| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Dennis Whyte |
| Physics operator(s): | |
| Engineering operator(s): | |
| Engineering Operator Run Comment |
| Session Leader Plans |
| Entered: Apr 3 2007 01:38:56:540PM |
| Author: Dennis Whyte |
| ECDC with vertical field
This will continue our first attempts (1070319XXX) at localizing plasma flux to surfaces during ECDC by applying a finite vertical field to the toroidal field. The main focus of today's experiment will be using the large area Langmuir probe on the S3 (Surface Science Station) to obtain radial profiles of the plasma properties by scanning the S3 radially through the chamber with the ECDC power, resonance loacation and Bv fixed. In addition we will use the Wide camera view and fixed probes with high gain to diagnose the plasma losses to surfaces. With fixed probes on 1070319 we found the radial width to be ~5-10 cm, However there were some hints that the plasma width changes with scanning the resonanc location, particularly to R > 62 cm which is when the resonance is located on the horizontal portion of the lower outer divertor target. The end goal is to obtain better localization for plasma cleaning and boronization film deposition. We will attempt to diagnose the following conditions B_v = 0 (reference) B_v / B_t ~ 10%, R_res = 60 cm (just inside the vertical target) B_v / B_t ~ 5% , R_Res = 60 cm (to see effect of Bv/Bt on SOL width) B_v/B_t ~10%, R_res = 70 cm (effect of placing resonance on horizontal target) The vertical field is being obtained by a manually connected current supply to the EF4 coils. 130 Amp in each EF4 coils = = 260 A PS current --> 9 mT vertical field. B_V/B_res (%) ~ 0.04 * I_coil_PS (A) Since this occurs outside of the usual C-Mod shots cycle we will use our own convention for shot numbers and will keep track of them self-consistently We will "slave" the shot number to the S3 shot convention which will begin at 601. The edge tree shots which will include the fixed probe data will have a shot convention starting at 901. The image file names will be correlated to the edge tree number. |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Apr 3 2007 07:08:12:090PM |
| Author: Dennis Whyte |
| The first successful physics experiment with S3!
We obtained many, many profiles of plasma Isat, density, etc. with the Langmuir probe on S3 in an attempt to understand and quantify the radial profiles during ECDC. To first order we recreated the results of two weeks ago in that the local plasma flux at the LH grill more or less disappears with the application of vertical field, although we have a better measure of this today with higher gain channels on the LH probe. We did two basic scans: 1) Fixing the location of the S3 probe at R ~ 168 cm and scanning the resonance location past it in 5 cm steps. 2) Fixing the resonance lcoation and scanning the probe /w changing Bv/Bt The radial profile is complicated. It appears that the peak Isat is broad and about 10 cm outboard of the resonance location. We don't know the cause of this (upper hybrid resonance?). The applicaiton of the vertical field made the radial profile considerably narrower in major radius, qualitatively consistent with images and fixed probes. This will require more analysis for firm conclusion about the optimal B-vertical, etc. |
| Physics Operator Summaries |
| Session Leader Comments | |||
| Apr 3 2007 02:29:21:510PM | 1070403601 | Dennis Whyte | No vertical field fiducial.
R_res = 60 cm B_v / Bt = 0 Power_RF= 2.5 kW S3 radial scan: 58 - 126 cm QMB frequency, radial position, and QMB temperatures appear reasonable for the scan. There appears to be a problem with the voltage sweep on the S3 langmuir probe, which should have a constant sweep on it, but doesn't. The 9xx shots will record the fixed probe data. We have the upper divertor fixed probes 12 and 14 on 50x gain and the LH grill probe on 50x gain. The FIXED PROBE DATA IS INVALID ON THIS SHOT DUE TO OVERCURRENTING |
| Apr 3 2007 05:38:57:840PM | 1070403602 | Dennis Whyte | No vertical field fiducial.
R_res = 60 cm B_v / Bt = 0 Power_RF= 2.5 kW Pressure = 2e-4 Torr S3 radial scan: 105 - 58 cm Will watch oscilloscope trace of S3 probe voltage to see what the problem is THIS SHOT DATA IS NULL. The I-V boards over currented due to increased gain. |
| Apr 3 2007 02:47:37:147PM | 1070403603 | Dennis Whyte | No vertical field fiducial.
R_res = 60 cm B_v / Bt = 0 Power_RF= 2.5 kW S3 radial scan: cm Gains have been reduced on the I-V boards to avoid over-currenting. Clear signal of plasma flux on LH probe. Fixed probes need capacitance tuning but show low signal as usual without vertical field. Good profile data from the S3 langmuir probe vs. R. |
| Apr 3 2007 02:59:34:650PM | 1070403604 | Dennis Whyte | No ECDC fiducial for zeroing probes
S3 radial scan: cm Brian Labombard has tuned the capicatances of the probes on S3 and LH launcher. Shot 904 on edge tree. Result: S3 Langmuir probe current is in the bit noise. QMB freq., sensor temperature etc., are very constant versus R. excellent test of stability of the the diagnostic signals versus probe position. |
| Apr 3 2007 03:00:28:493PM | 1070403604 | Dennis Whyte | No ECDC fiducial for zeroing probes
S3 radial scan: 105- 55 cm Brian Labombard has tuned the capicatances of the probes on S3 and LH launcher. Shot 904 on edge tree. Result: S3 Langmuir probe current is in the bit noise. QMB freq., sensor temperature etc., are very constant versus R. excellent test of stability of the the diagnostic signals versus probe position. |
| Apr 8 2007 09:36:19:430PM | 1070403605 | Dennis Whyte | B_v/Bt = 8 %
I_EF4_PS = 200 A R_res = 70 cm Power_RF= 2.5 kW S3 radial scan: 57 - 105 cm The speed of the scan will be doubled to halve the acquisition time. LH probe flux goes to ~ zero while the flux to the upper fixed probes becomes measurable (as with previous day) More localization of the plasma profile, but strangely broad INSIDe the resonance? I THINK I MESSED UP THIS SHOT DESIGNATION SINCE AN EXACT COPY OF 06? |
| Apr 3 2007 03:31:02:463PM | 1070403606 | Dennis Whyte | B_v/Bt = 8 %
I_EF4_PS = 200 A R_res = 70 cm Power_RF= 2.5 kW S3 radial scan: 57 - 105 cm The speed of the scan will be doubled to halve the acquisition time. LH probe flux goes to ~ zero while the flux to the upper fixed probes becomes measurable (as with previous day) More localization of the plasma profile, but strangely broad INSIDe the resonance? |
| Apr 3 2007 03:38:31:230PM | 1070403607 | Dennis Whyte | B_v/Bt = 8 %
I_EF4_PS = 200 A R_res = 70 cm Power_RF= 2.5 kW S3 radial scan: 57 - 105 cm The Langmuir probes are in Isat collection mode for this shot. No images for this shot. |
| Apr 3 2007 03:39:01:933PM | 1070403608 | Dennis Whyte | No ECDC fiducial for Isat colleciotn on probes
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| Apr 3 2007 07:13:11:073PM | 1070403609 | Dennis Whyte | R_res = 60 cm
B_v/Bt = 8% Probes are in Isat collection mode. Images are 909 a and 909 b to signify the probe outside and inside thr esonance respectively. Control room speculation is that the S3 probe itself may be perturbing. Shadow of s3 probe and its helicity is clear in images. It appears we have the same helicity as regular shots. POSSIBLE THAT THIS RESONANCE VALUE IS INCORRECT! MUST BE CHECKED VERSUS TREND DATA. |
| Apr 3 2007 04:17:22:137PM | 1070403611 | Dennis Whyte | R_res = 60 cm
B_v/Bt = 0 % Probes are in Isat collection mode. S3 swept from 57 cm to 105 cm. |
| Apr 3 2007 04:34:01:683PM | 1070403612 | Dennis Whyte | R_res = 50 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:37:23:540PM | 1070403613 | Dennis Whyte | R_res = 55 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:38:33:213PM | 1070403614 | Dennis Whyte | R_res = 60 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:40:58:887PM | 1070403615 | Dennis Whyte | R_res = 65 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:42:53:637PM | 1070403616 | Dennis Whyte | R_res = 70 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:46:03:713PM | 1070403617 | Dennis Whyte | R_res = 75 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:48:16:463PM | 1070403618 | Dennis Whyte | R_res = 80 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:49:58:200PM | 1070403619 | Dennis Whyte | R_res = 85 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:51:29:887PM | 1070403619 | Dennis Whyte | R_res = 85 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:53:10:730PM | 1070403620 | Dennis Whyte | R_res = 45 cm
B_v/Bt = 8 % Probes are in Isat collection mode. |
| Apr 3 2007 04:54:53:433PM | 1070403620 | Dennis Whyte | R_res = 45 cm
B_v/Bt = 8 % Probes are in Isat collection mode. Probe position: 68 cm |
| Apr 3 2007 05:36:52:667PM | 1070403621 | Dennis Whyte | R_res = 60 cm
B_v/Bt = 8 % D2 pressure = 5e-5 torr, lower than previous value of 2e-4 Torr Probes are in Isat collection mode. Probe position scanned. |
| Apr 3 2007 05:39:29:840PM | 1070403622 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 8% Pressure = 5e-5 Torr Probes in Isat mode |
| Apr 3 2007 05:49:27:433PM | 1070403623 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 8% Pressure = 5e-5 Torr Probes in Isat mode Repeat of the last shot, but pulling the S3 probe out rather than going in. |
| Apr 3 2007 06:07:26:340PM | 1070403624 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 0 % Pressure = 5e-5 Torr Probes in Isat mode The visible camera shows that the probe is perturbing the emissions as it moves radially inward This shows a clear difference, i.e. much broader in outboard radial profile than with Bv/Bt = 8%, although it's clear that the nearby limiter structures still effect the local plasma density |
| Apr 3 2007 06:06:06:247PM | 1070403625 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 2 % Pressure = 5e-5 Torr Probes in Isat mode Speeding up the probe scan rate (i.e. radial speed) so that we can get home tonight. |
| Apr 3 2007 06:14:47:760PM | 1070403626 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 4 % Pressure = 5e-5 Torr RF power = 2.45 kW Probes in Isat mode |
| Apr 3 2007 06:23:42:527PM | 1070403627 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 6 % Pressure = 5e-5 Torr Probes in Isat mode Missed Fixed Langmuir probe data shot. |
| Apr 3 2007 06:23:05:103PM | 1070403628 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 8 % Pressure = 5e-5 Torr Probes in Isat mode Slowed down the S3 probe movement since it was causing the slide mechanism to shake. |
| Apr 3 2007 06:27:39:230PM | 1070403629 | Dennis Whyte | B_res = 50 cm
B_v/Bt = 9.5 % (I_EF4 = 230 A) Pressure = 5e-5 Torr Probes in Isat mode |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |