| 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: May 8 2007 06:23:03:687PM |
| Author: Dennis Whyte |
| Boronization with vertical field
This boronization will not be our full MP for ECDC/BZN characterization, but rather a characterization of the BZN with fixed vertical field. This decision was affected by several considerations including the availability of EF4 supply, a stuck shutter on Thomson scattering, the absence of Bruce and the general newness of the S3 diagnostics. The day will be broken up into two parts. Part 1 (~9 - noon) In the morning the boronization system will be given a shakedown, but with a pure He bottle installed rather than the He+diborane bottle. This is to allow engineers to fix any problems in the PLC, etc. for the boronization system, while still allowing cell access . The shakedown will include He ECDC plasmas, so we will also shakedown remote control and data acquisition of S3 including probe data (which technically we've never taken in He plasmas). We'll insert S3 from home to the "safe" position with the head inserted manually just into the vessel before this, with the S3 turbo gate valve closed so it simulates what we'll get with the boronization. Also we must make sure to optimize/maximize N2 cooling flow in S3 in order to better control the QMB temperature. A key feature of the S3 shakedown is full remote control with visual confirmation from J. Terry's camera, good I_sat signal on the S3 probe and the temperature/frequency stability of the QMB's with our improved N2 cooling. Step 2 The next stage will be the boronization proper. According to Jim Irby this takes 30-60 minutes to set up since it requires scuba entry into the cell to bring in the diborane bottle, hook it up and turn open a manual valve. We'll leave S3 at the safe position. We will go through our S3 check list to verify everything on S3 before we leave the cell. We then proceed with the boronization plan at fixed vertical field Bz/Bt ~ 10%, so this will be a a truncated version of the MP shot plan). Our main objective is the quantification of the neutral versus ionic B film growth, and absolute numbers w.r.t. the growth rate + a radial profile of these properties. The decision for the duration of the BZN and the extent of the radial resonance scan will be based "on the fly" on those results. Shot plan 1) Bv/Bt = 8%, R_res = 60 cm. Place the S^3 head at the peak in the plasma profile, i.e. at the upper hybrid resonance ~ 65 cm. Run the boronization for 10 minutes with the S3 head rotated such that the side QMB face is normal to the field lines. Stop boronization and take periodic data acquisitions to monitor the head temperature and QMB frequency shift. Wait until these have equilibrated and calculate thickness of B film on each QMB. Our expectation is that after 10 minutes the QMB should be able to measure net film growth since between shot boronizations laid down ~10 nm films, and this should be accurately measured by the QMB. But at this point we'll need to assess if we see the BZN layer and need to adjust acquisition/BZN duration (longer or shorter). 2) Move the head to EC resonance and measure deposition rate 3) Move the head inside the deposition radius (5 cm) and measure deposition rate. 4) Move the head 5 cm outside the UH resonance, then increase in 5 cm steps out to the R_limiter+5 (~90 cm?) 5) Assess requirements for boronization duration and sweep range for remainder of boronization. S3 will be left at or near th resonance to monitor total film growth. |
| Physics Operators Plans |
| Entered: May 8 2007 04:00:49:027PM |
| Author: Jim Irby |
| Overnight ECDC in D2 at 2e-4 Torr, sweep 44 to 103 cm, dwell at 45 cm
Around 09:00 --- operation of boronization system in helium to check out hardware, procedure, and S^3. A-Port shutter will be open during helium operation, but closed during actual boronization. Around 12:00 --- install diborane bottle and begin boronization with Bt and Bv. Scans will be localized to R<=0.8 m. Take S^3 data. Around 17:00 --- having decided the best scan parameters continue boronization Around 23:00 --- four techs on hand to shut down boronization and close diborane bottle |
| Session Leader Summaries |
| Entered: May 9 2007 11:30:40:120PM |
| Author: Dennis Whyte |
| A very successful run for S3 diagnosis of boronization.
Kudos to the S3 team (Roman, Neils and Soren). The QMB's proved very reliable at getting real time deposition rates with ~ 180 s data acquisition times. The measured deposition signals (1-10 nm) were well out of the fluctuations in frequency documented from the temperature sensitivity (~0.1 nm) We made a brief attempt at optimizing the conditions of the boronization, although I'm confident more can be done. An important point was brought forth today in that BZN ECDC is done at much higher vessel pressure (~1 mTorr) compared to ECDC used for conditioning (~0.1 mTorr). In the He-only ECDC we documented with the camera views that this situation led to almost all of the ionization light coming from the H-port, with weak plasma light at other locations. This would seem to lead to unwanted B film accumulation near H-port. We found that applying vertical field (nominally at 8% Bv/Bt today) and lowering the pressure by a factor of ~2.5 that the H-port localization disappeard and we recovered our standard appearance of the axisymmetric ECDC plasma. This was our standard operating regime for the radial scan with S3. The basic conclusion of the s3 radial scan is that the local boron deposition rate is mostly strongly linked to plasma flux as diagnosed with the probe. This was for both the QMB oriented to face the field lines and for the QMB which views in the inward R direction. In fact when we pulled the S3 back to R~100 cm neither of the QMB's could measure any deposition outside their senstivity limit (1 Angstrom per 3 minutes). The deposition rate was peaked about 10 cm outside of the EC resonance, which is consistent with the location of the Upper Hybrid resonance. The peak // rate was ~ 8 nm / 3 minutes which crudely taking into account the pitch angle of the field would present ~ 20 nm / hour for horizontal surfaces (e.g. outer divertor shelf). The control room opinion is that the radially viewing QMB is being affected by ion flux, since the extremely rapid drop-off of deposition rate with radial distance from the UH resonance does not seem to jibe with simple expectations based on solid angle dispersion of neutral boron radicals from the ionization regions. Our estimate is that the boron ions have a gyroradius ~ 1cm, so they may be impacting the radial QMB and depositing some film. Near the UH resonance the deposition rate was >5 times on the // facing QMB than the radial QMB. The scan in QMB orientation showed the expected result of max. deposition when the QMB2 probe had it's face normal to the field lines. We saw an asymmetry in deposition rate looking up or down the field lines. We believe this is caused by the gas injection in the upper showerhead. So overall the boronization film deposition rates were highly localize to regions near the UH resonance. Based on this we limited the rest of the BZN to a scan from the inner wall to the outer divertor shelf. We'll see if this works tomorrow. |
| Physics Operator Summaries |
| Session Leader Comments | |||
| May 9 2007 01:18:18:867PM | 1070509601 | Dennis Whyte | he ECDC
R_res = 65 cm. B_Z = 0 vessel pressure 5 mTorr check isat signal strength during a S3 scan from 120 to 70 cm. The Isat clearly jumps up when the S3 gets inside the toroidal imiters at ~ 84 cm the isat "envelope" is actually max. at the 84 cm region |
| May 9 2007 03:00:57:500PM | 1070509611 | Dennis Whyte | Helium ECDC
R_res = 55 cm. I_EF4=214 Amps foreline pressure 50 mTorr, vessel pressure finally got some sweep data on probe. S3 moving from 90 cm - 58 cm Not cerain how localize the profile is..could be that the UH resonance has moved further out. Awaits probe analysis. |
| May 9 2007 03:01:14:220PM | 1070509612 | Dennis Whyte | No ECDC fiducial. |
| May 9 2007 03:11:53:740PM | 1070509613 | Dennis Whyte | No ECDC fiducial.
checking how the QMB's cool without ECDC |
| May 9 2007 03:29:16:900PM | 1070509614 | Dennis Whyte | No ECDC fiducial.
It's clear that the probe will take a long time to get back down to 20 C. The apparent change in QMB frequency / thickness is small, about 0.2 nm / C. So we might be better off running the QMB hotter when it's in the plasma, as long as the temperature does not drift too much. |
| May 9 2007 03:37:00:513PM | 1070509615 | Dennis Whyte | ECDC Helium
r_res = 65 cm, I_EF4 = 200 A s3 parked at 65 cm, testing the thermal stability of the QMBs |
| May 9 2007 03:45:42:673PM | 1070509616 | Dennis Whyte | ECDC Helium
r_res = 65 cm, I_EF4 = 200 A s3 parked at 65 cm, testing the thermal stability of the QMBs |
| May 9 2007 04:00:08:540PM | 1070509617 | Dennis Whyte | ECDC Helium
r_res = 65 cm, I_EF4 = 200 A s3 parked at 65 cm, testing the thermal stability of the QMBs QMB2 looks stable in temperature and frequency. |
| May 9 2007 04:02:22:477PM | 1070509618 | Dennis Whyte | ECDC Helium
r_res = 65 cm, I_EF4 = 200 A s3 parked at 90 cm ECDC was turned off at ~ 50 s of the shot. The change in temperature and QMB frequency is very noticeable, but the frequency was quite stable before the shut off. So it appears better to leave the ECDC on to get the QMB's to thermal equilibrium since the drift becomes < 0.1 nm over 200 seconds but we expect (hope) for higher deposition rates. |
| May 9 2007 04:07:59:633PM | 1070509619 | Dennis Whyte | Starting to setup for boronization, so
we've parked the s3 at 90 cm. We'll let if cool and monitor the QMB response. |
| May 9 2007 04:49:05:853PM | 1070509620 | Dennis Whyte | Cool down while we wait for BZN |
| May 9 2007 04:49:18:620PM | 1070509622 | Dennis Whyte | Cool down while we wait for BZN |
| May 9 2007 04:49:24:730PM | 1070509623 | Dennis Whyte | Cool down while we wait for BZN |
| May 9 2007 05:14:23:363PM | 1070509625 | Dennis Whyte | Cool down while we wait for BZN |
| May 9 2007 05:21:23:443PM | 1070509626 | Dennis Whyte | ECDC with BZN
10% diborane to 90 % He R_res = 60 cm. I_EF4 ~ 200 A Foreline pressure ~ 35 mTorr The shutter was closed for the camera view of the divertor is not completely blocked. This gives us the chance to see the plasma during BZN. We're convinced this is in the mode where the ionization light is not in H-port. The photodiode signal from ECDC is ~ 100, but when we had the H-port light localization it was more like 2000. The divertor camera view shows a localized stripe when placed at 60 cm. The s3 probe swing from 90 to 58 cm looks reasonable. this was in sweep mode so hard to control room anlyze the Isat profile. We'll next sweep in Isat mode for control room assessment of peak ion flux. |
| May 9 2007 05:31:32:573PM | 1070509627 | Dennis Whyte | ECDC with BZN
10% diborane to 90 % He R_res = 60 cm. I_EF4 ~ 200 A Foreline pressure ~ 35 mTorr S3 scan from 58 to 90 in Isat mode. Looks reasonable. |
| May 9 2007 05:45:55:407PM | 1070509628 | Dennis Whyte | Moved to R=70.0cm
3 minutes at 0 degrees. |
| May 9 2007 05:51:03:427PM | 1070509629 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+90" degrees (91.008) |
| May 9 2007 05:57:30:803PM | 1070509630 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+45" degrees (44.4) |
| May 9 2007 06:00:07:053PM | 1070509631 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-45" degrees (-44.424) |
| May 9 2007 06:09:13:290PM | 1070509632 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-90" degrees (-90) |
| May 9 2007 06:23:33:797PM | 1070509633 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+90" degrees |
| May 9 2007 06:30:06:440PM | 1070509634 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+95" degrees |
| May 9 2007 06:53:32:933PM | 1070509635 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+85" degrees |
| May 9 2007 06:54:00:433PM | 1070509636 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "+80" degrees |
| May 9 2007 07:14:14:503PM | 1070509637 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-90" degrees R_res=60 cm, I_EF4~200 A |
| May 9 2007 07:31:03:730PM | 1070509638 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-95" degrees R_res=60 cm, I_EF4~200 A |
| May 9 2007 07:44:53:483PM | 1070509639 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-85" degrees R_res=60 cm, I_EF4~200 A |
| May 9 2007 07:44:58:360PM | 1070509640 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-85" degrees R_res=60 cm, I_EF4~200 A |
| May 9 2007 07:45:05:093PM | 1070509641 | Dennis Whyte | Moved to R=70.0cm
3 minutes at "-80" degrees R_res=60 cm, I_EF4~200 A |
| May 9 2007 08:11:24:993PM | 1070509643 | Dennis Whyte | R=70.0cm (s3)
Increased pressure (foreline) to 50 mTorr 3 minutes at "-80" degrees R_res=60 cm, I_EF4~200 A The photodiode monitor in H-port birfucated to ~ 1000 counts (although intermittent) meaning that we have evidence that there is now enhanced ionization in H-port. The divertor view also changed, with the resonance stripe becoming sharper, and the flux tube of the s3 probe shadow becomes obvious. This gives us our orientation of the field such that looking into the vessel the field lines slant up towards the right (i.e. opposite of our experience with the old EF4 coil setup). So at ~ -80 we're pointing "up' the flux tube toward the upper divertor and the showerhead, probably explaining our variation of deposition rate with diborane injection. The deposition on QMB2 was 4 nm...not much lower than 42. |
| May 9 2007 08:13:45:543PM | 1070509644 | Dennis Whyte | R=70.0cm (s3)
Increased pressure (foreline) to 60 mTorr 3 minutes at "-80" degrees R_res=60 cm, I_EF4~200 A The divertor view noticeably dimmed. 6 nm deposition on qmb2. |
| May 9 2007 08:23:08:437PM | 1070509645 | Dennis Whyte | Repeat
No fluctuation of QMB2 with pressure. 6 nm net deposition. 1.5 nm on QMB1 |
| May 9 2007 08:33:07:627PM | 1070509646 | Dennis Whyte | R_s3=85 cm
R_res = 60 cm Moved the probe out behind the main limiters. The qMB2 change went to ~0.2 nm, so as expected in toroidal shadow of main limiter the deposition went to almost zero. The radial viewing qmb1 showed 1 nm change in 180s, so lower than at 70 cm, but only slightly reduced since the reduction in solid angle is not very large from "cylindrical" resonance surface. |
| May 9 2007 08:37:12:427PM | 1070509647 | Dennis Whyte | R_s3=85 cm
R_res = 60 cm reduced the pressure back to 35 mTorr in foreline to see if the neutral deposition rate changes in shadow of limiter. This is a good position to check for "antennae" deposition. QMB1 deposition dropped to 0.6 nm in 180 s from 1 nm in 180 s at higher pressure...so this may tell us that the lower pressure is better to reduce outboard deposition. |
| May 9 2007 08:47:24:023PM | 1070509648 | Dennis Whyte | R_s3=85 cm
R_res = 60 cm repeat. Again 0.6 nm deposition in 180 s,so very reproducible |
| May 9 2007 08:57:42:340PM | 1070509649 | Dennis Whyte | R_s3=105 cm
R_res = 60 cm Deposition has gone to zero on both qmbs! |
| May 9 2007 09:01:52:920PM | 1070509650 | Dennis Whyte | R_s3=95 cm
R_res = 60 cm orientation still -80 degrees |
| May 9 2007 09:07:23:360PM | 1070509651 | Dennis Whyte | R_s3=90 cm
R_res = 60 cm orientation -80 degrees |
| May 9 2007 09:16:53:270PM | 1070509652 | Dennis Whyte | R_s3=100 cm
R_res = 60 cm orientation -80 degrees |
| May 9 2007 09:31:41:717PM | 1070509653 | Dennis Whyte | R_s3 = 85 cm
R_res = 60 cm orientation -80 degrees ~0.7 nm on QMB1 in 180 ms. ~ zero on QMB 2 It seems clear that the depoosition on QMB1 is not really "neutrals" since it is correlating with the langmuir probe isat as we retract behind the toroidal limiters...so if it was neutrals the deposition should fall off as something like 1/R? Is this realistic? gryoradius of boron ion field ~ 1000 G ti ~ 10 eV (Nachtrieb) mass ~ 10 amu charge = 1 e rho_i ~ 1e2 * sqrt( ti * mass) / e B ~ 1 cm. so possible that the recession of the qmb1 is not sufficient to "block" ion deposition. |
| May 9 2007 09:28:21:593PM | 1070509654 | Dennis Whyte | R_s3=80cm
R_res = 60 cm orientation -80 degrees ~0.9 nm in 180 ms on qmb1 ~1.8 nm on qmb2 So sliding past the toroidal limiters has given us a sudden jump in qmb2 deposition rate compared to qmb 1. |
| May 9 2007 09:32:44:297PM | 1070509655 | Dennis Whyte | R_s3=75cm
R_res = 60 cm orientation -80 degrees ~1.5 nm on qmb1 ~ 2.5 nm on qmb2 |
| May 9 2007 09:47:53:630PM | 1070509657 | Dennis Whyte | R_s3=70cm
R_res = 60 cm orientation -80 degrees Take acquisition for > 5 minutes to be able to get time-averaged slope of deposition on qmb2 |
| May 9 2007 09:55:26:367PM | 1070509658 | Dennis Whyte | R_s3=65cm
R_res = 60 cm orientation -80 degrees relative size of "wiggles" on qmb2 decreased absolute deposition rate down to ~ 2.5 nm in 180 s on qmb2 0.3 nm in 180 s on qmb1 divertor camera shows shadow of probe. |
| May 9 2007 09:57:59:570PM | 1070509659 | Dennis Whyte | R_s3=60cm
R_res = 60 cm orientation -80 degrees wiggle is completely gone from qmb2 0.6 nm in 180 s on qmb1 1.4 nm in 180 s on qmb2 |
| May 9 2007 10:12:40:403PM | 1070509661 | Dennis Whyte | R_s3=58cm
R_res = 65 cm orientation -80 degrees Move the resonance 5 cm out to see well inside Ec resonance location with S3 qmb signals essentially show zero change if not decrease in thickness |
| May 9 2007 10:26:35:470PM | 1070509662 | Dennis Whyte | R_s3=105cm
We are now satisfied that this is providing a fairly localized boronization, so ee're setting the sweep for the remainder of the BZN keeping only to the inner wall to outer divertor region. R_min = 45 cm R_max = 65 cm R_res = 55 cm T_res 25 s Tsweep 60 s We took a S3 qmb run with it recessed to 105 cm to see the effect of sweep. |
| Physics Operator Comments | |||
| May 9 2007 12:50:02:543PM | Jim Irby | 1145: EF4 power supply under remote control --- beginning system checkout with helium
12:02 helium bottle open to diborane system 12:09 helium into vessel 12:30 helium ecdc operational | |
| Engineering Operator Comments | ||||
| Shot | Time | Type | Status | Comment |