Miniproposals

Miniproposal: 149a Date Filed: 7/23/1996 Title: ICRF Reversed Shear Mode First Author: Miklos Porkolab Session Leader: Steve Wukitch (shots 1-38) Session Leader: Miklos Porkolab (shots 1-38)

Engineering Operator Run Comment

MP149A ERS/PEP_Porkolab/Wukitch,Granetz

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:18:023PM

Author: To Be Determined

****980211****980211****980211****980211****980211****980211****980211****980211 MP#149 Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz Setup: First segment (breakdown)loaded from a recent discharge -- 980210020 (a standard 800 kA, nl_04~1.0x10^20 D(H) discharge) Second segment (beyond 0.1 sec) loaded from 980114019 (this is a 400 kA/0.1 sec ramp but has good outer gap) which was a good discharge from previous campaign. ECDC in deuterium overnight before the run. Second day after Monday night boronization. TF under hybrid control Gas setup - fill K-side with 30 PSI of D2, hybrid enable fill B-top with 6 PSI of D2, hybrid enable fill B-side-lower with 3 PSI of Ar, hybrid disable fill J-bottom with 20 PSI of H2, hybrid enable RF position feedback is off Gate Valves: GPC PCX (check with Rejean before opening) The goals for today are to: 1) Good RF into nominal 500 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (2-3 shots) would like to keep the density down -- may run some low density discharges to unload the walls if necessary which would require 4 discharges 2) Raise current ramp to 500-700 kA/0.1 sec (5 shots) vary the second power step in 3-4 steps (5 shots) if Ar is necessary for toroidal rotation, we will puff Ar (3 shots) >> ERS or delay onset of sawtooth 3) Vary the magnetic field (mostly lower) to see what effect it has on discharge development (4 shots) 4.9 T and 4.5 T Looking for positive effect on delaying the onset of ST 4) Inject Li pellet into 1 MW portion of discharge and step up the power in the second part >> extend PEP mode duration with reverse shear current profile (5-7 shots) probably will require multiple pellets timing of the RF and pellet will be varied >> pellet injection in the flat top during shot development is planned. Piggyback During the flat top, H will be puffed to vary the H/H+D concentration to look for its affect on total absorbed RF power at 5.4T. This will require PCX and will focus on H-mode discharges. ====================================================================== Summary: Although the plasma was uncooperative for many discharges (many disrupted and density feedback was malfunctioning -- see physop summary for details), most of the goals were accomplished. The most notable exception is scanning H because the disruptions made shots unreliable and tuning for both the rampup and flat top were fairly exclusive. Electron temperatures approaching 5 keV were obtained at densities around nl_04~0.7x10^20 m^-2. We found that a ramp rate of < 5.5 MA resulted in MHD modes which were related to impurity injections (almost always around 0.115 sec). Discharges 980211018-22 show this injection disappear and reappear by changing the ramp rate. Discharge 980211021 shows a good correlation between the activity starting before the moly injection. This implies the injection is due to a MHD triggered collapse. Scanning the magnetic field to move the heating off-axis was not beneficial. Onset of the first sawtooth crash was reduced considerably eventhough the central temperatures were similar (measured by the Michelson and YAG). Li pellets were injected both in the flat top and ramp up. The plasma accepted three big pellets readily even at 0.07 sec into the discharge. We found no enhanced confinement with the pellets early in the ramp up (0.07 and 0.12 sec), but PEP mode behavior was observed in discharges where the pellet was injected at 0.15 or 0.18 sec. The sawtooth onset was delayed in the latter case to ~2.6 sec. This suggests deeply reverse shear profiles do not help in obtaining PEP mode. PEP modes were readily obtained in the flat top. ST1 PS1 ST2 PS2 615 365 2516 784 001 data system test next shot: PCI and TCI gate valve, reload from 980114019 002 plasma early disruption #1 faulted miserably #2 ran with faults dI/dt~500 kA/.100 sec, but the current stalled for 0.1 sec after the initial rise ST onset @0.163 sec next shot: 583 392 2397 873 003 disruption recovery fizzle next shot: lowered the power 004 plasma early disruption another brick @0.55 sec Prf~2 MW by 0.1 sec ST onset @0.19 dI/dt~534 kA/.100 sec ELM free starting 0.265 sec next shot: 556 427 2312 1005 005 fizzle 006 plasma early disruption dI/dt~570 kA/.100 sec Prf~2 MW by 0.1 sec ST onset @0.203 sec next shot: 577 426 2301 1068 007 plasma ran through injection @0.116 sec kills the early ramp by cooling the plasma dI/dt~570 kA/.100 sec trip on #2 near 0.25 sec MHD mode activity before injection next shot: Li pellet @0.57 raise power earlier 008 plasma early disruption -- density feedback problem 009 dud next shot: change to z-meter feedback 010 fizzle 011 plasma #1 screen overcurrent still have an injection @0.11 sec late high density disruption Li pellet injected during flattop next shot: lowered power on #1 by 100 kW 552 426 2233 1047 012 fizzle 013 magnet resistance fault 014 plasma late disruption at high density injection is smaller and later nl_04~1.05 @0.1 sec compared to 980114019 nl_04~0.7 good RF pulse is 1 MW by 0.07, 2 MW by 0.075, and 2.5 MW by 0.1 sec which is what is requested next shot: lower nl_04 543 440 2221 1071 015 fizzle 016 plasma good early RF late RF is tripping -- Elm-free ST onset @0.21 sec next shot: lower gas puff early in discharge 017 plasma injection is still taking a bite out RF faults both early and late next shot: drop the current ramp rate 018 plasma ramp rate not signicantly changed next shot: drop the current ramp rate 019 plasma early disruption @.56 sec injection is now @0.15 instead of 0.115 sec dIp/dt~510 kA/0.1 comment: Weaver suggests the H concentration is <1%. PCX is not functioning, so we will break to add He to the stripping cell and the density feedback. I am suspicious that the H concentration is too low for optimum heating efficiency. Once we have a measure of the H/H+D, we will decide whether to change over to vary the H/H+D concentration. next shot: same current ramp rate 020 plasma early disruption at 0.42 good ramp up (<4 keV central Te) injection is near the end of the first RF pulse next shot: increase current ramp rate back to 570 kA/.1 sec 021 plasma early disruption at ~.54 injection is back at 0.119 sec central Te still makes it to 4 keV so the lower density compared to 016 results in higher Te ~550 kA/0.1 sec H/H+D~2.5-3% next shot: back to ~500 ka/.1 sec 586 397 2402 898 022 fizzle 4.9T 023 fizzle 024 plasma early disruption ramp up is reasonable ST onset is 0.187 which is earlier than 020 (0.235 sec) next shot: move to 5.7 T 025 plasma 5.7 T ramp up is reasonable ST onset is 0.205 next shot: repeat 592 392 2487 830 026 plasma 5.7 T ramp up is reasonable ST onset is 0.215 Off-axis heating is clearly worse than on-axis for delaying the sawteeth. next shot: back to 5.4 T and inject a single Li pellet @0.06 sec 027 plasma small pellet near 0.71 sec little effect on discharge development 028 plasma bigger pellet @0.068 little permanent effect on discharge development Te is notched but still obtains Te>4 keV next shot: fire two pellets one big followed by one small 029 fizzle next shot: fire two pellets one small followed by one big 030 plasma early disruption density has drifted low (nl_04->0.52) probably only one pellet was injected ST onset is 0.2 sec next shot: raise density back to nl_04->0.7 @ 0.1 sec) 031 plasma early disruption at 0.3 two pellets: small and then big delne=2.35, delt=0.0079 sec 032 plasma ran through two pellets: 2 big dlene=1.8, delt=0.013 next shot: three big pellets 033 plasma ran through three pellets (big) ST onset @0.2 sec del_ne=1.8, del_t=0.013 next shot: move two pellets to 0.18 034 plasma ran through two pellets (second penetrated) ST onset @0.26 has PEP mode like features next shot: move two pellets to 0.15 sec 035 magnet resistance fault next shot: adjust tune 571 412 2390 935 036 plasma hard disruption at 0.8 sec two pellets @ 0.156sec ST onset @0.277 sec has PEP mode like features next shot: move two pellets to 0.12 sec 037 plasma two pellets @0.12 sec not a PEP mode (neutrons are down by factor of 2) ST onset @0.25 sec next shot: move two pellets to 0.21 sec 038 fizzle Summary:

Physics Operator Summaries

Entered: Jul 7 2004 04:36:59:457PM

Author: To Be Determined

Physics operator summary for run 980211. MP 149 -- Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz Summary: This was not a fun day for the physics operator. All morning long we were alternating between disruptions and fizzles. This was partly due to lots of moly injections, and partly to problems with the TCI density feedback signal. After shot 9, we switched to using the Z-meter signal for density feedback. This brought about a host of difficulties, not the least of which is that its polarity in the hybrid has apparently changed sign since 1995. We continued to hobble along at very low density (nl04=0.3 to 0.4e20 m-2) with short, disruptive shots. Fortunately, this MP was primarily concerned with the current rampup only, so we actually got some useful results. The RF did a magnificent job all day long of coupling 2.5 MW of power into the current rampup phase. Lots of lithium pellets were injected successfully later in the day. Most of the goals for this MP were done to some extent, except for varying the H/D ratio. See Steve Wukitch's session leader report for information on possible PEP modes, B-field scans, etc. Note: Jim Irby found that the TCI problems are due to an obstruction which has fallen down his port. It is moving around and intermittantly blocking his beams. Physop things learned today: (1) The early disruptions were associated with running at very low densities (nl04=0.3-0.4e20 m-2). When we finally moved to slightly higher densities after shot 31, we consistently got full length shots. (2) Ramping up the current too fast (more than 0.50 MA at t=0.1 s) caused some type of injection event at t=0.11-0.12 s which defeated the attempts to get reversed shear, and even resulted in a noticeable glitch in the current ramp. This event may have been associated with MHD, but Joe Snipes could only find TAE's. ** Warning ** Most of the shots today used the Z-meter signal for density feedback, and therefore are not suitable as starting points for future runs. The startup segment had multiple changes made to the OH1 voltage programming (to change dIp/dt), and so it too is not for general use. Scorecard: 25 plasmas (most of these disrupted early) 9 fizzles 3 duds (2 magnet resistance faults) 1 test (reset MDS cycle) ---------- 38 total ------------------------------------------------------------------------------ Run Plan and Engineering Setup for Wednesday, 980211 (written by S. Wukitch) ECDC in deuterium overnight before the run. Second day after Monday night boronization. TF under hybrid control Gas setup - fill K-side with 30 PSI of D2, hybrid enable fill B-top with 6 PSI of D2, hybrid enable fill B-side-lower with 3 PSI of Ar, hybrid disable fill J-bottom with 20 PSI of H2, hybrid enable RF position feedback is off Gate Valves: GPC PCX (check with Rejean before opening) ------------------------------------------------------------------------------ The goals for today are to: 1) Good RF into nominal 500 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (2-3 shots) would like to keep the density down -- may run some low density discharges to unload the walls if necessary which would require 4 discharges 2) Raise current ramp to 500-700 kA/0.1 sec (5 shots) vary the second power step in 3-4 steps (5 shots) if Ar is necessary for toroidal rotation, we will puff Ar (3 shots) >> ERS or delay onset of sawtooth 3) Vary the magnetic field (mostly lower) to see what effect it has on discharge development (4 shots) 4.9 T and 4.5 T Looking for positive effect on delaying the onset of ST 4) Inject Li pellet into 1 MW portion of discharge and step up the power in the second part >> extend PEP mode duration with reverse shear current profile (5-7 shots) probably will require multiple pellets timing of the RF and pellet will be varied >> pellet injection in the flat top during shot development is planned. Piggyback During the flat top, H will be puffed to vary the H/H+D concentration to look for its affect on total absorbed RF power at 5.4T. This will require PCX and will focus on H-mode discharges. ------------------------------------------------------------------------------ Detailed shot log: Note: overnight ECDC in deuterium was done prior to today's run. Hybrid coldstart done; no errors found ($set default cmod$models:[hybrid.tcl] $@hybinit_dispatch $@show_bitbus_log Use editor search to verify no occurrences of "error" nor "not respond") Segment 1 (breakdown) loaded from a recent discharge -- 980210020 (a standard 800 kA, nl_04~1.0x10^20 D(H) discharge) Segment 2 (beyond 0.1 sec) loaded from 980114019 (this is a 400 kA/0.1 sec ramp but has good outer gap) which was a good discharge from previous MP 149 campaign. Shot 01 -- Test. Data system needed to be cycled due to earlier computer problem. Shot 02 -- Plasma. Disrupted at 0.77 s. Looks like a brick. There was an apparent discontinuity in Ip at segment switch. Density was nice and low (nl04=0.7-0.8e20 m-2). Next shot: increase Ip demand at beginning of segment 2 from 300 to 325 kA, in order to exactly match end of segment 1. Leave gain jump unchanged for now. Shot 03 -- Fizzle. Null looks okay. Post-disruption recovery? Next shot: no changes. Shot 04 -- Plasma. Another early disruption due to a brick at 0.57 s. Good early RF power. Still some hesitation in Ip at the segment switch. Next shot: change Ip programming in segment 2 to start at 0.55 MA at t=0.1 s, and increase quickly to 1 MA. Shot 05 -- Fizzle. Null looks okay. Another post-disruption recovery shot. Next shot: no changes. Shot 06 -- Plasma. Another early disruption. This one looks like it touched the outer limiter at 0.2 s. Brief ELM-free H-mode at 0.3 s. Good RF coupling. Next shot: move RCUR in a few mm after 0.1 s. Shot 07 -- Plasma. Made it to the rampdown. There was a problem with nl04 which affected the density feedback. Lots of discontinuities in coil currents at segment switch, along with Ip. There was an EF2U over-stress warning at that time also. There was also a big brick at 0.116 s which almost killed the plasma. Next shot: Slow down the CLEARIN motion during the first 0.5 s, as recommended by Steve Wolfe, to reduce demand on EF2's. Shot 08 -- Plasma, but disrupted at 0.13 s, due to some kind of injection. There's still a problem with the TCI and the density feedback. The injection does not seem to be coming from the antennas. Next shot: repeat with no changes. Shot 09 -- Dud! Null looks good. TCI density feedback is kaput. Next shot: increase pre-pulse gas puff from 12 to 15 ms. Switch to z-meter feedback of the density by loading in wire 14 from segment 2 from 951117010. See what we get. Shot 10 -- Fizzle. Null looks fair. Next shot: Subtract 10 amps from EF4 (-1330 to -1340 A) Shot 11 -- Plasma. Just made it to rampdown, when there was a density limit disruption. There was also a huge lithium pellet injected at 0.567 s. Next shot: reduce Z-meter density demand alot. Tweak Ip demand at t=0.1 s in segment 2. LPI turned off. Shot 12 -- Fizzle. Null has slightly too much Br. Next shot: reduce Br from 0.005 to 0.0045 T Shot 13 -- Dud. Magnet resistance fault. Next shot: repeat. Shot 14 -- Plasma. Just made it into rampdown. Density is too high again. No hesitation in Ip at segment switch this time. There was another (smaller) molybdenum injection, this time at 0.3 s. Density feedback does not seem to be actually controlling the valve. Steve Wolfe reports that the z-meter signal has apparently changed polarity since 1995. Next shot: change sign of coefficient for NL_ZMETER. Reduce density demand by 33%. Start CLEARIN rampdown earlier in current rampdown. Shot 15 -- Fizzle. Null is fine. Disruption recovery. Next shot: no changes. Shot 16 -- Plasma. Good shot. Multiple ELM-free H-modes. Ip=0.57 MA at 0.1 s. Density was at nl04=0.7e20 m-2 during the non-H-mode periods, but significantly higher than that during H-modes. It was also a little high during the early part of the shot. Next shot: reduce early gas puffing in segment 1. Shot 17 -- Plasma. Good shot. There's an injection event again at 0.11 s which is affecting everything. Steve Wukitch and Amanda think that it may be due to an MHD event initiated by the fast current rise. Multiple ELM-free H-modes again. Early density is better controlled. Next shot: decrease early OH1 pre-programmed voltage by 50 volts to reduce initial current ramp rate. Shot 18 -- Plasma. Good shot. Still had the injection problem at 0.115 s. Multiple ELM-free H-modes. Ip ramp rate is hardly reduced at all. Next shot: reduce OH1 pre-programmed voltage another 100 volts. Also give a small tweak to RCUR at 0.1 s. Shot 19 -- Plasma. Disrupted at 0.56 s, maybe due to an injection? The ramp rate was reduced (Ip=0.51 MA at 0.1 s), and the early problems at 0.115 s disappeared. However, there was an injection at 0.15 s. Next shot: no PCS changes. We are having a break now to allow cell access for Jim Irby and Rejean Boivin. Jim Irby reports that there's an obstruction in his beam path, and it's moving around from shot to shot. Shot 20 -- Plasma. Disrupted at 0.42 s. Not a happy plasma. Large molybdenum injections, but not before t=0.25 s. Good RF coupling during rampup. Steve Wukitch reports that sawtooth initiation is at 0.23 s on this shot, which is 30 ms later than previous shots today. Next shot: raise the Ip ramp rate back up to see if the early injection event comes back. Shot 21 -- Plasma. Disrupted at 0.54 s. Lots of dirt. The early injection event returned, and therefore seems to be associated with the faster current ramp. Ip reached 0.55 MA at 0.1 s. Next shot: reduce OH1 voltage back down to reduce ramp rate, and reduce toroidal B-field to 4.9 T (was 5.4 T) Shot 22 -- Fizzle. Null looks fair. Next shot: repeat. Shot 23 -- Fizzle. A little too much Bz. Next shot: change IC_EF4 from -1340 to -1355 A. Shot 24 -- Plasma, but disrupted at 0.34 s. Brick. Ip=0.50 MA at 0.1 s. Sawteeth begin 50 ms earlier than on shot 20. The early injection event is gone also. Next shot: increase Btor to 5.7 T, and add back the 15 amps to IC_EF4. Shot 25 -- Plasma. Disrupted at 0.45 s. Sawteeth start at 0.22 s. Next shot: repeat with no changes. Shot 26 -- Plasma. Disrupted at 0.48 s. Early hard x-rays. Next shot: go back to 5.4 T, and fire lithium pellet at 0.060 s. Also tweak CLEARIN around 0.35 s to get plasma farther off of inboard wall. Shot 27 -- Plasma. Disrupted at 0.77 s. nl04=0.5e20 m-2, and has been for most of the afternoon. Hard x-rays went away on their own. LPI fired, but it didn't go very deep. I don't see any sign of it. Next shot: try firing a bigger lithium pellet. Shot 28 -- Plasma. Disrupted at 1.02 s. Lithium pellet is apparently hitting the plasma at t=0.070 s. H-modes starting at 0.75 s, accompanied by lots of Prad. Ip=0.48 MA at 0.1 s. Next shot: fire a large pellet followed by a small pellet. Shot 29 -- Fizzle. Null looks good. Gas looks good. Next shot: just repeat. There will be a third lithium pellet, fired at t=0.56 s. Shot 30 -- Plasma. Disrupted at 0.50 s. Only one lithium pellet made it in during the early ramp. nl04=0.3-0.4e20 m-2, which is lower than desired. Next shot: increase density (Z-meter) demand in segment 2 by 50%, and increase valve voltage programming in segment 1. Try multiple lithium pellets again. Shot 31 -- Plasma. Disrupted at 0.33 s. Looks like a small Li pellet at 0.71 s followed by a large Li pellet at 0.75 s. No PEP mode. Density did not come up much (excluding the time around the Li injection). Next shot: fire two large lithium pellets early. Also increase background density. Shot 32 -- Plasma. Good shot. Density is up marginally. Double pellet injection at 0.070/0.072 s, and single pellet at 0.57 s. Multiple ELM-free H-modes. The last pellet may produce a PEP mode, but it may be confused by the transition to H-mode. Zeff is back at 1. Next shot: more tweaks to increase density. Inject 3 big lithium pellets at 0.070 s. Shot 33 -- Plasma. Good shot. Three Li pellets at 0.069, 0.072, 0.076 s, but no PEP mode. Density is around nl04=1.0e20 m-2. Next shot: fire double Li pellets later in the shot (0.18 s) and see if PEP mode is produced then. Shot 34 -- Plasma. Good shot. Double pellet at 0.1795 s, and single pellet at 0.58 s. Density pumpout is approx. 50 ms. PEP mode? Sawteeth start is delayed to 0.26 s. ERS? Next shot: fire double Li pellets at 0.15 s. Shot 35 -- Dud. Magnet resistance fault. Next shot: try again. Shot 36 -- Plasma. Disrupted at 0.80 s. Lots of molybdenum injections throughtout the discharge. Not any better than shot 34, and maybe even a little worse, as far as density pumpout time goes. First sawtooth crash is at 0.277 s. Next shot: fire double Li pellet at 0.120 s. Shot 37 -- Plasma. Good shot. Li pellets at 0.12 s did not have a longer pumpout time. The Li pellet at 0.575 s did look like PEP-mode. First sawtooth crash is at 0.25 s. Next shot: fire double Li pellet at 0.21 s. This will be the last shot today. Shot 38 -- Fizzle. Darn!! End of run.

Session Leader Comments
Feb 11 1998 08:03:26:760AM		Steve Wukitch	MP#149 Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz Setup: First segment (breakdown)loaded from a recent discharge -- 980210020 (a standard 800 kA, nl_04~1.0x10^20 D(H) discharge) Second segment (beyond 0.1 sec) loaded from 980114019 (this is a 400 kA/0.1 sec ramp but has good outer gap) which was a good discharge from previous campaign. ECDC in deuterium overnight before the run. Second day after Monday night boronization. TF under hybrid control Gas setup - fill K-side with 30 PSI of D2, hybrid enable fill B-top with 6 PSI of D2, hybrid enable fill B-side-lower with 3 PSI of Ar, hybrid disable fill J-bottom with 20 PSI of H2, hybrid enable RF position feedback is off Gate Valves: GPC PCX (check with Rejean before opening) The goals for today are to: 1) Good RF into nominal 500 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (2-3 shots) would like to keep the density down -- may run some low density discharges to unload the walls if necessary which would require 4 discharges 2) Raise current ramp to 500-700 kA/0.1 sec (5 shots) vary the second power step in 3-4 steps (5 shots) if Ar is necessary for toroidal rotation, we will puff Ar (3 shots) >> ERS or delay onset of sawtooth 3) Vary the magnetic field (mostly lower) to see what effect it has on discharge developmen
Feb 11 1998 08:49:30:840AM	980211002	Steve Wukitch	002 plasma early disruption #1 faulted miserably #2 ran with faults dI/dt~500 kA/.100 sec, but the current stalled for 0.1 sec after the initial rise ST onset @0.163 sec
Feb 11 1998 08:49:58:920AM	980211003	Steve Wukitch	003 fizzle
Feb 11 1998 09:14:53:080AM	980211004	Steve Wukitch	004 plasma early disruption another brick @0.55 sec Prf~2 MW by 0.1 sec ST onset @0.19 dI/dt~534 kA/.100 sec ELM free starting 0.265 sec
Feb 11 1998 09:15:33:310AM	980211005	Steve Wukitch	005 fizzle
Feb 11 1998 10:11:00:240AM	980211006	Steve Wukitch	006 plasma early disruption dI/dt~570 kA/.100 sec Prf~2 MW by 0.1 sec ST onset @0.203 sec
Feb 11 1998 10:11:25:070AM	980211007	Steve Wukitch	next shot: 577 426 2301 1068 007 plasma ran through injection @0.116 sec kills the early ramp by cooling the plasma dI/dt~570 kA/.100 sec trip on #2 near 0.25 sec
Feb 11 1998 10:11:42:680AM	980211008	Steve Wukitch	next shot: Li pellet @0.57 raise power earlier 008 plasma early disruption -- density feedback problem
Feb 11 1998 10:13:26:320AM	980211009	Steve Wukitch	009 dud
Feb 11 1998 10:59:44:060AM	980211010	Steve Wukitch	next shot: change to z-meter feedback 010 fizzle
Feb 11 1998 11:00:23:770AM	980211011	Steve Wukitch	011 plasma #1 screen overcurrent still have an injection @0.11 sec late high density disruption Li pellet injected during flattop next shot: lowered power on #1 by 100 kW 552 426 2233 1047
Feb 11 1998 11:00:58:680AM	980211012	Steve Wukitch	012 fizzle
Feb 11 1998 11:36:40:650AM	980211013	Steve Wukitch	013 magnet resistance fault
Feb 11 1998 11:37:02:320AM	980211014	Steve Wukitch	014 plasma late disruption at high density injection is smaller and later nl_04~1.05 @0.1 sec compared to 980114019 nl_04~0.7 good RF pulse is 1 MW by 0.07, 2 MW by 0.075, and 2.5 MW by 0.1 sec which is what is requested next shot: lower nl_04
Feb 11 1998 11:37:26:530AM	980211015	Steve Wukitch	015 fizzle
Feb 11 1998 12:09:33:480PM	980211016	Steve Wukitch	016 plasma good early RF late RF is tripping -- Elm-free ST onset @0.21 sec
Feb 11 1998 12:15:25:820PM	980211017	Steve Wukitch	017 plasma injection is still taking a bite out of the rampup RF faults both early and late next shot: drop the current ramp rate
Feb 11 1998 01:15:00:820PM	980211018	Steve Wukitch	018 plasma ramp rate not signicantly changed
Feb 11 1998 01:15:37:650PM	980211019	Steve Wukitch	019 plasma early disruption @.56 sec injection is now @0.15 instead of 0.115 sec dIp/dt~510 kA/0.1
Feb 11 1998 01:15:51:370PM	980211019	Steve Wukitch	019 plasma early disruption @.56 sec injection is now @0.15 instead of 0.115 sec dIp/dt~510 kA/0.1 sec
Feb 11 1998 01:16:27:340PM	980211020	Steve Wukitch	next shot: same current ramp rate 020 plasma early disruption at 0.42 good ramp up (<4 keV central Te) injection is near the end of the first RF pulse
Feb 11 1998 01:28:09:670PM	980211021	Steve Wukitch	021 plasma early disruption at ~.54 injection is back at 0.119 sec central Te still makes it to 4 keV so the lower density compared to 016 results in higher Te ~550 kA/0.1 sec next shot: back to ~500 ka/.1 sec and 4.9 T
Feb 11 1998 01:36:30:570PM	980211022	Steve Wukitch	022 fizzle
Feb 11 1998 02:03:51:440PM	980211023	Steve Wukitch	023 fizzle
Feb 11 1998 02:04:19:210PM	980211024	Steve Wukitch	024 plasma early disruption ramp up is reasonable ST onset is 0.187 which is earlier than 020 (0.235 sec)
Feb 11 1998 02:26:13:290PM	980211025	Steve Wukitch	025 plasma 5.7 T ramp up is reasonable ST onset is 0.205 sec worse than 5.4 T (020)
Feb 11 1998 02:27:36:600PM	980211026	Steve Wukitch	026 plasma 5.7 T ramp up is reasonable ST onset is 0.215 sec next shot: back to 5.4 T inject 1 Li pellet at 0.06 sec
Feb 11 1998 03:01:45:460PM	980211028	Steve Wukitch	028 plasma bigger pellet @0.068 little permanent effect on discharge development Te is notched but still is Te>4 keV @0.2 sec next shot: fire two pellets one big followed by one small
Feb 11 1998 03:06:18:330PM	980211029	Steve Wukitch	029 fizzle next shot: fire two pellets one small followed by one big
Feb 11 1998 03:25:12:850PM	980211030	Steve Wukitch	030 plasma early disruption density has drifted low (nl_04->0.52) probably only one pellet was injected ST onset is 0.2 sec next shot: raise density back to nl_04->0.7 @ 0.1 sec)
Feb 11 1998 04:02:49:460PM	980211031	Steve Wukitch	031 plasma early disruption at 0.3 two pellets: small and then big delne=2.35, delt=0.0079 sec
Feb 11 1998 04:03:12:980PM	980211032	Steve Wukitch	032 plasma ran through two pellets: 2 big dlene=1.8, delt=0.013 next shot: three big pellets
Feb 11 1998 04:03:36:520PM	980211033	Steve Wukitch	033 plasma ran through three pellets (big) ST onset @0.2 sec dlene=1.8, delt=0.013 next shot: move two pellets to 0.18 sec
Feb 11 1998 04:20:12:590PM	980211034	Steve Wukitch	034 plasma ran through two pellets (second penetrated) ST onset @0.26 has PEP mode like features next shot: move two pellets to 0.15 sec
Feb 11 1998 04:21:45:720PM	980211035	Steve Wukitch	035 magnet resistance fault
Feb 11 1998 04:38:04:340PM	980211036	Steve Wukitch	036 plasma hard disruption at 0.8 sec two pellets @ 0.156sec ST onset @0.277 sec has PEP mode like features next shot: move two pellets to 0.12 sec
Feb 11 1998 04:52:57:340PM	980211037	Steve Wukitch	037 plasma two pellets @0.12 not a PEP mode ST onset @0.25 sec next shot: move two pellets to 0.21 sec

Physics Operator Comments
Feb 11 1998 08:06:53:710AM		Robert Granetz	Note: overnight ECDC in deuterium was done prior to today's run. Hybrid coldstart done; no errors found ($set default cmod$models:[hybrid.tcl] $@hybinit_dispatch $@show_bitbus_log Use editor search to verify no occurrences of "error" nor "not respond") Segment 1 (breakdown) loaded from a recent discharge -- 980210020 (a standard 800 kA, nl_04~1.0x10^20 D(H) discharge) Segment 2 (beyond 0.1 sec) loaded from 980114019 (this is a 400 kA/0.1 sec ramp but has good outer gap) which was a good discharge from previous MP 149 campaign.
Feb 11 1998 08:11:24:180AM	980211001	Robert Granetz	Shot 01 -- Test. Data system needed to be cycled due to earlier computer problem.
Feb 11 1998 08:41:57:040AM	980211002	Robert Granetz	Shot 02 -- Plasma. Disrupted at 0.77 s. Looks like a brick. There was an apparent discontinuity in Ip at segment switch. Density was nice and low (nl04=0.7-0.8e20 m-2). Next shot: increase Ip demand at beginning of segment 2 from 300 to 325 kA, in order to exactly match end of segment 1. Leave gain jump unchanged for now.
Feb 11 1998 08:50:52:760AM	980211003	Robert Granetz	Shot 03 -- Fizzle. Null looks okay. Post-disruption recovery? Next shot: no changes.
Feb 11 1998 09:05:57:420AM	980211004	Robert Granetz	Shot 04 -- Plasma. Another early disruption due to a brick at 0.57 s. Good early RF power. Still some hesitation in Ip at the segment switch. Next shot: change Ip programming in segment 2 to start at 0.55 MA at t=0.1 s, and increase quickly to 1 MA.
Feb 11 1998 09:12:58:190AM	980211005	Robert Granetz	Shot 05 -- Fizzle. Null looks okay. Another post-disruption recovery shot. Next shot: no changes.
Feb 11 1998 09:30:03:010AM	980211006	Robert Granetz	Shot 06 -- Plasma. Another early disruption. This one looks like it touched the outer limiter at 0.2 s. Brief ELM-free H-mode at 0.3 s. Good RF coupling. Next shot: move RCUR in a few mm after 0.1 s.
Feb 11 1998 09:52:07:390AM	980211007	Robert Granetz	Shot 07 -- Plasma. Made it to the rampdown. There was a problem with nl04 which affected the density feedback. Lots of discontinuities in coil currents at segment switch, along with Ip. There was an EF2U over-stress warning at that time also. There was also a big brick at 0.116 s and almost killed the plasma. Next shot: Slow down the CLEARIN motion during the first 0.5 s, as recommended by Steve Wolfe, to reduce demand on EF2's.
Feb 11 1998 10:07:49:830AM	980211008	Robert Granetz	Shot 08 -- Plasma, but disrupted at 0.13 s, due to some kind of injection. There's still a problem with the TCI and the density feedback. The injection does not seem to be coming from the antennas. Next shot: repeat with no changes.
Feb 11 1998 10:34:24:160AM	980211009	Robert Granetz	Shot 09 -- Dud! Null looks good. TCI density feedback is kaput. Next shot: increase pre-pulse gas puff from 12 to 15 ms. Switch to z-meter feedback of the density by loading in wire 14 from segment 2 from 951117010. See what we get.
Feb 11 1998 10:39:41:900AM	980211010	Robert Granetz	Shot 10 -- Fizzle. Null looks fair. Next shot: Subtract 10 amps from EF4 (-1330 to -1340 A)
Feb 11 1998 10:56:25:100AM	980211011	Robert Granetz	Shot 11 -- Plasma. Just made it to rampdown, when there was a density limit disruption. There was also a huge lithium pellet injected at 0.567 s. Next shot: reduce Z-meter density demand alot. Tweak Ip demand at t=0.1 s in segment 2. LPI turned off.
Feb 11 1998 11:06:30:950AM	980211012	Robert Granetz	Shot 12 -- Fizzle. Null has slightly too much Br. Next shot: reduce Br from 0.005 to 0.0045 T
Feb 11 1998 11:35:06:400AM	980211014	Robert Granetz	Shot 14 -- Plasma. Just made it into rampdown. Density is too high again. No hesitation in Ip at segment switch this time. There was another (smaller) molybdenum injection, this time at 0.3 s. Density feedback does not seem to be actually controlling the valve. Steve Wolfe reports that the z-meter signal has apparently changed polarity since 1995. Next shot: change sign of coefficient for NL_ZMETER. Reduce density demand by 33%. Start CLEARIN rampdown earlier in current rampdown.
Feb 11 1998 11:38:59:560AM	980211015	Robert Granetz	Shot 15 -- Fizzle. Null is fine. Disruption recovery. Next shot: no changes.
Feb 11 1998 11:54:42:680AM	980211016	Robert Granetz	Shot 16 -- Plasma. Good shot. Multiple ELM-free H-modes. Ip=0.57 MA at 0.1 s. Density was at nl04=0.7e20 m-2 during the non-H-mode periods, but significantly higher than that during H-modes. It was also a little high during the early part of the shot. Next shot: reduce early gas puffing in segment 1.
Feb 11 1998 12:11:17:340PM	980211017	Robert Granetz	Shot 17 -- Plasma. Good shot. There's an injection event again at 0.11 s which is affecting everything. Steve Wukitch and Amanda think that it may be due to an MHD event initiated by the fast current rise. Multiple ELM-free H-modes again. Early density is better controlled. Next shot: decrease early OH1 pre-programmed voltage by 50 volts to reduce initial current ramp rate.
Feb 11 1998 12:24:00:200PM	980211018	Robert Granetz	Shot 18 -- Plasma. Good shot. Still had the injection problem at 0.115 s. Multiple ELM-free H-modes. Ip ramp rate is hardly reduced at all. Next shot: reduce OH1 pre-programmed voltage another 100 volts. Also give a small tweak to RCUR at 0.1 s.
Feb 11 1998 12:58:42:860PM	980211019	Robert Granetz	Shot 19 -- Plasma. Disrupted at 0.56 s, maybe due to an injection? The ramp rate was reduced (Ip=0.51 MA at 0.1 s), and the early problems at 0.115 s disappeared. However, there was an injection at 0.15 s. Next shot: no PCS changes. We are having a break now to allow cell access for Jim Irby and Rejean Boivin. Jim Irby reports that there's an obstruction in his beam path, and it's moving around from shot to shot.
Feb 11 1998 01:28:18:550PM	980211021	Robert Granetz	Shot 21 -- Plasma. Disrupted at 0.54 s. Lots of dirt. The early injection event returned, and therefore seems to be associated with the faster current ramp. Ip reached 0.55 MA at 0.1 s. Next shot: reduce OH1 voltage back down to reduce ramp rate, and reduce toroidal B-field to 4.9 T (was 5.4 T)
Feb 11 1998 01:42:18:530PM	980211022	Robert Granetz	Shot 22 -- Fizzle. Null looks fair. Next shot: repeat.
Feb 11 1998 01:48:48:500PM	980211023	Robert Granetz	Shot 23 -- Fizzle. A little too much Bz. Next shot: change IC_EF4 from -1340 to -1355 A.
Feb 11 1998 02:08:14:750PM	980211024	Robert Granetz	Shot 24 -- Plasma, but disrupted at 0.34 s. Brick. Ip=0.50 MA at 0.1 s. Sawteeth begin 50 ms earlier than on shot 20. The early injection event is gone also. Next shot: increase Btor to 5.7 T, and add back the 15 amps to IC_EF4.
Feb 11 1998 02:15:59:040PM	980211025	Robert Granetz	Shot 25 -- Plasma. Disrupted at 0.45 s. Sawteeth start at 0.22 s. Next shot: repeat with no changes.
Feb 11 1998 02:30:19:730PM	980211026	Robert Granetz	Shot 26 -- Plasma. Disrupted at 0.48 s. Early hard x-rays. Next shot: go back to 5.4 T, and fire lithium pellet at 0.060 s. Also tweak CLEARIN around 0.35 s to get plasma farther off of inboard wall.
Feb 11 1998 02:41:00:750PM	980211027	Robert Granetz	Shot 27 -- Plasma. Disrupted at 0.77 s. nl04=0.5e20 m-2, and has been for most of the afternoon. Hard x-rays went away on their own. LPI fired, but it didn't go very deep. I don't see any sign of it. Next shot: try firing a bigger lithium pellet.
Feb 11 1998 03:00:33:650PM	980211028	Robert Granetz	Shot 28 -- Plasma. Disrupted at 1.02 s. Lithium pellet is apparently hitting the plasma at t=0.070 s. H-modes starting at 0.75 s, accompanied by lots of Prad. Ip=0.48 MA at 0.1 s. Next shot: fire a large pellet followed by a small pellet.
Feb 11 1998 03:12:47:700PM	980211029	Robert Granetz	Shot 29 -- Fizzle. Null looks good. Gas looks good. Next shot: just repeat. There will be a third lithium pellet, fired at t=0.56 s.
Feb 11 1998 03:23:53:990PM	980211030	Robert Granetz	Shot 30 -- Plasma. Disrupted at 0.50 s. Only one lithium pellet made it in during the early ramp. nl04=0.3-0.4e20 m-2, which is lower than desired. Next shot: increase density (Z-meter) demand in segment 2 by 50%, and increase valve voltage programming in segment 1. Try multiple lithium pellets again.
Feb 11 1998 03:36:42:050PM	980211031	Robert Granetz	Shot 31 -- Plasma. Disrupted at 0.33 s. Looks like a small Li pellet at 0.71 s followed by a large Li pellet at 0.75 s. No PEP mode. Density did not come up much (excluding the time around the Li injection). Next shot: fire two large lithium pellets early. Also increase background density.
Feb 11 1998 03:53:20:020PM	980211032	Robert Granetz	Shot 32 -- Plasma. Good shot. Density is up marginally. Double pellet injection at 0.070/0.072 s, and single pellet at 0.57 s. Multiple ELM-free H-modes. The last pellet may produce a PEP mode, but it may be confused by the transition to H-mode. Zeff is back at 1. Next shot: more tweaks to increase density. Inject 3 big lithium pellets at 0.070 s.
Feb 11 1998 04:16:38:250PM	980211033	Robert Granetz	Shot 33 -- Plasma. Good shot. Three Li pellets at 0.069, 0.072, 0.076 s, but no PEP mode. Density is around nl04=1.0e20 m-2. Next shot: fire double Li pellets later in the shot (0.18 s) and see if PEP mode is produced then.
Feb 11 1998 04:18:13:310PM	980211034	Robert Granetz	Shot 34 -- Plasma. Good shot. Double pellet at 0.1795 s, and single pellet at 0.58 s. Density pumpout is approx. 50 ms. PEP mode? Sawteeth start is delayed to 0.26 s. ERS? Next shot: fire double Li pellets at 0.15 s.
Feb 11 1998 04:21:33:530PM	980211035	Robert Granetz	Shot 35 -- Dud. Magnet resistance fault. Next shot: try again.
Feb 11 1998 04:39:30:760PM	980211036	Robert Granetz	Shot 36 -- Plasma. Disrupted at 0.80 s. Lots of molybdenum injections throughtout the discharge. Not any better than shot 34, and maybe even a little worse, as far as density pumpout time goes. First sawtooth crash is at 0.277 s. Next shot: fire double Li pellet at 0.120 s.
Feb 11 1998 04:52:02:150PM	980211037	Robert Granetz	Shot 37 -- Plasma. Good shot. Li pellets at 0.12 s did not have a longer pumpout time. The Li pellet at 0.575 s did look like PEP-mode. First sawtooth crash is at 0.25 s. Next shot: fire double Li pellet at 0.21 s. This will be the last shot today.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:00:14:930AM	Test	Ok	cycle test/ OK
2	08:31:30:050AM	Test	Ok	no faults
3	08:46:57:120AM	Test	Ok	no faults
4	08:55:40:480AM	Test	Ok	no faults
5	09:08:33:400AM	Plasma	Ok
6	09:17:42:240AM	Plasma	Ok	no faults
7	09:32:44:800AM	Plasma	Ok	no faults/plasma
8	09:55:16:600AM	Plasma	Ok	no faults
9	10:07:51:140AM	Plasma	Ok
10	10:33:25:590AM	Plasma	Ok
11	10:42:50:410AM	Plasma	Ok
12	10:59:18:690AM	Plasma	Ok
13	11:08:43:020AM	Plasma	Bad	mag resist fault
14	11:17:37:840AM	Plasma	Ok
15	11:35:11:870AM	Plasma	Ok
16	11:44:29:570AM	Plasma	Ok
17	11:57:49:330AM	Plasma	Ok
18	12:13:03:580PM	Plasma	Ok
19	12:26:52:550PM	Plasma	Ok
20	12:59:08:160PM	Plasma	Ok
21	01:17:22:920PM	Plasma	Ok
22	01:29:59:070PM	Plasma	Ok
23	01:42:19:150PM	Plasma	Ok
24	01:52:18:140PM	Plasma	Ok
25	02:07:04:790PM	Plasma	Ok
26	02:18:53:980PM	Plasma	Ok
27	02:32:57:170PM	Plasma	Ok
28	02:47:23:320PM	Plasma	Ok
29	03:03:09:940PM	Plasma	Ok
30	03:13:57:980PM	Plasma	Ok
31	03:26:46:250PM	Plasma	Ok
32	03:39:32:080PM	Plasma	Ok
33	03:53:58:960PM	Plasma	Ok
34	04:06:17:070PM	Plasma	Ok
35	04:19:13:970PM	Plasma	Ok
36	04:28:38:280PM	Plasma	Ok
37	04:40:46:740PM	Plasma	Ok
38	04:56:28:200PM	Plasma	Ok