| Miniproposals | ||||||||||
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| Operators | |
| Session leader(s): | Dennis Whyte |
| Physics operator(s): | |
| Engineering operator(s): | |
| Engineering Operator Run Comment |
| automatically entered by signon - please replace with real comment |
| Session Leader Plans |
| Entered: Mar 19 2007 10:03:29:177AM |
| Author: Dennis Whyte |
| The purpose of this experiment is to provide better localization of the ECDC produced ion flux to plasma-facing surfaces by application of a vertical field during ECDC. Today will be an initial scoping study to see if our basic ideas about the effect of applying vertical field are correct. A power supply will be hooked up to the EF4 coils to provide ~250 A (for both coils which are in parallel). This will provide a vertical field ~10 mT and will be manually controlled. We will used langmuir probes, both in the divertors and on the LH grill, and the TV emissions to judge the effectiviness of the vertical field in localizing ion flux to surfaces. Our primary goal today is to judge whether the technique is sufficiently promising so as to arrange a more permanent power supply and switching for applying verticla field during ECDC conditioning.
Run plan 1. Establish base-line diagnosis of plasma and ion flux with pure B toroidal using Langmuir probes. 2. Increment vertical field in the following steps B/Bv (%) = 2, 4, 6, 8, 10 and measure changes in plasma conditions. Sweep the EC resonance location +/- 10 cm for diagnostic coverage. ***Useful conversions: B_resonance = 87.5 mT, 130 Amps in each EF4 coil produces 9mT (~uniform in R?) = 260 Amps on power supply So B_v/ B_res (%) ~ 0.04 * I_coil (A) 3. At maximum B/Bv ~ 10% perform RF power scan (1, 2, 3 kW). Sweep EC resonance. |
| Physics Operators Plans |
| Session Leader Summaries |
| Entered: Mar 19 2007 03:51:56:557PM |
| Author: Dennis Whyte |
| A successful run. We implemented the vertical
field in increments of 2% of Bv/Bt. Above 4% the images of plasma light showed a clear sharpening at the resonance location, an indication that we've narrowed the plasma radial width. The upper divertor probes indicated a radial width of the ion flux ~ 5 cm, roughly as expected. One of the main objective of the experiment was to show that the application of vertical field would greatly reduce the plasma flux seen to surfaces well outside the resonance, with the hope of reducing unwanted boronization films on antennae structures. The probes on the LH launcher indeed showed that the incident ion flux essentially disappeared with the applicaiton of Bv/Bt >~4%. The LH launcher was retracted a ~2 cm from its nominal location for calibrations (digital readout on position of launcher is 1894). We first attempted to used the 9, 10 lower divertor fixed probes to diagnose the flux pattern. While it was possible to see increased Isat signal, this proved to be difficult, mostly (we think) due to the changing poloidal angle of the lower outer target plates. From shot 916 we used the 12 and 14 upper divertor probes (with x50 increased gain) which are on the horizontal plate in the upper divertor. With B_v/Bt=10%, the resonance location/Bt was scanned across the probe radial locations. Control room analysis indicates that the flux was falling off very sharplly on the inside of the resonance location, while the flux decreased with ~5 cm folding length on the outside of the resonance. Based on probes and imaging, there was not much sharpening of the radial profile above Bv/Bt~4%. It's not clear why this limit was reached, since the transport ordering tells one that the profile should narrow further when Bv is increased. This may be a limitation set by the width of the RF power absorption (e.g. Upper Hybrid resonance). Nevertheless, a 5 cm flux width is probably sufficient for purposed of localizing B ionic deposition during boronizations. Another odd feature was that the sharpness of the plasma emission seemed to deteriorate when the EC resonanc was moved to R> 65 cm, i.e. when the resonance moved onto the lower divertor horizontal targets. This is counter-intuitive, since the connection length should even be shorter in this case, and should be investigated further. We also checked the probe signals with forward and reverse polarity on the B_vertical. This did not make a dramatic difference. |
| Physics Operator Summaries |
| Session Leader Comments | |||
| Mar 19 2007 11:01:38:290AM | 1070319001 | Dennis Whyte | Starting with pure Bt field.
- There is an interlock on the ECDC magnetron using a fiber measuring H-alpha light. The H-alpha signal strength looks marginal, so that the ECDC randomly trips off (although the camera images show lots of H-alpha light) Therefore for today we're going to jumper this interlock, but the fiber needs to be realigned. - EF4 coils are being cooled manually. |
| Mar 19 2007 11:39:00:087AM | 1070319002 | Dennis Whyte | B resonance = 60 cm, just inside vertical face of outer divertor.
B_vertical =0 P_forward (2.45 GHz) = 2.5 kW Trying to get a fiducial with zero B_v. From wide camera view the resonance appears in the radial center of the openings to the upper cryopump (which are centered at 60 cm, so we know the field resonance calculation is correct) , and just inside of the vertical outer divertor. Jim Terry has digitized Wide & JAnt camera views. |
| Mar 19 2007 11:50:02:853AM | 1070319901 | Dennis Whyte | NOTE: using 10703199XX shot number designation for test shots on
EDGE tree to archive probe data. B resonance = 62 cm, just inside vertical face, on horizontal target B_vertical =0 P_forward (2.45 GHz) = 2.5 kW On Wide camera view the resonance has moved to outer part of the opening into the cryopump. Don't understand why the recycling appears so much stronger on the lower half of vessel than the upper half. Wide and Jant images archived. Finite I sat signal on probes 9 and 10 in the lower divertor. Brian Labombard is archiving these with EDGE tree "shots". Ion grad B drift points down (we think) |
| Mar 19 2007 11:52:00:900AM | 1070319901 | Dennis Whyte | NOTE: using 10703199XX shot number designation for test shots on
EDGE tree to archive probe data. I will use this designation for the camera images too: /home/terry/cameras/wide_ecdc_9XX_00000001.jpg, etc /home/terry/cameras/jant_ecdc_9XX_00000001.jpg B resonance = 62 cm, just inside vertical face, on horizontal target B_vertical =0 P_forward (2.45 GHz) = 2.5 kW On Wide camera view the resonance has moved to outer part of the opening into the cryopump. Don't understand why the recycling appears so much stronger on the lower half of vessel than the upper half. Wide and Jant images archived. Finite I sat signal on probes 9 and 10 in the lower divertor. Brian Labombard is archiving these with EDGE tree "shots". Ion grad B drift points down (we think) |
| Mar 19 2007 12:09:26:120PM | 1070319903 | Dennis Whyte | B resonance = 65 cm
I_EF4=50 A B_vertical =1.73 mT Bv/Bt ~ 2% P_forward (2.45 GHz) = 2.5 kW On Wide camera view the resonance has moved to just outside the cryopump opening. |
| Mar 19 2007 12:12:06:463PM | 1070319904 | Dennis Whyte | B resonance = 65 cm
I_EF4=100 A B_vertical =3.46 mT Bv/Bt ~ 4% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:15:51:760PM | 1070319905 | Dennis Whyte | B resonance = 62 cm
I_EF4=100 A B_vertical =3.46 mT Bv/Bt ~ 4% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:24:03:620PM | 1070319906 | Dennis Whyte | B resonance = 60 cm
I_EF4=100 A B_vertical =3.46 mT Bv/Bt ~ 4% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:31:22:197PM | 1070319907 | Dennis Whyte | B resonance = 60 cm
I_EF4=150 A B_vertical =5.19 mT Bv/Bt ~ 6% P_forward (2.45 GHz) = 2.5 kW I_sat signals have disappeared on the LH grill (actually starting with the applicaiton of Bv/Bt~2% |
| Mar 19 2007 12:33:37:260PM | 1070319908 | Dennis Whyte | B resonance = 60 cm
I_EF4=200 A B_vertical =6.92 mT Bv/Bt ~ 8% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:38:18:510PM | 1070319909 | Dennis Whyte | B resonance = 60 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:45:14:213PM | 1070319910 | Dennis Whyte | B resonance = 61 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:49:57:633PM | 1070319910 | Dennis Whyte | B resonance = 61 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:50:07:573PM | 1070319911 | Dennis Whyte | B resonance = 62 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 12:57:10:417PM | 1070319912 | Dennis Whyte | B resonance =58 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:25:36:870PM | 1070319914 | Dennis Whyte | No ECDC reference shot for probesl.
B resonance =58 cm I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 0 kW |
| Mar 19 2007 02:18:32:633PM | 1070319916 | Dennis Whyte | B resonance = 50 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW Upper divertor probes on high gain (x50) upper probe 12: R=62.3 cm upper probe 14: R=64.3 cm |
| Mar 19 2007 01:38:05:540PM | 1070319917 | Dennis Whyte | B resonance = 55 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:39:48:133PM | 1070319918 | Dennis Whyte | B resonance = 60 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:41:34:777PM | 1070319919 | Dennis Whyte | B resonance = 65 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:45:41:277PM | 1070319920 | Dennis Whyte | B resonance = 70 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:48:55:277PM | 1070319921 | Dennis Whyte | B resonance = 62.5 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 01:55:05:167PM | 1070319922 | Dennis Whyte | B resonance = 57.5 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 02:35:43:010PM | 1070319923 | Dennis Whyte | B resonance = 60 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% REPEAT P_forward (2.45 GHz) = 2.5 kW Appears that radial e-folding distance ~5 cm based on looking at raw scope data for probes 12 and 14. Scope: ~/labombard/ecdc_probe_comparison |
| Mar 19 2007 02:36:58:197PM | 1070319924 | Dennis Whyte | B resonance = 55 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% Changed upper divertor probes on high gain (x50) in order to capture change in radial e-folding distance with the changin vertical field upper probe 8: R=57.8 cm upper probe 14: R=67.5 cm P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 02:52:26:730PM | 1070319925 | Dennis Whyte | B resonance = 60 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% Changed upper divertor probes on high gain (x50) back to original configuration. Could not get strong signal on probe 8 upper probe 12: R=57.8 cm upper probe 14: R=67.5 cm P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 02:53:31:683PM | 1070319926 | Dennis Whyte | B resonance = 60 cm
I_EF4=200 A Bv/Bt ~ 8% Start B_v scan down again to scope out changes in I_sat profile as Bv/Bt is reduce P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 02:55:50:133PM | 1070319927 | Dennis Whyte | B resonance = 60 cm
I_EF4=150 A Bv/Bt ~ 6% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 02:58:10:680PM | 1070319928 | Dennis Whyte | B resonance = 60 cm
I_EF4=100 A Bv/Bt ~ 4% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 03:03:20:040PM | 1070319930 | Dennis Whyte | B resonance = 60 cm
I_EF4= 0 A Bv/Bt ~ 0% P_forward (2.45 GHz) = 2.5 kW |
| Mar 19 2007 03:09:05:417PM | 1070319931 | Dennis Whyte | B resonance = 60 cm
I_EF4= -250 A Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW |
| Physics Operator Comments |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |
| System Availability | |||
| Mar 20 2007 08:49:26:097AM | |||
| B resonance =58 cm
I_EF4=250 A B_vertical =8.65 mT Bv/Bt ~ 10% P_forward (2.45 GHz) = 2.5 kW Move upper probes 12 and 14 to high gain channels. I-V curves wierd. | |||