Alcator C-Mod Run 930811 Information

Miniproposals

Miniproposal:

Date Filed:

Title:

First Author:

Session Leader: Bruce Lipschultz (shots 1-24)

Session Leader: Brian Labombard (shots 1-24)

Operators
Session leader(s):	Bruce Lipschultz,Brian Labombard
Physics operator(s):	John Goetz
Engineering operator(s):	Joe Daigle

Engineering Operator Run Comment
mp016 divertor

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:08:507PM

Author: To Be Determined

Physics operator summary for 930811.

EO: Daigle
PO: Goetz
SL: BLIP,BLAB

This run was based on MP016 - Scrapeoff Layer Characterization I; which is
to make lower x-point plasmas. The beginning shot was 930810025. Changes
required to this shot were: 1)move the x-point up slightly, and 2)make the
plasma more elliptical. Both of these objectives were achieved although the
plasmas obtained were not quite satisfactory for the Mini-proposal. Control
of the x-point was tried using pre-programmed current in the EF1's and EF2's.
This method is an unsatisfactory way of trying to twiddle in the desired x-point
location. The controllers KAPPA, Z_XL, and R_XL need to be implemented and
tweaked up. The ZCUR controller was very sensitive to the P and D gains and
was fighting the IC_EF1's. Severe oscillations and non-control were evident
over a very narrow range of the gains. Tweaking of the IC_EF1's did result
in achieving kappa=1.6 over the times of interest. This resulted in diverted
plasmas, but the oscillations in ZCUR caused the x-point to go back and forth
between upper and lower (and sometimes double). When the z-position was held
somewhat constant, the divertor did remain in the lower chamber, although the
strike point locations weren't acceptable to the session leaders. A rapid
outward movement of the first eight plasmas was due to a programmed voltage
on EF3 in anticipation of reversed EF4. When this voltage was removed, the
RCUR controller worked very well.

No engineering troubles today. The computer system got caught in a file access
lock state that was fixed after much hard work.

Overnight mini-bake and warm ECDC were performed before the run. Fill pressure
was 1.2e-5 and remained so throughout the run. Many pulses were added to
PULSE_GAS_3 during the run in order to flat-top the density. No attempt at
a density scan was done.

Scorecard: 22 shots - 20 plasmas + 2 data system tests

Shot summary for 930811
Reload of 930810025

1 P_0=1.2e-5 spike on PULSE_GAS_3 @.2sec plasma
2 spike on PULSE_GAS_3 @.15sec RCUR=.69 ZCUR=-.02 plasma
P_ZCUR=3. D_ZCUR=5.
3 EF1's to 2700A (.2->.4sec) plasma
4 ZCUR=-.03 spike on PULSE_GAS_3 @.25sec plasma
5 spike on PULSE_GAS_3 @.3sec, first spike .02sec earlier plasma
EF1's extended to .425sec @2700A
6 spike on PULSE_GAS_3 @.35sec EF1L to 2800A plasma
KAPPA controller on; P_kappa=1.0
7 EF1's moved earlier to .16sec plasma
8 P_ZCUR=4.0 RCUR=.69 plasma
9 data system test test
10 data system test test
11 P_ZCUR=5.0 D_ZCUR=8. P_KAPPA=2.0 plasma
remove positive swing on V_EF3 @.35sec
12 P_ZCUR=4.0 P_KAPPA=3.0 IC_EF1L=2950A IC_EF2L=875A plasma
13 P_ZCUR=5.0 D_ZCUR=10.0 IC_EF1L=2800A plasma
14 EF1's=3100A IC_EF2L=775A P_ZCUR=2.0 P_KAPPA=1.0 plasma
15 EF1's=3300A remove EF1 current dip @.1sec V_OH2's=-20V plasma
16 IC_EF2L=850A P_ZCUR=7.5 plasma
17 P_ZCUR=7.0 plasma
18 no changes plasma
19 no changes plasma
20 P_ZCUR=6.6 raise and widen second spike on PULSE_GAS_3 plasma
21 P_ZCUR=6.0 lower second spike on PULSE_GAS_3 plasma
22 no changes plasma

Physics Operator Summaries

Session Leader Comments

Aug 11 1993 08:58:08:810AM John Goetz Run 930811
EO: Daigle
PO: Goetz
SL: BLip

This run is based on MP016 - Scrapeoff Layer Characterization I - Make lower x-point
plasmas and diagnose them with the flush-mount probes and fast-scanning probe (FSP).
We plan to start with a setup of shot # 930810025 (@~380ms) from yesterday.
Changes that we are looking for are: (1)move the x-point back up slightly; (2) make
the plasma more elliptical (without upper x-point); (3) rf limiter must remain at
R=.96.
The plan is to settle on a discharge and then insert the scanning probe.
Assuming this is successful then we will do a density scan. At some point we plan
check the effect of Ar on the radiated power.

Aug 11 1993 09:34:50:570AM 930811001 Bruce Lipschultz shot # 001:
We didn't quite achieve the same conditions as 930811025. The plasma was
centered vertically on the midplane (yesterday it was 5 cm down) and the major radius
was 66.5 (x-rays) and 64 (from filament fit). However, the x-point did seem to be the
right height. Changes for shot # 002 will be to move the plasma out 2 cm and down
1 cm.

Aug 11 1993 09:52:21:900AM 930811002 Bruce Lipschultz shot # 002:
We got a double-null plasma. For the most part it was limited on the inner
and outer limiters - so a very wide plasma. For the next shot we will try to increase
the elongation in order to pull the plasma off the limiters.

Aug 11 1993 10:11:22:620AM 930811003 Bruce Lipschultz shot # 003
The plasma seems to divert around 350 ms. However, it still seems to be a
double-null. The x-point has moved out a bit and the plasma is slightly more
elongated. For the next shot, zcur=-3, ef2 lower decreased by 25 A to 750A, and
pulsed gas increased to try and flatten out the density.

Aug 11 1993 10:32:56:110AM 930811004 Bruce Lipschultz shot # 004
This shot is pretty similar. It moved down another .5 mm and so was
more single-null-like than double-null. The density needs to be raised early in
time - the SXR's are a little high and the density is staying low early in time.
We increased the first pulsed gas spike and moved it to 75 ms.
We also added another gas puff later in time. We took off
25A off of EF2 lower (now 725A).

Aug 11 1993 10:52:11:530AM 930811005 Bruce Lipschultz shot # 005
This shot is better in terms of plasma cleanliness. The density increased
early in time and stayed up. The sXR, HXR, bolos and Zeff all dropped. The plasma
position was virtually unchanged - semi-diverted late in time.
Changes for the next shot are: lower EF2 lower by 50 A to 675A; raise EF1
lower to 2800 A from 2700A (the changes in EF coils are to move the x-point out);
move the first gas puff earlier (60 ms ) and added another
puff at 350 ms; turned on the kappa controller.

Aug 11 1993 11:13:47:270AM 930811006 Bruce Lipschultz shot # 006
This shot is again an improvement in terms of density control. We are not
getting any improvement in position/divertor action. Changes for the next shot are
move the EF1 current flattop from 200 to 160 ms. There was a silicon injection on this
shot. The rf is supposed to start pulsing low power the next shot.

Aug 11 1993 11:32:00:020AM 930811007 Bruce Lipschultz shot # 007
This shot is similar to 006. We will try again try to change the plasma and x-point
position; rcur = .7 and lower EF2-lower by 50 A to 625 A. We increased the gain on zcur
as well. In addition the Ar is turned on the next shot at 200 ms.

Aug 11 1993 12:05:41:860PM 930811008 Bruce Lipschultz shot # 008
Still no particular success with x-point position. We will increase EF2 lower
back to its original level (725A) and try again.

Aug 11 1993 12:46:00:020PM 930811009 Bruce Lipschultz shot # 009
Because of problems with the datasystem, this shot is just to run the data system
after reboot.
Additional changes for shot 10 include: increase p_kappa from 1 to 2.0; EF2 lower
current to 775 A; Z_cur=5., D_zcur=8.; Ar puff to 100 msec; removed a positve porch
from V_EF3 - now @ -78V from 350 msec on.

Aug 11 1993 02:13:37:200PM 930811011 Bruce Lipschultz shot # 011
Because of problems with the datasystem, shot s 9 and 10 were tests of the
data system. Shot # 11 looks pretty good in terms of the x-point (r,z) = (56,-38).
For the next shot we will try to pull the x-point outward in major radius
earlier and pull the plasma off the inner wall (increase kappa). To do this we changed:
lower p_zcur to 4.; IC_ef2l -> 878 A @ 160 ms (from 775A) and ->825 A @ 400 msec;
IC_ef1L -> 2950A @ 160 msec and 400 msec; P_kappa to 3.0 (from 2.0). The Ar
puff was moved to 0 time.

Aug 11 1993 02:37:12:420PM 930811012 Bruce Lipschultz shot # 012
This shot was not an improvement. The kappa decreased from 1.6 to 1.4
and the x-point position did not change. We will switch ef1 back to where it
was last shot and leave everything else the same.

Aug 11 1993 03:00:24:530PM 930811013 Bruce Lipschultz shot # 013
The position and ellipticity are still not satifactory. We will try another tack;
go for a high-kappa double-null. For shot 14 we have changed the ef1's to 3100 A
for the flattop, IC_ef2l back to 725 A, p_zcur to 2.0 and p_kappa to 1.0 (from 3.0).

Aug 11 1993 03:19:33:390PM 930811014 Bruce Lipschultz shot # 014
The position and ellipticity were somewhat improved; kappa approaching 1.6
(from 1.4). There was a disruption at 450 ms when the impurity injector increased the
radiated power by too much for a falling current plasma.
For the next shot we will try to increase the ef currents (top and bottom)
to further increase kappa and also increase the OH2 currents to increase triangularity
and pull the plasma off the inner wall. The changes are: add 10V to V_oh2l & upper
(to -20V from -30V). Change I_EF1 (U&L) to 3300A.

Aug 11 1993 03:36:56:780PM 930811015 Bruce Lipschultz shot # 013
The position and ellipticity were somewhat improved again; The plasma was
diverted at earlier tmes (230-260 ms) as well as late in time.kappa approaching 1.6
(from 1.4). However, the plasma is approximately centered vertically.
For the next shot we will try to increase the ef2l current
to pull the lower x-point out in major radius. The changes are: EF2l from 775A to 850A.

Aug 11 1993 03:56:00:530PM 930811016 Bruce Lipschultz shot # 013
Again, the ellipticity is good. The plasma is diverted most of the discharge.
However, the plasma vertical position is oscillating so the plasma is changing
back and forth from upper x-point to lower x-point.
For the next shot we will try to decrease P_zcur to 7.0 from 7.5 to get rid
of the oscillation.

Aug 11 1993 04:17:26:260PM 930811017 Bruce Lipschultz shot # 017
Again, the ellipticity is good. The plasma is diverted less of the discharge.
In fact, Ian's reconstruction and FFIT don't agree. FFIT claims that the plasma is
lower-diverted from 200-320 ms. Ian's reconstruction claims it is never diverted.
Brian's flush-mount probes see plasma over the period 200 to 350ms. It is a
slot divertor at 350 ms. Bob's UV-bolometer has signal from 220 to 320 ms.
No changes fro the next shot in magnetics.

Aug 11 1993 04:30:00:960PM 930811018 Bruce Lipschultz shot # 018
Again, the ellipticity is good. The plasma is diverted for a similar amount of time in
comparison to the last shot.
For this shot Ian's reconstruction and FFIT do roughly agree. The plasma is
lower-diverted from 200-320 ms.
No changes for the next shot in magnetics. Brian is planning to put the FSP
all the way in the next shot (now closest approach is 2 cm).

Aug 11 1993 04:44:59:490PM 930811019 Bruce Lipschultz shot # 019
Again, the ellipticity is good. The plasma is diverted for a similar amount of time in
comparison to the last shot. The plasma oscillated in vertical position again. The
density has also been dropping, especially during diverted periods.
We will increase the gas puff for the next shot and decrease P_zcur from 7.
to 6.6.

Aug 11 1993 04:55:08:250PM 930811020 Bruce Lipschultz shot # 020
Again, the plasma vertical position was oscillatory
We will decrease P_zcur from 6.6 to 6.

Aug 11 1993 05:20:18:690PM 930811021 Bruce Lipschultz shot # 022
Plasma position was oscillatory. Otherwise a good shot.

Physics Operator Comments

Engineering Operator Comments

Shot Time Type Status Comment

1 09:09:36:880AM Plasma Ok Plasma first shot Power systems O.K.

2 09:30:41:420AM Plasma Ok plasma

3 09:52:07:340AM Plasma Ok plasma shot no faults.

4 10:09:28:980AM Plasma Ok plasma shot no faults.

5 10:30:14:110AM Plasma Ok plasma shot no faults

6 10:50:53:840AM Plasma Ok Plasma shot no faults

7 11:11:56:920AM Plasma Ok Plasma shot no faults.

8 11:35:18:850AM Plasma Ok 55ka plasma

9 12:38:41:810PM Test Ok power supplies were not energized.

10 01:34:20:130PM Test Ok data system

11 01:45:18:660PM Plasma Ok good plasma once again

12 02:12:26:800PM Plasma Ok Plasma shot No faults.

13 02:37:42:480PM Plasma Ok good shot, plasma

14 02:58:36:790PM Plasma Ok Plasma shot no faults.

15 03:20:36:240PM Plasma Ok plasma, good shot

16 03:40:17:180PM Plasma Ok plasma, good shot

17 03:56:04:100PM Plasma Ok plasma pulse no faults

18 04:15:32:820PM Plasma Ok Plasma shot No faults.

19 04:30:26:030PM Plasma Ok plasma shot O.K

20 04:45:15:860PM Plasma Ok plasma shot No faults.

21 04:58:57:760PM Plasma Ok plasma shot no faults.

22 05:12:15:620PM Plasma Ok Plasma shot no faults.

23 05:28:07:100PM Test Ok ef4 fwd only hybrid as with plasma shots -- no single phasing

24 05:39:11:140PM Test Ok ef4 double swing ok

Session Leader Comments
Aug 11 1993 08:58:08:810AM		John Goetz	Run 930811 EO: Daigle PO: Goetz SL: BLip This run is based on MP016 - Scrapeoff Layer Characterization I - Make lower x-point plasmas and diagnose them with the flush-mount probes and fast-scanning probe (FSP). We plan to start with a setup of shot # 930810025 (@~380ms) from yesterday. Changes that we are looking for are: (1)move the x-point back up slightly; (2) make the plasma more elliptical (without upper x-point); (3) rf limiter must remain at R=.96. The plan is to settle on a discharge and then insert the scanning probe. Assuming this is successful then we will do a density scan. At some point we plan check the effect of Ar on the radiated power.
Aug 11 1993 09:34:50:570AM	930811001	Bruce Lipschultz	shot # 001: We didn't quite achieve the same conditions as 930811025. The plasma was centered vertically on the midplane (yesterday it was 5 cm down) and the major radius was 66.5 (x-rays) and 64 (from filament fit). However, the x-point did seem to be the right height. Changes for shot # 002 will be to move the plasma out 2 cm and down 1 cm.
Aug 11 1993 09:52:21:900AM	930811002	Bruce Lipschultz	shot # 002: We got a double-null plasma. For the most part it was limited on the inner and outer limiters - so a very wide plasma. For the next shot we will try to increase the elongation in order to pull the plasma off the limiters.
Aug 11 1993 10:11:22:620AM	930811003	Bruce Lipschultz	shot # 003 The plasma seems to divert around 350 ms. However, it still seems to be a double-null. The x-point has moved out a bit and the plasma is slightly more elongated. For the next shot, zcur=-3, ef2 lower decreased by 25 A to 750A, and pulsed gas increased to try and flatten out the density.
Aug 11 1993 10:32:56:110AM	930811004	Bruce Lipschultz	shot # 004 This shot is pretty similar. It moved down another .5 mm and so was more single-null-like than double-null. The density needs to be raised early in time - the SXR's are a little high and the density is staying low early in time. We increased the first pulsed gas spike and moved it to 75 ms. We also added another gas puff later in time. We took off 25A off of EF2 lower (now 725A).
Aug 11 1993 10:52:11:530AM	930811005	Bruce Lipschultz	shot # 005 This shot is better in terms of plasma cleanliness. The density increased early in time and stayed up. The sXR, HXR, bolos and Zeff all dropped. The plasma position was virtually unchanged - semi-diverted late in time. Changes for the next shot are: lower EF2 lower by 50 A to 675A; raise EF1 lower to 2800 A from 2700A (the changes in EF coils are to move the x-point out); move the first gas puff earlier (60 ms ) and added another puff at 350 ms; turned on the kappa controller.
Aug 11 1993 11:13:47:270AM	930811006	Bruce Lipschultz	shot # 006 This shot is again an improvement in terms of density control. We are not getting any improvement in position/divertor action. Changes for the next shot are move the EF1 current flattop from 200 to 160 ms. There was a silicon injection on this shot. The rf is supposed to start pulsing low power the next shot.
Aug 11 1993 11:32:00:020AM	930811007	Bruce Lipschultz	shot # 007 This shot is similar to 006. We will try again try to change the plasma and x-point position; rcur = .7 and lower EF2-lower by 50 A to 625 A. We increased the gain on zcur as well. In addition the Ar is turned on the next shot at 200 ms.
Aug 11 1993 12:05:41:860PM	930811008	Bruce Lipschultz	shot # 008 Still no particular success with x-point position. We will increase EF2 lower back to its original level (725A) and try again.
Aug 11 1993 12:46:00:020PM	930811009	Bruce Lipschultz	shot # 009 Because of problems with the datasystem, this shot is just to run the data system after reboot. Additional changes for shot 10 include: increase p_kappa from 1 to 2.0; EF2 lower current to 775 A; Z_cur=5., D_zcur=8.; Ar puff to 100 msec; removed a positve porch from V_EF3 - now @ -78V from 350 msec on.
Aug 11 1993 02:13:37:200PM	930811011	Bruce Lipschultz	shot # 011 Because of problems with the datasystem, shot s 9 and 10 were tests of the data system. Shot # 11 looks pretty good in terms of the x-point (r,z) = (56,-38). For the next shot we will try to pull the x-point outward in major radius earlier and pull the plasma off the inner wall (increase kappa). To do this we changed: lower p_zcur to 4.; IC_ef2l -> 878 A @ 160 ms (from 775A) and ->825 A @ 400 msec; IC_ef1L -> 2950A @ 160 msec and 400 msec; P_kappa to 3.0 (from 2.0). The Ar puff was moved to 0 time.
Aug 11 1993 02:37:12:420PM	930811012	Bruce Lipschultz	shot # 012 This shot was not an improvement. The kappa decreased from 1.6 to 1.4 and the x-point position did not change. We will switch ef1 back to where it was last shot and leave everything else the same.
Aug 11 1993 03:00:24:530PM	930811013	Bruce Lipschultz	shot # 013 The position and ellipticity are still not satifactory. We will try another tack; go for a high-kappa double-null. For shot 14 we have changed the ef1's to 3100 A for the flattop, IC_ef2l back to 725 A, p_zcur to 2.0 and p_kappa to 1.0 (from 3.0).
Aug 11 1993 03:19:33:390PM	930811014	Bruce Lipschultz	shot # 014 The position and ellipticity were somewhat improved; kappa approaching 1.6 (from 1.4). There was a disruption at 450 ms when the impurity injector increased the radiated power by too much for a falling current plasma. For the next shot we will try to increase the ef currents (top and bottom) to further increase kappa and also increase the OH2 currents to increase triangularity and pull the plasma off the inner wall. The changes are: add 10V to V_oh2l & upper (to -20V from -30V). Change I_EF1 (U&L) to 3300A.
Aug 11 1993 03:36:56:780PM	930811015	Bruce Lipschultz	shot # 013 The position and ellipticity were somewhat improved again; The plasma was diverted at earlier tmes (230-260 ms) as well as late in time.kappa approaching 1.6 (from 1.4). However, the plasma is approximately centered vertically. For the next shot we will try to increase the ef2l current to pull the lower x-point out in major radius. The changes are: EF2l from 775A to 850A.
Aug 11 1993 03:56:00:530PM	930811016	Bruce Lipschultz	shot # 013 Again, the ellipticity is good. The plasma is diverted most of the discharge. However, the plasma vertical position is oscillating so the plasma is changing back and forth from upper x-point to lower x-point. For the next shot we will try to decrease P_zcur to 7.0 from 7.5 to get rid of the oscillation.
Aug 11 1993 04:17:26:260PM	930811017	Bruce Lipschultz	shot # 017 Again, the ellipticity is good. The plasma is diverted less of the discharge. In fact, Ian's reconstruction and FFIT don't agree. FFIT claims that the plasma is lower-diverted from 200-320 ms. Ian's reconstruction claims it is never diverted. Brian's flush-mount probes see plasma over the period 200 to 350ms. It is a slot divertor at 350 ms. Bob's UV-bolometer has signal from 220 to 320 ms. No changes fro the next shot in magnetics.
Aug 11 1993 04:30:00:960PM	930811018	Bruce Lipschultz	shot # 018 Again, the ellipticity is good. The plasma is diverted for a similar amount of time in comparison to the last shot. For this shot Ian's reconstruction and FFIT do roughly agree. The plasma is lower-diverted from 200-320 ms. No changes for the next shot in magnetics. Brian is planning to put the FSP all the way in the next shot (now closest approach is 2 cm).
Aug 11 1993 04:44:59:490PM	930811019	Bruce Lipschultz	shot # 019 Again, the ellipticity is good. The plasma is diverted for a similar amount of time in comparison to the last shot. The plasma oscillated in vertical position again. The density has also been dropping, especially during diverted periods. We will increase the gas puff for the next shot and decrease P_zcur from 7. to 6.6.
Aug 11 1993 04:55:08:250PM	930811020	Bruce Lipschultz	shot # 020 Again, the plasma vertical position was oscillatory We will decrease P_zcur from 6.6 to 6.
Aug 11 1993 05:20:18:690PM	930811021	Bruce Lipschultz	shot # 022 Plasma position was oscillatory. Otherwise a good shot.

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	09:09:36:880AM	Plasma	Ok	Plasma first shot Power systems O.K.
2	09:30:41:420AM	Plasma	Ok	plasma
3	09:52:07:340AM	Plasma	Ok	plasma shot no faults.
4	10:09:28:980AM	Plasma	Ok	plasma shot no faults.
5	10:30:14:110AM	Plasma	Ok	plasma shot no faults
6	10:50:53:840AM	Plasma	Ok	Plasma shot no faults
7	11:11:56:920AM	Plasma	Ok	Plasma shot no faults.
8	11:35:18:850AM	Plasma	Ok	55ka plasma
9	12:38:41:810PM	Test	Ok	power supplies were not energized.
10	01:34:20:130PM	Test	Ok	data system
11	01:45:18:660PM	Plasma	Ok	good plasma once again
12	02:12:26:800PM	Plasma	Ok	Plasma shot No faults.
13	02:37:42:480PM	Plasma	Ok	good shot, plasma
14	02:58:36:790PM	Plasma	Ok	Plasma shot no faults.
15	03:20:36:240PM	Plasma	Ok	plasma, good shot
16	03:40:17:180PM	Plasma	Ok	plasma, good shot
17	03:56:04:100PM	Plasma	Ok	plasma pulse no faults
18	04:15:32:820PM	Plasma	Ok	Plasma shot No faults.
19	04:30:26:030PM	Plasma	Ok	plasma shot O.K
20	04:45:15:860PM	Plasma	Ok	plasma shot No faults.
21	04:58:57:760PM	Plasma	Ok	plasma shot no faults.
22	05:12:15:620PM	Plasma	Ok	Plasma shot no faults.
23	05:28:07:100PM	Test	Ok	ef4 fwd only hybrid as with plasma shots -- no single phasing
24	05:39:11:140PM	Test	Ok	ef4 double swing ok