Alcator C-Mod Run 970625 Information

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Miniproposals
Miniproposal:158
Date Filed: 7/22/1996
Title:Fast disruption termination using massive D2 pellet injection
First Author:Robert Granetz
Session Leader:Robert Granetz (shots 1-22)

Operators
Session leader(s):Robert Granetz
Physics operator(s):Robert Granetz
Engineering operator(s):Bill Cochran,Frank Silva,Vinny Bertolino

Engineering Operator Run Comment
mp175/Terry/Cochran/Bertolino/Granetz/setup as for 970624038

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:17:007PM
Author: To Be Determined
Physics operator summary for run 970625

MP 158, Fast disruption termination using massive D2 pellet injection

SL: Granetz
PO: Granetz
EO: Silva, Cochran, Bertolino

Summary: A very successful run. We conclusively showed that massive D2 pellet
injection does NOT speed up the current quench at all, nor does it
reduce the halo current. The pellets typically raised the plasma
density momentarily to nebar=1.6e21 m-3 (about 3 times the Greenwald
limit), and lowered Te to 100-200 eV in the outer portion of the
plasma, but the current quench timescale was about 5 ms, which is the
typical value. The same result was obtained when we tried to kill a
VDE (shot 20). Simultaneous injection of D2 pellets and tungsten
(from the laser blowoff) did not do any better. We were able to kill
OH, L-mode, ELMy H-mode, and ELM-free H-modes, with identical results.
See shots 11, 13, 14, 16, 17, and 20. MP #158 has been completed.

Some progress was also made with the RF, but there are still a lot of
problems. Shot 16 had 2.2 MW.

Problems today: the TCI laser had some problems today, resulting in
loss of density feedback, and probably leading to some unexpected
disruptions. To get around this, we turned off the hybrid feedback
and pasted in an actual valve voltage trace from a good shot into the
pre-programmed voltage.

******* WARNING: IF YOU USE ONE OF TODAY'S SHOTS (AFTER 009) FOR FUTURE
SETUP'S, REMEMBER THAT THE DENSITY FEEDBACK IS TURNED OFF!

******* WARNING: IF YOU USE ONE OF TODAY'S SHOTS (AFTER 018) FOR FUTURE
SETUP'S, REMEMBER THAT THE ZCUR FEEDBACK IS TURNED OFF AFTER
T=1.10 SECONDS!

There was a unexplained fault with TF cabinet #1 (shot 020) which
caused a lot of unusual noise in the power room, and a lot of
electrical noise on the TF current. No problems were found in the
cabinet, however, and subsequent shots were fine.

Scorecard: 14 plasmas
4 fizzles
2 duds (1 magnetic resistance fault, 1 gas system problem)
2 tests
----------
22 total

------------------------------------------------------------------------------
Run Plan for Wednesday, 970625:

MP 158 -- Fast disruption termination using massive D2 pellet injection.

Engineering setup for Wednesday 25 June 1997:

** Please note: **

After the most recent plasma run (Tues), a series of shot cycles was run
for gas calibration purposes. Please be sure to have all necessary
trees turned back on again for the beginning of this run.

Overnight ECDC in deuterium.
Engineering setup as on 970624035, with TF under hybrid control
Plasma current to be set for 0.8 MA instead of 1.0 MA.
Density to be set for nl_04=1.0e20 m-2.
Segment 1 startup will be copied from 970624035.

Gas setup - fill K-side with 20 PSI of D2, hybrid enable
fill B-top with 6 PSI of D2, hybrid enable
fill B-side-lower with 4 PSI of Ar, hybrid enable
fill J-bottom with 4 PSI of Ne, DO NOT ENABLE

The following gate valves should be enabled, assuming no vacuum problems:

ECE and PI only! (not PCX, not TCX, not VUV)

The IG1 and IG2 turbopump gauges should be turned off.
The ratiomatic gauge should be turned off and its auto reset turned off.

-------------------------------------------------------------------------------
Detailed shot log:

Hybrid coldstart done; no problems.
Reload plasma shot from late yesterday (970624035), B=5.3 tesla
Reduce plasma current to 0.8 MA.
Reduce nl_04 to 1.0e20 m-2.

Because of an overnight fault in the pellet injector system, the
pellet injector will require 1.5 hours to recool. RF will make
use of the first part of the run.

Shot 01 -- Test of TF scanner.

Shot 02 -- Plasma, but no EFC, resulting in a disruption at 0.19 s. There was
also a PF crowbar.

Next shot: repeat with no changes, except try a 50 ms puff of neon
from J-bottom valve.

Shot 03 -- Plasma. Good shot. Prf=1 MW. A couple of ELMy H-modes. No neon.
The feedback signal for the antenna gap is now getting to the
hybrid (that's one problem fixed), but it is not correct.

We are having a break now to allow RF access to the cell.

Next shot: repeat with no changes, except this time enable the
J-bottom PLC bit (oops, operator error).

Shot 04 -- Plasma. Good shot. Got two good ELM-free H-modes. Neon got in.

Next shot: repeat.

Shot 05 -- Plasma. Good shot. Disrupted at 1.22 s. Prf>1 MW. Two more
ELM-free H-modes.

Next shot: pellet injection, all barrels enabled. Pellets should
hit plasma at t=1.170 s (600 microseconds prior to YAG pulse).
Turn off IGP1, IGP2, F-ratiomatic. Turn on PI gate valve.
Turn off and bypass IGT.
Setup fast windows starting at t=1.150 s.
Also turn on impurity injector to fire silicon at t=0.5 s.

** Start pellet injection next shot **

Shot 06 -- Plasma. Disrupted at t=1.00 s, which is well before the pellets
were fired. Pellet injector worked well. Some RF, but no H-modes.
No density signal. It turns out that the density feedback was
asking for lots of gas because of the lack of density signal.
I'm blaming the disruption on that, but the YAG gives ne0=3e20 m-3
only.

Next shot: try again, no changes.

Shot 07 -- Fizzle. Problems with the interferometer laser again. Chalk it up
to disruption recovery.

Next shot: try again, no changes.

Shot 08 -- Dud. Most power supplies didn't fire. Magnet resistance fault.

Next shot: try again, no changes.

Shot 09 -- Plasma. Disrupted at 1.03 s. No density again. Jim will need
cell access soon.

Next shot: move pellet injection to t=0.7095 s. RF will be on at
that time.
Also, assume there will be no density feedback signal. Copy PG3
voltage trace from shot 004 into voltage programming for segment 2,
and turn off feedback gain for nl_04.

Shot 10 -- Fizzle. Disruption recovery again?

Next shot: try again.

Shot 11 -- Plasma. Got it! Pellets were strung out over 1.5 ms, starting
at t=0.7074 s. Prf=0.9 MW at the injection. Current quench was
very slow, about 5 ms! I_halo_lower=120 kA (typical value).

Next shot: repeat, perhaps with more RF power.

Shot 12 -- Fizzle. Disruption recovery?

Next shot: repeat.

Shot 13 -- Plasma. Got another one! Density on this shot (and previous one)
reaches nebar=1.6e21 !!!. Plasma takes a relatively long time to
begin to quench, and the current quench again takes 5 ms. Typical
halo currents, as well. Prf was again 1 Mw, but this shot was
killed during an ELM-free H-mode. Martin reports that the pellets
were less strung out than previously.

Next shot: repeat, except turn off RF at 0.6 s. (It will probably
be a fizzle anyway.)

Shot 14 -- Plasma. Got another one. This was killed in ohmic L-mode. Same
results as previous shots.

We are having a break now to allow access to the cell for multiple purposes.

Next shot: turn RF back on.
Try firing tungsten simultaneously with the pellets.

Shot 15 -- Dud. Null looks okay. All supplies fired. Steve Wolfe has found
that the hybrid gas pulse did not get to the valve.

Next shot: try again. RF will be going. Tungsten will be
injected at t=0.708 s, along with the D2 pellets.

Shot 16 -- Plasma. Another successful kill. Typical quench time, typical
halo current. It doesn't look like the tungsten made it in.
Good RF ... 2.2 MW! ELM-free H-modes.

Next shot: try again. Move tungsten injection earlier. Increase
neon puff from 50 to 60 ms.

Shot 17 -- Plasma. Another successful kill. Same results. RF didn't work
as well. Tungsten got in, but didn't cool the plasma enough to
speed up the current quench.

Next shot: change gears and try killing VDE's. Turn off the
ZCUR feedback gain at t=1.10 s. Move fast windows to t=1.10 s
RF will be on.

Shot 18 -- Fizzle. Null is so-so.

Next shot: repeat with no changes.

Shot 19 -- Plasma. VDE went upwards, with plasma termination at t=1.131 s.
Z-centroid from x-rays was at +0.02 m at t=1.12 s, with the pellet
firing at 1.17 s. Very fast current quench (2 ms). Multiple
H-modes.

Next shot: delay start of VDE by 50 ms (gains turn off at t=1.150 s)

Shot 20 -- Plasma. Good VDE, but there was a really wierd noise coming from
the power room. There is a lot of noise on the TF current and
Btor during the flattop. Apparently a current sensor in one of the
TF cabinets became very noisy. Pellets hit the plasma when it
was 3 cm down. Perfect timing. Still did not speed up the current
quench though. Typical halo current. That completes MP 158 !

We are having a break now to allow access to the power room to work on the
TF supply.

Shot 21 -- PLC test of TF at 100 kA. Looks good.

Next shot: normal plasma with RF. No pellets.

Shot 22 -- Plasma. Good VDE, but we didn't want this to be a VDE. I forgot to
turn on the ZCUR feedback for the entire shot ... operator error!

End of run

Physics Operator Summaries
Entered: Jul 7 2004 04:36:57:850PM
Author: To Be Determined
Physics operator summary for run 970625

MP 158, Fast disruption termination using massive D2 pellet injection

SL: Granetz
PO: Granetz
EO: Silva, Cochran, Bertolino

Summary: A very successful run. We conclusively showed that massive D2 pellet
injection does NOT speed up the current quench at all, nor does it
reduce the halo current. The pellets typically raised the plasma
density momentarily to nebar=1.6e21 m-3 (about 3 times the Greenwald
limit), and lowered Te to 100-200 eV in the outer portion of the
plasma, but the current quench timescale was about 5 ms, which is the
typical value. The same result was obtained when we tried to kill a
VDE (shot 20). Simultaneous injection of D2 pellets and tungsten
(from the laser blowoff) did not do any better. We were able to kill
OH, L-mode, ELMy H-mode, and ELM-free H-modes, with identical results.
See shots 11, 13, 14, 16, 17, and 20. MP #158 has been completed.

Some progress was also made with the RF, but there are still a lot of
problems. Shot 16 had 2.2 MW.

Problems today: the TCI laser had some problems today, resulting in
loss of density feedback, and probably leading to some unexpected
disruptions. To get around this, we turned off the hybrid feedback
and pasted in an actual valve voltage trace from a good shot into the
pre-programmed voltage.

******* WARNING: IF YOU USE ONE OF TODAY'S SHOTS (AFTER 009) FOR FUTURE
SETUP'S, REMEMBER THAT THE DENSITY FEEDBACK IS TURNED OFF!

******* WARNING: IF YOU USE ONE OF TODAY'S SHOTS (AFTER 018) FOR FUTURE
SETUP'S, REMEMBER THAT THE ZCUR FEEDBACK IS TURNED OFF AFTER
T=1.10 SECONDS!

There was a unexplained fault with TF cabinet #1 (shot 020) which
caused a lot of unusual noise in the power room, and a lot of
electrical noise on the TF current. No problems were found in the
cabinet, however, and subsequent shots were fine.

Scorecard: 14 plasmas
4 fizzles
2 duds (1 magnetic resistance fault, 1 gas system problem)
2 tests
----------
22 total

------------------------------------------------------------------------------
Run Plan for Wednesday, 970625:

MP 158 -- Fast disruption termination using massive D2 pellet injection.

Engineering setup for Wednesday 25 June 1997:

** Please note: **

After the most recent plasma run (Tues), a series of shot cycles was run
for gas calibration purposes. Please be sure to have all necessary
trees turned back on again for the beginning of this run.

Overnight ECDC in deuterium.
Engineering setup as on 970624035, with TF under hybrid control
Plasma current to be set for 0.8 MA instead of 1.0 MA.
Density to be set for nl_04=1.0e20 m-2.
Segment 1 startup will be copied from 970624035.

Gas setup - fill K-side with 20 PSI of D2, hybrid enable
fill B-top with 6 PSI of D2, hybrid enable
fill B-side-lower with 4 PSI of Ar, hybrid enable
fill J-bottom with 4 PSI of Ne, DO NOT ENABLE

The following gate valves should be enabled, assuming no vacuum problems:

ECE and PI only! (not PCX, not TCX, not VUV)

The IG1 and IG2 turbopump gauges should be turned off.
The ratiomatic gauge should be turned off and its auto reset turned off.

-------------------------------------------------------------------------------
Detailed shot log:

Hybrid coldstart done; no problems.
Reload plasma shot from late yesterday (970624035), B=5.3 tesla
Reduce plasma current to 0.8 MA.
Reduce nl_04 to 1.0e20 m-2.

Because of an overnight fault in the pellet injector system, the
pellet injector will require 1.5 hours to recool. RF will make
use of the first part of the run.

Shot 01 -- Test of TF scanner.

Shot 02 -- Plasma, but no EFC, resulting in a disruption at 0.19 s. There was
also a PF crowbar.

Next shot: repeat with no changes, except try a 50 ms puff of neon
from J-bottom valve.

Shot 03 -- Plasma. Good shot. Prf=1 MW. A couple of ELMy H-modes. No neon.
The feedback signal for the antenna gap is now getting to the
hybrid (that's one problem fixed), but it is not correct.

We are having a break now to allow RF access to the cell.

Next shot: repeat with no changes, except this time enable the
J-bottom PLC bit (oops, operator error).

Shot 04 -- Plasma. Good shot. Got two good ELM-free H-modes. Neon got in.

Next shot: repeat.

Shot 05 -- Plasma. Good shot. Disrupted at 1.22 s. Prf>1 MW. Two more
ELM-free H-modes.

Next shot: pellet injection, all barrels enabled. Pellets should
hit plasma at t=1.170 s (600 microseconds prior to YAG pulse).
Turn off IGP1, IGP2, F-ratiomatic. Turn on PI gate valve.
Turn off and bypass IGT.
Setup fast windows starting at t=1.150 s.
Also turn on impurity injector to fire silicon at t=0.5 s.

** Start pellet injection next shot **

Shot 06 -- Plasma. Disrupted at t=1.00 s, which is well before the pellets
were fired. Pellet injector worked well. Some RF, but no H-modes.
No density signal. It turns out that the density feedback was
asking for lots of gas because of the lack of density signal.
I'm blaming the disruption on that, but the YAG gives ne0=3e20 m-3
only.

Next shot: try again, no changes.

Shot 07 -- Fizzle. Problems with the interferometer laser again. Chalk it up
to disruption recovery.

Next shot: try again, no changes.

Shot 08 -- Dud. Most power supplies didn't fire. Magnet resistance fault.

Next shot: try again, no changes.

Shot 09 -- Plasma. Disrupted at 1.03 s. No density again. Jim will need
cell access soon.

Next shot: move pellet injection to t=0.7095 s. RF will be on at
that time.
Also, assume there will be no density feedback signal. Copy PG3
voltage trace from shot 004 into voltage programming for segment 2,
and turn off feedback gain for nl_04.

Shot 10 -- Fizzle. Disruption recovery again?

Next shot: try again.

Shot 11 -- Plasma. Got it! Pellets were strung out over 1.5 ms, starting
at t=0.7074 s. Prf=0.9 MW at the injection. Current quench was
very slow, about 5 ms! I_halo_lower=120 kA (typical value).

Next shot: repeat, perhaps with more RF power.

Shot 12 -- Fizzle. Disruption recovery?

Next shot: repeat.

Shot 13 -- Plasma. Got another one! Density on this shot (and previous one)
reaches nebar=1.6e21 !!!. Plasma takes a relatively long time to
begin to quench, and the current quench again takes 5 ms. Typical
halo currents, as well. Prf was again 1 Mw, but this shot was
killed during an ELM-free H-mode. Martin reports that the pellets
were less strung out than previously.

Next shot: repeat, except turn off RF at 0.6 s. (It will probably
be a fizzle anyway.)

Shot 14 -- Plasma. Got another one. This was killed in ohmic L-mode. Same
results as previous shots.

We are having a break now to allow access to the cell for multiple purposes.

Next shot: turn RF back on.
Try firing tungsten simultaneously with the pellets.

Shot 15 -- Dud. Null looks okay. All supplies fired. Steve Wolfe has found
that the hybrid gas pulse did not get to the valve.

Next shot: try again. RF will be going. Tungsten will be
injected at t=0.708 s, along with the D2 pellets.

Shot 16 -- Plasma. Another successful kill. Typical quench time, typical
halo current. It doesn't look like the tungsten made it in.
Good RF ... 2.2 MW! ELM-free H-modes.

Next shot: try again. Move tungsten injection earlier. Increase
neon puff from 50 to 60 ms.

Shot 17 -- Plasma. Another successful kill. Same results. RF didn't work
as well. Tungsten got in, but didn't cool the plasma enough to
speed up the current quench.

Next shot: change gears and try killing VDE's. Turn off the
ZCUR feedback gain at t=1.10 s. Move fast windows to t=1.10 s
RF will be on.

Shot 18 -- Fizzle. Null is so-so.

Next shot: repeat with no changes.

Shot 19 -- Plasma. VDE went upwards, with plasma termination at t=1.131 s.
Z-centroid from x-rays was at +0.02 m at t=1.12 s, with the pellet
firing at 1.17 s. Very fast current quench (2 ms). Multiple
H-modes.

Next shot: delay start of VDE by 50 ms (gains turn off at t=1.150 s)

Shot 20 -- Plasma. Good VDE, but there was a really wierd noise coming from
the power room. There is a lot of noise on the TF current and
Btor during the flattop. Apparently a current sensor in one of the
TF cabinets became very noisy. Pellets hit the plasma when it
was 3 cm down. Perfect timing. Still did not speed up the current
quench though. Typical halo current. That completes MP 158 !

We are having a break now to allow access to the power room to work on the
TF supply.

Shot 21 -- PLC test of TF at 100 kA. Looks good.

Next shot: normal plasma with RF. No pellets.

Shot 22 -- Plasma. Good VDE, but we didn't want this to be a VDE. I forgot to
turn on the ZCUR feedback for the entire shot ... operator error!

End of run

Session Leader Comments

Physics Operator Comments
Jun 25 1997 08:54:59:470AMRobert GranetzRun Plan for Wednesday, 970625:

MP 158 -- Fast disruption termination using massive D2 pellet injection.

Engineering setup for Wednesday 25 June 1997:

** Please note: **

After the most recent plasma run (Tues), a series of shot cycles was run
for gas calibration purposes. Please be sure to have all necessary
trees turned back on again for the beginning of this run.

Overnight ECDC in deuterium.
Engineering setup as on 970624035, with TF under hybrid control
Plasma current to be set for 0.8 MA instead of 1.0 MA.
Density to be set for nl_04=1.0e20 m-2.
Segment 1 startup will be copied from 970624035.

Gas setup - fill K-side with 20 PSI of D2, hybrid enable
fill B-top with 6 PSI of D2, hybrid enable
fill B-side-lower with 4 PSI of Ar, hybrid enable
fill J-bottom with 4 PSI of Ne, DO NOT ENABLE

The following gate valves should be enabled, assuming no vacuum problems:

ECE and PI only! (not PCX, not TCX, not VUV)

The IG1 and IG2 turbopump gauges should be turned off.
The ratiomatic gauge should be turned off and its auto reset turned off.
Jun 25 1997 08:55:41:080AMRobert Granetz Hybrid coldstart done; no problems.
Reload plasma shot from late yesterday (970624035), B=5.3 tesla
Reduce plasma current to 0.8 MA.
Reduce nl_04 to 1.0e20 m-2.

Because of an overnight fault in the pellet injector system, the
pellet injector will require 1.5 hours to recool. RF will make
use of the first part of the run.
Jun 25 1997 08:59:16:350AM970625001Robert GranetzShot 01 -- Test of TF scanner.
Jun 25 1997 09:30:53:160AM970625002Robert GranetzShot 02 -- Plasma, but no EFC, resulting in a disruption at 0.19 s. There was
also a PF crowbar.

Next shot: repeat with no changes, except try a 50 ms puff of neon
from J-bottom valve.
Jun 25 1997 09:52:26:120AM970625003Robert GranetzShot 03 -- Plasma. Good shot. Prf=1 MW. A couple of ELMy H-modes. No neon.
The feedback signal for the antenna gap is now getting to the
hybrid (that's one problem fixed), but it is not correct.

We are having a break now to allow RF access to the cell.

Next shot: repeat with no changes, except this time enable the
J-bottom PLC bit (oops, operator error).
Jun 25 1997 10:16:27:900AM970625004Robert GranetzShot 04 -- Plasma. Good shot. Got two good ELM-free H-modes. Neon got in.

Next shot: repeat.
Jun 25 1997 11:19:16:730AM970625005Robert GranetzShot 05 -- Plasma. Good shot. Disrupted at 1.22 s. Prf>1 MW. Two more
ELM-free H-modes.

Next shot: pellet injection, all barrels enabled. Pellets should
hit plasma at t=1.170 s (600 microseconds prior to YAG pulse).
Turn off IGP1, IGP2, F-ratiomatic. Turn on PI gate valve.
Turn off and bypass IGT.
Setup fast windows starting at t=1.150 s.
Also turn on impurity injector to fire silicon at t=0.5 s.
Jun 25 1997 10:53:38:140AM970625006Robert GranetzShot 06 -- Plasma. Disrupted at t=1.00 s, which is well before the pellets
were fired. Pellet injector worked well. Some RF, but no H-modes.
No density signal. It turns out that the density feedback was
asking for lots of gas because of the lack of density signal.
I'm blaming the disruption on that, but the YAG gives ne0=3e20 m-3
only.

Next shot: try again, no changes.
Jun 25 1997 11:10:38:770AM970625007Robert GranetzShot 07 -- Fizzle. Problems with the interferometer laser again. Chalk it up
to disruption recovery.

Next shot: try again, no changes.
Jun 25 1997 11:17:55:960AM970625008Robert GranetzShot 08 -- Dud. Most power supplies didn't fire. Magnet resistance fault.

Next shot: try again, no changes.
Jun 25 1997 11:36:31:620AM970625009Robert GranetzShot 09 -- Plasma. Disrupted at 1.03 s. No density again. Jim will need
cell access soon.

Next shot: move pellet injection to t=0.7095 s. RF will be on at
that time.
Also, assume there will be no density feedback signal. Copy PG3
voltage trace from shot 004 into voltage programming for segment 2,
and turn off feedback gain for nl_04.
Jun 25 1997 11:43:43:280AM970625010Robert GranetzShot 10 -- Fizzle. Disruption recovery again?

Next shot: try again.
Jun 25 1997 12:04:09:660PM970625011Robert GranetzShot 11 -- Plasma. Got it! Pellets were strung out over 1.5 ms, starting
at t=0.7074 s. Prf=0.9 MW at the injection. Current quench was
very slow, about 5 ms! I_halo_lower=120 kA (typical value).

Next shot: repeat, perhaps with more RF power.
Jun 25 1997 12:15:57:030PM970625012Robert GranetzShot 12 -- Fizzle. Disruption recovery?

Next shot: repeat.
Jun 25 1997 12:26:30:870PM970625013Robert GranetzShot 13 -- Plasma. Got another one! Density on this shot (and previous one)
reaches nebar=1.6e21 !!!. Plasma takes a relatively long time to
begin to quench, and the current quench again takes 5 ms. Typical
halo currents, as well. Prf was again 1 Mw, but this shot was
killed during an ELM-free H-mode. Martin reports that the pellets
were less strung out than previously.

Next shot: repeat, except turn off RF at 0.6 s. (It will probably
be a fizzle anyway.)
Jun 25 1997 12:44:49:790PM970625014Robert GranetzShot 14 -- Plasma. Got another one. This was killed in ohmic L-mode. Same
results as previous shots.

We are having a break now to allow access to the cell for multiple purposes.

Next shot: turn RF back on.
Try firing molybdenum simultaneously with the pellets.
Jun 25 1997 01:47:14:370PM970625015Robert GranetzShot 15 -- Dud. Null looks okay. All supplies fired. Steve Wolfe has found
that the hybrid gas pulse did not get to the valve.

Next shot: try again. RF will be going. Molybdenum will be
injected at t=0.708 s, along with the D2 pellets.
Jun 25 1997 02:05:39:680PM970625016Robert GranetzShot 16 -- Plasma. Another successful kill. Typical quench time, typical
halo current. It doesn't look like the molybdenum made it in.
Good RF ... 2.2 MW! ELM-free H-modes.

Next shot: try again. Move moly injection earlier. Increase neon
puff from 50 to 60 ms.
Jun 25 1997 02:29:55:520PM970625018Robert GranetzShot 18 -- Fizzle. Null is so-so.

Next shot: repeat with no changes.
Jun 25 1997 02:52:00:230PM970625019Robert GranetzShot 19 -- Plasma. VDE went upwards, with plasma termination at t=1.131 s.
Z-centroid from x-rays was at +0.02 m at t=1.12 s, with the pellet
firing at 1.17 s. Very fast current quench (2 ms). Multiple
H-modes.

Next shot: delay start of VDE by 50 ms (gains turn off at t=1.150 s)
Jun 25 1997 03:23:23:960PM970625020Robert GranetzShot 20 -- Plasma. Good VDE, but there was a really wierd noise coming from
the power room. There is a lot of noise on the TF current and
Btor during the flattop. Apparently a current sensor in one of the
TF cabinets became very noisy. Pellets hit the plasma when it
was 3 cm down. Perfect timing. Still did not speed up the current
quench though. Typical halo current. That completes MP 158 !

We are having a break now to allow access to the power room to work on the
TF supply.
Jun 25 1997 04:10:50:250PM970625021Robert GranetzShot 21 -- PLC test of TF at 100 kA. Looks good.

Next shot: normal plasma with RF. No pellets.
Jun 25 1997 04:16:07:300PM970625022Robert GranetzShot 22 -- Plasma. Good VDE, but we didn't want this to be a VDE. I forgot to
turn on the ZCUR feedback for the entire shot ... operator error!

Engineering Operator Comments
ShotTimeTypeStatusComment
107:25:48:670AMTestOkTF Scanner test
208:48:12:890AMPlasmaOkno efc, oh2lo comm fault
309:16:06:070AMPlasmaOkno faults
410:05:27:100AMPlasmaOkno faults
510:17:09:850AMPlasmaOkno faults
610:40:58:760AMPlasmaOkno faults
711:00:16:180AMPlasmaOkno fault
811:11:08:000AMPlasmaBadefc,ef2 only worked
911:19:30:050AMPlasmaOk
1011:40:10:630AMPlasmaOk
1111:49:08:200AMPlasmaOk
1212:03:21:020PMPlasmaOk
1312:12:55:940PMPlasmaOk
1412:28:44:120PMPlasmaOk
1501:36:18:550PMPlasmaOk
1601:49:11:590PMPlasmaOk
1702:06:38:040PMPlasmaOk
1802:24:45:540PMPlasmaOk
1902:34:25:480PMPlasmaOk
2002:51:55:520PMPlasmaOk
2104:01:41:990PMTestOk
2204:12:15:880PMPlasmaOk