Miniproposals

Miniproposal: 149a Date Filed: 7/23/1996 Title: ICRF Reversed Shear Mode First Author: Miklos Porkolab Session Leader: Steve Wukitch (shots 1-19) Session Leader: Miklos Porkolab (shots 1-19)

Engineering Operator Run Comment

MP: 149/Porkolab,Wukitch,Granetz

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:17:803PM

Author: To Be Determined

****980114****980114****980114****980114****980114****980114****980114****980114 MP#149 Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz Setup: First segment (breakdown)loaded from a recent discharge -- 980106025 (a standard 800 kA, nl_04~1.0x10^20 D(H) discharge) Second segment (beyond 0.1 sec) loaded from 970620023 which was a good discharge from previous campaign. 1.5 hours of ECDC in deuterium before the run. TF under hybrid control Gas setup - fill K-side with 20 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 enable RF position feedback is off The goals for today are to: 1) Good RF into nominal 400 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (5 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) Lower the current ramp to 300 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 If no evidence of ERS mode, switch to PEP mode. ERS will be identified by large increase in density and stored plasma energy. 3) 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) >> Pellet injection in the flat top during shot development is planned. vary the timing of the RF and pellet injection vary the density nl_04 = [0.8,1.2,1.6] ST1 PS1 ST2 PS2 001 plasma RF: start 0.05 at 300 kW each stepup 0.1 to 1 MW each ramp E-port later 002 plasma 591 407 2535 936 good early RF 1.75 MW by .110 and 4 keV central Te good baseline for 510 kA/0.1 sec 003 plasma working to lower the dI/dt nl_04~0.6 no H-mode to very late 004 plasma 589 394 2450 957 current ramp rate is slower 420 kA/0.1 sec 005 plasma current ramp rate is 410 kA/0.1 sec short H-mode toward end of early heating ******** long break to fix TF breaker ******** sensor which distributes signal was busted and replaced by one from the spare breaker ******** gas burp which may affect H concentration and machine conditioning at 12:52 Ptorr->3x10^-4 torr 006 plasma 595 385 2458 885 perhaps a pellet at 0.84 -- no pellet 007 plasma 300 kA/.1 sec 591 395 still no pellet changed pulse length to 0-1.0 crowbarred FMIT#1 300 kA/.1 sec before 0.1 sec and 235 kA/.1 sec after 008 pellet disrupted plasma 300 kA/.1 sec plus ramping to 1 MA by .200 after .1 sec too fast of a ramp 009 fizzle 010 fizzle 300 kA/.1 sec then ramping to 1 MA by 0.5 sec 011 plasma 300 kA/0.1 sec before .1 sec and 150 kA/0.1 sec after pellet injection 012 plasma raised density -- Zeff and Te came down, but sawteeth started 40 msec earlier 2442 907 013 plasma lost DAQA and data moved the plasma out 1 cm at 0.08 sec to try to improve earlier coupling RF seems to couple better before 0.1 sec -- less trips 014 plasma OK; better earlier heating; sawtooth delayed by 30 ms, to 150 ms into discharge; 015 Plasma OK; more power earlier; 606 375 2433 862 sawteeth delayed by another 30 ms, to about 180 ms; 016 dud -- power cycle 017 more power earlier; good plasma; 615 365 2516 784 rf power partially dropped out at 130 ms; lower Te; earlier sawteeth; PEP mode late into the shot; 018 Plasma. Good shot. Good early RF power. Lithium pellet injected at 0.108 s. It momentarily trips the RF. Sawtooth initiation was delayed until t=0.190 s. pellet into ramp -- tripped both transmitters (~0.1 sec) 019 plasma delayed sawteeth to 0.21 sec changed the ramp rate (moved crowbar back to .12 sec) moved pellet to .15 sec This was definitely an informative day. We were able to slow the ramp rate to 300 kA/0.1 sec and there was much less observed MHD activity. The sawtooth initialization was earlier in the slower ramp rate discharges: initial post 0.1 sec Tinit ramp rate ramp rate (sec) 980114011 300 kA/.1 sec 166 kA/.1 sec 0.16 980114007 300 kA/.1 sec 235 kA/.1 sec 0.17 980114008 300 kA/.1 sec 360 kA/.1 sec 0.17 980114005 410 kA/.1 sec 200 kA/.1 sec 0.17 980114002 510 kA/.1 sec 220 kA/.1 sec 0.21 This trend suggests a faster ramp rate is better for delaying the onset of sawteeth which needs to be further. Furthermore, TAE modes were observed, adding significant new data to our TAE database; also, the tearing mode activity observed in previous runs durung the initial rampup phase was noticeably absent this time, presumably due to the slower ramp rates. Increased puffing caused sawtooth initialization time to decrease, but the central temperature and line density at 0.1 sec are nearly identical. However, Zeff was significantly reduced. 980114011 300 kA/.1 sec 166 kA/.1 sec 0.16 980114012 300 kA/.1 sec 150 kA/.1 sec 0.12 Decreasing the outer gap at 0.08 sec increased the RF coupling and allowed higher coupled power before 100 msec: Prf early Te[keV] 980114012 300 kA/.1 sec 150 kA/.1 sec 0.12 <0.5 MW 1.45 980114014 300 kA/.1 sec 150 kA/.1 sec 0.155 1.4 MW 1.65 980114015 300 kA/.1 sec 150 kA/.1 sec 0.18 1.9 MW 2 This seems to be an effective means of delaying the sawtooth onset. With the slow ramp there are sawteeth before the RF for 12,14, and 15 around 0.05 sec which are stabilized with increasing duration with increasing RF power before 0.1 sec. Li pellets were successfully shot into the early ramp (980114018 and 19), but probably did not penetrate deep into the plasma and did not trigger PEP mode. The plasma temperature was too high for deep penetration. PEP and P modes were achieved in the flat top part of the discharge. This run indicates two items to pursue in the future with regards to the ramp up alone: increase early ramp rate and decrease the outer gap so that significant RF power can be coupled as early as possible. I would start with 019 the next time and increase the current rise rate and decrease the outer gap. For combining pellet injection and ramp up, the pellet should be injected before the plasma becomes too hot. So the pellet should be injected before the temperature becomes too high. The H fraction was between 2-5% on the day as measured by both PCX and spectroscopy (R. Boivin and J. Weaver [U. Maryland]). The RF operationally had difficulty with screen overcurrents which caused crowbarring fo the high voltage during the discharge. This only emphasizes the need to finish the pullback circuit. Furthermore more power can be coupled earlier if we can make the outer gap smaller earlier in the discharge.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:58:753PM

Author: To Be Determined

Physics operator summary for run 980114 MP 149A -- Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz Summary: Despite a shortened amount of run time, we managed to have a successful day, in the sense that we accomplished everything we had planned to try, and learned some valuable physics lessons as well. The initial current rise was slowed to 290 kA at t=0.100 s. Density was kept low at nl04=5-7e20 m-2. Optimization of the outer gap allowed 2.4 MW of ICRF to be coupled into the plasma starting at t=0.070 s. Lithium pellets were injected early as well. However, the sawtooth initiation time was only delayed by 80 ms or less, and there was no sign of enhanced confinement. By the end of the run, we had pretty much concluded that slowing down the Ip ramp rate was not the way to go. Problems today: One of the TF breakers broke, costing us about 3.5 hours of run time. We would have lost the entire run, if we hadn't been able to cannibalize a part from a "spare" breaker. There was also a momentary air leak which occurred just after the breaker was repaired. The torus gauge went up into the 10**-3 torr range, but quickly returned to normal. There were no deleterious after-effects. Plasma operation was very robust. Scorecard: 16 plasmas 2 fizzles 1 dud, sort of (dummy shot cycle) 0 tests ---------- 19 total ------------------------------------------------------------------------------ Run Plan and Engineering Setup for Wedensday, 980114 MP: 149A Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz ------------------------------------------------------------------------------ Engineering setup as on 971218015: Two hours of ECDC in deuterium before the run, if possible. 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 1.5 PSI of Ar, hybrid enable The following gate valves should be enabled, assuming no vacuum problems: ECE a good discharge from the previous campaign is 970620023 The goals for today are to: 1) Good RF into nominal 400 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (5 shots) 2) Lower the current ramp to 300 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 If no evidence of ERS mode, switch to PEP mode. ERS will be identified by large increase in density and stored plasma energy. 3) 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) >> Pellet injection in the flat top during shot development is planned. ------------------------------------------------------------------------------- Detailed shot log: Note: 1.5 hours of 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") Load segment 1 from shot 980106025 Load segment 2 from shot 970620023 (from last ICRF RS run), except: Reduce slow ZCUR P and D gains from 1.5 to 1.0 from t=0.10 to 0.25 s, and to 0.7 from t=0.25 s onward. RF feedback on RCUR is turned off (RF_LOAD_E = 0.0) 1 MW of RF will turn on very early (before t=0.1 s), with another 1-2 MW of RF following shortly thereafter. Shot 01 -- Plasma. Good shot. ELM-free H-modes starting at t=0.2 s. Sawteeth started around t=0.16 s. Prf=300 kW at t=0.070 s, then 1 MW after t=0.1, then 2 & 3 MW eventually. Next shot: try to reduce early dIp/dt, decrease early outer gap, and early density. Turn on Ip feedback in segment, starting at t=0.070 s. Decrease Ip waveform to 0.3 MA at t=0.1 s (starting at 0.070 s). Match Ip to 0.3 MA at beginning of segment 2. Reduce early gas valve programming after t=0.1 s. Increase early RCUR slightly. Shot 02 -- Plasma. Good shot. Density was lower (nl_04=0.44e20 m-2 at 0.1 s, and 0.7e20 m-2 for most of shot. Te reached about 4 keV at 0.2 s. Two ELM-free H-modes late in flattop. Prf=0.2 MW at 0.05 s, then 2 MW at 0.1 s. Ip rampup is faster, if anything, than the previous shot! Funny burst-like things on the early ECE. Next shot: try to reduce Ip ramp rate again. Tweak early OH1 voltage programming down by 100 volts starting around t=0.05 s. Shot 03 -- Plasma. Good shot. Good low density. Ip ramp is only marginally slower, reaching 0.48 MA at 0.1 s. Loop voltage did indeed decrease by more than a volt after t=0.070 s. Next shot: reduce early OH1 voltage another 100 volts. Steve Wolfe is trying to set up a fast sampling window from t=0.050 to 0.180 s. Shot 04 -- Plasma. Good shot. Ip ramp definitely slowed somewhat on this one. Ip=0.42 MA at 0.1 s. Sawtoothing starts around 0.18 s. Next shot: reduce early OH1 voltage even more. Shot 05 -- Plasma. Good shot. Ip ramp only marginally slower; 0.41 MA at 0.1 s. Next shot: continue reducing OH1 voltage in both segments 1 and 2. From t=0.08 to 0.12 the preprogrammed OH1 voltage is -150 V ! Also, Earl will inject a lithium pellet at t=0.84 s. During a break to allow lab access for Amanda, a problem has cropped up with one of the TF breakers. This will result in an extended break in the run. The run is restarting at 13:15, after nearly a 4 hour break to fix the breaker. There was also a momentary air leak just before restarting. The torus gauge jumped up to 3e-4 torr before coming back down to the 8 scale. Shot 06 -- Plasma. Good shot. Ip is now down to 385 kA at 0.1 s. Prf=0.45 MW at t=0.07 s. No lithium pellet. Next shot: move the OH1 and OH2 crowbar times back grom 0.120 s to 0.070 s. This is again to try and reduce the early Ip ramp. Shot 07 -- Plasma. Good shot. Ip finally hesitates at 290 kA from t=0.07 to 0.11 s. Sawtoothing still starts around 0.18 s though. Next shot: keep everything the same up to 0.1 s, then ramp the current quickly to 1 MA. Lithium will be injected at 0.74 s. Shot 08 -- Plasma. Earl killed it at 0.75 s with the lithium injection. Lots of PF coils reached their current limits, and there were also stress warnings on the EF2's. Next shot: reduce Ip rampup rate. Turn on RF heating later in the shot to try and survive the lithium injection. Shot 09 -- Fizzle. Null looks good. Chalk it up to disruption recovery. Next shot: due to mounting concerns about coil stresses, reduce the current rampup rate by aiming for 1 MA at t=0.5 s. Shot 10 -- Fizzle. Br looks a bit high. Next shot: decrease Br by 0.001 T (0.006 to 0.005) Shot 11 -- Plasma. Good shot. Ip pretty much follows the demand programming, reaching 1 MA around 0.5 s. There were several ELM-free H-modes. Next shot: Increase density to nl_04=7.5e19 m-2 and early gas puffing. It is hoped that this will reduce Zeff and improve the skin current effect. Shot 12 -- Plasma. Good shot. Density was a bit higher, as requested. However, sawtoothing started even earlier, at 0.12 s. Lithium pellet injected at 0.74 s again, but it's only going in about halfway. Zeff came down quite a bit. Next shot: try to decrease the outer gap by 1 cm at t=0.080 s (for better RF coupling). Shot 13 -- Plasma. Good shot. Probably disrupted during rampdown, but DAQA hung and most data were lost. RF instrumentation indicates that coupling did indeed improve somewhat. We don't really know what the outer gap behavior was though. Next shot: try reducing outer gap by another 1 cm at t=0.08-0.11 s. Shot 14 -- Plasma. Good shot. Prf gets to 1 MW at 0.74 s and stays at or above this level. Prf goes to 2.4 MW after 0.1 s. Lithium pellet had a bigger effect on density this time. Sawtoothing starts at t=0.15-0.16 s. Next shot: Increase RCUR another 5 mm to reduce gap another 1 cm. Shot 15 -- Plasma. Good shot. Good early RF coupling. Sawtoothing begins at t=0.17 s, which is noticeably delayed compared to shot 12. Lithium pellet injected at t=0.65 s. Next shot: increase RF power. No PCS changes. Shot 16 -- Dud (sort of). Alternator fault prior to shot cycle, but executed cycle anyway to reset things. Shot 17 -- Plasma. Good shot. Very, very impressive early RF power into the plasma. 1+ MW from t=0.053 s, and 2+ MW from t=0.070 s. But sawtoothing started at 0.16 s! Next shot: inject lithium pellet at 0.1 s. Shot 18 -- Plasma. Good shot. Good early RF power. Lithium pellet injected at 0.108 s. It momentarily trips the RF. Sawtooth initiation was delayed until t=0.190 s. Next shot: change gears. Go back to a near normal Ip ramp rate early in the shot, without changing any of the outer gap changes, or the density changes. Easiest way to do this (in view of the time constraints) is to simply return the crowbar times on the OH1 and OH2's back to t=0.12 s (from 0.070 s). Also, delay lithium pellet until t=0.15 s. Shot 19 -- Plasma. Good shot. Got the faster early current rise, and good early RF power, and a lithium pellet at 0.157 s. Sawtoothing starts at 0.21 s. No PEP mode with early pellet. A later pellet at 0.63 s may cause a PEP mode. Pellet penetration with ICRF on is noticeably worse than with RF off. End of run.

Session Leader Comments
Jan 14 1998 07:47:06:300AM		Steve Wukitch	MP#149 Optimize Reverse Shear Mode in D(H) discharges The goals for today are to: 1) Good RF into nominal 400 kA/0.1 sec current ramp -- 1 MW early RF followed by a step to higher power (2.5-3 MW) (5 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) Lower the current ramp to 300 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 If no evidence of ERS mode, switch to PEP mode. ERS will be identified by large increase in density and stored plasma energy. 3) 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) >> Pellet injection in the flat top during shot development is planned. vary the timing of the RF and pellet injection vary the density nl_04 = [0.8,1.2,1.6]
Jan 14 1998 08:54:04:360AM	980114001	Steve Wukitch	001 plasma RF: start 0.05 at 300 kW each -- only got #1 stepup 0.1 to 1 MW each ramp E-port later
Jan 14 1998 09:04:00:920AM	980114002	Steve Wukitch	ST1 PS1 ST2 PS2 002 plasma 591 407 2535 936 good early RF 1.75 MW by .110 and 4 keV central Te good baseline for 460 kA/0.1 sec
Jan 14 1998 09:17:29:530AM	980114003	Steve Wukitch	003 plasma working to lower the dI/dt nl_04~0.6 no H-mode to very late
Jan 14 1998 09:32:50:820AM	980114004	Steve Wukitch	004 plasma 589 394 2450 957 current ramp rate is slower 420 kA/0.1 sec
Jan 14 1998 09:52:53:560AM	980114004	Steve Wukitch	005 plasma raised early power to 2.1 MW current ramp rate is 410 kA/0.1 sec
Jan 14 1998 02:06:28:300PM	980114006	Steve Wukitch	006 plasma 595 385 2458 885 perhaps a pellet at 0.84 -- no pellet
Jan 14 1998 02:11:26:300PM	980114007	Steve Wukitch	007 plasma 300 kA/.1 sec 591 395 still no pellet changed pulse length to 0-1.0 crowbarred FMIT#1
Jan 14 1998 02:12:38:270PM	980114008	Steve Wukitch	008 pellet disrupted plasma 300 kA/.1 sec plus ramping to 1 MA by .200 sec after .1 sec too fast of a ramp after 0.1 sec
Jan 14 1998 02:12:56:240PM	980114009	Steve Wukitch	009 fizzle
Jan 14 1998 02:28:54:140PM	980114010	Steve Wukitch	010 fizzle
Jan 14 1998 02:50:32:140PM	980114011	Steve Wukitch	011 plasma 300 kA/0.1 sec before .1 sec and 150 kA/0.1 sec after pellet injection @ 0.74 sec
Jan 14 1998 03:09:50:570PM	980114012	Steve Wukitch	012 plasma raised density -- Zeff and Te came down, but sawteeth started 40 msec earlier 2442 907
Jan 14 1998 03:43:34:220PM	980114014	Steve Wukitch	014 plasma OK; better earlier heating; sawtooth delayed by 30 ms, to 150 ms into discharge;
Jan 14 1998 03:56:43:240PM	980114015	Steve Wukitch	015 Plasma OK; more power earlier; 606 375 2433 862 sawteeth delayed by another 30 ms, to about 180 ms;
Jan 14 1998 07:46:53:780PM	980114016	Steve Wukitch	016 no plasma -- power cycle
Jan 14 1998 07:47:12:140PM	980114017	Steve Wukitch	017 more power earlier; good plasma; 615 365 2516 784 rf power partially dropped out at 130 ms; lower Te; earlier sawteeth; PEP mode late into the shot
Jan 14 1998 07:48:29:290PM	980114018	Steve Wukitch	018 Plasma. Good shot. Good early RF power. Lithium pellet injected at 0.108 sec; momentarily trips the RF. Sawtooth onset delayed until t=0.190 s.
Jan 14 1998 07:49:07:610PM	980114019	Steve Wukitch	019 plasma delayed sawteeth to 0.21 sec changed the ramp rate (moved crowbar back to .12 sec) moved pellet to .15 sec

Physics Operator Comments
Jan 14 1998 07:25:04:980AM		Robert Granetz	Run Plan for Wedensday, 980114 MP: 149A Optimize Reverse Shear Mode in D(H) discharges SL: Porkolab/Wukitch PO: Granetz ------------------------------------------------------------------------------ Engineering setup as on 971218015: Two hours of ECDC in deuterium before the run, if possible. 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 1.5 PSI of Ar, hybrid enable The following gate valves should be enabled, assuming no vacuum problems: ECE
Jan 14 1998 07:32:32:940AM		Robert Granetz	Detailed shot log: Note: 1.5 hours of 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") Load segment 1 from shot 980106025 Load segment 2 from shot 970620023 (from last ICRF RS run), except: Reduce slow ZCUR P and D gains from 1.5 to 1.0 from t=0.10 to 0.25 s, and to 0.7 from t=0.25 s onward. RF feedback on RCUR is turned off (RF_LOAD_E = 0.0)
Jan 14 1998 08:50:12:860AM	980114001	Robert Granetz	Shot 01 -- Plasma. Good shot. ELM-free H-modes starting at t=0.2 s. Sawteeth started around t=0.16 s. Prf=300 kW at t=0.070 s, then 1 MW after t=0.1, then 2 & 3 MW eventually. Next shot: try to reduce early dIp/dt, decrease early outer gap, and early density. Turn on Ip feedback in segment, starting at t=0.070 s. Decrease Ip waveform to 0.3 MA at t=0.1 s (starting at 0.070 s). Match Ip to 0.3 MA at beginning of segment 2. Reduce early gas valve programming after t=0.1 s. Increase early RCUR slightly.
Jan 14 1998 09:06:22:000AM	980114002	Robert Granetz	Shot 02 -- Plasma. Good shot. Density was lower (nl_04=0.44e20 m-2 at 0.1 s, and 0.7e20 m-2 for most of shot. Te reached about 4 keV at 0.2 s. Two ELM-free H-modes late in flattop. Prf=0.2 MW at 0.05 s, then 2 MW at 0.1 s. Ip rampup is faster, if anything, than the previous shot! Funny burst-like things on the early ECE. Next shot: try to reduce Ip ramp rate again. Tweak early OH1 voltage programming down by 100 volts starting around t=0.05 s.
Jan 14 1998 09:18:32:990AM	980114003	Robert Granetz	Shot 03 -- Plasma. Good shot. Good low density. Ip ramp is only marginally slower, reaching 0.48 MA at 0.1 s. Loop voltage did indeed decrease by more than a volt after t=0.070 s. Next shot: reduce early OH1 voltage another 100 volts. Steve Wolfe is trying to set up a fast sampling window from t=0.050 to 0.180 s.
Jan 14 1998 09:26:52:880AM	980114004	Robert Granetz	Shot 04 -- Plasma. Good shot. Ip ramp definitely slowed somewhat on this one. Ip=0.42 MA at 0.1 s. Sawtoothing starts around 0.18 s. Next shot: reduce early OH1 voltage even more.
Jan 14 1998 09:47:45:810AM	980114005	Robert Granetz	Shot 05 -- Plasma. Good shot. Ip ramp only marginally slower; 0.41 MA at 0.1 s. Next shot: continue reducing OH1 voltage in both segments 1 and 2. From t=0.08 to 0.12 the preprogrammed OH1 voltage is -150 V ! Also, Earl will inject a lithium pellet at t=0.84 s.
Jan 14 1998 01:15:56:980PM	980114006	Robert Granetz	During a break to allow lab access for Amanda, a problem has cropped up with one of the TF breakers. This will result in an extended break in the run. The run is restarting at 13:15, after nearly a 4 hour break to fix the breaker. There was also a momentary air leak just before restarting. The torus gauge jumped up to 3e-4 torr before coming back down to the 8 scale.
Jan 14 1998 01:31:32:980PM	980114006	Robert Granetz	Shot 06 -- Plasma. Good shot. Ip is now down to 385 kA at 0.1 s. Prf=0.45 MW at t=0.07 s. No lithium pellet. Next shot: move the OH1 and OH2 crowbar times back grom 0.120 s to 0.070 s. This is again to try and reduce the early Ip ramp.
Jan 14 1998 01:48:40:690PM	980114007	Robert Granetz	Shot 07 -- Plasma. Good shot. Ip finally hesitates at 290 kA from t=0.07 to 0.11 s. Sawtoothing still starts around 0.18 s though. Next shot: keep everything the same up to 0.1 s, then ramp the current quickly to 1 MA. Lithium will be injected at 0.74 s.
Jan 14 1998 02:05:44:020PM	980114008	Robert Granetz	Shot 08 -- Plasma. Earl killed it at 0.75 s with the lithium injection. Lots of PF coils reached their current limits, and there were also stress warnings on the EF2's. Next shot: reduce Ip rampup rate. Turn on RF heating later in the shot to try and survive the lithium injection.
Jan 14 1998 02:29:10:150PM	980114010	Robert Granetz	Shot 10 -- Fizzle. Br looks a bit high. Next shot: decrease Br by 0.001 T (0.006 to 0.005)
Jan 14 1998 02:50:40:270PM	980114011	Robert Granetz	Shot 11 -- Plasma. Good shot. Ip pretty much follows the demand programming, reaching 1 MA around 0.5 s. There were several ELM-free H-modes. Next shot: Increase density to nl_04=7.5e19 m-2 and early gas puffing. It is hoped that this will reduce Zeff and improve the skin current effect.
Jan 14 1998 03:10:28:080PM	980114012	Robert Granetz	Shot 12 -- Plasma. Good shot. Density was a bit higher, as requested. However, sawtoothing started even earlier, at 0.12 s. Lithium pellet injected at 0.74 s again, but it's only going in about halfway. Zeff came down quite a bit. Next shot: try to decrease the outer gap by 1 cm at t=0.080 s (for better RF coupling).
Jan 14 1998 03:24:17:560PM	980114013	Robert Granetz	Shot 13 -- Plasma. Good shot. Probably disrupted during rampdown, but DAQA hung and most data were lost. RF instrumentation indicates that coupling did indeed improve somewhat. We don't really know what the outer gap behavior was though. Next shot: try reducing outer gap by another 1 cm at t=0.08-0.11 s.
Jan 14 1998 03:42:14:760PM	980114014	Robert Granetz	Shot 14 -- Plasma. Good shot. Prf gets to 1 MW at 0.74 s and stays at or above this level. Prf goes to 2.4 MW after 0.1 s. Lithium pellet had a bigger effect on density this time. Sawtoothing starts at t=0.15-0.16 s. Next shot: Increase RCUR another 5 mm to reduce gap another 1 cm.
Jan 14 1998 03:53:41:530PM	980114015	Robert Granetz	Shot 15 -- Plasma. Good shot. Good early RF coupling. Sawtoothing begins at t=0.17 s, which is noticeably delayed compared to shot 12. Lithium injection at 0.65 s. Next shot: increase RF power. No PCS changes.
Jan 14 1998 04:03:59:810PM	980114016	Robert Granetz	Shot 16 -- Dud (sort of). Alternator fault prior to shot cycle, but executed cycle anyway to reset things.
Jan 14 1998 04:31:15:550PM	980114017	Robert Granetz	Shot 17 -- Plasma. Good shot. Very, very impressive early RF power into the plasma. 1+ MW from t=0.053 s, and 2+ MW from t=0.070 s. But sawtoothing started at 0.16 s! Next shot: inject lithium pellet at 0.1 s.
Jan 14 1998 04:50:07:340PM	980114018	Robert Granetz	Shot 18 -- Plasma. Good shot. Good early RF power. Lithium pellet injected at 0.108 s. It momentarily trips the RF. Sawtooth initiation was delayed until t=0.190 s. Next shot: change gears. Go back to a near normal Ip ramp rate early in the shot, without changing any of the outer gap changes, or the density changes. Easiest way to do this (in view of the time constraints) is to simply return the crowbar times on the OH1 and OH2's back to t=0.12 s (from 0.070 s). Also, delay lithium pellet until t=0.15 s.
Jan 14 1998 05:02:48:650PM	980114019	Robert Granetz	Shot 19 -- Plasma. Good shot. Got the faster early current rise, and good early RF power, and a lithium pellet at 0.157 s. Sawtoothing starts at 0.21 s. No PEP mode with early pellet. A later pellet at 0.63 s may cause a PEP mode. Pellet penetration with ICRF on is noticeably worse than with RF off. End of run.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:29:57:020AM	Plasma	Ok	no faults/plasma
2	08:51:40:250AM	Plasma	Ok	no faults/plasma
3	09:04:38:990AM	Plasma	Ok	no faults/plasma
4	09:19:04:170AM	Plasma	Ok	no faults plasma
5	09:33:52:080AM	Plasma	Ok	no faults plasma
6	01:15:36:160PM	Plasma	Ok	no faults plasma
7	01:32:45:390PM	Plasma	Ok	no faults plasma
8	01:49:25:890PM	Plasma	Ok	ef2 upper a,b type 1 fault, (ioc) breakers pulled
9	02:10:32:070PM	Plasma	Ok	no faults
10	02:23:46:930PM	Plasma	Ok	no faults
11	02:33:03:840PM	Plasma	Ok	no faults plasma
12	02:51:19:300PM	Plasma	Ok
13	03:12:08:480PM	Plasma	Ok
14	03:30:48:890PM	Plasma	Ok
15	03:44:12:530PM	Plasma	Ok
16	03:58:07:510PM	Test	Ok
17	04:19:40:670PM	Test	Ok
18	04:36:35:510PM	Plasma	Ok
19	04:51:50:190PM	Plasma	Ok