Alcator C-Mod Run 1040316 Information

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Miniproposals
Miniproposal:341
Date Filed: 6/4/2003
Title:Power Absorption in ITBs
First Author:Catherine Fiore
Session Leader:Catherine Fiore (shots 1-26)

Operators
Session leader(s):Catherine Fiore
Physics operator(s):Robert Granetz
Engineering operator(s):Gary Dekow,Bill Byford

Engineering Operator Run Comment
MP 341 Power Absorption in ITB SL: C. Fiore, PO: R. Grantz, EO: Dekow,By

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:03:507PM
Author: Catherine Fiore
SL Fiore
PO Granetz

In this run we hope to complete MP 341 which ended prematurely when we lost
the FMIT 4 output tube. We will start with shot 29 from 1040309 and
re-establish the ITB from that shot. We will start with somewhat lower
central ICRF power than on shot 29, and scan up until we lose the ITB.
Once this is done, we should change the off axis power and repeat the
central power scan. If time allows, we can try this at the higher field.

----------------------------------------------------------------------------
The PhysOp showed up with his snowboard and boots, ski helmet and goggles,
prepared to head for the hills the minute it started to snow. This obviously
caused the run to be plagued with data system problems as it had on Monday.
The porblems persisted until it started to snow late in the day. We were
able to make ITBs when we did have shots, but they had problems with
excess radiation which caused premature back transitions. Since we need
to maximize the core power for this run, it is clear that we should
boronize before attempting it again. We were not able to get as much central
ICRF power in before destroying the ITB as we had in the run from 1040309,
suggesting that the impurities and radiated power may be a contributing factor
in limiting our ability to stabilize and hold the ITB at high central power.

Shot summary:

1040316001 A good ITB develops but terminates in a back transition at
1.2 s. The 70 Mhz power did not come on.

1040316002 A good ITB develops and the 70 Mhz central heating came on
at 1 s with 0.8 MW. The ITB continued to grow until it ended in a back
transition at 1.15 s. The plasma disrupted at 1.4 s.

1040316003 The plasma disrupted right after it went into H-mode.

1040316004 Hmode with many back transitions. No ITB.

1040316005 Beginning of data system problems. Not much of the data was
actually stored.

1040316006 Hmode with many back transitions. Not all of the data was
recorded.

1040316007-1040316010 Data system recovery. I just tried to look at
what was in the tree for shot 7 and it closed my scope.

1040316011 Ohmic plasma. No H-mode. We did not turn on the rf filaments
in time to have power for this shot.

1040316012
H-mode with ITB starting but ends in a back transition. Similar to earlier
shots today.

1040316013 H-mode with ITB , probably clamped by central ICRF.

1040316014 H-mode with ITB , but the central ICRF wiped it out.
We will make them fire later at t=1.2 s.

1040316015 H-mode with ITB , but disrupted when the central ICRF came on.
We will fire the central rf at 1.1s

1040316016 H-mode with ITB , but it had a back transition just after the
central ICRF came on. We will fire the central rf at 1.s again.

1040316017 H-mode with ITB , but the central ICRF at 1MW blew it away.
We will increase the target density to 1.2 10^20

1040316018 An H-mode with ITB formed but the rf had trouble with the higher
target density and was not able to stay on. The central rf did not come on at
all. We will have to decrease the target density to recover, and try to
back off on the central ICRF power in order to preserve the ITB.

1040316019 An H-mode with ITB develops but it is destroyed by the central
ICRF at 1.MW.

1040316020 An H-mode with ITB develops but it back transitions just as the
central ICRF is turned on.

1040316021 An H-mode with ITB develops but is wiped out by central ICRF power
at 1 MW.

Physics Operator Summaries
Entered: Jul 7 2004 04:36:49:520PM
Author: Robert Granetz
Physics operator summary for run 1040316 (Tuesday):

MP 341 -- Power Absorption in ITBs

Session leader: C. Fiore
Physics operator: R. Granetz

Summary: We lost about half the day to computer problems. But even with
the reduced run time, we got a very clear result on the
mini-proposal: with the present machine conditions, the operating
parameter space (Prf on-axis, target density, RF turn-on time) is
very tiny...basically just a single set of operating conditions.
See the session leader's summary for more details.

When the computers ran okay, the machine performed well. There
were no fizzles. We did struggle with a high TF resistance
reading, which may or may not be real. One of the BP_JK magnetics
signals had a consistently high baseline offset, and we'll have to
check into it on the next maintenance day. It's not used in the
hybrid, so it didn't affect the run.

Scorecard: 16 plasmas
0 fizzles
0 duds (no TF)
5 tests or no-power shot cycles
0 aborted and/or screwed up by computer problems
0 beam-into-gas calibration shots with B-field(s)
----------
21 total

-------------------------------------------------------------------------------
Engineering setup for Tuesday, 16 Mar 2004

MP 341: Power Absorption in ITB

Session leader: C. Fiore
Physics operator: R. Granetz

ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00.
Bake at 60 C overnight as well.

Run begins at 09:00 and ends at 17:00.

Power systems the same as 1040315016 (0.8 MA, 4.5 T, lower X-point)

A-coils should be disabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Disable NINJA

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics:
Standard core profile diagnostics, specifically including Hirex (for Ti
profiles and rotation), core TS, VB, GPC 1 and 2, FRC ECE, neutrons
Desirable diagnostics:
DNB and all beam diagnostics

-------------------------------------------------------------------------------
RF Setup: All four transmitters in RUN-ON by 08:00

-------------------------------------------------------------------------------
Run Plan:

Finish off the MP begun yesterday (1040315). Specifically, we still need
to determine the highest on-axis power we can use without destroying the
high-field side resonance ITB (4.5 T), and document the confinement
properties. If we complete the 4.5 T experiments, we can then proceed to
the low-field side resonance, using the 70 MHz for off-axis heating at
5.6 T and 80 MHz on-axis.

We will start with a shot like 1040315016, which had 2.5 MW of off-axis
80 MHz and 0.8 MW of on-axis 70 MHz. We will then increase the on-axis
power until we get clear indication of loss of the core barrier. We will
also try varying the off-axis power to see how that affects the amount of
core heating allowed.

-------------------------------------------------------------------------------
ECDC was done overnight, but no bake.

Hybrid coldstart done by the engineering group; no errors found

Loaded PCS from shot 1040315016 (all segments)

-------------------------------------------------------------------------------

The start of the run will be delayed in order to repair some RF equipment.

Shot 01 -- Plasma. Good shot. 0.8 MA, 4.5 T. 2.5 MW of 80 MHz (off-axis,
high-field side), 0 MW of 70 MHz (on-axis). There was a weak
ITB until t=1.2 s.

Next shot: turn on J-port RF at t=1.1 s to provide on-axis
heating.

Shot 02 -- Plasma. Disrupted at t=1.4 s. TCI failed during the shot, but
it didn't have anything to do with the disruption. Prf=2.5 MW
off-axis and 0.75 MW on-axis. The on-axis RF starts at t=1.0 s,
not 1.1 s. ITB forms, and the peaking is arrested by the
on-axis heating (as seen on Catherine's ratio of central Dalsa
to outer Dalsa).

Next shot: try reducing the density by 10% (1.0 -> 0.9e20 m-2).
Leave on-axis RF start time at t=1.0 s.

Also, at Jim Irby's request, I've added an 0.5 s flat porch onto
the TF trace from t=2.38-2.88 s at 50 kA.

Shot 03 -- Plasma. Disrupted at t=0.9 s. Radiated power problem?
Injection?

Next shot: at Steve's suggestion, move RXL out by 1 cm, on order
to avoid possible touching of the inboard limiter edge.

Shot 04 -- Plasma. Good shot. Looks like the RXL tweak got rid of the
disruption. Lots of back transitions due to RF faults. Got a
brief ITB during the first EDA.

Next shot: improve RF tuning.

The run will be delayed in order to change over some TF resistance taps.

Shot 05 -- Test. No-power shot cycle. The computers are crashing.

Shot 06 -- Plasma. Good shot. Lots of short EDA's and back transitions.
Prf=2.5 MW off-axis, 0.75 MW on-axis. Lots of data acquisition
problems.

Next shot: back off 0.5 cm on the earlier RXL tweak
(i.e. subtract 0.5 cm from RXL).

We are having an extended delay to work on the computers.

Shot 07 -- Test (maybe...not sure what the shot number is).

Shot 08 -- Test (maybe...not sure what the shot number is).

Shot 09 -- Test (maybe...not sure what the shot number is).

Shot 10 -- Test (maybe...not sure what the shot number is).

Shot 11 -- Plasma. Good shot. Ohmic. Looks like all the data came
through. TF resistance data looks very good (1.2 micro ohms).

Next shot: add another 0.25 s to the TF back porch flattop.
Turn RF back on.

Shot 12 -- Plasma. Good shot. Prf=2.5 MW off-axis, 0.8 MW on-axis. I
think we had an ITB, but there's no TS data on this shot.

Next shot: increase density to 1.1e20 m-2.

Shot 13 -- Plasma. Good shot. Prf=2.5 MW off-axis, 0.8 MW on-axis. I
think we had a better ITB, but again there's no TS data. We've
left messages for Jerry Hughes and Dmitri to turn the TS back
on. Dalsa shows clear peaking.

Next shot: increase 70 MHz (on-axis) power to 1 MW (from 0.8 MW)

Shot 14 -- Plasma. Good shot. Prf=2.5 NW off-axis, 1.0 MW on-axis. This
was enough central power to kill the ITB.

Next shot: delay the start of the on-axis RF until t=1.2 s (had
been starting at 1.0 s)

Shot 15 -- Plasma. Disrupted at t=1.21 s, probably because the ITB was
allowed to go to 1.2 s before on-axis heating was turned on.

Next shot: move start time of on-axis RF to t=1.1 s.

Shot 16 -- Plasma. Good shot. On-axis RF starts at t=1.1 s. The ITB does
not stop rising, however, and eventually it back-transitions.

Next shot: move start time of on-axis RF back to 1.0 s.

Shot 17 -- Plasma. Good shot. Exactly the same RF timing and power as on
shot 14, with exactly the same result...a MW of on-axis RF kills
the ITB.

Next shot: raise nl_04 to 1.2e20 m-2 (from 1.1e20)

Shot 18 -- Plasma. Disrupted at t=1.4 s. Got the higher target density,
and the ITB lasted longer. The on-axis RF didn't come on, so
the ITB eventually disrupted the plasma, similar to earlier
shots today.

Next shot: reduce the density back to 1.1e20 m-2 and reduce the
on-axis RF power to 0.9 MW.

Shot 19 -- Plasma. Good shot. On-axis RF power of 0.9 MW was enough to
arrest the ITB.

Next shot: reduce on-axis RF power to 0.8 MW, which previously
did not arrest the ITB, thus resulting in a radiative
disruption.

Shot 20 -- Plasma. Good shot. Prf off-axis=2.6 MW, Prf on-axis=0.84 MW.
Strange result...the ITB collapsed just as the on-axis RF was
turning on.

Next shot: repeat with no changes

Shot 21 -- Plasma. Good shot. Prf off-axis=2.6 MW, Prf on-axis=0.84 MW.
This was enough to arrest the ITB.

End of run.

Session Leader Comments
Mar 16 2004 09:31:17:553AMCatherine Fiore

In this run we hope to complete MP 341 which ended prematurely when we lost
the FMIT 4 output tube. We will start with shot 29 from 1040309 and
re-establish the ITB from that shot. We will start with somewhat lower
central ICRF power than on shot 29, and scan up until we lose the ITB.
Once this is done, we should change the off axis power and repeat the
central power scan. If time allows, we can try this at the higher field.
Mar 16 2004 12:20:18:457PM1040316001Catherine Fioretest
Mar 16 2004 02:36:23:970PM1040316011Catherine FioreOhmic plasma. The rf did not have enought time to warm up their filaments
after the shut down for data system repair.
Mar 16 2004 02:54:13:677PM1040316012Catherine FioreH-mode with ITB starting but ends in a bac transition. Similar to earlier shots
today.
Mar 16 2004 03:19:20:910PM1040316013Catherine FioreH-mode with ITB , probably clamped by central ICRF.
Mar 16 2004 03:24:16:750PM1040316014Catherine FioreH-mode with ITB , but the central ICRF wiped it out. We will make them
fire later at t=1.2 s.
Mar 16 2004 03:36:54:383PM1040316015Catherine FioreH-mode with ITB , but disrupted when the central ICRF came on. We will fire the
central rf at 1.1s
Mar 16 2004 03:55:10:903PM1040316016Catherine FioreH-mode with ITB , but it had a back transition just after the central ICRF came on. We will fire the
central rf at 1.s again.
Mar 16 2004 04:04:58:203PM1040316017Catherine FioreH-mode with ITB , but the central ICRF blew it away. We will increase the
target density to 1.2 10^20
Mar 16 2004 04:17:03:523PM1040316018Catherine FioreH-mode with ITB , but no central ICRF.

Physics Operator Comments
Mar 15 2004 04:36:53:220PMRobert GranetzEngineering setup for Tuesday, 16 Mar 2004

MP 341: Power Absorption in ITB

Session leader: C. Fiore
Physics operator: R. Granetz

ECDC overnight in D2 at 2e-4 Torr, stopping by 07:00.
Bake at 60 C overnight as well.

Run begins at 09:00 and ends at 17:00.

Power systems the same as 1040315016 (0.8 MA, 4.5 T, lower X-point)

A-coils should be disabled.

Gas setup:
fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid enabled (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill C-side with 30 psi D2 Hybrid enabled (PG3)

Disable NINJA

Enable the following gate valves, assuming no vacuum problems:
ECE, VUV, DNB

Necessary diagnostics:
Standard core profile diagnostics, specifically including Hirex (for Ti
profiles and rotation), core TS, VB, GPC 1 and 2, FRC ECE, neutrons
Desirable diagnostics:
DNB and all beam diagnostics

-------------------------------------------------------------------------------
RF Setup: All four transmitters in RUN-ON by 08:00

-------------------------------------------------------------------------------
Run Plan:

Finish off the MP begun yesterday (1040315). Specifically, we still need
to determine the highest on-axis power we can use without destroying the
high-field side resonance ITB (4.5 T), and document the confinement
properties. If we complete the 4.5 T experiments, we can then proceed to
the low-field side resonance, using the 70 MHz for off-axis heating at
5.6 T and 80 MHz on-axis.

We will start with a shot like 1040315016, which had 2.5 MW of off-axis
80 MHz and 0.8 MW of on-axis 70 MHz. We will then increase the on-axis
power until we get clear indication of loss of the core barrier. We will
also try varying the off-axis power to see how that affects the amount of
core heating allowed.
Mar 16 2004 08:34:27:747AMRobert Granetz ECDC was done overnight, but no bake.

Hybrid coldstart done by the engineering group; no errors found

Loaded PCS from shot 1040315016 (all segments)
Mar 16 2004 08:56:59:767AMRobert GranetzThe start of the run will be delayed in order to repair some RF equipment.
Mar 16 2004 10:00:20:823AM1040316001Robert GranetzShot 01 -- Plasma. Good shot. 0.8 MA, 4.5 T. 2.5 MW of 80 MHz (off-axis,
high-field side), 0 MW of 70 MHz (on-axis). There was a weak
ITB until t=1.2 s.

Next shot: turn on J-port RF at t=1.1 s to provide on-axis
heating.
Mar 16 2004 10:31:04:827AM1040316002Robert GranetzShot 02 -- Plasma. Disrupted at t=1.4 s. TCI failed during the shot, but
it didn't have anything to do with the disruption. Prf=2.5 MW
off-axis and 0.75 MW on-axis. The on-axis RF starts at t=1.0 s,
not 1.1 s. ITB forms, and the peaking is arrested by the
on-axis heating (as seen on Catherine's ratio of central Dalsa
to outer Dalsa).

Next shot: try reducing the density by 10% (1.0 -> 0.9e20 m-2).
Leave on-axis RF start time at t=1.0 s.

Also, at Jim Irby's request, I've added an 0.5 s flat porch onto
the TF trace from t=2.38-2.88 s at 50 kA.
Mar 16 2004 10:47:22:463AM1040316003Robert GranetzShot 03 -- Plasma. Disrupted at t=0.9 s. Radiated power problem?
Injection?

Next shot: at Steve's suggestion, move RXL out by 1 cm, on order
to avoid possible touching of the inboard limiter edge.
Mar 16 2004 11:16:13:330AM1040316004Robert GranetzThe run will be delayed in order to change over some TF resistance taps.
Mar 16 2004 12:22:55:517PM1040316005Robert GranetzShot 05 -- Test. No-power shot cycle. The computers are crashing.
Mar 16 2004 12:34:27:243PM1040316006Robert GranetzShot 06 -- Plasma. Good shot. Lots of short EDA's and back transitions.
Prf=2.5 MW off-axis, 0.75 MW on-axis. Lots of data acquisition
problems.

Next shot: back off 0.5 cm on the earlier RXL tweak
(i.e. subtract 0.5 cm from RXL).
Mar 16 2004 01:10:17:340PM1040316006Robert GranetzWe are having an extended delay to work on the computers.
Mar 16 2004 01:51:56:183PM1040316006Robert GranetzShot 07 -- Test (maybe...not sure what the shot number is).
Mar 16 2004 02:06:11:420PM1040316006Robert GranetzShot 08 -- Test (maybe...not sure what the shot number is).
Mar 16 2004 02:06:19:517PM1040316006Robert GranetzShot 09 -- Test (maybe...not sure what the shot number is).
Mar 16 2004 02:25:41:653PM1040316010Robert GranetzShot 10 -- Test (maybe...not sure what the shot number is).
Mar 16 2004 02:42:51:140PM1040316011Robert GranetzShot 11 -- Plasma. Good shot. Ohmic. Looks like all the data came
through. TF resistance data looks very good (1.2 micro ohms).

Next shot: add another 0.25 s to the TF back porch flattop.
Turn RF back on.
Mar 16 2004 02:53:56:660PM1040316012Robert GranetzShot 12 -- Plasma. Good shot. Prf=2.5 MW off-axis, 0.8 MW on-axis. I
think we had an ITB, but there's no TS data on this shot.

Next shot: increase density to 1.1e20 m-2.
Mar 16 2004 04:58:47:103PM1040316013Robert GranetzShot 13 -- Plasma. Good shot. Prf=2.5 MW off-axis, 0.8 MW on-axis. I
think we had a better ITB, but again there's no TS data. We've
left messages for Jerry Hughes and Dmitri to turn the TS back
on. Dalsa shows clear peaking.

Next shot: increase 70 MHz (on-axis) power to 1 MW (from 0.8 MW)
Mar 16 2004 04:59:00:447PM1040316014Robert GranetzShot 14 -- Plasma. Good shot. Prf=2.5 NW off-axis, 1.0 MW on-axis. This
was enough central power to kill the ITB.

Next shot: delay the start of the on-axis RF until t=1.2 s (had
been starting at 1.0 s)
Mar 16 2004 04:59:39:230PM1040316015Robert GranetzShot 15 -- Plasma. Disrupted at t=1.21 s, probably because the ITB was
allowed to go to 1.2 s before on-axis heating was turned on.

Next shot: move start time of on-axis RF to t=1.1 s.
Mar 16 2004 05:00:08:950PM1040316016Robert GranetzShot 16 -- Plasma. Good shot. On-axis RF starts at t=1.1 s. The ITB does
not stop rising, however, and eventually it back-transitions.

Next shot: move start time of on-axis RF back to 1.0 s.
Mar 16 2004 05:00:47:747PM1040316017Robert GranetzShot 17 -- Plasma. Good shot. Exactly the same RF timing and power as on
shot 14, with exactly the same result...a MW of on-axis RF kills
the ITB.

Next shot: raise nl_04 to 1.2e20 m-2 (from 1.1e20)
Mar 16 2004 05:01:14:763PM1040316018Robert GranetzShot 18 -- Plasma. Disrupted at t=1.4 s. Got the higher target density,
and the ITB lasted longer. The on-axis RF didn't come on, so
the ITB eventually disrupted the plasma, similar to earlier
shots today.

Next shot: reduce the density back to 1.1e20 m-2 and reduce the
on-axis RF power to 0.9 MW.
Mar 16 2004 05:01:38:983PM1040316019Robert GranetzShot 19 -- Plasma. Good shot. On-axis RF power of 0.9 MW was enough to
arrest the ITB.

Next shot: reduce on-axis RF power to 0.8 MW, which previously
did not arrest the ITB, thus resulting in a radiative
disruption.
Mar 16 2004 05:02:08:453PM1040316020Robert GranetzShot 20 -- Plasma. Good shot. Prf off-axis=2.6 MW, Prf on-axis=0.84 MW.
Strange result...the ITB collapsed just as the on-axis RF was
turning on.

Next shot: repeat with no changes
Mar 16 2004 04:56:07:300PM1040316021Robert GranetzShot 21 -- Plasma. Good shot. Prf off-axis=2.6 MW, Prf on-axis=0.84 MW.
This was enough to arrest the ITB.

Engineering Operator Comments
ShotTimeTypeStatusComment
109:49:39:067AMPlasmaOk
210:10:12:743AMPlasmaOk
310:33:53:743AMPlasmaOk
410:50:55:150AMPlasmaOk
511:42:30:483AMPlasmaBadIgor Failure
612:06:00:547PMPlasmaOk
1002:18:56:677PMTestOk
1102:30:46:380PMPlasmaOk
1202:45:17:050PMPlasmaOk
1302:58:17:357PMPlasmaOk
1403:17:19:940PMPlasmaOk
1503:30:29:323PMPlasmaOk
1603:43:29:193PMPlasmaOk
1703:58:06:300PMPlasmaOk
1804:11:44:887PMPlasmaOk
1904:24:44:413PMPlasmaOk
2004:37:43:500PMPlasmaOk
2104:50:36:447PMPlasmaOk
2205:29:11:677PMTestBad
2305:32:48:120PMTestBad
2405:38:33:320PMTestBad
2505:44:00:250PMTestBad
2605:49:26:420PMTestBad