Miniproposals

Miniproposal: 079 Date Filed: 1/23/1995 Title: Toroidal Field Scan with ICRF Heating First Author: Yuichi Takase Session Leader: Ian Hutchinson (shots 1-20) Session Leader: Yuichi Takase (shots 21-36)

Engineering Operator Run Comment

bertilino/silva

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:12:147PM

Author: To Be Determined

SL: Hutchinson (1st half) Low Field Startup Takase (2nd half) ICRF BT Scan PO: Hutchinson EO: Silva/Bertolino MP079 ICRF Toroidal Field Scan The objective of the second half of run was to study the effect of off-axis ICRF heating by varying the toroidal field. A downward scan was accomplished at nel_04=1.1e20/m2 and Ip=0.8MA with approximately 2.5MW of RF power. No H minority was added to ensure localization of the power deposition zone to the fundamental H resonance layer (addition of H will shift the power deposition zone toward the high field side). The ohmic stored energy (EFIT) was found to be independent of the toroidal field, at about 47kJ for the present condition. With on-axis heating, the stored energy increases to 80kJ during the L-mode phase (90kJ during the H-mode phase, see shot 950201027). The stored energy increment decreases as the resonance layer is shifted away from the center. With the resonance layer shifted half way out the stored energy (RF heated) was 60kJ, and no stored energy increase was observed when the resonance layer was shifted by r/a >= 3/4. For on-axis heating, H-mode transitions were observed on all shots with resonance layer located at r/a <= 1/4. We still have a difficulty maintaining constant power through L-H transitions, but we were able to keep reasonable power across the transition and observe the stored energy increase (from L to H-mode) on some shots. We will be making more improvements in this area. The outer gap was 1.5cm or greater on most shots, except shots 23 and 25 which had an outer gap of 1.0cm. The density was constant at nel_04=1.1e20, except for shots 17, 20, and 21 which were lower density (nel_04=0.8e20). The following is a list of toroidal field and RF power. shot BT(T) Prf(MW) 17 3.77 0.8 20 3.77 1.1 21 5.15 1.35 22 5.15 2.7 23 5.34 3.1 25 5.34 3.0 26 5.34 3.2 27 5.34 2.65 28 4.84 2.4 29 4.45 2.4 30 4.11 2.4 31 4.11 2.4 32 5.34 2.4 33 5.48 2.3 34 5.48 2.2 36 5.07 2.2 When the administrative limit on the toroidal field is raised, we should complete the upward scan. We should also repeat the scan with higher minority concentration.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:53:067PM

Author: To Be Determined

1.Low Field Initiation. 2.TF Field scan with RF. 950201 _______________________________________________________ PO, SL : Hutch SL: Takase, Part 2, RF. EO: Silva Objectives: The objective of part 1 was to obtain an initiation on the TF ramp at about 3.4T so that it is trivial to obtain TF fields during the main plasma from 3.5T and up by simply changing the TF demand current. Part 2 was to use this to scan the field for the RF to move the resonance in the plasma. Both objectives were accomplished in fine style. RF details may be found in the SL log of Takase. Outline: Using a shot from 27 Jan 95, various tweaks were applied. Mostly to overcome a bounce on the outboard because of rapid current rise. The important favourable tweaks, other than correcting for the different Bt pickup are: Symmetrize the EF1s during the precharge: Shots 5- Raising the fill (maximum successful 3.0) Shots 8,19,.. Initiate EF2s at -.5s (vs -.4) helps EF1s. Shots 6- Lower OH2 commutation resistors by 1.2 mOhm. Shots 15- Restore RCUR offset to 8000. Shots 20- Raise initial RCUR P gain to 9.5 (maxed out) Shots 20- Some early Moly problems were experienced. Shot 24 is a horror. Little or no significant changes were made in PCS after shot 26. The TF scan using demand worked well. We were unable to exceed 5.5T because of administrative limits inherited from Fairfax and built into Paragon. These are to be raised on Monday. Computing: The first 20 shots went much faster than the last 16 because of the very slow IGOR once everything was turned on. Restarting the the servers definitely helped to spedd things up, later on. Scorecard: Shot,Duration(s),Ipmax(MA) Shot,Duration(s),Ipmax 1 0.000 0.022 2 0.000 0.013 3 0.000 0.024 4 0.000 0.013 5 0.000 0.010 6 0.000 0.026 7 0.000 0.029 8 0.000 0.023 9 0.000 0.026 10 0.000 0.024 11 0.000 0.018 12 0.000 0.024 13 0.000 0.031 14 0.000 0.029 15 0.000 0.029 16 0.377 0.541 17 1.081 0.825 18 0.000 0.050 19 0.000 0.044 20 0.870 0.903 21 1.559 0.819 22 1.375 0.835 23 1.402 0.830 24 0.271 0.574 25 1.418 0.830 26 1.440 0.835 27 1.453 0.835 28 1.457 0.823 29 1.461 0.815 30 1.423 0.811 31 1.421 0.811 32 1.411 0.833 33 1.435 0.831 34 1.434 0.836 35 0.000 0.016 36 1.419 0.824 Finished summary for 950201 Total of 36 shots. 36 shots. 18 plasmas. 14 fizzles. 4 duds. Fizzle = gt 17 lt 50kA. Details: Load shot 950127025. Which was a slot at 800kA. This initiation is the important thing. Moved TF initiation to -.52s and called for 110kA. Moved EF2 initiation to -.5s (from -.4) in the expectation that this will help ensure that we get all supplies to their demand. Reloaded all fluxihh predictors. Called RCUR in segment 1 (Not yet in segment 2) Fill at 1.5e-5 1 PS dud EF2s failed to fire. Discovered to be a "feature" of the EF2 circuit. The power supply actually comes on in its own sweet time. The initiate is just a switch closing that needs voltage there to close. EF2 Initiate back to .4s. 2 Dud Bz seems too positive by quite a bit. OH2U=22440, OH2L=21472. EF4 to 1185A from 1085 A. 3 Fiz Imbalance on EF2U=-1735 EF2L=-1681. EF1s regulated a bit better. Slightly too positive index. OH1 Voltage to -100V from -75 in first 6ms. 4 Dud Went the wrong way. Oops. OH1 to -50V. 5 Dud Copied EF1L trace to EF1 upper to symmetrize. Fill to 1.8 Am informed that the EF2V problem is that the Hybrid must be drawn earlier. 6 Fiz Nearly went. Second current rise. Looks like a bounce. Drew EF2 voltage up earlier: 0.65s. EF2 initiate to -0.5s. OH2s to 0V from +15V during 5-10ms. 7 Fiz Reached 38kA and bounced four times. Fill to 2.0 OH2s to -10V EF4 t0 -1150A. 8 Fiz Similar breakdown OH2s to -20V 9 Fiz 30kA late. Br offset to 5mT from 6mT. 10 Fiz Break slightly later. Br offset to 5.5mT EF4 to -1120A. 11 Fiz Very late Break: 25ms. Must have raised BZ past what it will take. EF4 to -1180A. 12 Fiz Still late. Found br offset at 6.5mT. Finger problem? Fill to 2.2 13 Fiz Breakdown at 6ms 38 kA bounce at 15ms. OH2 to -25V OH1 to +20V from +75 in early phase. 14 Fiz Rather similar 38kA bounce at 17ms. Lowered The OH2 commutation resistors by 1.2 mohm. OH2 to -20V. 15 Fiz Many bounces at about 30kA. Set RCUR segment 1 offset to +5000. 16 Pla Still seems rather outside at 20-25 ms, where there is a pause. Goes bad at about 130ms in segment 2. Lowered NL04 in segment 2 to around .8e20. 17 Pla Disrupt at 1.07s. 3.7 Tesla. Drew RXL to -.01m, raised gain to 3. Kept Fast ZCUR up a little longer. 18 FizB 54kA 30ms bounce. Raise fill to 2.5e-5 19 FizB 50kA at 29ms. Lower ZCUR offset to 6mT. Raise RCUR gain to 9.5 in initiation. RAise RCUR offset to 8000. 20 Pla Disrupt at 0.866. Looks like the RF killed it. Good initiation. Called for TF=150kA. Declare the low field startup developed. RF run from here on. 21 Pla 5.1T no EF4 positive current, but a nice plasma. Good ramp down. RF fired. Raised nel to 1.1e20 Dropped the .3s fast zcur. 22 Pla 5.1T PCS crashed. So restarting and calling all seg 2 predictors. RCUR offset to 8000. drawn to .667 from .657. Called all fluxihh predictors for wires 1-9. Asked for 5.3 T 23 Pla Current Rises slower. Higher zmeter burnout. RCUR seems now to be giving what is requested to within a few mm. Consequence was that the plasma was further in early where I had not compensated. 24 Pla Disrupts at .24s. Moly monitor gives giant signal and plasma goes very resistive. Repeat to see if this happens twice. 25 Pla It doesn't. Fill to 2.7 Increased the gas at .1s and the nel at .1 to .2s Drew RCUR out by about 1cm early. Drew RCUR in about 2.5mm to .6625. 26 Pla Moly much less. Looks happier. Repeat. 27 Pla IGOR IS GETTING SLOW AGAIN. ZXL gain to 4., i.e. 15 s^-1. RXU to -.03 from -.035. Ask for 141kA, 4.8T 28 Pla OK rather slow current rise. ZXU to .03 from .025. Ask for 130 kA TF. 4.4T 29 Pla Got it. Ask for 120 KA, 4.1T. 30 Pla Got it. Repeat. 31 Pla OK. Ask for 156kA, 5.3 T. Gain on Moly reduced. 32 Pla Hmode trips the RF. Ask 168kA, 5.7T. (Highest B yet run). Paragon allows only 160kA. 33 Pla Get 5.48T. Not going to push the paragon problem. Do it in a more measured way. Curretn a bit ragged near cross-over. Fill to 3e-5 34 Pla Fill to 3.2e-5 Ask 148kA, 5.0T. 35 Fiz I guess there is a limit to how high one can raise the fill. Fill to 2.8e-5 D=2 of Nel4. 36 Pla

Session Leader Comments
Feb 1 1995 01:48:54:630PM	950201021	Yuichi Takase	Starting from shot 021: MP079 - ICRF BT scan 5.15T, Bringing up the RF power (0.7MW + 1.0MW)
Feb 1 1995 01:50:51:970PM	950201022	Yuichi Takase	Starting from shot 022: 5.15T, 2.7MW, H-modes, 46 --> 74kJ
Feb 1 1995 01:57:05:690PM	950201023	Yuichi Takase	Starting from shot 023: 5.36T, 3.1MW, H-modes, 46 --> 80kJ
Feb 1 1995 02:02:08:740PM	950201024	Yuichi Takase	Shot 024: Early disruption
Feb 1 1995 02:05:06:230PM	950201025	Yuichi Takase	Shot 025: D port transmitter overloaded. 3MW for 40msec, 49 --> 84 kJ
Feb 1 1995 02:16:32:200PM	950201026	Yuichi Takase	Shot 026: Increased outer gap from 1.0 to 1.6cm 3.2MW for 44msec, 48 --> 80 kJ
Feb 1 1995 02:36:08:090PM	950201027	Yuichi Takase	Shot 027: 2.7MW for 60msec, 47 --> 91 kJ (H-mode)
Feb 1 1995 03:01:13:630PM	950201027	Yuichi Takase	Shot 027: 4.8T 2.4MW for 150msec, 47 --> 79 kJ (H-mode) --> 69 kJ (L-mode)
Feb 1 1995 03:18:10:800PM	950201028	Yuichi Takase	Shot 028: 4.8T 2.4MW for 150msec, 47 --> 79 kJ (H-mode) --> 69 kJ (L-mode)
Feb 1 1995 03:27:21:150PM	950201029	Yuichi Takase	Shot 029: 4.5T 2.4MW for 200msec, 47 --> 60 kJ (L-mode)
Feb 1 1995 04:02:51:890PM	950201030	Yuichi Takase	Shot 030: 4.1T 2.4MW for 30msec
Feb 1 1995 04:11:03:370PM	950201031	Yuichi Takase	Shot 031: 4.1T 2.4MW for 200msec, 45 kJ (no heating)
Feb 1 1995 04:14:00:740PM	950201032	Yuichi Takase	Shot 032: 5.3T 2.4MW for 30msec, H-mode killed RF.
Feb 1 1995 04:29:28:180PM	950201033	Yuichi Takase	Shot 033: 5.5T (this is as far as we can go today). 2.3MW for 30msec, H-mode killed D-port, E-port was OK.
Feb 1 1995 04:46:56:530PM	950201034	Yuichi Takase	Shot 034: 5.5T (this is as far as we can go today). 2.3MW for 70msec, 46 --> 86 kJ.
Feb 1 1995 04:57:32:970PM	950201035	Yuichi Takase	Shot 035: Fizzle.

Physics Operator Comments

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:36:37:390AM	Plasma	Ok	no ef2
2	08:53:13:150AM	Plasma	Ok	no fault
3	09:05:48:630AM	Plasma	Ok	no faults, breakdown
4	09:17:44:640AM	Plasma	Ok	no faults
5	09:28:12:390AM	Plasma	Ok	no faults
6	09:37:45:910AM	Plasma	Ok	no faults
7	09:48:36:830AM	Plasma	Ok	no faults, breakdown
8	10:00:00:040AM	Plasma	Ok	no faults, breakdown
9	10:11:56:990AM	Plasma	Ok	no faults
10	10:21:56:650AM	Plasma	Ok	no faults
11	10:31:57:770AM	Plasma	Ok	no faults
12	10:41:55:850AM	Plasma	Ok	no faults
13	10:52:35:080AM	Plasma	Ok	no faults
14	11:06:04:750AM	Plasma	Ok	no faults
15	11:20:23:280AM	Plasma	Ok	no faults
16	11:30:13:100AM	Plasma	Ok	no faults, plasma
17	11:45:45:190AM	Plasma	Ok	oh2l comm faul
18	12:04:03:950PM	Plasma	Ok	no faults
19	12:14:34:770PM	Plasma	Ok	no faults
20	12:27:51:280PM	Plasma	Ok	no faults plasma
21	12:41:07:380PM	Plasma	Ok	ef4fg breakers opened
22	12:55:24:350PM	Plasma	Ok	no faults
23	01:17:16:050PM	Plasma	Ok	no faults
24	01:32:46:580PM	Plasma	Ok	no faults
25	01:46:01:620PM	Plasma	Ok	no faults
26	02:04:47:290PM	Plasma	Ok	no faults
27	02:22:09:280PM	Plasma	Ok	no faults
28	02:47:56:650PM	Plasma	Ok	no faults
29	03:12:13:720PM	Plasma	Ok	no faults
30	03:34:21:410PM	Plasma	Ok	no faults
31	03:49:31:590PM	Plasma	Ok	no faults
32	04:03:26:350PM	Plasma	Ok	no faults
33	04:18:46:870PM	Plasma	Ok	no faults
34	04:32:59:100PM	Plasma	Ok	no faults
35	04:48:21:480PM	Plasma	Ok	no faults
36	05:00:20:640PM	Plasma	Ok	disruption induced comm faults