| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Dennis Whyte |
| Physics operator(s): | Steve Wolfe |
| Engineering operator(s): | Andy Pfeiffer,Bill Parkin,Ed Fitzgerald |
| Engineering Operator Run Comment |
| automatically entered by signon - please replace with real comment |
| Session Leader Plans |
| Entered: Oct 16 2009 08:24:29:530AM |
| Author: Dennis Whyte |
| Characterization and Optimization of I-mode
---------------------------------- Day 2.5 The purpose of these experiments is to characterize the necessary parameters to obtain I-mode (a.k.a. enhanced L-mode) while documenting I-mode plasma characteristics and optimizing I-mode towards its application in Alcator C-Mod for high confinement at low density. The experiment will focus on expanding the available I-mode operating space by exploring the effects of shaping, density, q95, and Ip with a goal of obtaining basic scaling relationships for further use on C-Mod and possible exploration on other devices. Reference shot: We realized after Day 2 (which was actually a very short day due to alternator problems) that we had not obtained exact shaping we wanted, so Wolfe will re-develop this shape to desired quantities... mostly focussed on getting matched q95 to 2008 shots) Cryopump ON Toroidal Field: 5.0 - 5.8 T (clockwise) Plasma Current: 0.8 - 1.4 MA Working Gas Species: D2 Density: Target NL04 densities from 0.3 to 1 (1e20) Boronization Requested: NO ICRF Power: > 5 MW, Each shot will have 4 steps in RF of 200 ms each. Diagnostics: ECE with varying B field Edge TS with alignment for pedestal/edge as reference shot Note: DNB is offline so no pedestal diagnosis available from CXRS Run Plan -------- Our second day only garnered a completion of step 3. The analysis to date suggested that q95 was the most important parameter in H-mode avoidance which may affect our choices in the scans. However this can be confused with shape dependencies too. We'll start today with a focus on tweaking the shape to better match 2008 shots and lower q95 at 1.35 MA + work on earlier density control for the density scans of steps 4 and 5. - RF power will ramp up to the first step rather than turn on to full power immediately. 4. Density scan at high Ip / low q95 N.B. ordering of density scan is reversed from MP Reference shape: #1080416015, Ip = 1.35 MA, Bt = 5.63 T 6 shots a) NL04 = 0.5e20, Prf steps: 4.3, 4.6, 4.9, 5.2 (or lowest density achievable) b) NL04 = 0.6e20, Prf steps: 4.3, 4.6, 4.9, 5.2 c) NL04 = 0.7e20, Prf steps: 4.3, 4.6, 4.9, 5.2 d) NL04 = 0.8e20, Prf steps: 4.3, 4.6, 4.9, 5.2 e) NL04 = 0.9e20, Prf steps: 4.3, 4.6, 4.9, 5.2 f) NL04 = 1.0e20, Prf steps: 4.3, 4.6, 4.9, 5.2 5. Density scan at low Ip / high q95 (3b forms part of scan) Reference shape: #1080416015, Ip = 1.0 MA, Bt = 5.63 T 6 shots a) NL04 = 0.3e20, Prf steps: 3.1, 3.2, 3.3, 3.4 (or lowest density achievable) b) NL04 = 0.4e20, Prf steps: 3.1, 3.2, 3.3, 3.4 c) NL04 = 0.5e20, Prf steps: 3.1, 3.2, 3.3, 3.4 d) NL04 = 0.6e20, Prf steps: 3.1, 3.2, 3.3, 3.4 e) NL04 = 0.7e20, Prf steps: 3.1, 3.2, 3.3, 3.4 f) NL04 = 1e20, Prf steps: 3.1, 3.2, 3.3, 3.4 When we get through this we move the "shaping study" 6. Increase κ to ~1.7, same triangularity ~ 0.6 as Day 1 (Circle 2 Fig. 3) 3 shots a) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.8e20, Prf steps: 3.1, 3.2, 3.3, 3.4 b) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.5e20 (or lowest possible) , Prf steps: 3.1, 3.2, 3.3, 3.4 c) Ip = 1.35 MA, Bt = 5.63 T, q95 ~ 2.9, NL04 = 0.8e20, Prf steps: 4.3, 4.6, 4.9, 5.2 7. Increase κ to ~1.8 (or max.), same triangularity ~ 0.6 as Day 1 (Circle 3 Fig. 3) 3 shots a) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.8e20, Prf steps: 3.1, 3.2, 3.3, 3.4 b) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.5e20 (or lowest possible) , Prf steps: 3.1, 3.2, 3.3, 3.4 c) Ip = 1.35 MA, Bt = 5.63 T, q95 ~ 2.9, NL04 = 0.8e20, Prf steps: 4.3, 4.6, 4.9, 5.2 8. Keep κ at ~1.8 (or max.), increase triangularity to 0.8 (Circle 4 Fig. 3) 3 shots a) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.8e20, Prf steps: 3.1, 3.2, 3.3, 3.4 b) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.5e20 (or lowest possible) , Prf steps: 3.1, 3.2, 3.3, 3.4 c) Ip = 1.35 MA, Bt = 5.63 T, q95 ~ 2.9, NL04 = 0.8e20, Prf steps: 4.3, 4.6, 4.9, 5.2 9. Reduce κ to ~1.7 (or max.), keep triangularity at 0.8 (Circle 5 Fig. 3) 3 shots a) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.8e20, Prf steps: 3.1, 3.2, 3.3, 3.4 b) Ip = 1 MA, Bt = 5.63 T, q95 ~ 3.9, NL04 = 0.5e20 (or lowest possible) , Prf steps: 3.1, 3.2, 3.3, 3.4 c) Ip = 1.35 MA, Bt = 5.63 T, q95 ~ 2.9, NL04 = 0.8e20, Prf steps: 4.3, 4.6, 4.9, 5.2 10. Steady demonstration shot Type #1: �??ITER q=3�?? 4 shots Bt=5.4 T, q95~3, shape: TBD Variables (influenced on parameter scan results of 2-4. - target density: NL04 ~ 0.5-0.7 to reduce pedestal collisionality to ITER target 0.08 - RF: constant through shot, ~ 4.5 - 5 MW 11. Steady demonstration shot Type #2: Low collisionality AT / LH target 4 shots Bt= TBD, q95~4, shape: TBD Variables (influenced on parameter scan results of 2-4. - target density: minimum possible NL04 ~ 0.5-0.7 - RF: constant through shot, ~ 3.5 - 4 MW |
| Physics Operators Plans |
| Entered: Oct 15 2009 02:38:55:203PM |
| Author: Steve Wolfe |
| Physop plan and engineering setup for Friday, Oct 16, 2009
MP#579 "Characterization and optimization of I-mode" SL: Whyte PO: wolfe ----------------- Engineering Setup ----------------- Overnight 60C bake and ECDC in helium: ------------------------------ ECDC Parameters ------------------------------ gas and pressure: He at 5e-5 Torr sweep: 44/45/103 cm scan: 20/120 s Run begins at 09:00 and ends at 17:00 NOTE: A boronization has been scheduled for Friday night, after the completion of the run. Therefore we will remain in CONTROLLED ACCESS from 17:00 to about 18:00, and the cell and power room will then be closed for boronization until Saturday morning. Power systems as on: 1091009013 Acoil: +Dtop -Dbot -Jtop +Jbot (standard) Hybrid Enabled Gas setup: Fill B-Top with 6 psi D2 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 D2 Hybrid enabled (PG3) fill NINJA with 10 psi D2 DISABLED Enable gatevalves and shutters: ECE, VUV, Z-bolo, HIREX_SR Torvac gatevalve toggle (yes/no): No Boronization(yes/no): no Overnight ECDC (yes/no): YES ICRF(yes/no): yes (all transmitters) LH(yes/no): no DNB(yes/no): no Cryopump (yes/no): YES (all shots) Vessel temperature: 35/35/35 -------------------------------------------------- Physop plan: Start from 1091009013 (1.35MA, 5.6T, 8e19 program) and modify ZCUR from -.005 to +.001 to reduce kappa from 1.7 to 1.64, perhaps with some adjustment to prevent the density dip between .38 and .55sec (try diverting earlier), and reduce the flattop nl04 to 5e19 to start the density scan of part 4 of the MP. We may need to repeat the 8e20 point from the reference shot, which was step 3e but also part of the density scan. I expect locked mode problems at the lower densities in this scan; up to SL how long we take trying to get rid of these, but it may be worth one shot to try tweaking the B21_PROJ observer to give more A-coil current and see if it helps. The scan is supposed to cover 0.5 to 1.3e20 at 1.35MA . Continuing the run plan, step 5 goes back to 1.0MA, and carries out a density scan from 0.3 to 1.0e20, with similar rf waveforms with itty-bitty steps at each density. May need to adjust zcur to preserve elongation. We'll attempt this going from low to high density, although we may pick up some of the intermediate points first by accident, since we'll be starting from the high density end-point of scan 4. Step 6 is the "shaping study", which should be a lot of fun. This will be done first at 1MA, nl04=0.8e20, which is close to one of the scan 5 points, but with elongation increased to 1.7. This is close to 1091009009 which was k=1.67. Some adjustment may need to be made to keep the lower triangularity fixed. The plan calls for two densities (0.8 and 0.5e20, then a high current version (1.35MA) which is called out as q95=2.9; however, since 1091009013 was at this current with kappa=1.699 and had q95=3.1, this may already be done, or else we would need to reduce the kappa to get the lower q95. This needs to be discussed with SL if we get this far. Step 7 is the same as step 6 but at higher elongation, nominally 1.8 instead of 1.7. It also calls out the same q95 for the same current and field, which seems inconsistent unless he wants to decrease minor radius as well as increase height. SL needs to clarify. We seem to have some headroom on vertical stability on 1091009009 and 13, so 1.8 should be doable. I don't expect to get past step 7, but if we do the rest of the run plan is in the MP, and probably under SL_PLAN. The next step would be increased triangularity. ----------------------------------------- After the run, we will go to controlled access (keys required!) until no later than 18:00, then close up for boronization until Saturday morning. We anticipate that if the run is successful we will reach the neutron alert level (10^14 neutrons) during the day. Therefore, any cell access would require use of the geiger counter survey meter and wearing of film badges. If it is possible to delay in-cell work until Saturday, that would be advisable. |
| Session Leader Summaries |
| Entered: Oct 16 2009 06:35:23:157PM |
| Author: Dennis Whyte |
| A very productive day.
Early shots we had to work through density control so that we could avoid locked mode disruptions. Also tuned up ICRH Started at 1.35 MA, q95~2.9 First good shot #9. These were plagues with impurity injections during flattop. One of the recipes to avoid this became sweeping the strikepoint around, so indicating that we were getting the upper divertor too toasty with stationary strikepoint positions. shot 13 was lowest density in Step 4 at q95~2.9 at NL04~0.75 but at this point we noted the plasmas were suffering dithering into brief H-mode periods. Plus the impurity injection were still plaguing us. Move the X-Point closer to the plate (#16) to avoid putting heat onto bad places like upper corner and cryo tiles. This "unsteady" aspect of the 1.35 MA shots makes them difficult to assess. Interestingly, more power would seem to get rid of the dithering (?) which we saw through the day. At this point we went to 1.2 MA to avoid the delays from disruptivity and hopefully get better density control 1.2 MA, q95~3.3 ---------------- We performed a density scan here. #25 and #26 are a great comparison. Our expectations about I-mode getting really awesome at low density were not borne out. Note that 26 has lower density NL04~0.7 than NL04~0.9 in 25, yet 25 has higher Te_ped and confinement! #25 also has higher radiated power at lower density? Anyway I think this and the 1.35 MA experience is telling us that I-mode doesn't necessarily like low density. Of course we were also having impurity injection problems today. Starting raising density (#28- 30) and the I-modes generally improved although we were still bothered by the injections. Shot 28 seemd to hit a "sweet spot" for density and we got past 1e14 n/s and a hot Te_ped Getting sick of injections I decided to try using some neon in the shot a la Reinke's experiments. This seemed to have quite a positive effect #31 vs #30 on injections although our Ne puff was too large and it hit down our performance. We backed off on the neon for shot 33 at NL04=1.0. This produced our trophy shot with a beautifully clear transition to I-mode and very constant W and neutrons > 1e14 n/s. For the last shot we tried a 1.35 MA again (NL04=1.1) hoping things would be cleaner with the neon (compare to 16). This worked... we got again a clear transition to I-mode but it was short lived due to an H-mode transition. Great data correlating the transitions on edge ECE and reflectometers for this shot. |
| Physics Operator Summaries |
| Entered: Oct 16 2009 06:02:58:833PM |
| Author: Steve Wolfe |
Physop summary for Friday, Oct 16, 2009
MP#579 I-mode
SL: Whyte
PO: wolfe
EO: Pfeiffer, Parkin,
The initial 1.35MA part of the run was plagued by disruptions of various
sorts, including a lot that were just unexplained. We raised the density
fairly early and made some tweaks in feedforward and NL04 gains to try to
get rid of dips and subsequent locked mode problems. I ended up with D=10,
P=5,and some pg3 feedforward, which seemed to give a reasonably stable
target.
We made a lot of small shape changes, first to try to get the original SL
request, then adjustments to try to get rid of injections, which seemed to be
correlated with having strike point in the inner corner. These had the side
effect of moving q95 around in the range 3.1 > q95 > 2.8, and probably
resulted in some of the disruptions.
There were only a few full length, or even most of flattop, shots at 1.35MA,
but some of these did have I-mode ELMs, and some were dithering on the edge of
H-mode. See SL summary for details.
At shot#19 we punted the 1.35MA and dropped to 1.2MA (q~3.4) to try to do the
density scan there, intermediate between case 4 and 5 of the MP run plan. We
ran as low as 7e19 and as high as 1.2e20. Zeff was reading very high (like 4)
except at the highest densities, but performance wan't too bad, with L/I-mode
energies over 170kJ. We were still having problems with injections, some
leading to disruptions. On shot#23 I implemented an RXU sweep to try to reduce
the localized heat loads, with possibly favorable results.
On shot#31 we started using neon puffing, initially 200msec@2psi, and this had
a strong benficial effect on the injections and on prad. This technique needs
to be explored further. We did two shots with 2psi and two at 1.1psi.
Shot#33 was at 1.2MA, 1.0e20 and had a sustained I-mode over 180kJ and neutron
rate over 1e14/sec. The last shot, at 1.35MA, 1.1e20 (target) produced two
ELM-free H-modes over 230kJ and 1.7e14neut/sec. All of the neon-seeded shots
had low or no injections and controlled Prad in the L- and I-modes, although
Prad ran up in H-modes, so we apparently would need a different neon
prescription for those. It seems surprising that the neon would last through
the pulse in the I-mode cases, since it should be pumped by the cryopump, but
the 200msec puff seemed to be sufficient. Shot#32, with 2psi, had an abrupt
change in Prad (down) at ~1.3sec corresponding to entry into I-mode; this
might be interpreted as a reduction in the neon radiation due to pumping, but
it seems too abrupt.
I was fighting runaways for most of the day, but these finally went away
beginning with #31. I had increaed the pg4 puff from 50 to 52msec, which was
in the range that had not been successful in suppressing the runawsys earlier;
not clear why it seemed better on this shot; possibly related to higher target
densities without disruption in the preceding discharge. This was also the
first neon shot (which can't be causally related to the low runaways on 31) and
all the subsequent shots were also runaway-free.
In the end we deviated considerably from the run plan, but got a fair bit of
useful data on I-modes and H-mode thresholds in USN (which really look like
their are more hidden variables than places to hide), and at least one "trophy
I-mode shot" on #33.
Scorecard:
Tests/NoPower shots 0
Duds 0
Fizzles 6
Plasmas 28 (11 full length)
=========== ==
Shots 34
|
| Session Leader Comments | |||
| Oct 16 2009 10:21:49:320AM | 1091016001 | Dennis Whyte | Start today trying to get consistent shaping
for q95~2.9 with higher triangularity + work out early density control /w cyro so that we get lower density at flattop, but no early runaways and /or later locked modes at this higher Ip Early disruption. |
| Oct 16 2009 10:22:09:147AM | 1091016002 | Dennis Whyte | Disruption at 0.8 s
kappa: 1.66, upper delta ~ 0.67, q95 ~2.92 RF was happy up until this point. Wolfe believes cause of disruption was injection. |
| Oct 16 2009 10:22:27:540AM | 1091016005 | Dennis Whyte | Disruption at 0.8 s
kappa: 1.64, upper delta ~ 0.67, q95 ~2.85:" Good Turned off RF on this shot Disruption is not caused by injection but probably locked mode. We are still getting large swings in early density from difficulties of the fuelling keeping up with the cryo. |
| Oct 16 2009 10:35:58:887AM | 1091016006 | Dennis Whyte | Fizzle |
| Oct 16 2009 10:49:32:813AM | 1091016007 | Dennis Whyte | Disruption, but later.
It looks like our problem is locked modes due to transients in the density. the early nl04 dip starts a mode that we get through, but then when the density dips again at higher Ip in flattop, it disrupts. This is supported by the timing of the disruptions and MHD signals. |
| Oct 16 2009 11:07:56:100AM | 1091016008 | Dennis Whyte | Shot ran through.
Got 8e19 target density w/o locked modes. RF matching wasn't great so power was jumping around Missed ECE on this shot. A lot of ELMs in this shot H98 suffered: ~ 0.88 No H-mode transition. |
| Oct 16 2009 11:30:32:393AM | 1091016009 | Dennis Whyte | Better density control on this.
RF was more steady and got to Wth ~ 165 kJ and H98~0.95 No H-mode transition Disrupted at 1.25 apparently due to an injection, which actually started at 1.1 s. next shot: reduce gap from 2 to 1.5 cm Also tweak the strikepoints to outboard a bit. It appears that we're having an issue with the ISP hitting into the upper inner corner. The high-Z injection could be from over-heating in that location... and at the same time we need to avoid putting the outer strikepoint on the discontinuous tiles at the cryo entrance! |
| Oct 16 2009 11:44:09:273AM | 1091016011 | Dennis Whyte | Fizzle |
| Oct 16 2009 12:14:43:127PM | 1091016012 | Dennis Whyte | This was getting to a nice I-mode (pedestal Te ~700 eV, H98 > 0.9
constant nl04~0.8, increased by RF to 0.9) but we had another impurity injection. We are still suspecting overheating in the upper divertor. Next shot: move X-point higher to decrease the radial distance of separation between the two strikepoints. |
| Oct 16 2009 12:19:14:503PM | 1091016013 | Dennis Whyte | The injections were smaller in this case but
perturbating. Nice density control. we pulled the X-point a little higher on this shot. the problem is that we are getting dithering H-modes with each sawtooth crash in these shots and RF power ~3.8 MW. this makes the "I-Mode" very transient. It looks like we're at the lower density limit (NL04 = 0.8) at this plasma current / q95. The H-mode is just too easy to access. Plus we're battling the 1.35 MA disruptions which makes exploration difficult. So consider shot 13 lowest density step in Step 4. q95=2.95, kappa=1.65, delta = 0.64 H quality not reliable since dW/dt was still large. |
| Oct 16 2009 12:40:09:513PM | 1091016014 | Dennis Whyte | Early disruption
|
| Oct 16 2009 12:40:13:840PM | 1091016015 | Dennis Whyte | Early disruption
|
| Oct 16 2009 01:00:23:333PM | 1091016016 | Dennis Whyte | Higher X-point, kappa 1.67
Avoided injections... good! NL04=0.9 Again we see apparent H-mode dithers due to sawtooth. I-mode? hard to tell with dithering. Stored energy much lower than 1.35 MA 1080416028 shot. No definitive H-mode transition: so up power on next shot. |
| Oct 16 2009 01:19:38:387PM | 1091016018 | Dennis Whyte | Disrupted again.
It looks like we are really struggling with q95 hovering around 3 and the plasma's have very high disruptivity. We are going to try get the density scan at a higher q95~3.45 at lower Ip to help with disruptivity. |
| Oct 16 2009 01:37:58:317PM | 1091016019 | Dennis Whyte | Dithering H-modes again. higher q95 but
we did not get a clear H-mode transition. This makes me worry that we pushed the X-point so high that we're not far from limited (or we are limited) and this is giving atypical results. Next Will keep other things the same and lower X-point by 5mm. Also will lower RF power slightly since we expect H-mode threshold to be lower. |
| Oct 16 2009 02:21:43:873PM | 1091016022 | Dennis Whyte | Dithering improved with lower X-point.
An interesting observation is that the dithering seemed to diminish (i.e. less H-modes) as we increased the RF power through the shot. q95=3.3, NL04 = 0.9, kappa = 1.65, Wth~150 kJ at 1.15 seconds, H98~0.9 Prad has some positive time derivative. No H-modes (except dithers) But we had injections at 0.9 and 1.2, the last of which disrupted the plasma |
| Oct 16 2009 02:46:22:117PM | 1091016023 | Dennis Whyte | Swept the strikepoints to avoid big injections.
And we didn't get a disruption...check! but still injection at 0.7 s. Qualifies as I-mode. H98>0.9, toasty pedestal: ~700 eV 160 kJ stored energy. Earl reports Zeff ~ 4... huh? Almost 1e14 n/s. Quite repetitive ELMs. |
| Oct 16 2009 02:59:03:340PM | 1091016025 | Dennis Whyte | Sweeps were started earlier. Shot ran through.
Impurity injection or source at 1.3 s at the last RF step up which degraded the confinement. L-mode ELMs again. 8e13 n/s, H98~0.95, Prad ~ 3 MW It almost seems like there is a weak particle transport barrier in this shot. Not really H-mode, but similar. Up to 4.8 MW without H-mode transition. Step 4, NL04=0.9 |
| Oct 16 2009 03:06:49:623PM | 1091016026 | Dennis Whyte | Step 4, NL04=0.7
Performance was actually degraded compared to the NL04=0.9 shot. This looks to be due to higher radiated power (despite lower density!) leading lower pedestal Te and lower stored energy ~ 125 kJ. No H-mode even with 4.7 MW of RF power. Got a disruption at the last power step. |
| Oct 16 2009 03:41:07:387PM | 1091016028 | Dennis Whyte | Step 4, NL04=1.0 q95 ~ 3.3
Very good I-mode shot. Got a brief H-mode at 1.45 s at 4.8 MW RF Some wild behavior in this as power goes up, the "h-mode" dithers seem to go away? One can see the effect of LBO at 0.8, 1 1.2 seconds. There are hints at lower power that the plasma retains the impurities longer, but not at higher power when Prad tends to decrease? Neutrons over 1e14 n/s. Wth up to 180 kJ. |
| Oct 16 2009 03:54:46:000PM | 1091016029 | Dennis Whyte | Step 4, NL04=1.1 q95 ~ 3.3
H-mode at 0.98 s at 4.4 MW Nominal I-mode (very brief) between 0.9 and 0.98 s. Interesting evolution of the separtrix Te with the small step in RF. Suggest something more like a "transition" to I-mode. |
| Oct 16 2009 04:06:50:930PM | 1091016030 | Dennis Whyte | Step 4, NL04=1.2 q95 ~ 3.3
D tripped out so not so interesting. Lots of injections. I've had it... here comes some neon |
| Oct 16 2009 04:23:54:170PM | 1091016031 | Dennis Whyte | Step 4, NL04=1.2 q95 ~ 3.3
/w neon injection Shot cleaned up, but pedestal stayed cold |
| Oct 16 2009 04:41:44:223PM | 1091016032 | Dennis Whyte | Step 4, NL04=1.0 q95 ~ 3.3
/w neon injection Much cleaner than 28 but the neutron count is lower probably too much neon? (Matt's suggestion) A very nice late I-mode but not so stationary There is a strong Prad reduction at 1.3 second, then T_ped starts increasing and we get a nice I-mode Stored energy goes up to near 200 kJ and we get a clear H-mode transition at 1.44 s. Very interesting transition |
| Oct 16 2009 04:55:20:383PM | 1091016033 | Dennis Whyte | Step 4, NL04=1.0 q95 ~ 3.3
/w neon injection but 1.1 psi in plenum Much cleaner than 28 and the neutron count in the 3rd power step was very constant at 1.2e14 n/s No ELMs Clear break in slope / transition into I-mode in the 3rd RF step. With apologies to the C-Mod team: this is a trophy shot |
| Physics Operator Comments | |||
| Oct 16 2009 07:26:32:273AM | Steve Wolfe | Starting setup for Friday run MP#579 Reports from the alternator drive repair last night are favorable, alternator is presently at 501rpm and rising. At this point we anticipate an on-time start at 9:00 PCS setup: load from 1091009013 (1.35MA, TF=-156.4ka,nl04=8e19) Seg2: Change zcur program from -.005 to +.001 to adjust elongation; I think my original estimate may be off (small) by a factor of two, but I don't want to go too far at 1.35MA close to q=3 Clearin at .294s from -.022 to -.0025 for earlier diversion nl04 flattop from 8 to 5e19 starting at 0.6sec, max from 1e20 to 8e19 at .34sec Seg1: PG4 is at 55msec (end at -.3sec instead of -.5) Has a big pg3 puff in seg1; leave it for now, scale back later? rcur offset=2000 Br_0 offset=0.0005 EF4=-1300 * set zcur to 0 at/after 0.1sec Load at 16-Oct-2009 07:26:21.00 Open tree /home/wolfe/pcs_scratch -1 Open tree done | |
| Oct 16 2009 07:38:22:543AM | Steve Wolfe | Continuing setup for first shot: Note that seg1 pg3 puff starts at .05sec. Why?? Move start of pg3 to .025, lower last half to 50V Also note that initial TF is at -156.4kA, like seg2; won't hurt, leave it. Load at 16-Oct-2009 07:38:08.00 Open tree /home/wolfe/pcs_scratch -1 Open tree done | |
| Oct 16 2009 09:07:17:123AM | 1091016001 | Steve Wolfe | Shot#1: Attempt at 1.35MA USN like 1091009013 with nl04=5e19, higher zcur (lower kappa), earlier divert. Likely issues: early vde, locked mode, q=3, early strike location Result: early disruption around 0.4sec, vertical problem, also q95 just under 3. Doesn't look like a locked mode, hadn't really diverted yet. |
| Oct 16 2009 09:42:15:960AM | 1091016002 | Steve Wolfe | Shot#2: reduce pg4 from 55 to 50msec slow down clearin increase (start ramp at .2, end at .38); may have found out why the divert was so late in the original? Complicated by oh1 crossover around 0.3sec, that seems to be the only supply other than efc that rails, but the ef2 lag was the cause of the vertical issue I think. Result: disrupts at .67sec in flattop. q95=2.9, kappa=1.67, rf is on at 2.5MW, nl04=6.5e19 There is an injection starting at .669sec that causes a rise in voltage demand. That could be the problem or it could be q=3. Next: raise zcur to +6mm, try again |
| Oct 16 2009 09:46:41:010AM | 1091016003 | Steve Wolfe | Shot#3: raise zcur to +6mm, try again, no startup change. result: fizzle |
| Oct 16 2009 10:10:29:080AM | 1091016004 | Steve Wolfe | Shot#4: Try again, no dpcs change let it clean up. raised zcur to +6mm from .001 (for #3) result: disrupts around the same time, got kappa=1.64,q95=2.88 First thing still seems to be halpha increase (injection?) .645sec I don't think there's a locked mode, and I don't see a mag fluct until right at the disruption, but it still could be 3/1. Try again with no rf |
| Oct 16 2009 10:19:04:253AM | 1091016005 | Steve Wolfe | Shot#5: Try again with no rf, see if that injection is related or even relevant. disrupts at same time, so it's not the rf. sawteeth look a bit ratty, locked mode? Try raising density back to 8e19, turn rf back on. |
| Oct 16 2009 10:26:52:367AM | 1091016006 | Steve Wolfe | Shot#6: Try raising density back to 8e19 in flattop, peak at 1e20, turn rf back on. drop nl04 gain from 9 to 5 before .5sec result: fizzle cryopump dump. 1e-5 at pulse |
| Oct 16 2009 10:47:54:690AM | 1091016007 | Steve Wolfe | Shot#7: repeat. Try raising density back to 8e19 in flattop, peak at 1e20 drop nl04 gain from 9 to 5 before .5sec cryo seems to be holding this time (Sue has it on manual) result: same disruption time. still lousy density control, probably still getting a locked mode looks like it sticks/slips with about 25msec period after .45sec, not as obvious on sawteeth as usual though. Next: put in some pg3 feedforward |
| Oct 16 2009 11:02:13:303AM | 1091016008 | Steve Wolfe | Shot#8: pg3 to 40V between .32 and .43sec raise NL04 D gain to 10 4.3e-7 at init, not sure cryo is pumping properly result: made it through, injection at 1.2sec, ELMs probably I-modish, density is unsteady but no big dips, averaging around 8e19, don't seem to be h-modes gas is trying to follow kappa=1.635, q95=2.87 |
| Oct 16 2009 11:11:21:087AM | 1091016009 | Steve Wolfe | Shot#9:nl04 P=5, D=10 all the way through pg3 to 20V after .43sec. Trying to smooth out density result: runaways early, disrupts at 1.25sec (where the injection happened on 8) Next: raise pg4, increase rcur by 2mm to decrease outer gap. |
| Oct 16 2009 11:23:16:827AM | 1091016010 | Steve Wolfe | Shot#10:raise pg4 from 50 to 54msec, add to pg3 in seg1 (deal with runaways) increase rcur by 2mm (to .658) to decrease outer gap (will decrease kappa) leave rxu alone (SL was considering decreasing triangularity) cryopump burped in init, coming back down... 4.5e-7 in check Result: fizzle, probably too much pg4, I think cryo was ok. Would be nice if the ratiomatic was working! Chalk it up to the disruption Next: repeat |
| Oct 16 2009 11:34:43:097AM | 1091016011 | Steve Wolfe | Shot#11: RXU out by 1cm to -.03 (SL changed his mind) Changes made for shot#10: pg4 at 54msec, added to pg3 in seg1 (deal with runaways) increased rcur by 2mm (to .658) to decrease outer gap (will decrease kappa) result: fizzle. Next: pg4 back to 50msec |
| Oct 16 2009 11:53:23:337AM | 1091016012 | Steve Wolfe | Shot#12: PG4 from 54 to 50msec Change made for #11: RXU out by 1cm to -.03 Changes made for shot#10: added to pg3 in seg1 (deal with runaways) increased rcur by 2mm (to .658) to decrease outer gap (will decrease kappa) Note: RGA died several shots ago, so we're really flying blind on vacuum IGT 2.5e-7 at INIT (was over 4e-7 last shot) result: disrupted earlier, .87sec Looks like the shape changes did as intended, du drops to .63, q95=2.88, k=1.64. next: move zxu up closer to plate. |
| Oct 16 2009 12:07:31:373PM | 1091016013 | Steve Wolfe | Shot#13: zxu from .005 to .01 igt=4.9e-7 at INIT (cryo on) result: disrupts at 1.07sec something bad happens at 0.9sec, injection seem on bolo, not on halpha density and Te both drop, maybe some core mhd there triggered by st Next: raise ZXU again |
| Oct 16 2009 12:23:19:083PM | 1091016014 | Steve Wolfe | Shot#14: zxu from .01 to .015 raise nl04 from 8 to 9e19 result: early disruption .3sec, something may come in at .29, but it's not huge. oh1 crowbarred, pf breaker pulled, after the disruption Next: repeat |
| Oct 16 2009 12:41:22:793PM | 1091016015 | Steve Wolfe | Shot#14: repeat zxu at.015 nl04 at 9e19 2.3e-7 in init result: another short disruption, with runaways this time. 0.24sec this time, I know I didn't change anything that early. marfe starts at ..2, radiation goes up, voltage goes up. The only change was zxu point at .564, but it's just possible that the interpolation to previous point at .238 matters,so insert an anchor at .4sec to keep everything before that fixed as on 13. Next: |
| Oct 16 2009 12:55:01:003PM | 1091016016 | Steve Wolfe | Shot#15: Anchor zxu trace at 0.4sec to be the same as #13, just to be sure. decrease pg3 in seg1 zxu at.015 nl04 at 9e19 2.3e-7 in init result: made it through rampdown, no runaways, some elms or maybe dithers k=1.68, q95 is up to 3.1, aout=.22, Wmhd=151kJ Next: repeat at higher rf power |
| Oct 16 2009 01:10:26:413PM | 1091016017 | Steve Wolfe | Shot#16: repeat at higher rf power 2.8e-7 in init Result: Another early disruption, with runaways. goes at 0.46sec, just after it goes diverted, almost to flattop, q05=3.1 There are a couple of injections at .3, .4sec, but not huge. no marfe. could be q=3 problem. Next: pg4 to 52 |
| Oct 16 2009 01:16:05:730PM | 1091016018 | Steve Wolfe | Shot#18: raise pg4 from 50 to 52msec, try again at higher rf power 2.6e-7 in init Result: disrupts at .7sec, still has runaways injections at .5sec, Next: go to 1.2MA, get well away from q95=3 |
| Oct 16 2009 01:30:07:720PM | 1091016019 | Steve Wolfe | Shot#19: go to 1.2MA, get well away from q95=3 pg4 to 54msec Result: plas,ma disrupts at 1.4sec, still runways. Little H-modes. small injection at 0.9sec, bigger one at the end. k=1.67, q95=3.4 Next: Drop zxu by 5mm, raise pg3 in seg1 |
| Oct 16 2009 01:42:16:910PM | 1091016020 | Steve Wolfe | Shot#20: Drop zxu from .015 to .01, raise pg3 in seg1 drop tf in seg 1 to -150kA: it's actually still rising at t=0, want to eliminate variability, small Bz, index change from normal Result: fizzle. I'm going to blame it on the previous disruption, rather than the seg1 changes I made. Next: repeat |
| Oct 16 2009 01:52:56:133PM | 1091016021 | Steve Wolfe | Shot#21: Repeat Changes for shot#20: Dropped zxu from .015 to .01, raised pg3 in seg1 dropped tf in seg 1 to -150kA to eliminate variability, small Bz, index change from normal start Result: fizzle Next: drop pg4 back to 50msec |
| Oct 16 2009 02:13:15:580PM | 1091016022 | Steve Wolfe | Shot#22: drop pg4 from 54 to 50msec Changes for shot#20: Dropped zxu from .015 to .01, raised pg3 in seg1 dropped tf in seg 1 to -150kA to eliminate variability, small Bz, index change from normal start Result: plasma disrupts at 1.25sec, runaways still there. Injection at .87 takes a bite out, another at 1.2sec kills up to 150kJ, 4MW. Next: put in an rxu sweep to try to reduce melting |
| Oct 16 2009 02:25:15:200PM | 1091016023 | Steve Wolfe | Shot#23: put in an rxu sweep between -.03 and -.04 and back again Pushed the button too soon, Yijun didn't get the last rf step programmed result: plasma made it through, still has runways Elms are back, one big injection at .75sec, smaller one at 1sec up to 160kJ at 4.2MW Next: increase pg3 again |
| Oct 16 2009 02:35:52:363PM | 1091016024 | Steve Wolfe | Shot#24: increase pg3 again, trying to get rid of the runaways without fizzling result: disrupts at .7, the injection got it that time. next: reverse the phase of the rxu sweep |
| Oct 16 2009 02:51:25:180PM | 1091016025 | Steve Wolfe | Shot#25: reverse the phase of the rxu sweep, which means it will be moving at 0.7sec move seg1 rcur in from .64 to .63 at .05sec Result: plasma full length, with runaways Injection at 1.3sec but it survives; seems to coincide with final rf step. Up to 165kJ, ELMs are present between 1 and 1.3sec next: nl04 to 7e19 |
| Oct 16 2009 03:03:54:780PM | 1091016026 | Steve Wolfe | Shot#26: nl04 from 9 to 7e19 reduce feedforward from 20 to 10V Result: plasma with runaways, disrupts at 1.3sec density was down to 7e19, Wmhd=125kJ, Next: raise density |
| Oct 16 2009 03:16:27:457PM | 1091016027 | Steve Wolfe | Shot#27: nl04 from 7e19 to 1e20 raise feedforward from 10 to 30V Resist urge to raise pg4 again Ed is now waiting 12min for magnet cooling to reduce ratcheting Result: fizzle |
| Oct 16 2009 03:28:59:820PM | 1091016028 | Steve Wolfe | Shot#28: tweak reverse rxu sweep so it doesn't go to the corner until 1.5sec nl04 from 7e19 to 1e20 raise feedforward from 10 to 30V Have Tommy pump out bside lower and fill with 2psi neon, in case SL decides we want to try it. Result: plasma full length, runaways, ELMs, H-mode at the EOF This shot had it all. Up to around 180kJ Next: nl04 to 1.1e20 |
| Oct 16 2009 03:47:14:750PM | 1091016029 | Steve Wolfe | Shot#29: nl04 to 1.1e20 feedforward puff up to 50V start, 40V level NL04 gain from P=5 to 7 after 0.7sec result: plasma full length, big injection at 1.1 h-modes at .95 and 1.3sec, second one gets over 210kJ Still have runaways early. Next: nl04=1.2e20 |
| Oct 16 2009 03:59:31:020PM | 1091016030 | Steve Wolfe | Shot#30: nl04 to 1.2e20, leave pg3 alone Result: plasma full length, lots of runaways, no h-mode this time, small injections all through less power, D tripped early, got to 4MW max Next: Repeat, enable B-side lower (neon) |
| Oct 16 2009 04:18:39:027PM | 1091016031 | Steve Wolfe | Shot#31: nl04 at 1.2e20, try for full rf, puff neon from 550 to 750msec (2psi) pg4 from 50 to 52ms Result: plasma full length, runaways beter, H-mode at the end, one injection .8sec, but survives and prad drops during rest of shot Got the RF, everything is much steadier. Next: NL04 back to 1.0e20, increase neon puff length |
| Oct 16 2009 04:35:24:017PM | 1091016032 | Steve Wolfe | Shot#32: nl04 from 1.2 to 1e20, seg2 pg3 to 40/30V leave puff neon from 550 to 750msec (2psi) result: plasma full length , no runaways, H-mode at the end. No injection this time, looks like an I-mode transition at 1.3sec Maybe neon is pumping out then, prad drops at rf power increase Next: reduce neon to 1.25psi and repeat |
| Oct 16 2009 04:46:15:163PM | 1091016033 | Steve Wolfe | Shot#33: reduce neon to 1.1psi and repeat with same timing (.55 to .75) result: plasma full length, neuts steady at 1e14/sec from 1.2 to 1.5sec in I-mode, H-mode at EOF, raises the Prad. Next: raise Ip to 1.35MA Or not, SL is thinking again |
| Oct 16 2009 05:01:58:670PM | 1091016034 | Steve Wolfe | Shot#34: raise Ip to 1.35MA, 1.1e20, leave feedforward as is leave Neon puff @1.1psi .55 to .75sec plasma full length with 2 H-modes, up to 1.7e15neut/sec W=237kJ, but prad is screaming up in each H-mode, probably needed more neon for the H-mode. END OF RUN, maybe come back to it later. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 09:00:13:230AM | Plasma | Ok | |
| 2 | 09:25:46:100AM | Plasma | Ok | |
| 3 | 09:44:50:790AM | Plasma | Ok | |
| 4 | 09:57:36:450AM | Plasma | Ok | |
| 5 | 10:10:49:783AM | Plasma | Ok | |
| 6 | 10:23:46:083AM | Plasma | Ok | |
| 7 | 10:38:47:183AM | Plasma | Ok | |
| 8 | 10:52:17:470AM | Plasma | Ok | |
| 9 | 11:05:28:070AM | Plasma | Ok | |
| 10 | 11:19:12:467AM | Plasma | Ok | |
| 11 | 11:32:06:080AM | Plasma | Ok | |
| 12 | 11:44:50:023AM | Plasma | Ok | |
| 13 | 11:57:40:560AM | Plasma | Ok | |
| 14 | 12:12:22:987PM | Plasma | Ok | OH1 self powered circuit fired after disruption |
| 15 | 12:31:08:290PM | Plasma | Ok | |
| 16 | 12:44:35:343PM | Plasma | Ok | |
| 17 | 12:57:40:143PM | Plasma | Ok | |
| 18 | 01:11:23:570PM | Plasma | Ok | |
| 19 | 01:24:09:717PM | Plasma | Ok | |
| 20 | 01:38:04:160PM | Plasma | Ok | |
| 21 | 01:50:48:460PM | Plasma | Ok | |
| 22 | 02:03:29:060PM | Plasma | Ok | |
| 23 | 02:17:55:310PM | Plasma | Ok | |
| 24 | 02:30:28:453PM | Plasma | Ok | |
| 25 | 02:43:03:490PM | Plasma | Ok | |
| 26 | 02:56:31:383PM | Plasma | Ok | |
| 27 | 03:11:42:047PM | Plasma | Ok | |
| 28 | 03:24:20:990PM | Plasma | Ok | |
| 29 | 03:39:27:370PM | Plasma | Ok | |
| 30 | 03:53:59:737PM | Plasma | Ok | |
| 31 | 04:09:22:943PM | Plasma | Ok | |
| 32 | 04:24:50:247PM | Plasma | Ok | |
| 33 | 04:40:21:207PM | Plasma | Ok | |
| 34 | 04:56:03:603PM | Plasma | Ok | |
| System Availability | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Oct 16 2009 08:59:46:950AM | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Oct 16 2009 12:57:18:643PM | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Oct 16 2009 02:54:03:540PM | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 350 C delta-T on K Limiter. Every good shot is heating it up. Maybe the earlier disruptions were it trying to defend itself from the threat of melting. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||