| Miniproposals | ||||||||||
|
| Operators | |
| Session leader(s): | Steve Wolfe |
| Physics operator(s): | Joseph Snipes |
| Engineering operator(s): | Sam Pierson,Bill Parkin,Gary Dekow |
| Engineering Operator Run Comment |
| MP#525 ELM control experiments using the A-coil SL: Wolfe, Whyte PO: Sni |
| Session Leader Plans |
| Entered: Feb 12 2008 05:20:23:383PM |
| Author: Steve Wolfe |
Correction to boronization request for 1080213: I made a mistake in the parameters I sent to Joe, which he included in his PO_PLAN. The correct values are (I think): Boronization Parameters -------------------------------------- Foreline(TC6) pressure request: 70 mTorr (same as 1080129) sweep (rmin/rdwell/rmax): 55/70/80 cm (DIFFERENT from 1080129) scan: 60/120 s (same as 1080129) dP: 120 psi (same as 1080129) EF4: 200 A (same as 1080129) The ecdc parameters were correct: Post boronization ECDC (ending by 7:30 am) ---------------------- sweep: 44/45/103cm scan: 20/120 s 5e-5torr he4 (2hrs) 2e-4 Torr D2 (1 hr) |
| Entered: Feb 17 2008 01:43:51:507PM |
| Author: Steve Wolfe |
SL_PLAN for Wednesday, Feb 13, 2008 MP#525 ELM control experiments using the A-coil SL: Wolfe, Whyte PO: Snipes The goal of this experiment is to determine whether n=1 fields from the A-coil can affect the ELM behavior in C-Mod discharges, and if so to document the effect over a range of perturbation amplitudes and plasma parameters (mainly q95). We will be using the JFT2-M shape which has been previously shown to result in large, nominally Type 1, ELMs. The experiment requires Prf>4MW, with as much power as possible supplied by E-port with the FFT in use to track the load changes associated with the ELMs. If reproducible, fairly frequent ELMs are not produced the experiment cannot proceed. An overnight boronization is requested; if the boronization is degraded during the course of the experiment we may require between-shot boronization. We should not need the cryopump. The A-coils will be run in their standard configuration (+Dtop -Dbot -Jtop +Jbot), but with current up to the maximum available from the supply. Key diagnostics include: Standard magnetics D-alpha HIREX_Sr (for rotation measurements, need to give them some argon) For effects on pedestal: Edge Thomson Scattering (aligned for JFT2-M shape) ECE (at least one of the GPC arrays) For effects on ELMs: Fast Magnetics (at 10MHz) PCI (at 10MHz) Fast diode arrays and cameras for ELM views. We will start by establishing an ELMy target shot, which may take a little time because of boronization recovery issues. If this cannot be done then punt and change to backup experiment. Once reliable ELMs are observed, run A-coil current to maximum and look for effects. If ELM effects are observed, scan perturbation amplitude to document threshold. In either case, do a q-scan (up in current) to determine the applicable range, if any. Aside from changes in ELM frequency and/or amplitude, things to look for include appearance of locked modes, changes in rotation (braking), and changes in pedestal parameters. Shot sequence: -------------- 1) Establish ELMing shot with standard A-coil programming (B21_PROJ waveform = 0). Load seg2 from 1080108012 (900kA, nl04=6e19) RF at sufficient power with flat waveform from 0.7 to 1.5sec [4-8 shots]. Note: We want rotation measurements to check on magnetic braking, but if we can't get ELMs without turning off the Argon then we turn off the argon. If we don't get ELMs after 10 plasmas, then punt. 2) Draw B21_PROJ waveform to .002 T between 0.9< t< 1.4sec (or in the middle of the ELMy period) and look for changes in ELMs, rotation, pedestal, locked modes, during pulse. This should result in maximum. If change in ELMs is observed, or we get locked modes, then reduce B21_PROJ program until effects go away. [2-8 shots] Note: I think this programming will work for controlling the a-coil current. If not, then we'll revert to drawing waveforms for V10 (ACOIL_CUR) directly, and zeroing the B21_PROJ gains and Integrator C gate at 0.9sec. 3) With A-coil current at maximum value (without locked modes) perform a q-scan to determine range of effect, if any: Ip=0.95, 1.0, 1.05, 0.85, 0.8, 0.75MA (or stop when effect goes away or we stop getting ELMs). If necessary, reduce a-coil amplitude to avoid locked modes at higher currents. If we don't see any effect over this range, then punt. [6-10 shots] 4) If any time remains, increase elongation at constant current with A-coil current at maximum and document effects on ELMs. [shots available] |
| Physics Operators Plans |
| Entered: Feb 13 2008 08:36:40:397AM |
| Author: Joseph Snipes |
| Physop and Engineering Setup for Wednesday, 1080213
MP525 ELM Control Experiments using the A-coil Session Leaders: S. Wolfe/D. Whyte Physop: J. Snipes Overnight Boronization Boronization Parameters -------------------------------------- Foreline(TC6) pressure request: 70 mTorr sweep (rmin/rdwell/rmax): 55/70/80 cm scan: 20/120 s dP: 120 psi EF4: 200 A Post boronization ECDC (ending by 7:30 am) ---------------------- sweep: 44/45/103cm scan: 20/120 s 5e-5torr he4 (2hrs) 2e-4 Torr D2 (1 hr) Power systems as on 1080108012 A-coil configuration: normal [Dtop -Dbot -Jtop +Jbot] and enabled. Gas Setup: fill B-Top with 6 psi D2 Hybrid enabled (PG4) fill B-side lower with 1 psi Ar Hybrid ENABLED (PG1) leave B-side upper as is Hybrid DISABLED (PG2) fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3) NINJA disabled Enable the following gate valves and shutters: ECE, VUV, Z-bolo shutters, DNB Torvac setup: Gate valves open during pulse. ICRF: D E and J-port ready at the beginning of run for full power Constant ICRF power between 0.5 s to 1.5 s starting at 4 MW LH: Not needed CRYOPUMP: not needed Run plan: We will be starting with shot 1080108012 in the JFT-2M shape at Ip = 0.9 MA, nl04 = 0.6 x 10^20 m^-2, 5.4 T and attempt to get plasmas with large ELMs (dubious Type I). Then, we will apply the A-coil asymmetric external field to see if it affects the ELMs in any way. See the SL_PLAN for details. |
| Session Leader Summaries |
| Entered: Feb 17 2008 01:26:16:237PM |
| Author: Steve Wolfe |
Summary for Wed, Feb 13, 2008
MP#525 ELM control experiments using the A-coil
SL: Wolfe, Whyte
PO: Snipes
EO: Pierson, Parkin, Dekow
We completed most of the run plan, but despite early indications
on shot 11 and some succeeding shots,
that we were suppressing the ELMs, we ended up concluding that
this was not the case. A clear counterexample is the pair
1080213026 and 027, at 850kA (q95=3.7), both of which had
ELMs throughout most of the H-mode period, with A-coil at
3800A and 300A respectivly. We also obtained cases with ELMs
with full A-coil current at Ip=900, 950, and 800kA, covering a
range 3.3< q95 < 3.9. Getting ELMs at the higher q95 required more
rf power, but 4MW was sufficient.
The experiment got off to a slow start because we got several
disruptions, along with injections that compromised the H-modes,
during the setup phase. During this period we ended up reducing
the RF, thinking it responsible for some disruptions, which was
probably incorrect. Eventually, after moving rxl out by 5mm we got
non-disruptive shots (from #10 on) with Prf=3MW. These had decent,
but not extremely robust ELMs, which turned out to be rather sensitive
to rises in density and Prad, as well as variation in triangularity
later in the shot. The first shots with extra A-coil current (#11, 12,
13) appeared to reduce the number of ELMs, even at < 3800A. It even
seemed that the ELMs returned as we decreased the current to 2300A
(B21_PROJ=2G) on #15. However, lowering the current further (B21_PROJ=-3G,
Acoil~400A, shots#16) did not result in more ELMs, although there
were more on shot#18, with the same acoil but different timing. It
turned out that the ELMs were much more prevalent in the first 100ms
or so of the H-mode. Shot#20 and 21 still had ELMs during this period,
despite high A-coil current starting from 0.6sec. All subsequent shots
were taken with the a-coil either full on (B21_PROJ=7G) or near
zero (B21_PROJ= -3G) between .6 and 1.4sec. None showed suppression,
or even convincing changes in the ELM frequency or amplitude.
In none of today's shots did we observe locked modes due to the
applied B21 perturbations, which is probably consistent with
expectations for the H-mode density and calculated net 2/1 field
-3< B21 < 7G . There was no obvious gross braking effect, although this
should be examined in more detail. Control room examination of
pedestal parameters did not indicate significant variation in the
pedestals up to maximum availanle Acoil current.
These results, together with the calculations of chirikov parameter
done previously (assuming these are confirmed for the present shots),
appear to contradict the interpretation of the JET results with
similar n=1 perturbation amplitudes which did show an effect on
ELMs over a range 3< q95 < 4.8 when sigma_chirikov > 1 .
Since we did not go past q95=4, we cannot
rule out an effect there, but ELMs were more difficult to produce
as we raised q, so we would probably need more power to explore
this regime. If we had had more time we probably could have done
this, since there were only a few trips at the 4MW level on the
last few shots.
We should also look more carefully at the expected
region of ergodization compared to the location of the pedestal in
these shots, and include the effect of the edge bootstrap current
on the equilibrium shear, which may reduce the Chirikov parameter
in the critical location. It is also possible that it may be
necessary to consider the plasma response to the perturbation, including
shielding effects due to rotation.
Today's experiment did expand somewhat the parameter range, particularly
in q95, for which ELMs were observed in the JFT2-M shape, and
hopefully got good profile and ELM dynamics data over this range.
We also had good HIREX_Sr data for rotation with maximum n=1 perturbation,
which should be of interest for evaluation of resonant magnetic braking of
the intrinsic rotation in the absence of locked modes.
Useful shots from this run:
Shot# Prf Ip Acoil
------ ----- --- -------
4 <4 0.90 1500-1800
10 3 0.90 1500-1800
11 3 0.90 3800
12 3 0.90 3800
13 3 0.90 3450
14 3 0.90 3450
15 3 0.90 2300
16 3 0.90 400
18 3 0.90 400
19 3 0.90 3800
20 3 0.90 3300
21 3 0.95 3800
23 3.5 0.95 1500-1800
24 3.5 0.85 1400-1700
25 3.5 0.85 1400-1700
26 3.5 0.85 3800
27 3.5 0.85 300
28 3.5 0.80 3800
30 3.5 0.80 300
31 3.5 0.80 300
32 4.0 0.80 3800
33 4.0 0.95 3800
|
| Physics Operator Summaries |
| Entered: Feb 13 2008 05:12:37:777PM |
| Author: Joseph Snipes |
| It was a good run. Except for some short delays due to the data system and a brief cell access for the Z-meter, the run went smoothly and the machine ran well. There was one data system test before 9:00 am and there were three fizzles. The rest of the plasmas reached flattop. Before shot 9, there were several disruptions in the middle of the RF pulse. We felt they might be due to the plasma shape, so RXL was pushed out by 5 mm on shot 9. Br0 seemed to change a bit at breakdown and may have been responsible for the fizzles. The physics plan was more or less achieved and it showed that the A-coils have little impact on the ELMs, though many other things do affect them. There were 33 shots, 29 plasmas, 3 fizzles, and 1 test shot.
Shot,Duration(s),Ipmax(MA),Result Shot,Duration(s),Ipmax,Result | 01 0.000 0.002 Dud | 02 1.859 0.903 Plasma | | 03 0.812 0.990 Plasma | 04 1.878 0.920 Plasma | | 05 0.920 0.964 Plasma | 06 0.831 0.962 Plasma | | 07 0.973 0.964 Plasma | 08 0.970 0.983 Plasma | | 09 0.615 0.920 Plasma | 10 1.938 0.921 Plasma | | 11 1.932 0.920 Plasma | 12 1.930 0.923 Plasma | | 13 1.933 0.921 Plasma | 14 1.894 0.921 Plasma | | 15 1.886 0.921 Plasma | 16 1.893 0.920 Plasma | | 17 0.000 0.059 Fizzle | 18 1.897 0.921 Plasma | | 19 1.849 0.913 Plasma | 20 1.894 0.920 Plasma | | 21 1.891 0.969 Plasma | 22 0.000 0.062 Fizzle | | 23 1.881 0.971 Plasma | 24 1.891 0.873 Plasma | | 25 1.938 0.877 Plasma | 26 1.936 0.876 Plasma | | 27 1.939 0.879 Plasma | 28 1.935 0.824 Plasma | | 29 0.000 0.064 Fizzle | 30 1.938 0.826 Plasma | | 31 1.935 0.827 Plasma | 32 1.903 0.827 Plasma | | 33 1.886 0.979 Plasma Date 1080213: 33 shots. 29 plasmas. 3 fizzles. 1 duds. 0 System Error. (Plasma = Ip gt 80.0 kA Dud = H_alpha lt 0.40 V) Total plasma duration: 48.97 s (exceeding -100 kA) |
| Session Leader Comments | |||
| Feb 13 2008 08:22:37:407AM | 1080213001 | Steve Wolfe | Shot#1: data system test cycle |
| Feb 13 2008 09:25:17:693AM | 1080213002 | Steve Wolfe | Shot#2: First plasma attempt, rf tuning up. plasma full length, Got rf from D,E; J faulting on pressure Got H-mode, very ratty. ECE gate valve not enabled at ECE station. Next: repeat, hope for more rf |
| Feb 13 2008 09:35:28:190AM | 1080213002 | Steve Wolfe | Shot#3: Data system delay. |
| Feb 13 2008 09:58:09:997AM | 1080213003 | Steve Wolfe | Shot#3: disrupted at .8 sec, during rf. |
| Feb 13 2008 10:11:54:510AM | 1080213004 | Steve Wolfe | Shot#4: plasma full length, h-mode Got some elms until 1sec Next: try for flatter power, ~3.5 to 4MW |
| Feb 13 2008 10:22:47:587AM | 1080213005 | Steve Wolfe | Shot#5: disrupts around 0.9sec again. H-mode started well, some elms getting 4MW, but J still faulting. Next: decrease target density, per JT recommendation |
| Feb 13 2008 10:41:08:233AM | 1080213006 | Steve Wolfe | Shot#6: disrupted at .82sec, Higher neuts, I don't see any convincing ELMs before the disruption. RF was down to 3.6MW already. Next: back down on power to 3MW |
| Feb 13 2008 10:54:32:873AM | 1080213007 | Steve Wolfe | Shot#7: back down on power to 3MW Another disruption, at 0.96sec Forgot to toggle ece gate valve. Questionable elms. JT thinks they are, certainly not as regular as earlier today. next: raise nl04 to 6.5e19 |
| Feb 13 2008 11:08:41:467AM | 1080213008 | Steve Wolfe | Shot#8: raise nl04 to 6.5e19 Still disrupting about the same time. Rf at 3MW, no elms, Next: move rxl out by 5mm, 6e19. |
| Feb 13 2008 11:44:19:947AM | 1080213009 | Steve Wolfe | Shot#9:move rxl out by 5mm, nl04 back to 6e19. early disruption, .6sec before the rf. Big bite out of the current at 0.1sec. JT points out a glowing object on the ef1 shelf on wide1, in front of J-port. |
| Feb 13 2008 11:55:57:600AM | 1080213010 | Steve Wolfe | Shot#10: plasma full length 2h-modes, 1 injection, ELMs after 1sec. Acoil current is ~1500A rising to 1800 during H-mode. Next: try adding acoil pulse (B21_PROJ to .0015 T between .85 and 1.4 |
| Feb 13 2008 12:13:32:340PM | 1080213011 | Steve Wolfe | Shot#11: Try for a-coil during H-mode pulse B21_proj programmed for 1.5mT plasma full length. No elms!!! Got A-coil at 4000A until 2sec. Got 3MW of RF. It looks good, but no ELMs before acoil, so you don't see them go away. The integral gain is screwing up the way the acoil works when it's saturating. The actual net is getting to like 6G, so we are way over. May need to go back to direct programming on the current. Next: delay b21_proj pulse to 1sec |
| Feb 13 2008 12:19:38:440PM | 1080213012 | Steve Wolfe | Shot#12: delay b21_proj pulse to 1sec It seems to work, we see elms before 1.1, then only two more 1.188 and 1.263 It may be working. Next: reduce demand on b21_proj to .0005 (we're actually getting about .0006) |
| Feb 13 2008 12:32:30:690PM | 1080213013 | Steve Wolfe | Shot#13: reduce b21_proj to .0005, same timing plasma, h-mode, elms mostly still gone after 1.1sec acoil current=3460A. Next: same amplitude, but start at .7-.75sec, down at 1.05-1.1sec |
| Feb 13 2008 12:47:04:220PM | 1080213014 | Steve Wolfe | Shot#14: same amplitude, but start at .7-.75sec, down at 1.05-1.1sec plasma, h-mode, couple of elms early and a couple late. Not so good. last elm is 0.88, which is after the current comes up. However, the late ones are not more frequent than shot 13. Next: decrease b21 to .0002 |
| Feb 13 2008 12:56:39:467PM | 1080213015 | Steve Wolfe | Shot#15: decrease b21 to .0002, same timing plasma, more elms. acoil=2300A Missing Ip, tci, ece data |
| Feb 13 2008 01:04:20:163PM | 1080213015 | Steve Wolfe | Shot#15: decrease b21 to .0002, same timing plasma, more elms. acoil=2300A Missing Ip, tci, ece data Magnetics data is missing, so no Ip, no EFIT. Apparently the server got aborted. Next: b21_proj to -.0003 |
| Feb 13 2008 01:26:13:423PM | 1080213016 | Steve Wolfe | Shot#16: b21_proj to -.0003T Lots of radiation , looks like little accumulating injections Only a few elms on this one, fewer than on 15. Acoil down to 400A. next: change timing .6 to 1.4sec |
| Feb 13 2008 01:28:45:973PM | 1080213017 | Steve Wolfe | Shot#17:change timing .6 to 1.4sec, still -3G fizzle |
| Feb 13 2008 01:43:59:757PM | 1080213018 | Steve Wolfe | Shot#18:change timing .6 to 1.4sec, still -3G plasma full length, elms are back. Next: back to +5G, same timing |
| Feb 13 2008 02:00:37:900PM | 1080213019 | Steve Wolfe | Shot#19: back to +5G, same timing Big bite out of the current almost loses it big marfe, then a big radiative event in the h-mode. Small if any elms, but this is not conclusive since the shot has problems all the way through. Acoil current is 3800A, doesn't quite reach target 5G, due to different PF currents |
| Feb 13 2008 02:18:50:437PM | 1080213020 | Steve Wolfe | Shot#20: repeat at +5G, same timing plasma h-mode, still some elms early in H-mode. Maybe we're fooling ourselves. getting 3300A. Next: raise Ip to 950, increase B21_proj to 7G |
| Feb 13 2008 02:31:36:483PM | 1080213021 | Steve Wolfe | Shot#21: raise Ip to 950, increase B21_proj to 7G Acoil 3800A, radiated power increasing, still have six or seven elms before 0.9sec. Next: increase rf by 0.5MW, drop B21 to zero |
| Feb 13 2008 02:38:56:773PM | 1080213022 | Steve Wolfe | Shot#22: increase rf by 0.5MW, drop B21 to zero fizzle |
| Feb 13 2008 02:56:03:527PM | 1080213023 | Steve Wolfe | Shot#23: increase rf by 0.5MW, drop B21 to zero Very few elms, lots of injections, up to 4MW of Prad Got 3.5MW of RF, not too many faults. Acoil 1500 to 2000A Next: drop Ip to 850ka, keep RF, A-coil the same |
| Feb 13 2008 03:03:20:440PM | 1080213024 | Steve Wolfe | Shot#24: drop Ip to 850ka, keep RF, B21 the same Have elms between .75 and .95, then the density rises and injections increase. Next: decrease nl04 |
| Feb 13 2008 03:18:33:507PM | 1080213025 | Steve Wolfe | Shot#25: decrease nl04, trying for more consistent elms. Elms betweem .78 and .9sec, maybe killed by injection. Next: B21 to 7G, RF will try getting more from D/E, less from J |
| Feb 13 2008 03:36:52:650PM | 1080213026 | Steve Wolfe | Shot#26: B21 to 7G, RF will try getting more from D/E, less from J Lots more elms. continuing to 1.35sec Prad flat around 1.6MW. That looks like a great counter example. Next: acoil to -3G, nail it down. |
| Feb 13 2008 03:52:17:527PM | 1080213027 | Steve Wolfe | Shot#27: acoil to -3G, nail it down. plasma with ELMs, no difference. acoil is down to 300A. A-coil is NOT affecting these ELMs q95=3.7 Next: 800kA, B21 back to +7G |
| Feb 13 2008 04:05:18:357PM | 1080213028 | Steve Wolfe | Shot#28: 800kA, B21 back to +7G plasma hardly any ELMs , q95=3.9 Prad low, no injections in H-mode until late Next: back to -3G, see if there are any ELMs to suppress. |
| Feb 13 2008 04:15:16:790PM | 1080213029 | Steve Wolfe | Shot#29: 800kA, B21 back to -3G, see if ELMs return fizzle. |
| Feb 13 2008 04:33:15:577PM | 1080213030 | Steve Wolfe | Shot#30: 800kA, B21 back to -3G, see if ELMs return Again only a few ELMs. Prad is much higher than on 28. J-port doesn't really turn on till .89sec, which is when Prad starts up. next: repeat |
| Feb 13 2008 04:45:30:823PM | 1080213031 | Steve Wolfe | Shot#31: repeat, try for better rf RF looks fine. Only a few elms, it looks like we don't get them at this q. |
| Feb 13 2008 04:58:00:603PM | 1080213032 | Steve Wolfe | Shot#32: raise power to 4MW. back to 7G. ELMs between .75 and 1.0, so it doesn't suppress at this q either. Next: back to 950kA |
| Feb 13 2008 05:11:16:573PM | 1080213033 | Steve Wolfe | Shot#33: back to 950kA, drop b21 at 1.2sec just in case plasma, multiple H-modes, some scraggly ELMs all the way through. q95=3.3. RF at 4MW with some dropouts. High radiation. Looks like this is a negative result at all q values, despite the encouraging apparent effect on shot#11. |
| Physics Operator Comments | |||
| Feb 13 2008 09:21:11:843AM | 1080213002 | Joseph Snipes | Shot 2: Copied shot 1080108012 then loaded segment 1 from shot 1080211010 for the startup. Increased argon puff to 100 ms duration from 0.35 to 0.45 s. Good shot. |
| Feb 13 2008 09:54:40:320AM | 1080213003 | Joseph Snipes | Shot 3: Repeat trying to get more ICRF power. Disrupted at 0.8 s. Large
increase in Prad as soon as the ICRF turns on. |
| Feb 13 2008 10:04:08:800AM | 1080213004 | Joseph Snipes | Shot 4: Reduced prepuff by 4 ms to 19 ms duration. Good shot. |
| Feb 13 2008 10:19:43:457AM | 1080213005 | Joseph Snipes | Shot 5: Increased prepuff by 2 ms to 21 ms duration. Disrupted at 0.91 s. |
| Feb 13 2008 10:31:34:393AM | 1080213006 | Joseph Snipes | Shot 6: Reduced prepuff by 2 ms to 19 ms duration. Reduced nl04 to 5 x 10^19 m^-2. Disrupted at 0.82 s. |
| Feb 13 2008 10:53:38:433AM | 1080213007 | Joseph Snipes | Shot 7: Repeat. Disrupted at 0.97 s. |
| Feb 13 2008 10:59:18:067AM | 1080213008 | Joseph Snipes | Shot 8: Raised nl04 to 6.5 x 10^19 m^-2. Still disrupted at 0.96 s. |
| Feb 13 2008 11:45:56:947AM | 1080213009 | Joseph Snipes | Shot 9: Increased RXL from -0.055 to -0.05 m to try to avoid touching the inner nose with the LCFS. Dropped nl04 to 6 x 10^19 m^-2. Disrupted at 0.61 s. |
| Feb 13 2008 11:48:19:323AM | 1080213010 | Joseph Snipes | Shot 10: Try again. There is something glowing on the inner shelf near J-port in the WIDE-1 camera view, but it does not seem to be responsible for the disruption.
Good shot. |
| Feb 13 2008 12:08:22:113PM | 1080213011 | Joseph Snipes | Shot 11: Turned on B21_PROJ from 0.85 to 1.4 s at 0.0015 T. Good shot! It appears that the A-coils eliminate the ELMs. |
| Feb 13 2008 12:19:19:143PM | 1080213012 | Joseph Snipes | Shot 12: Changed B21_PROJ start time to 1.05 s flattop. Good shot. There are
more ELMs before 1 s, but there do appear to be a few after 1 s as well. |
| Feb 13 2008 12:28:36:560PM | 1080213013 | Joseph Snipes | Shot 13: Changed B21_PROJ amplitude to 0.0005 T. Good shot. There do appear to be fewer ELMs after 1 s than before. |
| Feb 13 2008 12:47:05:753PM | 1080213014 | Joseph Snipes | Shot 14: Start B21_PROJ to flattop at 0.75 and begin down at 1.05 s, still at 0.0005 T. Good shot. |
| Feb 13 2008 12:53:11:573PM | 1080213015 | Joseph Snipes | Shot 15: Reduce B21_PROJ to 0.0002 T. Good shot. ELMs have come back. |
| Feb 13 2008 01:17:58:693PM | 1080213016 | Joseph Snipes | Shot 16: Set B21_PROJ to -0.0003 T. ELMs seem to be gone except for a few back transitions. |
| Feb 13 2008 01:28:46:987PM | 1080213017 | Joseph Snipes | Shot 17: Changed B21_PROJ timing to start at 0.6 and end at 1.4 s. Fizzle! |
| Feb 13 2008 01:41:58:067PM | 1080213018 | Joseph Snipes | Shot 18: Repeat. Good shot. ELMs have returned. |
| Feb 13 2008 01:57:43:270PM | 1080213019 | Joseph Snipes | Shot 19: Increased prepuff by 4 ms to 23 ms duration. Reduced Br0 by 0.5 mT to -0.5 mT. Changed B21_PROJ to +0.0005 T. Nice startup but a horrible current rise with a huge drop in current and a MARFE. Not a good comparison shot. |
| Feb 13 2008 02:09:25:160PM | 1080213020 | Joseph Snipes | Shot 20: Repeat without the dip in the current and without the MARFE. Good shot. ELMs have returned. |
| Feb 13 2008 02:24:08:850PM | 1080213021 | Joseph Snipes | Shot 21: Reduced prepuff by 2 ms to 21 ms duration. Raised B21_PROJ to 0.0007 T and raised Ip to 0.95 MA. Good shot. The A-coils are as high as they can go and there are still a few ELMs, though perhaps some of them have been suppressed. |
| Feb 13 2008 02:34:34:970PM | 1080213022 | Joseph Snipes | Shot 22: Set B21_PROJ to zero. Raise ICRF by 0.5 MW. Fizzle! |
| Feb 13 2008 02:50:09:520PM | 1080213023 | Joseph Snipes | Shot 23: Reduced prepuff by 2 ms to 19 ms duration. Good shot. Very few ELMs
without the A-coil. |
| Feb 13 2008 03:02:14:533PM | 1080213024 | Joseph Snipes | Shot 24: Increased prepuff by 1 ms to 20 ms duration. Reduced Ip to 0.85 MA.
Good shot. Some ELMs. |
| Feb 13 2008 03:16:22:347PM | 1080213025 | Joseph Snipes | Shot 25: Reduced nl04 to 5 x 10^19 m^-2. Good shot. Several ELMs are then stopped by an impurity injection at 0.9 s. |
| Feb 13 2008 03:28:12:750PM | 1080213026 | Joseph Snipes | Shot 26: Repeat with B21_PROJ set to 0.0007 T from 0.65 to 1.35 s. Good shot.
Even more ELMs. It seems clear that the A-coil does not have much effect on the ELMs. |
| Feb 13 2008 03:49:54:730PM | 1080213027 | Joseph Snipes | Shot 27: Set B21_PROJ to -0.0003 T. Good shot. Lots of ELMs as before. So, it is clear that while a lot of things do affect the ELMs, the A-coil is not one of them.
|
| Feb 13 2008 04:04:01:900PM | 1080213028 | Joseph Snipes | Shot 28: Set Ip to 0.8 MA and B21_PROJ back to 0.0007 T. Good shot. Very few ELMs. |
| Feb 13 2008 04:13:52:053PM | 1080213029 | Joseph Snipes | Shot 29: Set B21_PROJ to -0.0003 T. Fizzle! |
| Feb 13 2008 04:27:14:820PM | 1080213030 | Joseph Snipes | Shot 30: Try again with no changes. Good shot. Very few ELMs. |
| Feb 13 2008 04:40:47:430PM | 1080213031 | Joseph Snipes | Shot 31: Repeat with steadier RF. Good shot. A few ELMs at the beginning of
the H-mode. |
| Feb 13 2008 04:52:50:503PM | 1080213032 | Joseph Snipes | Shot 32: Repeat with higher RF power and B21_PROJ at 0.0007 T. Good shot. There are some ELMs early in the H-mode. |
| Feb 13 2008 05:04:53:173PM | 1080213033 | Joseph Snipes | Shot 33: Raised Ip to 0.95 MA. Changed the B21_PROJ end time to 1.2 s. Good shot. Very few ELMs in several H-modes. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 08:22:13:180AM | Plasma | Ok | |
| 2 | 09:17:47:560AM | Plasma | Ok | |
| 3 | 09:49:53:750AM | Plasma | Ok | |
| 4 | 10:02:18:733AM | Plasma | Ok | |
| 5 | 10:15:59:830AM | Plasma | Ok | |
| 6 | 10:29:33:563AM | Plasma | Ok | |
| 7 | 10:44:03:737AM | Plasma | Ok | |
| 8 | 10:57:05:173AM | Plasma | Ok | |
| 9 | 11:32:00:697AM | Plasma | Ok | |
| 10 | 11:46:37:730AM | Plasma | Ok | |
| 11 | 11:59:13:057AM | Plasma | Ok | |
| 12 | 12:12:31:510PM | Plasma | Ok | |
| 13 | 12:25:10:883PM | Plasma | Ok | |
| 14 | 12:37:53:303PM | Plasma | Ok | |
| 15 | 12:50:28:867PM | Plasma | Ok | |
| 16 | 01:13:53:313PM | Plasma | Ok | |
| 17 | 01:27:05:767PM | Plasma | Ok | |
| 18 | 01:39:28:983PM | Plasma | Ok | |
| 19 | 01:53:14:283PM | Plasma | Ok | |
| 20 | 02:06:51:487PM | Plasma | Ok | |
| 21 | 02:19:44:547PM | Plasma | Ok | |
| 22 | 02:32:58:500PM | Plasma | Ok | |
| 23 | 02:45:43:170PM | Plasma | Ok | |
| 24 | 02:58:22:263PM | Plasma | Ok | |
| 25 | 03:12:18:480PM | Plasma | Ok | |
| 26 | 03:25:24:530PM | Plasma | Ok | |
| 27 | 03:47:20:023PM | Plasma | Ok | |
| 28 | 03:59:53:570PM | Plasma | Ok | |
| 29 | 04:12:17:363PM | Plasma | Ok | |
| 30 | 04:24:44:033PM | Plasma | Ok | |
| 31 | 04:37:17:597PM | Plasma | Ok | |
| 32 | 04:50:08:203PM | Plasma | Ok | |
| 33 | 05:02:37:733PM | Plasma | Ok | |
| System Availability | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Feb 13 2008 08:21:47:907AM | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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