Miniproposals

Miniproposal: 268 Date Filed: 4/7/2000 Title: Conditioning of D-, E-, or J-Port ICRF Antenna First Author: Gerd Schilling Session Leader: Rejean Boivin (shots 1-20)

Engineering Operator Run Comment

MP#268 SL:Boivin PO:Snipes EO:Byford/Parkin

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:25:773PM

Author: To Be Determined

MP#268 ICRF SL: Boivin EIC: Byford PO: Snipes Today we are continuing in getting J operational. We will concentrate in trying to get longer pulse out of J and to document/diagnose the potential problem associated with impurity production. One important way to do that is to compare short pulse with high power with long pulse at lower power thus comparing power versus energy deposited. We observed generally today that later in the shot impurities were brought in, especially after H-modes. Changes in vertical position, gaps did not prove to be very effective, especially when we look at a bright lower corner (H-side) of the J antenna. Later on we went to higher density, helping somewhat, but we started to get apparent bricks and disruption. Most of the injections did not necessarily occur from the antenna itself and thus the conclusions are obscured. They were further obscured when later on we (re)discovered that EF1 and some EF2 signals (currents) were picking up some RF, sometimes at irregular intervals, thus complicating the interpretation of impurity generation. We obtained EDAs with J but they are peculiar as they as low in confinement quality, as visible in the "saturation" density during the H-mode. Tomorrow we will continue in trying to obtain longer pulse, with higher density as it seems to have helped today.

Physics Operator Summaries

Entered: Jul 7 2004 04:37:12:770PM

Author: To Be Determined

Physop Summary for Tuesday, Dec 5, 2000 MP#268 ICRF SL: Boivin EIC: Byford PO: Snipes Engineering Setup ------------------ Conditioning: ECDC overnight in D2, ending 2 hours before start of run RF Setup: --------- XMTRs 1,2 3 and 4 should be made ready by 8:00 (run-on). Power systems as on 1001204019 Gas system: fill B-top with 6 psi of D2 Hybrid ENABLED fill B-side lower with 1 psi of Ar Hybrid DISABLED fill B-side upper with 35 psi of D2 Hybrid DISABLED, for ECDC fill C-side with 30 psi of D2 Hybrid ENABLED leave J-bot as is Gate valves: ECE, VUV, Beast, DNB (if requested) Plan -------------------- Further tests of J-port performance as a four-strap. Fire J-port into plasma, nominal density, preferably lower current (0.8 MA) to start with. May start with upper null briefly to condition the antennas but then return to lower null plasmas for H-mode coupling, eventually moving to higher current. Summary: Overall, it was an O.K. run. There were a few power supply problems and there were disruptions on most shots. Some of the disruptions seemed to be caused by arcing in the J-port antenna. However, toward the end of the day, we had several disruptions (e.g., 17, 18, 19) that did not have high radiation from the ICRF antenna. Wolfe found jumps in the inputs to EF2 from the hybrid that may be due to RF pickup that then cause the power supplies to jump and led to the disruptions. The cabinets may need to be closed up to avoid RF pickup in the power room. Shot 1: Copied shot 1001204019 except increased pre-puff from 20 to 22 ms duration. Back to nl04 feedback since the TCI appears to be working again. Good shot. Full length plasma. Shot 2: Increased Br0 from 1.5 mT to 2 mT since there was a hesitation in the current rise and it was operating better at a measured Br0 of -0.5 mT while shot 1 had a measured Br0 of about -1.3 mT. DNB should open on this shot, so I'll drop the prefill to 20 ms. Good shot. Full length plasma. However, the startup hesitated even more. Shot 3: Reduced pre-puff to 18 ms duration. Good shot. Full length plasma. Startup hesitates even more! Shot 4: Enabled Ar puff with 30 ms duration. Increased pre-puff to 21 ms duration. Good shot. Disrupted at 1.35 s. Lost nl04 at 0.2 s so the gas went full on and eventually led to a density limit disruption. Shot 5: Returned to NL_ZMETER density feedback set to 0.35, which should maintain about 7 x 10^19 m^-2 if we don't get a fizzle. Also, reduced pre-puff to 17 ms duration expecting lots of gas to have evolved off the walls after that disruption. Good shot all the way down. Good current rise as well though the pressure was down to 0.051 mTorr. Shot 6: Anticipating somewhat less gas, increased pre-puff to 20 ms duration. Reduced Br0 by 0.5 mT to 1.5 mT since the measured Br0 has increased to 0 mT. Good shot. Disrupted at 1.3 s apparently due to interaction with the J-port antenna in the lower corner on the H-port side. Shot 7: Decreased pre-puff to 17 ms duration following the disruption. Also raised density by increasing NL_ZMETER from 0.35 to 0.4. Disrupted at 1.45 s perhaps again due to the J-port antenna. Shot 8: Raised NL_ZMETER to 0.45 to again try to increase the density. The TCI is still dead, so we can rely on the Thomson to know the density. Raised ZCUR by 0.5 cm to -1.0 cm. Early disruption at 0.55 s caused by a fault in OH2L that began at 0.52 s. Shot 9: Repeat. EF4 power supply failed at -1.1 s. No plasma. Shot 10: Repeat, but hopefully with the power supplies functioning properly. Got plasma, but disrupted at 1.18 s probably due to arcing in the J-port antenna again. Shot 11: Reduced RCUR by 1 mm to 0.660 m to increase the outer gap. Good shot. Full length plasma. Shot 12: Reduced RCUR by another mm to 0.659 m to further increase the outer gap. Disrupted at 1.22 s probably again due to the J-port antenna. Shot 13: Raised NL_ZMETER from 0.45 to 0.55. Good shot. Full length plasma. Shot 14: Try to get higher power out of J-port. Disrupted at 0.92 s probably due to the J-port RF again, though the videos were not so clear. Reached about 1.4 MW out of J-port. Shot 15: Started ECDC just before this shot for ~10 minutes. Decent shot, but it disrupted at 1.25 s probably due to the J-port RF again. Shot 16: Raised NL_ZMETER to 0.65. Fizzle! Shot 17: Changed EF4 from -1300 A to -1315 A at breakdown. Reduced Br0 offset from 1.5 mT to 1.0 mT. Disrupted early at 0.75 s. It is not clear that this disruption was due to the RF, though it was during 1.3 MW of RF from J-port. The video showed no clear excess radiation from the antenna. Breakdown is obviously better, though still not as good as before. Shot 18: Lowered the TF current from 150 kA to 146.6 kA to get to 5.2 T in segment 2. Disrupted at 1.12 s, this time probably due to the RF. Shot 19: Repeat. Disrupted at 1.24 s. Wolfe has discovered on shot 18 and this shot that the EF1's and EF2's are getting an incorrect demand signal from the Hybrid computer that is different from the equivalent digitized outputs. It may be RF pickup in the AFOL's that is forcing the EF supplies to cause the plasma to disrupt. Shot 20: Repeat without the RF to see if the disruption still occurs.

Session Leader Comments

Physics Operator Comments
Dec 5 2000 09:31:53:653AM		Joseph Snipes	Run Plan for Tuesday, Dec 5, 2000 MP#268 ICRF SL: Boivin PO: Snipes Engineering Setup ------------------ Conditioning: ECDC overnight in D2, ending 2 hours before start of run RF Setup: --------- XMTRs 1,2 3 and 4 should be made ready by 8:00 (run-on). Power systems as on 1001204019 Gas system: fill B-top with 6 psi of D2 Hybrid ENABLED fill B-side lower with 1 psi of Ar Hybrid DISABLED fill B-side upper with 35 psi of D2 Hybrid DISABLED, for ECDC fill C-side with 30 psi of D2 Hybrid ENABLED leave J-bot as is Gate valves: ECE, VUV, Beast, DNB (if requested) Plan -------------------- Further tests of J-port performance as a four-strap. Fire J-port into plasma, nominal density, preferably lower current (0.8 MA) to start with. May start with upper null briefly to condition the antennas but then return to lower null plasmas for H-mode coupling, eventually moving to higher current.
Dec 5 2000 08:56:57:250AM	1001205001	Joseph Snipes	Shot 1: Copied shot 1001204019 except increased pre-puff from 20 to 22 ms duration. Back to nl04 feedback since the TCI appears to be working again. Good shot. Full length plasma.
Dec 5 2000 09:19:47:077AM	1001205002	Joseph Snipes	Shot 2: Increased Br0 from 1.5 mT to 2 mT since there was a hesitation in the current rise and it was operating better at a measured Br0 of -0.5 mT while shot 1 had a measured Br0 of about -1.3 mT. DNB should open on this shot, so I'll drop the prefill to 20 ms. Good shot. Full length plasma. However, the startup hesitated even more.
Dec 5 2000 09:35:44:437AM	1001205003	Joseph Snipes	Shot 3: Reduced pre-puff to 18 ms duration. Good shot. Full length plasma. Startup hesitates even more!
Dec 5 2000 10:01:27:607AM	1001205004	Joseph Snipes	Shot 4: Enabled Ar puff with 30 ms duration. Increased pre-puff to 21 ms duration. Good shot. Disrupted at 1.35 s. Lost nl04 at 0.2 s so the gas went full on and eventually led to a density limit disruption.
Dec 5 2000 10:25:11:450AM	1001205005	Joseph Snipes	Shot 5: Returned to NL_ZMETER density feedback set to 0.35, which should maintain about 7 x 10^19 m^-2 if we don't get a fizzle. Also, reduced pre-puff to 17 ms duration expecting lots of gas to have evolved off the walls after that disruption. Good shot all the way down. Good current rise as well though the pressure was down to 0.051 mTorr.
Dec 5 2000 10:58:05:340AM	1001205006	Joseph Snipes	Shot 6: Anticipating somewhat less gas, increased pre-puff to 20 ms duration. Reduced Br0 by 0.5 mT to 1.5 mT since the measured Br0 has increased to 0 mT. Good shot. Disrupted at 1.3 s apparently due to interaction with the J-port antenna in the lower corner on the H-port side.
Dec 5 2000 11:10:57:857AM	1001205007	Joseph Snipes	Shot 7: Decreased pre-puff to 17 ms duration following the disruption. Also raised density by increasing NL_ZMETER from 0.35 to 0.4. Disrupted at 1.45 s perhaps again due to the J-port antenna.
Dec 5 2000 11:37:08:153AM	1001205008	Joseph Snipes	Shot 8: Raised NL_ZMETER to 0.45 to again try to increase the density. The TCI is still dead, so we can rely on the Thomson to know the density. Raised ZCUR by 0.5 cm to -1.0 cm. Early disruption at 0.55 s caused by a fault in OH2L that began at 0.52 s.
Dec 5 2000 11:59:02:950AM	1001205009	Joseph Snipes	Shot 9: Repeat. EF4 power supply failed at -1.1 s. No plasma.
Dec 5 2000 01:15:15:373PM	1001205010	Joseph Snipes	Shot 10: Repeat, but hopefully with the power supplies functioning properly. Got plasma, but disrupted at 1.18 s probably due to arcing in the J-port antenna again.
Dec 5 2000 01:30:03:280PM	1001205011	Joseph Snipes	Shot 11: Reduced RCUR by 1 mm to 0.660 m to increase the outer gap. Good shot. Full length plasma.
Dec 5 2000 01:59:35:047PM	1001205012	Joseph Snipes	Shot 12: Reduced RCUR by another mm to 0.659 m to further increase the outer gap. Disrupted at 1.22 s probably again due to the J-port antenna.
Dec 5 2000 02:23:12:107PM	1001205013	Joseph Snipes	Shot 13: Raised NL_ZMETER from 0.45 to 0.55. Good shot. Full length plasma.
Dec 5 2000 02:49:56:750PM	1001205014	Joseph Snipes	Shot 14: Try to get higher power out of J-port. Disrupted at 0.92 s probably due to the J-port RF again, though the videos were not so clear. Reached about 1.4 MW out of J-port.
Dec 5 2000 03:16:30:123PM	1001205015	Joseph Snipes	Shot 15: Started ECDC just before this shot for ~10 minutes. Decent shot, but it disrupted at 1.25 s probably due to the J-port RF again.
Dec 5 2000 03:40:57:390PM	1001205016	Joseph Snipes	Shot 16: Raised NL_ZMETER to 0.65. Fizzle!
Dec 5 2000 04:09:12:920PM	1001205017	Joseph Snipes	Shot 17: Changed EF4 from -1300 A to -1315 A at breakdown. Reduced Br0 offset from 1.5 mT to 1.0 mT. Disrupted early at 0.75 s. It is not clear that this disruption was due to the RF, though it was during 1.3 MW of RF from J-port. The video showed no clear excess radiation from the antenna. Breakdown is obviously better, though still not as good as before.
Dec 5 2000 04:21:31:640PM	1001205018	Joseph Snipes	Shot 18: Lowered the TF current from 150 kA to 146.6 kA to get to 5.2 T in segment 2. Disrupted at 1.12 s, this time probably due to the RF.
Dec 5 2000 04:55:10:047PM	1001205019	Joseph Snipes	Shot 19: Repeat. Disrupted at 1.24 s. Wolfe has discovered on shot 18 and this shot that the EF1's and EF2's are getting an incorrect demand signal from the Hybrid computer that is different from the equivalent digitized outputs. It may be RF pickup in the AFOL's that is forcing the EF supplies to cause the plasma to disrupt.
Dec 5 2000 05:12:11:827PM	1001205020	Joseph Snipes	Shot 20: Repeat without the RF to see if the disruption still occurs. Good shot.
Dec 5 2000 05:12:32:390PM	1001205020	Joseph Snipes	Summary: Overall, it was an O.K. run. There were a few power supply problems and there were disruptions on most shots. Some of the disruptions seemed to be caused by arcing in the J-port antenna. However, toward the end of the day, we had several disruptions (e.g., 17, 18, 19) that did not have high radiation from the ICRF antenna. Wolfe found jumps in the inputs to EF2 from the hybrid that may be due to RF pickup that then cause the power supplies to jump and led to the disruptions. The cabinets may need to be closed up to avoid RF pickup in the power room.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:55:10:420AM	Plasma	Ok
2	09:09:36:547AM	Plasma	Ok
3	09:29:34:217AM	Plasma	Ok
4	09:50:51:577AM	Plasma	Ok
5	10:15:29:327AM	Plasma	Ok
6	10:38:19:093AM	Plasma	Ok
7	11:03:19:123AM	Plasma	Ok
8	11:26:46:420AM	Plasma	Ok
9	11:49:08:933AM	Plasma	Bad	ef4 forward cabinet fuse loss.
10	12:58:05:700PM	Plasma	Ok
11	01:23:59:700PM	Plasma	Ok
12	01:49:16:967PM	Plasma	Ok
13	02:14:36:060PM	Plasma	Ok
14	02:39:48:560PM	Plasma	Ok
15	03:09:53:623PM	Plasma	Ok
16	03:33:04:093PM	Plasma	Ok
17	03:52:58:967PM	Plasma	Ok
18	04:18:12:047PM	Plasma	Ok
19	04:43:44:030PM	Plasma	Ok
20	05:06:56:140PM	Plasma	Ok