| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Ed Synakowski |
| Physics operator(s): | Steve Wolfe |
| Engineering operator(s): | Bill Parkin,Bill Byford |
| Engineering Operator Run Comment |
| MP#405 L-mode momentum confinement time determined from fast SSEP change |
| Session Leader Plans |
| Entered: Mar 10 2005 05:54:20:823PM |
| Author: John Rice |
| MP 405 L-mode Momentum Confinement Time Determined from Fast SSEP Change set up vanilla shot, 0.8 MA, 5.4 T, nl04 1.0 in LSN then switch to USN with a step in SSEP going from -0.5 to +0.5. determine toroidal velocity profile evolution from HIREX array. if successful, map out momentum confinement as a function of plasma current. |
| Entered: Mar 10 2005 06:33:54:400PM |
| Author: Ed Synakowski |
| Perturbative momentum transport - technique development and initial documentation
This experiment is aimed at developing a new technique for measuring momentum transport. The highest priority is to develop the control techniques for modifying ssep rapidly, where "rapid" is defined to be on the order of or faster than an energy confinement time. The basic idea picks up on the observations of LaBombard, Rice et al. over the last year or so regarding the dependence of edge flow velocity on configuration (LSN, USN, balanced), and how this flow velocity defines a boundary condition for core flows. The experiment will be done in L mode. The first step will be to make a rapid swing from LSN to USN, with Wolfe at the controls to minimize the time required to make this change. In the meantime, the core rotation measurements will be made to assess the size change in the rotation that is measured during this swing. It is likely that a density of 1.5e20 or more will be best for this measurement, as the largest difference in the rotation velocities observed in steady-state revealed a moderately strong density dependence. An important consideration in the experiment is the quality of the Ar spectra, so adjustments will likely be made in Ar puffing. Presuming that a momentum pulse is observed in the HIREX measurements, optimization will take place in the data acquisition time, Ar levels, etc.. This optimization will likely take place as the ssep changes are modified as well. In particular, one goal is to have a return configuration change, i.e. a square hat in ssep from LSN to USN and back. Having a flattop of at least a confinement time in each configuration may allow boxcar averaging of spectral data. Another goal is making the configuration change as brief as possible while still consistent with a good measurement. This may prove to be a valuable technique in the H mode, where the goal will be to be as minimally perturbing to the H mode state as possible. If this proves successful, then an optimized setup in ssep changes, Ar levels, and HIREX data acquisition will be used to scan a small set of plasma parameters. Plasma current will be the first to be scanned. Second priority is the plasma density. In short, the plan is as follows: - minimize the time for configuration change from LSN to USN, aiming for a ssep change from about -5 mm to +5 mm. Starting condition is 800 kA, 5.4 T, nl04. - increase and reduce the plasma density to identify the condition for maximum change in the density. - optimize measurement of rotation change through Ar gas puff, data acquisition. - docuement optimized condition well, e.g. multiple shots for statistics - develop square wave change in ssep (-5 mm to +5 mm to -5 mm) with flattops and dwell times of order or greater than taue. - shorten flattop periods to identify limiting factors in rotation pulse measurements - with optimal setup, perform variations in Ip. Likely at least two densities at the new currents. 1.2 MA is a likely starting point, then down to 0.5 MA. - higher field and lower field, assuming a wildly, amazingly successful day. Success will be declared if the basic elements of the technique are developed, and one condition is well documented. |
| Physics Operators Plans |
| Entered: Mar 10 2005 04:40:07:887PM |
| Author: Steve Wolfe |
| Engineering setup and Physics Operator plan
for Friday, 11-Mar-2005 MP#405 L-mode momentum confinement time determined from fast SSEP change SL: Rice, Synakowski PO: wolfe Engineering setup: ------------------- Overnight ECDC in D2, bake at 60C Power system as on 1050303004 Note: A-coils must be put back in standard configuration +Dtop -Dbot -Jtop +Jbot before run. Gas Setup: fill B-top with 6psi D2, Hybrid ENabled fill B-main (ex C-side) 30 psi D2, ENabled fill B-side lower 2 psi Argon, ENabled leave B-side upper as is (He3), DISabled fill lower capillaries (NINJA plenum) 10 psi D2 Enable ECE, Z-bolo shutters (assuming no vacuum problems) GV1 closed; bypass to RGA open Pump valves closed in pulse and 5minutes after shot Run Plan: ---------- The main problem for the physop in this run is to get a fast SSEP transition from lower null to upper null, and if possible back, perhaps for multiple times in a single shot. The goal is to change the dominant xpoint faster than a momentum diffusion time, which is approximately 20-25msec. A 10ms transition would be considered good. Start from seg4 of 1050303004 (SSEP control) reduce current to 0.8MA increase nl04 to 1.0e20 flatten rcur to produce outer gap constant ~1.5cm (check with Brian, in case he wanted this change) Program SSEP change from -.005 to .005 between 0.9 and 1.0sec Note that zcur is programmed to be -1cm. Probably want to either set this to zero or move it up simultaneously. Once I get the before and after conditions satisfactory, begin trying to shorten the transition time. We should have fast efit running on these shots, programmed to run at 1ms intervals during the time of the transition. Determine how fast we can actually make the switch from LSN to USN. If this is short enough, proceed to making a reverse transition. Then try multiple transitions, as called for by the SL's. If we get that far, proceed to different plasma conditions, as called for in the MP: Higher and lower density, then higher and lower current (1.2MA and 0.5MA). Take 2 or 3 shots at each condition. |
| Session Leader Summaries |
| Entered: Mar 12 2005 12:43:43:043PM |
| Author: Ed Synakowski |
| Perturbative momentum transport summary - Synakowski, Rice
â?¢ With a primary goal being the assessment of the viability of using a rapid LSN -> USN transition as a means of inducing a velocity pulse originating at the edge, it looks as though the response time limit is about 50 - 60 ms for a requested control system change. This is slower than expected, and if true may limit the utility of this for L mode. HOWEVER, it is likely that there is still value of such an edge perturbation in H modes or ITB plasmas, where expected momentum confinement times (assuming it is similar to tau-e) are considerably longer than this. â?¢ Operations were tough all day, with influxes in the USN configuration compounding the control challenges. ============================== The effect of configuration variation from LSN to USN on the core rotation was in fact observed in a single discharge. The primary condition was ohmic, 5.4 T, 800 kA, average target density of 1.4e14 cm-3. The battles of the day were configuration control (managing the rapid changes) and impurity influx in the USN configuration. It looks like shot 004 may have marked the start of the influx problem. Rapid EFIT analysis (EFIT01) revealed that fluxes may have struck an upper chamber structure after the switch to USN. It is not certain that this is the cause, but nevertheless increases in Prad were routines seen upon completion of the switch, and generally resulted in early termination of the discharge. Late in the day, plasmas in USN throughout the pulse were run, and some resulted in impressive displays of material influx as seen in diagnostics such as H-alpha as well as some of the RF/LH camera views. Adequate Ar signal levels were obtained that suggest that multiple configuration changes in a shot, or shot averaging, might yield a good measure of momentum confinement, especially in plasmas with longer confinement times such as H modes, EDA H modes, or ITB plasmas. So to this extent the experiment was a success, and it is worth considering development of an H mode/ITB momentum confinement proposal if the USN impurity influx problem can be managed (hopefully a good weekend of GDC will go in the direction of helping this problem). Due to the influx and control problems, no effort was begun regarding performing a parameter scan of any sort. |
| Physics Operator Summaries |
| Entered: Mar 11 2005 07:09:53:980PM |
| Author: Steve Wolfe |
| Physop Summary for Friday, Mar 11
MP#405 Fast SSEP change for momentum diffusion measurements SL: Synakowski PO: wolfe EO: Pfeiffer, Dekow, Parkin, Byford This was a difficult day, partly because the experiment was intrinsically hard, and partly because after shot 4 we had problems that seem to be indicative of dirt or something out of place in the upper divertor. This manifested as increased radiation and injection events when we went to positive ssep. Hopefully a weekend of ecdc will help clean up. In the end, I think we may have demonstrated that the maximum rate at which we can swing ssep from negative to positive is about 50-60ms. This is longer than the momentum confinement time in L-mode plasmas, and so implies that the technique is not feasible for the measurement as proposed. The best example is the final shot, #27, in which the ssep demand was a 10ms ramp from -7mm to -3mm (which actually corresponded to -5mm to -1mm) did not reach target until 55msec. This was about half the slew we actually wanted for the experiment. While there is some headroom on the gain, we seem to be at power supply limits for the controller used for SSEP. One way out might be to try to do the experiment using fast zcur control to move a nearly balanced DN up and down, rather than trying to do the transition by driving the X-points up and down with the plasma more or less stationary. This technique would definitely require additional development. Note that all ssep control shots today used seg4. We also ran a few upper null plasmas using seg3. We still have not demonstrated acceptable control of an upper null using SSEP control. Using a clearin predictor referenced to the upper null location was somewhat successful (see shot 4), but still allowed the gaps to change from the previous values. The problem may be that the ssep control moves the upper xpoint below the nominal location. Shot 4 was the best (only) example of a lower to upper transition more or less controlled into rampdown. The L->U ramp in this case was 100msec. This shot may have damaged something in the upper chamber, because all subsequent shots that were run upper null had lots of injections and very poor control. The strikepoints during shot 4 were on the ceiling during flattop, but may have interacted badly with the gussets during rampdown. After shot 4, we tried to speed up the ramp, first to 50msec and then to 25. These shots had poor gap control during and following the transition and disrupted by 1.2sec. At shot#8 I tried changing the SSEP controller to be orthogonal to ZXU and not to ZXL, and reducing the gain on ZXL. However, I later discovered that I had somehow expunged the 12700 A-m offset in the second clearin predictor in setting up this shot. This introduced a large thrash in the clearin error signal at 0.9 sec when the predictor switched in. That, rather than the change of controller was probably responsible for the nearly instantaneous disruption on this shot, and on shot 10 where I removed the new ssep controller. For shot 11 I reloaded the seg from shot 7, which reproduced the disruption on that shot, after a couple hundred msec on the upper null. After a few more unsuccessful attempts to get decent operation on the upper null, changing gains and such, we decided to try a straight upper null program, using seg 3 which had also been loaded from 1050303. These shots, #20-23, were also dirty and full of injections and early disruptions, demonstrating that at least part of the problem was with the upper divertor, rather than with SSEP control or transitioning from lower to upper. Since the upper divertor shots did not seem to be improving, we finished the run by going back to lower null and doing the SSEP sweep only as far as DN (program to -.002 and -.003) on shots 24-27. Of these, shot 27 is the best example, as described above. Startup continued to be problematic today, although fizzles were less of a problem than the last couple of days. There were a number of high runaway discharges, all arising out of bouncy (outside strikes) startups. I raised the rcur offset in seg1 to 2000 at shot 3 and that seemed to help but did not eliminate the problem. The pre-puff still seemed to need to be high, relative to previous weeks. Some of the early shots had unexplained excess density, reminiscent of the Wednesday experience. Since NINJA had been puffing at about the time we saw the rise and the pg3 shut off, I had them turn off, but that was almost certainly not the cause of the problem. Scorecard: Tests 0 Duds 0 Fizzles 3 Plasmas 24 ------- -- Shots 27 |
| Session Leader Comments | |||
| Mar 11 2005 04:33:33:027PM | Ed Synakowski | USN only. Short and bright (just over > 0.5 s). SO the problem is not only control... | |
| Mar 11 2005 04:48:55:747PM | Ed Synakowski | Longer! Under considerable distress. Went out to 1.25 s or so, the longest in a quite a while. | |
| Mar 11 2005 11:12:54:367AM | 1050311001 | Ed Synakowski | This shot will be an attempt to go from LSN to USN from 0.9 to 1.0 s. ICRF will condition starting at 1.4 s.
Died around 1.2 s, after the move to USN. Lots of hard X-rays as seen on the speckles of the plasma TV monitor. Undershot on the requested current - looked like it was in distress. Overshot on density. EFIT says that the requested quilibrium change was successful, however. EFIT01 being run as well as usual analysis to track fast changes in the equilibria. ninja puff request will be cut way back. Steve has to make a large number of changes... LH will go in at 400 ms on the next shot. |
| Mar 11 2005 11:36:56:663AM | 1050311002 | Ed Synakowski | This plasma died even earlier, around 0.5 s. Density excursion at around 0.3 s. Will ask for no NINJA gas on the next shot. |
| Mar 11 2005 11:40:25:880AM | 1050311003 | Ed Synakowski | Better in terms of pulse length. Died just after 1.5 s. Density still too high, but better (line average peaks at around 2 near 850 ms). Made a decent configuration change from 0.9 - 1.0 s.
HIREX was hit hard by hard x-rays. Ip was closer to 800 kA level. In LSN, MARFE in upper part of vessel. In LSN, MARFE moves to the lower chamber. |
| Mar 11 2005 11:49:30:100AM | 1050311003 | Ed Synakowski | Better in terms of pulse length. Died just after 1.5 s. Density still too high, but better (line average peaks at around 2 near 850 ms). Made a decent configuration change from 0.9 - 1.0 s.
HIREX was hit hard by hard x-rays. Ip was closer to 800 kA level. In LSN, MARFE in upper part of vessel. In LSN, MARFE moves to the lower chamber. Steve has worked on startup in an effort to beat down the density, and perhaps help the hard x-ray situation. |
| Mar 11 2005 12:11:25:553PM | 1050311004 | Ed Synakowski | Hard x-rays better. A burst of D-alpha at the start of the USN phase - hitting something? Nel is lower, close to the target value.
First sign of success in the HIREX signal! A change in the central rotation that takes place on the same time scale as the SSEP change. This shot actually made out to nearly 1.7 s, well into the Ip rampdown. John will ask for more Ar for the next shot (20 ms more). Next shot will try to make the ssep change 50 ms faster, from 900 to 950 ms. |
| Mar 11 2005 12:25:38:443PM | 1050311005 | Ed Synakowski | Shot terminated after 1.1 s. Vertical instability? Small glitch on D-alpha at the top of the SSEP change. MARFE towards the end. Density a bit high.
Ohmic heating takes off right after the SSEP change. Bolometer nearly triples in signal. Fast EFIT01 did not go through. |
| Mar 11 2005 12:41:24:473PM | 1050311006 | Ed Synakowski | Shot lost right after the SSEP transition, near 1 s. Vertically unstable.
Will raise the density a skootch, from .8 to .9 nl04 |
| Mar 11 2005 01:06:34:600PM | 1050311007 | Ed Synakowski | Again, terminated early. Distress again begins at 950 ms time, start of USN period. |
| Mar 11 2005 01:10:31:600PM | 1050311008 | Ed Synakowski | Unstable again. Steve is scratching his chin... |
| Mar 11 2005 01:54:17:507PM | 1050311010 | Ed Synakowski | Quick demise again at 950 ms at top of LSN -> USN transition. Read Steve's notes.
|
| Mar 11 2005 03:12:25:960PM | 1050311011 | Ed Synakowski | virtually identical to 007, which has its own difficulties but at least they are reproducible.
John has some HIREX data that shows the general shift to more counter-directed rotation after the switch. Since this is so similar to 007, I am wondering if these data can be averaged. |
| Mar 11 2005 02:31:15:803PM | 1050311012 | Ed Synakowski | Died near 830 ms, BEFORE planned SSEP step. Something fell in, perhaps. Mo? Something radiates 10 MW, albeit briefly.
Will redo, since all of programmed changes were for after this time. |
| Mar 11 2005 02:47:04:960PM | 1050311013 | Ed Synakowski | Another early demise. Unclear what is going on. |
| Mar 11 2005 03:04:27:367PM | 1050311014 | Ed Synakowski | Terminated just before 1 s. |
| Mar 11 2005 03:10:57:113PM | 1050311015 | Ed Synakowski | Lost density feedback, and thereful control. Loads of runaways. Still died at the top of the LSN -> USN switch. |
| Mar 11 2005 03:48:57:937PM | 1050311017 | Ed Synakowski | Distress at .73, early termination. |
| Mar 11 2005 04:10:19:213PM | 1050311018 | Ed Synakowski | Made it farther (almost 1.2 s).
But ohmic input power skyrockets after the switch. Is it beginning to limit on the outboard side after the switch? Looks like it, according to EFIT01 analysis. Maybe hitting something out there that is then introducing gunk. |
| Mar 11 2005 04:27:32:073PM | 1050311019 | Ed Synakowski | Similar pathology. Rained on with sparks near 1 s, according to J port antenna view.
Steve will try UN all the way through on the next shot. |
| Mar 11 2005 04:36:08:760PM | 1050311020 | Ed Synakowski | USN only. Short and bright (just over > 0.5 s). SO the problem is not only control... |
| Mar 11 2005 04:49:19:200PM | 1050311021 | Ed Synakowski | Longer! Under considerable distress. Went out to 1.25 s or so, the longest in a quite a while. |
| Mar 11 2005 05:36:58:870PM | 1050311024 | Ed Synakowski | This was an attempt to stop just shy of diverted USN. This plasma lasted longer than any other, except shot 004.
Loads of hard x-rays. Evidence for junk falling in after 1 s on D-alpha. Camera shows lots of gub coming in early, too (early in the ramp, 100 ms neighborhood). |
| Physics Operator Comments | |||
| Mar 11 2005 08:38:43:647AM | Steve Wolfe | Setting up for the run, more or less as indicated in the plan:
Load from 1050303004. Note that while the titles of segs 2-4 say these are 0.8MA, they are not. Seg 2 is 1.2MA, and seg4, which is the one I'm after, is 1.05MA. In seg4: Change ip to 800ka, nl04 to 1.0e20, SSEP program from -.005 to +.005 between 0.9sec and 1.0sec copy trace from wire 11 to 12, just in case. I don't need the second ssep wire, but I may want to look at an alternative clearin that maps to the upper xpoint. Put a second clearin on wire 9, with gains off and referencing zxa=+.394,offset=12700 On all_v, shorten acoil_cur trace from 10sec to 2.5 put oh2 voltages to ~20V through eof, as in seg2 I should probably put the zcur to 0, but I'll wait a shot on that. Also, I'll leave the rcur and rxl programming as is until I get a targeting evaluation from Blab. Now for the startup. Joe was making a lot of changes yesterday, and seemed to be getting improved startups toward the end of the day. However, the breakdown was rather late on the last shot. Import seg1 from 1050310026, change IC_ef4 from -1345 to -1355 leave pg4 at 21ms and Br0 at -.002 Note that in both seg1 and seg4 the chopper voltage is non-zero in flattop (150 in seg 1 and 100 in seg4).This affects the bias (average) current and should no longer be set this way. Checking, the bias is low on 1050303004. Set the chopper voltage to zero on ALL_V's in both seg 1 and 4 Load into model | |
| Mar 11 2005 09:22:42:287AM | Steve Wolfe | Note that the gain switching in seg4 has SSEP gain at 6
from the start of the segment, and ZXU gain dropping from 2.0 to 0.2 at about 200ms. I may want to consider a change in the SSEP controller to make it ortho to ZXL instead of ZXU at the time I go upper null, and also bring ZXU gain back on and drop ZXL gain (from 8) at that time. This is an additional complication, on top of the change in clearin reference, for the UN part of the discharge. If I do this, I'll want the ZXU position program to be close to nominal. The waveform is presently drawn to +.03, which is probably appropriate for the lower null, and ZXL should probably be more like -.03 in the upper null phase. | |
| Mar 11 2005 09:42:01:680AM | Steve Wolfe | Also note that the upper null program in seg3
has ZXU=.005, RXU=-.02 straight across, while the seg 4 program is ZXU=.03 and RXU moving out from -.02 at 0.8sec to -.006 at 1.5sec. EFIT for 1050303004 does show a small, ~1cm, outward drift in RXU. This may or may not be a good thing. To keep the strike off the gusset I may want to leave the program more negative, but I have to watch the ef2u current to see it doesn't go to zero; it's ok on the old shot, but that's at different current and density. Go ahead and make the change to RXU=-.02 in flattop, then back in in rampdown, and see what happens. Still leaving the funny sweep in RXL. Load into model Load at 11-Mar-2005 09:41:50.00 Open tree /home/wolfe/pcs_scratch -1 Open tree done | |
| Mar 11 2005 11:15:48:430AM | 1050311001 | Steve Wolfe | Shot#1: First try at lower to upper.
Plasma to 1.2sec, didn't like something anbout the upper null. Startup is ratty, several bounces;lots of hard xrays. Current is low. SSEP looks like it is starting -.3 going to +.5 Clearin also takes a big jump. Strike point is going close to the gusset by the time it disrupts. Clearin on wire 4 thinks it's happy, but the one referencing the upper null on wire 9 is at zero in the first half and shows the increase to 10000A-m at the switch, i.e. it is right all the way through. The current is off because the seg4 still is using the old rogowski values! It never got re-called, which means Ian or whoever ran the whole day with the wrong value! Next shot: Call the alg of Ip, offset to -70000. Add a second alg line to clearin referencing the upper null starting 0.9sec. If I need to do this several times, it isn't going to be possible to program multiple chops with the present user interface. EF2's are getting pretty low; reduce pre-program on EF4 from 2000 to 1000 Now for the startup. IC_EF4 from -1355 back to -1345 pg4 from 21 to 24ms Change SSEP program to start at -.007 and end at +.003 (there may be a problem with the -2500 value in the offset, but I don't want to think about which way it needs to go). Gas is off after .64sec. Request NINJA to reduce puff by at least a factor 2. |
| Mar 11 2005 11:29:35:380AM | 1050311002 | Steve Wolfe | Shot#2: Early disruption
big density increase at 0.3sec. NINJA claims it isn't them, but turn them off anyway. Startup still ratty, not as bad on the hards. next shot: rcur offset from 1500 to 2000 in seg1 |
| Mar 11 2005 11:46:53:287AM | 1050311003 | Steve Wolfe | shot#3: plasma to 1.6sec
Density is too high early. Where's it coming from? Valve is off from 600msec to 1.1sec Gaps are better, still some thrash at the transition. Startup barely made it- one big bounce and recovers. Lots of hards again. Next shot: reduce .1sec Ip point from 700kA to 550kA Slow down density rate of rise, reduce seg4 pg3 pulse Increase pg4 to 26ms |
| Mar 11 2005 12:08:23:490PM | 1050311004 | Steve Wolfe | Shot#4: plasma to 1.7sec
density is better controlled, still has a step in current at the gain switch. Startup is better, no bounce. Outer gap is dropping some at L->U transition Inner gap is too, still need better clearin control John wants 20ms more on argon EF2U is going close to zero at the transition, and EF4 swings negative, and it's during crossover that we get a dalpha burst. next shot: Try ef2byef4 target at -3000 shorten the transition to 50ms Since I'm not sure what to do about the clearin, leave it |
| Mar 11 2005 12:27:59:320PM | 1050311005 | Steve Wolfe | Shot#5: L->U programmed from .9 to .95sec
Changed ef2_by_ef4 to -3000A Disrupts at 1.2 Voltage goes up right after L->U; why? Marfe at 1.2sec Gap control looks worse on this one. ZXU is actually down to .36 when it goes to UN. John wants lower density. Change zcur to zero, move zxl down at transition. |
| Mar 11 2005 12:44:26:320PM | 1050311006 | Steve Wolfe | Shot#6:nl04 to 0.8e20, zcur to 0, zxl to -.01 at .95sec
Disrupts at 0.98sec, VDE May have been the zxl change at high gain? next shot: nl04 to 0.9, remove the zxl jump, reduce gain on zxl from 8 to 1 at .95 |
| Mar 11 2005 01:05:09:427PM | 1050311007 | Steve Wolfe | Shot#7: nl04 to 0.9,
remove the zxl jump, reduce gain on zxl from 8 to 1 at .95 Hard xrays again, disrupts at 1.2 again. Startup bounced again. EF2U goes to zero at 1sec, I may need to change the controllers on both clearin and ssep during the upper null. Next shot: Change clearin controller at .95, zxa=.394. I don't think that actually will do anything Change ssep controller to be ortho to zxu instead of zxl after .95 That seems to require factor 2 longer time constant, not sure why Increase pg4 from 26 to 28 |
| Mar 11 2005 01:34:24:427PM | 1050311008 | Steve Wolfe | Shot#8: Plasma to .95, seems to have died right
at the time I changed the controllers. The new ssep controller is very different, in ways I don't really understand. Maybe the controller code is broken. Call it again. The constraints should be such that the coefficients should be proportional to the normal zxl controller, but it is very different. Recall the original one and get rid of the switch. |
| Mar 11 2005 01:35:10:710PM | 1050311008 | Steve Wolfe | Shot#8: Plasma to .95, seems to have died right
at the time I changed the controllers. The new ssep controller is very different, in ways I don't really understand. Maybe the controller code is broken. Call it again. The constraints should be such that the coefficients should be proportional to the normal zxl controller, but it is very different. Recall the original one and get rid of the switch. This ought to put it back the way it was. |
| Mar 11 2005 03:45:57:803PM | 1050311008 | Steve Wolfe | Somehow on this shot the 12700 offset in the clearin predictor
got lost. This may explain the disaster at .9 which I attributed to the controller switch which I also implemented on this shot. |
| Mar 11 2005 01:39:52:693PM | 1050311009 | Steve Wolfe | Shot#9: fizzle. Moves in.
Drop pg4 back to 25msec |
| Mar 11 2005 01:54:40:850PM | 1050311010 | Steve Wolfe | Shot#10: Still trying with a single ssep controller
This ought to be like shot 7, which isn't a great target to shoot for, but I need to see if the ssep controller is really the reason for the huge slam on shot 8 Disrupts hard at .952, just like 8. Apparently that was not the problem. I still have the clearin changed controller in there, but those looked identical. Also I recalled the alg for ssep. Just reload the segment from shot 7 and try again. |
| Mar 11 2005 02:19:52:053PM | 1050311011 | Steve Wolfe | Shot#11: reload the segment4 from shot 7 and try again.
plasma to 1.2, looks like shot 7. next shot: Try going even faster, reduce clearin and ssep gains after .9sec |
| Mar 11 2005 02:30:37:490PM | 1050311012 | Steve Wolfe | Shot#12: ssep ramp in 25msec,
clearin gain from 9 to 5 at .9 ssep gain from 6 to 3 at .95 Increase argon another 20ms for JR disrupts at .84, before anything is supposed to happen. Possibly unrelated injection. Try that one again |
| Mar 11 2005 02:46:46:380PM | 1050311013 | Steve Wolfe | Shot#13: ssep ramp in 25msec,
clearin gain from 9 to 5 at .9 ssep gain from 6 to 3 at .95 Disrupts at .72sec. Something is coming in at 0.68 John says not Moly. Startup is as little slow one more try |
| Mar 11 2005 02:56:58:757PM | 1050311014 | Steve Wolfe | Shot#14: ssep ramp in 25msec,
clearin gain from 9 to 5 at .9 ssep gain from 6 to 3 at .95 pg4 down to 23msec Disrupts at .96 sec. Just past the switch. Fast efit says the ssep is almost following demand, gets to +2mm at .938, but then starts being unstable. We're losing vertical stability at the same time. That may be the limitation, the elongation is going up, n/ncrit gets to 1.2 by .95sec Both gaps are growing, which may be because I reduced clearin gain. |
| Mar 11 2005 03:05:35:537PM | 1050311014 | Steve Wolfe | Shot#14: ssep ramp in 25msec,
clearin gain from 9 to 5 at .9 ssep gain from 6 to 3 at .95 pg4 down to 23msec Disrupts at .96 sec. Just past the switch. Fast efit says the ssep is almost following demand, gets to +2mm at .938, but then starts being unstable. We're losing vertical stability at the same time. That may be the limitation, the elongation is going up, n/ncrit gets to 1.2 by .95sec Both gaps are growing, which may be because I reduced clearin gain. Found something, maybe. There is a zero offset in the second clearin gain. I could swear I set that, but there is a definite jump in apparent clearin error. Set the offset to 12700 and try again |
| Mar 11 2005 03:20:53:520PM | 1050311015 | Steve Wolfe | Shot#15:Runaways, tci failed and turned off gas.
Disrupted at .96, so this is another ssep switch disruption Still has a jump in the clearin value, And it still seems to be vertically unstable. The second clearin seems to have been there since shot2 It also still isn't following ssep at 25ms Reduce the ramp back to 50msec |
| Mar 11 2005 03:37:24:130PM | 1050311016 | Steve Wolfe | Shot#16:Reduce the L->U ramp back to 50msec
fizzle Bounces? But it seems to be going in at the time. |
| Mar 11 2005 03:49:28:433PM | 1050311017 | Steve Wolfe | Shot#17:Drop pg4 to 21msec
Still with the L->U ramp back to 50msec Plasma to .75sec, probably another injection. I'm going to drop the gain on nl04 before .6 sec because the gas is flopping around, and try again. |
| Mar 11 2005 04:10:18:213PM | 1050311018 | Steve Wolfe | Shot#18: drop the gain on nl04 before .6 sec
because the gas is flopping around, and try again. Still trying to get to the switch with the reduced speed and correct clearin predictor. While I'm at it, back off 20ms on the argon puff plasma to 1.14, past the L->U swing, but the control is still bad. Outer gap is getting close to zero. Need to recover clearin control. put clearin gain back up at 1sec |
| Mar 11 2005 04:29:49:480PM | 1050311019 | Steve Wolfe | Shot#19: Notch in clearin gain between .9 and 1 to try to recover
some gap control. plasma to 1.14sec Almost the same. I can move the plasma in at the same time, which may help. However, Jim Irby points out that there is a rain of sparks from above the JANT camera view. Instead, let's run an upper null all the way through. |
| Mar 11 2005 04:39:07:340PM | 1050311020 | Steve Wolfe | Shot#20: Try an upper null.
Turn on seg 3, change nl4 to 9e19 Give John 70msec of Ar Disrupts at 0.55sec, looks ugly for awhile before. This one is touching the outer limiter at 0.4sec, which is not the cause of the problem but I probably should move in a bit. |
| Mar 11 2005 04:49:31:590PM | 1050311021 | Steve Wolfe | Shot#21: Adjust Rcur a little inward and try again for upper null.
plasma to 1.26 seconds but lots of junk coming in. next shot: try again with increased clearin |
| Mar 11 2005 05:04:43:527PM | 1050311022 | Steve Wolfe | Shot#22: clearin from 0 to .0025
Short again, .55sec Startup is a little slow, and bd is a little late. next shot: drop pg4 2ms and move clearin increase a bit later |
| Mar 11 2005 05:22:25:963PM | 1050311023 | Steve Wolfe | Shot#23: pg4 to 19ms, clearin .0025 point to .514sec from .414
plasma to .8sec, something bad happens at .67 Next shot: Go back to seg4 and swing up from -.007 to -.002 just shy of upper null |
| Mar 11 2005 05:36:16:950PM | 1050311024 | Steve Wolfe | Shot#24:Go back to seg4 and swing up from -.007 to -.002 in 30msec
just shy of upper null Remove clearin notch, second clearin predictor, ssep gain drop Lots of runaways this time, but it lasted to 1.65 ssep is just about zero after 1sec. Lots of injections after 1 second. Startup bounced again, amaybe a couple times. Looks like the ssep excursion takes about 60-70msec next shot: increase pg4 by 2msec, decrease ssep final to -.003 |
| Mar 11 2005 05:45:16:353PM | 1050311025 | Steve Wolfe | Shot#25:increase pg4 by 2msec, decrease ssep final to -.003 in 10msec
fizzle, looks like one bounce and done. Another 2ms on pg4 and hope it goes |
| Mar 11 2005 06:03:21:463PM | 1050311026 | Steve Wolfe | Shot#26:increase pg4 by 3msec, to 24msec
ssep final to -.003 in 10msec Early disruption .7sec. Something is falling in. |
| Mar 11 2005 07:11:12:073PM | 1050311027 | Steve Wolfe | Shot#27: One last try.
Plasma into rampdown Few or no injections Hesitation in startup, but no runaways. SSEP gets to about -.001 at .954 and oscillates about that level. In some ways this is the best shot of the day. Thanks to Bill and the alternator crew for allowing us one more shot after 18:00. I think that 50-60ms is about as fast as we can swing it. This probably means that this technique is not going to be suitable for the momentum confinement measurement, even if the control in the upper null state could be improved. The limitation may be the EF1U and EF2U slew rates. EF2U actually seems to have enough voltage, but the lag between demand and supply voltage seems to be about 10msec. EF1U demand is going from +200 to -200V, and the supply never gets below -40V. I missed removing one gain switch, the drop in zxl gain at .95sec, which is visible as a drop in the ef1L voltage, but that's not really at issue. It may be possible to go a little faster by increasing the gain, but this is already ringing and is pushing on power supply lags for the thyristor supplies, especially ef2. |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| 1 | 10:36:01:537AM | Plasma | Ok | |
| 2 | 11:14:16:507AM | Plasma | Ok | |
| 3 | 11:30:57:083AM | Plasma | Ok | |
| 4 | 11:48:30:570AM | Plasma | Ok | |
| 5 | 12:11:20:037PM | Plasma | Ok | |
| 6 | 12:29:27:477PM | Plasma | Ok | |
| 7 | 12:45:01:897PM | Plasma | Ok | |
| 8 | 01:05:09:350PM | Plasma | Ok | |
| 9 | 01:36:11:007PM | Plasma | Ok | |
| 10 | 01:48:40:570PM | Plasma | Ok | |
| 11 | 02:04:50:913PM | Plasma | Ok | |
| 12 | 02:23:20:583PM | Plasma | Ok | |
| 13 | 02:35:50:257PM | Plasma | Ok | |
| 14 | 02:48:20:617PM | Plasma | Ok | |
| 15 | 03:07:11:617PM | Plasma | Ok | |
| 16 | 03:32:36:803PM | Plasma | Ok | |
| 17 | 03:45:00:130PM | Plasma | Ok | |
| 18 | 03:57:48:860PM | Plasma | Ok | |
| 19 | 04:12:23:370PM | Plasma | Ok | |
| 20 | 04:30:27:057PM | Plasma | Ok | |
| 21 | 04:42:53:510PM | Plasma | Ok | |
| 22 | 04:58:21:917PM | Plasma | Ok | |
| 23 | 05:11:28:010PM | Plasma | Ok | |
| 24 | 05:28:39:200PM | Plasma | Ok | |
| 25 | 05:42:04:293PM | Plasma | Ok | |
| 26 | 05:54:50:557PM | Plasma | Ok | |
| 27 | 06:07:14:480PM | Plasma | Ok | |