: Turned off SSEP control and increased gain on ZXU to 6 to have control over the elongation. Put a step in CLEARIN at OH1 crossover to try to eliminate the plasma touching the inner wall and outboard limiter. It worked! Still, there is an increase in density at that time as the plasma goes detached. Good shot. |
| May 23 2003 02:17:16:180PM | 1030523019 | Joseph Snipes | Shot 19: Increased RXL out to 1.5 cm from 0.6 s on to pull the strike point out of the slot and put it on the vertical plate. Raised Ip to 0.55 MA again maitaining a ramp to 0.61 MA to keep the current constant. Fizzle! |
| May 23 2003 02:30:20:800PM | 1030523020 | Joseph Snipes | Shot 20: Startup was nearly identical to shot 3 from today, which had a fine current rise. Wolfe suggests decreasing the prepuff, so I took 2 ms off of it to make it 27 ms duration. Try again. Good shot. |
| May 23 2003 02:51:35:883PM | 1030523021 | Joseph Snipes | Shot 21: Increased ZXU to 0.07 to reduce the elongation. Fizzle! |
| May 23 2003 03:07:25:900PM | 1030523022 | Joseph Snipes | Shot 22: Repeat. Good shot. Still getting density peak at crossover. Elongation did not go down much. |
| May 23 2003 03:18:53:417PM | 1030523023 | Joseph Snipes | Shot 23: Increase ZXU to 0.09 m and decrease ZCUR by 0.5 cm to -1.5 cm. Fizzle! |
| May 23 2003 03:33:10:127PM | 1030523024 | Joseph Snipes | Shot 24: Took out two early points in the gas preprogramming to reduce further the early density. Increased CLEARIN by 3 mm to 0.007 m between 0.6 and 0.9 s to attempt to keep the density bump down. Good shot. |
| May 23 2003 03:42:14:743PM | 1030523025 | Joseph Snipes | Shot 25: Lowered ZCUR by another 0.5 cm to -0.02 m. Increased early Ip to 0.8 MA ramping back down to 0.55 MA by 0.8 s. Fizzle! |
| May 23 2003 04:05:51:837PM | 1030523026 | Joseph Snipes | Shot 26: Repeat. Good shot. |
| May 23 2003 04:15:11:733PM | 1030523027 | Joseph Snipes | Shot 27: Increased CLEARIN to 0.007 m throughout the shot. Fizzle! |
| May 23 2003 04:25:36:737PM | 1030523028 | Joseph Snipes | Shot 28: Decreased prepuff by 2 ms to 25 ms duration. Changed CLEARIN from 0.35 to 0.6 to 0.007 m then returned it to 0.0035 m for the rest of the shot. Good shot. |
| May 23 2003 04:41:50:037PM | 1030523029 | Joseph Snipes | Shot 29: Decreased prepuff by 2 ms to 23 ms duration. Increased Ip to 0.65 MA after the initial rampdown. Ramped RXL inward by 1.5 cm to 0 between 0.735 s and 1 s. Fizzle! |
| May 23 2003 04:59:11:850PM | 1030523030 | Joseph Snipes | Shot 30: Repeat. Good shot. |
| May 23 2003 05:16:10:850PM | 1030523030 | Joseph Snipes | Summary: Running high density disruptions apparently overgasses the walls making breakdown unreliable so that almost every other shot was a fizzle. A few ms lower prepuff is insufficient to resolve this problem. Perhaps, a larger decrease in prepuff might help, but it was not attempted. A large MARFE was present on all discharges that we tried to get rid of but were only successful in delaying by going to higher current. The result was that very little of the miniproposal was accomplished. Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax 1 0.802 0.669 2 1.084 0.707 3 1.735 0.668 4 0.000 0.032 5 1.783 0.671 6 1.711 0.647 7 0.000 0.032 8 0.754 0.645 9 0.000 0.036 10 1.064 0.640 11 0.000 0.028 12 1.222 0.647 13 1.921 0.646 14 1.872 0.635 15 1.863 0.607 16 0.000 0.032 17 1.872 0.736 18 1.862 0.721 19 0.000 0.032 20 1.866 0.737 21 0.000 0.031 22 1.873 0.742 23 0.000 0.033 24 1.827 0.740 25 0.000 0.032 26 1.820 0.814 27 0.000 0.033 28 1.815 0.812 29 0.000 0.038 30 1.806 0.818 Finished summary for 1030523 Total of 30 shots. 30 shots. 19 plasmas. 11 fizzles. 0 duds. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:12:31:630AM | Plasma | Ok | |
| 2 | 09:39:17:820AM | Plasma | Ok | |
| 3 | 10:07:17:280AM | Plasma | Ok | |
| 4 | 10:26:15:767AM | Plasma | Ok | |
| 5 | 10:45:59:780AM | Plasma | Ok | |
| 6 | 11:08:41:497AM | Plasma | Ok | |
| 7 | 11:21:34:587AM | Plasma | Ok | |
| 8 | 11:34:08:143AM | Plasma | Ok | |
| 9 | 11:47:57:827AM | Plasma | Ok | |
| 10 | 12:00:34:933PM | Plasma | Ok | |
| 11 | 12:16:20:970PM | Plasma | Ok | |
| 12 | 12:28:59:153PM | Plasma | Ok | |
| 13 | 12:45:05:537PM | Plasma | Ok | |
| 14 | 12:57:56:690PM | Plasma | Ok | |
| 15 | 01:15:14:487PM | Plasma | Ok | |
| 16 | 01:29:51:557PM | Plasma | Ok | |
| 17 | 01:44:50:093PM | Plasma | Ok | |
| 18 | 02:01:05:690PM | Plasma | Ok | |
| 19 | 02:15:23:137PM | Plasma | Ok | |
| 20 | 02:28:33:307PM | Plasma | Ok | |
| 21 | 02:45:33:963PM | Plasma | Ok | |
| 22 | 02:58:12:160PM | Plasma | Ok | |
| 23 | 03:11:09:060PM | Plasma | Ok | |
| 24 | 03:24:52:320PM | Plasma | Ok | |
| 25 | 03:40:19:357PM | Plasma | Ok | |
| 26 | 03:53:59:617PM | Plasma | Ok | |
| 27 | 04:10:44:543PM | Plasma | Ok | |
| 28 | 04:23:46:290PM | Plasma | Ok | |
| 29 | 04:39:55:480PM | Plasma | Ok | |
| 30 | 04:52:34:663PM | Plasma | Ok | |