| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | Steve Scott |
| Engineering operator(s): | Andy Pfeiffer,Gary Dekow,Ed Fitzgerald |
| Engineering Operator Run Comment |
| MP#580 Comparison of Type I ELM access and characteristics in He4 and |
| Session Leader Plans |
| Entered: Oct 26 2010 01:45:59:450PM |
| Author: Matt Reinke |
| An alternate ending to the run if Steve decides to punt is to run a few shots of MP534 - Foil/AXUV Bolometer Calibration in Helium. Although we had x2 days in 7/10 we never got the high radiation shots for confirmation of the cross-calibration between AXUV diodes and foil bolometers. Steve will have already changed over the isotope and conditioned up the ICRF so this shouldn't take more than a few shots.
CRYOPUMP would be required which has ~45 cool-down time since Steve isn't using it. Start cool down if Wolfe is making noises about how bad the run is going... 1) Load 1100720015 (USN, 800 kA, nl04~0.7, cryopump). Change Bt back to 5.4 T. Set 1.5 psi Ar in B-side lower, enable and puff from 0.3-0.4. ICRF from 0.5-1.5 at 3+ MW. 2) Demonstrate 3-4 MW of steady ICRF power. 3) Enable Ar puff from 0.3-1.3 seconds. 4) Repeat at least once. If there's extra time, try it with Ne. |
| Entered: Oct 27 2010 07:50:57:457AM |
| Author: Steve Wolfe |
Draft Run plan for Wednesday, Oct 27
MP#580 Comparison of Type I ELM access and characteristics in He4 and
D plasmas in C-Mod
SL: Wolfe
PO: Scott
Run setup:
Overnight ECDC in helium (P=5e-5Torr)
Power systems as on 1101026015
Special gas setup: helium in B-top (6psi) and B-main(40psi);
NINJA plenum should be pumped out and filled with
10psi helium.
NINJA and Argon puff disabled to start, may enable
once we see some ELMs.
ICRH: up to 5MW (all antennas) probably required
LH: Not required.
Cryopump: not required for MP#580, but if we decide to abandon the effort
after 15 shots or so, we may want it turned on for MP#534 (standby
experiment).
Diagnostics needed: TS, ECE's, H-alpha and He light signals, bolos, TCI,
neutrons, fast diodes, cameras (with
helium filters);
Other useful diags: PCI, core and SOL reflectometers, HIREX (if Ar level
is acceptable).
Run plan:
1. Using helium startup and main fueling, reproduce equilibrium from good,
robustly Elming; as of now, best choice appears to be 1101026015, which is
not that great. Start with RF pulse similar to 1101026015, but start ramp
at 1.5MW, ramping to 3.5MW/
Verify helium as main ion species (low neutron rate, Zeff, helium and D-alpha
light signals, etc); probably will
take several shots to remove last of D, even after He ECDC. Tune up RF using
waveform from target shot on 1101026. Notes from previous He runs, e.g.
1090821, indicate nl04 P and D gains should be changed to 2, probably will
need some adjustment of early pg3 puffing. [3-5 shots]
2a. Establish ELMy discharge (or not). If ELMs do not appear in original
configuration, try raising ICRF power to max available, then varying density,
current, shaping. Monitor pedestal parameters, compared to similar discharges
in D2, to guide search. If successful, move on to step 3. [1-15 shots]
NOTE: during 1101026 a glowing tile appeared on the floor, near GH, which
sourced a lot of Mo injections and at least one disruption. If we cannot
avoid injections in a configuration close to the ELMy shape, we will have
to abandon this experiment and go to a backup.
2b. If we run out of things to try without producing ELMs, changeover to D
majority to verify that ELMs are still produced as on previous run. Then, if
there is time remaining, cede the remainder of the day to a backup experiment.
This could be one of the four MP's presently scheduled for Thursday.
Alternatively, Matt wants a few helium majority shots with heavy argon puffing
for MP#534 (bolo calibration), but this would require cooling the cryopump,
which is not otherwise required.
[3-10 shots]
3. If ELMs are obtained, scan power down to find ELM threshold level, up to
determine scaling of frequency with power. Evaluate global confinement and
pedestal parameters. Use staircase RF power waveform to save shots in power
scan. Consider reducing initial step sufficiently to bracket
L-H threshold in helium in this shape. [4-6 shots].
4. Density scan: At a fixed power (or staircase waveform) and current, scan
target density up and down from initial condition. Compare to previous density
scans at 800 or 900kA in D. [4-5 shots]
5. Current scan. Revisit several currents from Tuesday's scans, including
highest accessible current (probably 1MA); use staircase rf power waveform.
If there is time, do coarse density scan at each current.
[time remaining]
|
| Physics Operators Plans |
| Entered: Oct 26 2010 05:09:00:770PM |
| Author: Steve Scott |
| -----------------
Engineering Setup ----------------- Run begins at 09:00 and ends at 17:00 Power systems as on: 1101026015 Acoil: +Dtop -Dbot -Jtop +Jbot (standard) Hybrid Enabled Gas setup: Fill B-Top with 6 psi HELIUM-4 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi HELIUM-4 Hybrid enabled (PG3) fill NINJA with 10 psi HELIUM-4 DISABLED Enable gate-valves and shutters: ECE, VUV, HiREX Sr, Xeus Leave z-bolo shutter as is (should be open) Torvac gatevalve toggle (yes/no): no Boronization(yes/no): no Overnight ECDC (yes/no): yes ICRF(yes/no): yes. all antennas, up to 5 MW LH(yes/no): no Cryopump (yes/no): maybe (not needed to start) DNB (yes/no): desired Vessel temperature: 35/35/35 ------------------------------ ECDC Parameters (if requested) ------------------------------ gas and pressure: HELIUM at 5.e-5 Torr sweep: 44/45/103 cm scan: 20/120 s duration: overnight ------------ PO PLAN ------------ First shot- 1 Reproduce shot 1101026015 from yesterday, but modified RF power waveform: ramp from 1.5 --> 3.5 MW. Over several shots, monitor plasma composition so check that we have helium plasmas. Also monitor Prad, impurities, and video camera to look for tile overheating on divertor floor. Decision point: if high RF power causes excessive tile heating, consider abandoning this expt and move to another one. The following assumes that we continue with MP580. 2a Shots (1-15): Establish ELMy H-mode plasma by varying PRF, NeL, Ip, shaping. 2b: *IF* suitable ElMs not obtained in 2a: replace helium with D2 in PG3, PG4, and NINJA. Repeat some (2a) plasmas in deuterium, to verify that with the moon in its current phase, we can still get ELMs in deuterium under these conditions. Then, this MP terminates for the day, and we proceed to an alternate MP for the remainder of the run day. Take something from Thursday, or else run some helium plasmas for Matt Reinke (needs cryopump). 3. *IF* ELMs are in fact obtained in step 2a: reduce PRF to identify power threshold for triggering ELMs, and increase PRF to measure scaling of ELM frequency with PRF. These shots will use 'staircase' PRF waveform. Lowest power in waveform should be slightly below the expected LH threshold. 4-6 shots. 4. *IF* ELMs are obtained in 2a: perform scan of target (pre- H-mode) density with values both lower and higher than initial condition. 4-5 shots. 5. *IF* ELMs are obtained in 2a: revisit several values of Ip from yesterday's run, including highest (1 MA). these shots will use staircase PRF waveform. If time permits, do a coarse density scan at each current. 3 If ELMs are obtained in step #2 (3 shots) determine power threshold and ELM frequency versus RF power using a 'staircase' PRF waveform. 4 If ELMs are obtained in step #2, and if density has not already been varied in step #2 Perform 5-shot density scan [ 5 shots] 5 If ELMs obtained in step #2, and if Ip not already varied in step #2 Perform 3-shot Ip scan 6 Switch over to deuterium plasmas: replace helium with D2 in PG3, PG4, and NINJA. Take several shots [4-10] to changeover to majority Deuterium plasma. |
| Session Leader Summaries |
| Entered: Oct 27 2010 06:07:18:357PM |
| Author: Steve Wolfe |
Session Leader Summary for Wednesday, Oct 27, 2010
MP#580 Comparison of Type I Elms in He and D plasmas
SL: wolfe
PO: Scott
EO: Pfeiffer, Dekow, Fitzgerald
The run got off to a bad start, but ended up accomplishing most of the run
plan and getting some useful data on ELMs (and other phenomena) in helium
H-modes. We were unable to get a successful startup
using helium pre-puff. After 2 fizzles and 3 duds on the first 5 shots, and a
delay because of a snafu with Alcdaq3 losing its userid data, we put D2 back
in B-top for shot#6. This resulted in a runaway startup that only made it to
.4sec, eventually getting killed by dpcs_xjump due to excessive runaways. The
density dropped precipitously to ~1e19 after the plasma diverted, which gave
rise to enhanced runaways and tripped the xjump.
On shot#7 we had a fizzle that was caused by a power supply problem in EF1L;
the internal current reading had a 1.3kA offset, which made the supply think
it was on the PLC current rail, although the actual bus current was low by
400A at about 5.4kA. Troubleshooting this problem took over an hour.
Once we got going again, we started getting good results. The first full
length shot was #9 and it had ELMs, actually better looking than the reference
shot 1101026015 in D2. We proceeded to tune the density, which was pretty much
determined by the early puff rate, and set up power steps on the RF. Good
shots in this sequence were
#10: RF ramping up, ELMs from 1.1 to 1.4sec
11: RF steps increasing
12: RF steps decreasing
Note: Shots 9-12 had EOF at 1.4sec, and last RF step on #11&12 came in
rampdown. Flattop was extended to 1.5sec for the rest of the day
It appeared to me that the ELM frequency and amplitude were positive functions
of input power, but this impression needs to be confirmed quantitiatively. It
could be that varying density was the primary effect.
We then carried out a density scan at 900kA (part 4 of the run plan), and then
got some data at 1MA and at 750kA (part 5). Best examples, with robust ELMs and decent
H98, were #15 and 22. Additional shots of interest were:
#13: RF flat at 3MW, Helium NINJA puff for GPI later in shot
14: lower density, ELMs before disruption
15*: Excellent full length shot with ELMs throughout, density rise in H-mode
probably due to NINJA
17, 18: Higher density, with argon puff for hirex Ti
19-20, trying for 4MW, some good periods but not steady
21: Highest edensity in scan at 3MW (nl04=9.5e19 target),
H-modes terminated with ELMs that tripped the RF, led to H->L
22* 1MA case, solidly ELMing, 3MW, same target density as 15
23: Higher power, but disrupts
25,26: 750kA 3MW cases, disrupt during H-mode but some ELMs
27-28: lower power at 750kA, no ELMs but Jerry says there is something
like a QC mode. L-mode-like confinement.
29: Back at 1MA, but with slightly higher density, power down to 2.5MW.
Good looking ELMs but poor confinement.
We still need to get a better handle on the helium to deuterium ratio in these
discharges, but based on the neutron rates, which were under 3e12 all day and
down to < 1e12 by the end, nD must be pretty low. Zave was coming out around
3. The Dalpha signal was not negligible during flattop, and increased during
RF, and of course the breakdown was in D2 so the D-alpha was apparent there,
although the helium light was dominant after about .03sec.
Pedestal parameters for the ELMy discharges appear to be in the range found
for D2 plasmas; Detailed comparison remains to be done. Jim Terry got good
ELM data from the APD system; see his notes under spectroscopy. The DNB was
firing well all day, and hopefully we will have some CXRS data for pedestal
and core. Dan reported that some ELMs were visible on the surface
thermocouples on the lowest tile of the outer divertor.
|
| Physics Operator Summaries |
| Entered: Oct 27 2010 06:45:36:543PM |
| Author: Steve Scott |
| Plasma scorecard
Power supply tests: 1 Fizzles 4 Duds 3 Plasmas 21 full-length 14 disruptions 7 (includes disr. in rampdown) Today was a reasonably successful run following a frustrating start. We started with the plasma from yesterday, 110102615, but switched both the prefill gas and main gas puffing to helium. The first several shots of the day were attempts (ultimately unsuccessful) to get breakdown in helium. We varied the gas puff both up and down, but ultimately gave up. Then on shot 7 we experienced a problem on EF1 that took ~70 minutes to repair. The first successful plasma was shot 9 at 12:20 PM. The only other major problem of the day was disruptions caused by impurity injections. These happened on shots 6, 14, 16, 21, 23, 25, and 26. On shots 6 and 16 the plasma disrupted in the Ohmic, pre-RF portion of the shot 21 it disrupted in the rampdown. On shots 14, 23, 25 and 26 the disruption occurred during RF. There is some correlation with RF power: reducing the RF power seems to reduce the probability of disruption. Matt reports that most of the disruptions were moly injections, although one of the early ones was iron. We got some nice IR video of some disruptions, being caused by UFOs that emanate from the lower divertor region. We managed to get good ELMs in helium H-mode plasmas and we were able to get some variation in RF power, plasma current, and density. Generally, the ELMs went away at the lowest currents (0.75 MA) and as the density was increased. The shots include some RF 'ramps', some 'staircase', and others had 'flattop' waveforms. Generally, RF worked pretty well at power levels of 3 MW and below, but it was reasonably ratty as the power approached 4 MW. Peak RF power was 4 MW today. |
| Session Leader Comments | |||
| Oct 27 2010 09:15:39:867AM | 1101027001 | Steve Wolfe | Shot#1: First try for helium ELMs (first He startup since 1090821?) result: fizzle. Looks like too much gas, moves in; doesn't burn out There is also an unpleasantly large Dalpha level (Da~.4, HeII~.3 at breakdown). Ratiomatic reads around .03, so it's definitely Helium in the plenum. Next: drop pg4 and remove pg3 in seg1 and try again |
| Oct 27 2010 09:19:21:710AM | 1101027002 | Steve Wolfe | Shot#2: dud. looks like we went too far. And put some back and try again |
| Oct 27 2010 09:38:28:090AM | 1101027003 | Steve Wolfe | Shot#3: another dud, maybe we went the wrong way. Br is still looking a bit negative, better than on 1 and 2 Try 27msec on pg4, at least get back to a fizz leave pg3 off |
| Oct 27 2010 09:52:03:977AM | 1101027004 | Steve Wolfe | Shot#4: Another dud. Pressure is higher than on #1 Raise pg4 one more time, then punt the helium startup and put D2 in B-top And we're getting an error trying to load pcs "error in remote copying to alcdata-models/.../pcs/" Josh is checking |
| Oct 27 2010 10:34:30:310AM | 1101027005 | Steve Wolfe | Shot#5: Josh is still hacking at Steve Scott's account and others on alcdaq3. Meanwhile, on cmodws50, I did ssh wolfe@cmodws50 and unset pcs_scratch, so it doesn't pick up my scratch area. Steve still physop'ing, under my account. Note that when I tried su -l wolfe it wouldn't allow X under my account on his workstation. Raised pg4 to 30msec, last try for a helium breakdown Result: fizzle, looks a lot like shot#1, breakdown a little later Punt on this, can't keep wasting time. Put D2 in B-top and put back seg1 from shot#1 (25msec on pg4, early puff on pg3). Cross fingers |
| Oct 27 2010 10:48:32:750AM | 1101027006 | Steve Wolfe | Shot#6: Try again, with D2 in b=top, still helium in pg3. plasma disrupts at .4sec, lots of runaways. DPCS xjump kills it. Density drops to 1e19 at .3sec. Starts to fall around .25sec, about when it diverts; gas doesn't come back on until .27 and then it's too little too late. Runaways build up when the density falls. Need to fix seg1 pg3 and provide some feedforward in seg2 I think. |
| Oct 27 2010 11:10:59:340AM | 1101027007 | Steve Wolfe | Shot#7: fizzle. disruption recovery? Breakdown is later, bz is positive and the current checker claims ef1l is differnt by 6%, oh2's by 2%. EF1L is in fact low by 400A or so. Looks like an offset in the power supply current reading on EF1L was ~300A on shot#6, 1300A on shot#7, reading over 7kA, so it probably thinks the supply is on the rail. And we see that the supply voltage is not responding to the increased demand from dpcs trying to get the correct current. |
| Oct 27 2010 12:21:33:233PM | 1101027007 | Steve Wolfe | Shot#8: EF1 test under PLC control, to verify the problem is fixed. 2kA test successful, offset is under 100A |
| Oct 27 2010 12:44:31:890PM | 1101027009 | Steve Wolfe | Shot#9: plasma full length, h-modes, early marfe No runaways. breakdown ok, Bz still a little high Got ELMs! density is between 7 and 8e19 before rf, no gas after the feedforward ends at .25sec Teped 500-600eV, peped bi=ouncing around, but may be above 15kPa betap95 between .1 and .2. GPc8 sees drops at the ELMs ELM freq may be increasing with power, hard to tell Neuts less than 3e12 Next: drop seg2 helium feedforward, and reduce seg1 pg3 puff |
| Oct 27 2010 12:54:01:527PM | 1101027010 | Steve Wolfe | Shot#10: repeat with less early puff, see if density comes down Try for steadier power at end of ramp. Plasma full length, no marfe, ELMs nl04 is down, 5 to 6e19 target, still no feedback puff ELMs clearly present between 1.1 and 1.4sec Te95 around 600eV, getting over 100eV drops on gpc8 at the elms Next: Staircase RF at 2,3,4MW |
| Oct 27 2010 01:06:08:340PM | 1101027011 | Steve Wolfe | Shot#11: Staircase RF at 2,3,4MW leave gas program the same, hope density comes down a little more on its own, without getting down too far plasma full length, ELMy good rf steps at 2 and 3MW, all faulting at the high power step Frequency and amplitude of elms is higher at the higher step, or maybe just later in shot Peped is up to 20kPa, betap95 has points between .2 and .3 Next: reverse staircase, 3,2,1MW |
| Oct 27 2010 01:19:19:617PM | 1101027012 | Steve Wolfe | Shot#12: reverse staircase, 3,2,1MW plasma full length, ELMs persist through full pulse, maybe bigger and more frequent early? Lose ELMs and H=mode after 1.4sec, so 1MW is below threshold Still plenty of ELMs between 1.35 and 1.4 Steve Scott points out that Ip ramps down starting at 1.4sec; Next: extend flattop, make flat RF at 3MW, GPI Ninja will start at 1.25sec |
| Oct 27 2010 01:43:54:960PM | 1101027013 | Steve Wolfe | Shot#13: call for steady 3MW RF, NINJA in He at 1.25sec ELMs stop around 1.4sec, despite steady RF. Nl04 rises around the same time. This seems to be the NINJA coming in (a little later than expected) JT reports he can see them on APD's. Dan Brunner sees some pulses on the lower divertor surface tc's Next: try reducing density, decrease pg3 puff in seg1, eliminate in seg2 |
| Oct 27 2010 01:54:46:743PM | 1101027014 | Steve Wolfe | Shot#14: try reducing density, decrease pg3 puff in seg1, eliminate in seg2 disrupted at 1.1sec, during RF and early H-mode density got down to 3.7e19, and gas puff came back on (weakly), before disruption. There were ELMs starting around .97sec. Looks like something comes in at 1.03sec, big radiation event. I'm guessing Mo. Yep, Matt has confirmed it. Klimiter is showing yellow alert Neutron rate is up to 5e12 before the disruption Next: Try for a little higher density. Leave Prf at 3MW for now, may need to back down |
| Oct 27 2010 02:08:06:820PM | 1101027015 | Steve Wolfe | Shot#15: Try for a little higher density. Leave Prf at 3MW for now, may need to back down plasma full length (I expected a fizz) Lots of ELMs, pretty steady. They last until 1.5sec, despite a rise in density during the H-mode. RF pretty steady at 3MW H98 between 0.8 and 1.0 2pi diode between .5 and 1.0MW, Klimiter is tan (15MJ/m2) Next: Repeat, with some argon for HIREX, to nail down the Ti and get an estimate of nD from neuts (on this shot they were between 2:3e12/sec) |
| Oct 27 2010 02:22:03:037PM | 1101027016 | Steve Wolfe | Shot#16: Repeat, with some argon for HIREX, to nail down the Ti and get an estimate of nD from neuts (on this shot they were between 2:3e12/sec) Disruption at 0.6sec before RF Matt claims it's an Fe injection. Next: raise nl04 demand to 6e19, leave argon on for now. |
| Oct 27 2010 02:34:16:763PM | 1101027017 | Steve Wolfe | Shot#17: raise nl04 demand to 6e19, leave argon on for now. plasma full length Few elms, neuts below 1e12, H-mode looks very unsteady, D has a long dropout, only 2MW between .95 and 1.3sec Nl04 gets above 7e19 before RF, the slow response with the helium puff is a killer for feedback. next: repeat, see if RF can stay on better. |
| Oct 27 2010 02:49:14:857PM | 1101027018 | Steve Wolfe | Shot#18: repeat, see if RF can stay on better. plasma full length, more elms, still not as dense as earlier. 2pi bolo is between 1:1.5MW, neuts below 1e12. Good steady RF, only a couple of dropouts Target nl04~7.5e19, during H-mode 1.15e20 before NINJA, rising to 1.3e20 H98 down to 0.6, PePed between 10:15kPa, TePed~400:500eV Next: raise Power to 4MW, |
| Oct 27 2010 03:01:38:573PM | 1101027019 | Steve Wolfe | Shot#19: raise Power to 4MW, same density plasma. ELMs seem more sparse RF not steady, J and D faulting, some periods up to 4MW Neutrons still ~1e12 2pi getting up to 1.8MW, Pmain to around 2.5MW, not winning on Pnet Next: try again, turn off argon |
| Oct 27 2010 03:10:58:883PM | 1101027020 | Steve Wolfe | Shot#20: Power to 4MW, same density, argon off plasma, Prad 1.5MW dropping to < 1MW, still not great ELMs J and D still faulting Next: back down the power to 3MW, raise nl04 demand from 6 to 8e19 Expect ELMs to go away at that level |
| Oct 27 2010 03:35:21:877PM | 1101027021 | Steve Wolfe | Shot#21: back down the power to 3MW, raise nl04 demand from 6 to 8e19 Expect ELMs to go away at this level, doubt we'll get EDA though Result: multiple (7) H-modes, radiating away, ELM=free to H->L Complicated by dropouts on D & E at each transition. (I think) Could be ELMs that trip the RF and lead to H->L target nl04=9.5e19, density at H->L transitions (or ELMs) 1.5e20 Didn't get Edge TS on this shot. Next: Back to lower density, as on #15, raise current to 1MA |
| Oct 27 2010 03:43:00:743PM | 1101027022 | Steve Wolfe | Shot#22: Back to lower density, as on #15, raise current to 1MA plasma, ELMs, RF good and steady Wmhd over 100kJ, falling to 90, H98 dropping from .9 to .8 Te95 over 600eV, PePed around 15kPa, betap95 ~.15 Nl04 in H-mode rising from 1 to 1.2e20 Neuts < 2e12, Nice shot Next: Raise power to 3.6MW, same target |
| Oct 27 2010 03:55:46:590PM | 1101027023 | Steve Wolfe | Shot#23: Raise power to 3.6MW, same target disrupts at 1.1sec, lots of injections before disruption shower coming out of divertor on wide 2. Maybe a few ELMs in there too, but 22 was a much better example Next: Back to 3MW and drop current to 750kA |
| Oct 27 2010 04:06:16:240PM | 1101027024 | Steve Wolfe | Shot#24: Back to 3MW and drop current to 750kA Fizzle. I think this one was the 1MA disruption, although the breakdown is pretty late. Next: Try again. |
| Oct 27 2010 04:23:39:377PM | 1101027025 | Steve Wolfe | Shot#25: Back to 3MW and drop current to 750kA Disrupts at 1.1sec, during the rf Eruption from the divertor again. Maybe a few small ELMs before the end, maybe not Density is falling after .95sec, following the first injection. L-mode nl04 was 6e19 Next: raise nl04 demand from 5 to 6e19 |
| Oct 27 2010 04:40:35:533PM | 1101027026 | Steve Wolfe | Shot#26: Back to 3MW and drop current to 750kA raise nl04 demand from 5 to 6e19 Disrupted again, a little later. Similar shower from the divertor floor ELMs not as nice as at higher currents H98~0.9 with nominal Pnet~2MW Next: drop power to 2MW |
| Oct 27 2010 04:50:56:673PM | 1101027027 | Steve Wolfe | Shot#27: drop power to 2MW, partial power scan at this current plasma full length, no eruption this time Also no ELMs and maybe no H-mode? There is a small density jump and drop in HeII light at .898sec, small jump in Te8. H98~.0.7, 2pi goes to 0.7MW and then falls, along with nl04. I think it's a very wimpy H-mode, with no ELMs Next: raise P to 2.5MW |
| Oct 27 2010 04:58:31:943PM | 1101027028 | Steve Wolfe | Shot#28: raise P to 2.5MW, still at 750kA Plasma full length, still no ELMs but it does seem to be in H-mode Prad flat at 1MW Next: Put current back to 1MA, leave rf at 2.5MW |
| Oct 27 2010 05:21:15:720PM | 1101027029 | Steve Wolfe | Shot#29: Put current back to 1MA, leave rf at 2.5MW See if we can get some ELMs back, pick up a slightly different power at the higher current Result: plsma to 1.6sec, ELMs are back Solid RF at 2.5MW, no faults. L-mode target at 7.5e19, H-mode from 1.1 to 1.2e20 Confinement is not good though, H98~0.6 to 0.7, Pnet~2MW. Neuts < 5e11. Considerably lower than #22 at 3MW, but slightly lower density. I forgot to lower the demand which was raised while we were at lower current. So more of a density scan than power scan, maybe. End of Run |
| Physics Operator Comments | |||
| Oct 27 2010 09:03:31:977AM | 1101027001 | Steve Scott | Set up as for 1101026015. 5.4 Tesla, 0.9 MA, NeL=4.e19. HELIUM
Desired RF: ramp 1.5 --> 3.5 MW at 0.8 thru 1.5 sec. Made a change in proportional and derivative controls for NL04 (set to 2.0 on each) Result: fizzle. |
| Oct 27 2010 09:09:35:410AM | 1101027002 | Steve Scott | Change: reduce PG4 to a 20ms prepuff. Also set PG3 to zero. |
| Oct 27 2010 09:17:31:990AM | 1101027002 | Steve Scott | Change: reduce PG4 to a 20ms prepuff. Also set PG3 to zero.
Result: dud. so we need to increase the gas a little on the next shot. |
| Oct 27 2010 09:24:41:087AM | 1101027003 | Steve Scott | Change: increase prepuff (PG4) to 22 ms. |
| Oct 27 2010 09:29:10:357AM | 1101027003 | Steve Scott | Change: increase prepuff (PG4) to 22 ms.
Result: dud. |
| Oct 27 2010 09:43:13:597AM | 1101027004 | Steve Scott | Change: increase prepuff (PG4) to 27 ms. Note that this is now
2ms longer than we originally started with, on shot 1. Result: another dud. |
| Oct 27 2010 09:50:35:447AM | 1101027004 | Steve Scott | Change: increase prepuff (PG4) to 27 ms. Note that this is now
2ms longer than we originally started with, on shot 1. Result: dud. |
| Oct 27 2010 09:52:07:830AM | 1101027005 | Steve Scott | DELAY: problem loading waveforms with DPCS. Josh looking into the problem |
| Oct 27 2010 10:29:58:393AM | 1101027005 | Steve Scott | DELAY: problem loading waveforms with DPCS. Josh looking into the problem.
We are having a short (5 min) controlled access NOW. Josh reports identifying a problem with alcdaq3: it seems to have lost information about user privileges. It will take about 10 minutes to fix. So expect a shot at 10:12. temporary fix: will run dpcs under wolfe's privilege change: extend prepuff to 30ms result: fizzle |
| Oct 27 2010 10:47:11:930AM | 1101027006 | Steve Scott | We will now give up on trying to break down in helium. So replace gas in B-top with 6 psi deuterium.
Load segment #1 from shot 1 from today (= 25 ms prepuff). No other changes. result: plasma! But disrupted at ~ 0.415 seconds. aborted due to high hard x-ray. So need to increase density on next shot. |
| Oct 27 2010 11:07:43:593AM | 1101027007 | Steve Scott | Change: increase PG3 prepuff magnitude to 100/50 (no change in timing) and add a PG3 puff, magnitude 50, time=0.1-0.25 sec.
result: fizzle. There seems to be a problem with EF1 control. We will have a controlled access to investigate. |
| Oct 27 2010 12:33:34:473PM | 1101027008 | Steve Scott | Power supply test to evaluate fix on EF1-lower. Successful. Now resume today's exciting run.
Result: first good plasma of the day. RF was pretty good; a little ratty at the end. Ohmic NeL was a little high (0.8e19 versus 0.5e19 yesterday). |
| Oct 27 2010 12:57:55:110PM | 1101027010 | Steve Scott | Change: reduce puff at 0.1-0.25 sec from demand=50 to demand=25.
Also reduce PG3 puff (nominally -0.02 to 0.08) demand at the end from 50 to 25. Result: good plasma. Target density was reduced to ~0.7e19. |
| Oct 27 2010 12:52:59:533PM | 1101027011 | Steve Scott | Change: replace 'ramp' on PRF waveform with a staircase (2.0 --> 3.0 --> 4.0)
No DPCS changes. |
| Oct 27 2010 01:00:31:997PM | 1101027011 | Steve Scott | Change: replace 'ramp' on PRF waveform with a staircase (2.0 --> 3.0 --> 4.0)
No DPCS changes. Result: full length plasma. target density same as previous shot. Got the 2 MW and 3MW staircase RF powers, but not the final rise to 4 MW. |
| Oct 27 2010 01:06:07:453PM | 1101027011 | Steve Scott | Change: temporarily abandon hope of 4MW. Change the PRF waveform: 3.0 --> 2.0 --> 1.0. No DPCS changes. |
| Oct 27 2010 01:14:57:570PM | 1101027012 | Steve Scott | Change: temporarily abandon hope of 4MW. Change the PRF waveform: 3.0 --> 2.0 --> 1.0
Result: good plasma. Experienced an iron injection at 1.27 sec. |
| Oct 27 2010 01:37:41:510PM | 1101027013 | Steve Scott | Changes: Extend Ip and TF and ZXU flattops to 1.5 sec and ask for 3.0 MW flattop
GPI gas puffing approved. Result: good plasma. Got extended Ip, Bt flattop. Plasma performance (e.g neutrons) starts to deteriorate at 1.4 sec and see fewer ELMs then. Some increase in density between 1.4 and 1.5 sec. timing of gpi: starts at 1.3 sec |
| Oct 27 2010 01:51:01:767PM | 1101027014 | Steve Scott | Changes: reduce prefills. Move timing of gpi puffing (now starts at 1.25 sec)
result: target NeL reduced to ~0.4e19. Plasma disrupted circa 1.17 due to large moly injection |
| Oct 27 2010 02:07:07:887PM | 1101027015 | Steve Scott | Changes: increase prefill puffing, increase Nel demand to 5.e19, increase proportional feedback for NeL from 2 to 3.
Result: good plasma. Got target Nel=0.7e19. The NINJA puffing for GPI seems to cause a small density rise at the end, along with a reduction in Te0 and a small reduction in stored energy. But ELMs persist. |
| Oct 27 2010 02:03:34:723PM | 1101027016 | Steve Scott | Enable B-side lower (argon; 1 psi). there is already a programmed puff, 0.30 to 0.35 sec. |
| Oct 27 2010 02:19:51:110PM | 1101027016 | Steve Scott | Enable B-side lower (argon; 1 psi). there is already a programmed puff, 0.30 to 0.35 sec.
Result: disrupted early, circa 0.6 sec. Matt reports an iron injection. |
| Oct 27 2010 02:32:41:463PM | 1101027017 | Steve Scott | Change: increase NeL demand from 5.0e19 to 6.0e19.
Result: good plasma, full length. Not too many ELMs. PRF alternates between 2 and 3 MW due to faults on D-antenna. Target NeL was about 7.e19, i.e. a little larger than our demand. |
| Oct 27 2010 02:43:48:947PM | 1101027018 | Steve Scott | Changes: none. Repeat last shot, hoping to get the desired PRF.
Result: nice shot. Good PRF waveform. Target NeL = 7.e19 and NeL during RF is higher than on previous shot. |
| Oct 27 2010 02:48:47:283PM | 1101027019 | Steve Scott | Changes: no DPCS modifications. Ask for PRF increase to 4 MW. |
| Oct 27 2010 02:58:54:390PM | 1101027019 | Steve Scott | Changes: no DPCS modifications. Ask for PRF increase to 4 MW.
Result: good plasma. RF got to 4 MW, but power waveform is pretty ratty. NeL (target) = 8.e19. |
| Oct 27 2010 03:11:36:963PM | 1101027020 | Steve Scott | Change: disable argon permissive. No other DPCS changes.
Result: good shot. Got PRF=4MW for a while, but RF power waveform is pretty ratty. Next shot: increase target density, and reduce PRF. |
| Oct 27 2010 03:27:29:997PM | 1101027021 | Steve Scott | Change: increase target NeL to 8.0e19. Reduce PRF demand to 3.0 (flattop).
Result: good plasma. disrupts in rampdown at 1.8 sec -- looks like caused by an impurity injection. Several ELM-free periods; ELMs seem to cause RF faults, and then the density collapses. So the density time history is a series of sawtooth-like structures. |
| Oct 27 2010 03:39:33:567PM | 1101027022 | Steve Scott | Changes: reload shot 15 from today, then increase Ip to 1.0 MA
Result: good shot. Target NeL just under 6.0e19 (demand=5.e19). Very nice PRF waveform at 3 MW. Got ELMs. SL is happy. |
| Oct 27 2010 03:53:21:690PM | 1101027023 | Steve Scott | Changes: no DPCS changes. Try to raise PRF to 3.6 MW.
result: got plasma, but disrupted at 1.1 sec following several Prad spikes. Shortly after the start of RF we got a brief ELM-free period, during which the density and Prad increased. Then got some ELMs, and some moly injections, leading to the disruption. |
| Oct 27 2010 04:07:47:720PM | 1101027024 | Steve Scott | Change: decrease Ip at flattop to 750 kA. Also, reduce PRF to 3.0 MW
result: fizzle. No obvious cause other than the disruption on the previous shot. |
| Oct 27 2010 04:27:35:910PM | 1101027025 | Steve Scott | Changes: none. Repeat last shot, hopefully sans the fizzle.
Result: plasma. Disrupted circa 1.08, probably due to impurity injections. Nice IR images of UFO starting from lower divertor. Cause of disruption is a moly injection. |
| Oct 27 2010 04:31:00:673PM | 1101027026 | Steve Scott | Changes: Increase NeL demand from 5.0e19 to 6.0e19.
Result: plasma. Disrupted again, 1.25 sec, following a large Prad spike. Stuff flying around inside vessel clearly visible in WIDE2 camera view. |
| Oct 27 2010 04:44:38:687PM | 1101027027 | Steve Scott | Changes: reduce the RF power to 2 MW, hopefully this will eliminate the
impurity injections. Result: plasma. no disruption. Nice 2MW RF waveform. No visible ELMs. energy confinement within 10% of ITER-89. |
| Oct 27 2010 04:56:57:183PM | 1101027028 | Steve Scott | Change: "goldilocks" value of RF power. 3 MW seems too much - get impurity injections. 2 MW is too little - plasma seems to remain in L-mode. So try PRF=2.5 MW this shot.
Result: full-length plasma. Small Prad burst at 0.52 sec. Energy confinement about the same as previous shot (i.e. within 10% of Lmode). Got 2.5 MW. |
| Oct 27 2010 05:09:38:887PM | 1101027029 | Steve Scott | Changes: increase flattop Ip to 1.0 MA. Leave PRF=2.5 MW.
Result: plasma. disrupted in rampdown at 1.65 sec. Nice PRF waveform. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:01:30:970AM | Plasma | Ok | |
| 2 | 09:14:14:260AM | Plasma | Ok | |
| 3 | 09:26:46:090AM | Plasma | Ok | |
| 4 | 09:39:25:453AM | Plasma | Ok | |
| 5 | 10:24:31:837AM | Plasma | Ok | |
| 6 | 10:37:42:310AM | Plasma | Ok | |
| 7 | 10:55:17:370AM | Plasma | Ok | |
| 8 | 12:17:21:947PM | Test | Ok | EF1L PLC Test |
| 9 | 12:28:08:453PM | Plasma | Ok | |
| 10 | 12:42:34:120PM | Plasma | Ok | |
| 11 | 12:55:45:460PM | Plasma | Ok | |
| 12 | 01:08:20:747PM | Plasma | Ok | |
| 13 | 01:25:50:310PM | Plasma | Ok | |
| 14 | 01:42:52:483PM | Plasma | Ok | |
| 15 | 01:55:58:927PM | Plasma | Ok | |
| 16 | 02:13:41:383PM | Plasma | Ok | |
| 17 | 02:26:09:260PM | Plasma | Ok | |
| 18 | 02:38:49:597PM | Plasma | Ok | |
| 19 | 02:53:51:087PM | Plasma | Ok | |
| 20 | 03:06:23:020PM | Plasma | Ok | |
| 21 | 03:20:07:347PM | Plasma | Ok | |
| 22 | 03:34:20:520PM | Plasma | Ok | |
| 23 | 03:48:34:020PM | Plasma | Ok | |
| 24 | 04:01:47:227PM | Plasma | Ok | |
| 25 | 04:14:49:880PM | Plasma | Ok | |
| 26 | 04:27:27:830PM | Plasma | Ok | |
| 27 | 04:39:46:790PM | Plasma | Ok | |
| 28 | 04:52:12:993PM | Plasma | Ok | |
| 29 | 05:05:24:190PM | Plasma | Ok | |
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