Alcator C-Mod Run 1000928 Information

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Miniproposals
Miniproposal:253
Date Filed: 3/23/2000
Title:Very Low Power EDA H-modes
First Author:Martin Greenwald
Session Leader:Martin Greenwald (shots 1-29)

Operators
Session leader(s):Martin Greenwald
Physics operator(s):Bill Rowan
Engineering operator(s):Bill Parkin,Bill Byford

Engineering Operator Run Comment
MP253 Low Power Ohmic H Mode EDA SL:Greenwald, PO: Rowan, EO Byford/Park

Session Leader Plans

Physics Operators Plans

Session Leader Summaries
Entered: Jul 7 2004 03:49:24:947PM
Author: To Be Determined
Run Summary for 1000829
MP 253 Very Low Power EDA

Session Leader - M. Greenwald
Phys Op - W. Rowan


Background and Plan:

With its good energy confinement, moderate particle confinement and
lack of large ELMs, the EDA H-mode could be a highly favorable
regime for a tokamak reactor - if we can understand the underlying
physics sufficiently to extrapolate into new regimes. The key to
understanding EDA seems to be in the quasi-coherent fluctuations
which have been observered by the reflectometer, PCI, and probes.
These fluctuations seem always to accompany EDA and have been shown
to drive significant particle flux. We want to understand the
relationship between the mode and the local pedestal profiles
allowing us to evaluate the micro and macro-stability. The first
step will be to localize the mode relative to the density and
temperature pedestals. We will try to correlate both mode amplitude
and convected flux with the local gradients.

Because the range of the scanning probe is limited by incident heat
flux, we attempt to run EDA H-modes at the lowest possible powers.
Following the recipe that was successful previously, we begin with
OH h-modes discharges at relatively low q and then scan Bt and Ip to
raise q allowing access to the EDA regime.

The new wrinkle here is the new probe head on ASP. This restores the
6 mm spacing. We will also try some puffing with FSP to look for
flows during the H-mode. The loose ground that cause problems with
Ly_alpha data in the previous run should also be fixed.

==============================

Results:

A good day. Ohmic H-modes were easy to get. The EDAs were more clear
than some previous oh runs. The Q-C fluctuations were clearly seen
on the pci, reflectometer, electrostatic probes.

We should have some good data for analysis of fluctuation driven
flux. It looked like the FSP had some shorting or other technical
problems on some shots - so care will have to be taken in choosing
the data for the analysis.

We should also have decent Ly_alpha data to look at Deff, etc.

Some progress was made on localizing the mode. As before, it is
clearly seen in the steep density gradient region Images of carbon
plumes from the gas puffer in FSP showed a flow reversal just
outside the region where the QC mode began. This might be
interpreted to localize the mode relative to the Er well.

On several shots 26,27,28,29, it appeared that the north floating
probe of ASP traversed the entire mode. If so, the structure would
be not much more than 2mm in width.

We saw consistent density peaking in the ohmic h-mode phase.

================================

Shots suitable for further analysis include:

1000928002
1000928004
1000928009 start of scanning probe work
1000928010
1000928011
1000928012
1000928013
1000928014
1000928015
1000928016
1000928017
1000928021
1000928022
1000928023
1000928026
1000928027
1000928028
1000928029

Physics Operator Summaries
Entered: Jul 7 2004 04:37:12:147PM
Author: To Be Determined
Physop summary for 1000928


Engineering setup for Thursday, Sept 28, 2000
---------------------------------------
MP#253 Low-Power Ohmic H-Mode EDA
SL: Greenwald
PO: Rowan
EO: Byford/Parkin


Overnight ECDC in D2, stopping 1-2 hours before run.

Run begins 9:00 and ends at 17:00

Power System Setup: Same as on 1000622022

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid DISABLED
fill B-side upper with 35 psi of D2 Hybrid DISABLED, available ECDC
fill C-side with 30 psi of D2 Hybrid enabled
leave J-bottom as is Hybrid DISABLED

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

DNB gate valve will be disabled.


Run Plan
-------------------
Continuation of MP 253 Low-Power Ohmic H-Mode EDA
The main new thing will be the wider spacing on the a-side scanning probe.
The aim is to get more data on the k spectrum and particle transport driven by the
quasi-coherent mode. We also hope to get better data on the ionization source
(Ly_alpha) than last time. We're interested in getting the best data we can
on edge profiles and fluctuations.

Run Summary
--------------------
The first shot was a fizzle. BR_0 was negative with respect to the last shot
yesterday (9/27/00). In retrospect, I should have replaced segment 1 of the
reference shot with segment 1 from a good shot on 9/27 before starting the run.
I did that after the first shot and the second shot was good.

Shots 005-008 were duds. Fiddled with the gas after each of the first 3. Then
increased sparker voltage and ran ECDC for fifteen minutes after shot 008.
Also, stopped the RF conditioning shots. Shot 009 was good. I have no idea
which of these -- if any -- is is important. If there are duds in the near
future, it might be worthwhile to try to sort this out if the SL is willing to
sacrifice a significant number of shots.

Shots 019 and 020 were fizzles. Late breakdown. I tried ECDC for fifteen minutes
after the first of these. Then reduced the gas after the second. Shot 021 was
successful.

The remainder of the shots were good.

Score card.
Plasmas 22
Fizzles 3
Duds 4
Total 29




Details of the run
-----------------------

Started pcs and loaded shot 1000622022
Load at 28-Sep-2000 08:08:50.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done


Did a coldstart. Last few lines:
rtnode -- data loaded, A matrix responds
rtnode -- data loaded, M matrix responds
rtnode -- data loaded, PID matrix responds
RT_NODE Done
28-SEP-2000 08:12:50.87 doing TCL command TYPE *************** END COLD
START ******************
*************** END COLDSTART ******************

001. Fizzle
BR_0 was negative with respect to the last shot yesterday (1000927013) and with
respect to the reference shot (1000622022)
Imported segment 01 from shot 1000927013.
Pressure and BZ_0 look okay to me.

002. Plasma.

003. Plasma. Disruption at 0.99s.
Not sure about this disruption. Small indication on 2pi bolometer.
Also ramping the field. With regard to this disruption, will try again
and see if it happens at the same time.
Next shot: Change TF rampup from 1.3 s to 1.15 s to avoid disruption that
we expect to develop at late times based on the reference shots.

004. Plasma. Disruption on the current rampdown.
Next shot: Changes in the magnetic field after 1 s to move the ramp

005. Dud. Gas is low. It started low this morning and has not come up
shot by shot as I thought that it might.
Next shot. add 2 ms of gas to the prefill

006. Dud. Prefill pressure dropped.
Next shot. Added 2 ms of gas to the prefill. Expecting 24 ms prefill
Verified load/clean
Load at 28-Sep-2000 10:32:45.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done

007. Dud. Prefill pressure increased to 0.05 mT to 0.06 mT
Next shot. Added 1 ms of gas to the prefill.
Verified load/clean
Load at 28-Sep-2000 10:48:58.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done

008. Dud.
For next shot: Returning to what worked before.
Increased sparker voltage to 800
Starting ECDC for 15 minutes between shots.

009. Plasma.
Next shot: Small change in field ramp after 1 s.
Verified load:
Load at 28-Sep-2000 11:33:00.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done

010. Plasma.
Next shot. Moved ZXL lower by approximately 7 mm after 1 s

011. Plasma
On this shot zxl was ramped from 1 s to 1.3 s for probes.
Next shot. Increased the ramp so that zxl is lower by 3 mm at 1.3 s

012. Plasma.
Next shot. No changes.

013. Plasma. Disruption just before 1.5 s.
Next shot. No changes.

014. Plasma. Disruption just after 1.5 s.
This and the previous disruption appear to be related to an
impurity injection
Next shot. No changes.

015. Plasma. Disruption just after 1.6 s IP ramp down starts at 1.5 s
Next shot. No change in plasma setup.
Plume probe in operation.

016. Plasma.
Next shot. No changes.

017. Plasma. Disruption at 1.26 s.
Next shot. No changes

018. Plasma. Disruption at 1.45 s
Next shot. No changes.

019. Fizzle.
ECDC for 15 minutes before the next shot.
Next shot. No changes in pcs. Plume probe off.

020. Fizzle. Late breakdown.
Next shot. Reduced prefill by 2 ms.

021. Plasma.
Next shot. No changes in pcs. Burping probe back on.

022. Plasma.
Next shot. No changes in pcs

023. Plasma.
Next shot. No changes in pcs

024. Plasma. Disruption at 1.4 s.
Next shot. Adjusted zxl for probe at 1.4 s

025. Plasma. Disrupted at 1.2 s.
Next shot. No changes in pcs.

026. Plasma. Disrupted at 1.5 s.
Next shot. No changes in pcs.

027. Plasma.
Next shot. No changes in pcs.

028. Plasma.
Next shot. No changes in pcs.

029. Plasma.
Last shot.


Session Leader Comments
Sep 28 2000 08:51:46:450AMMartin GreenwaldMP 253 - Low power Ohmic EDA

With its good energy confinement, moderate particle confinement and
lack of large ELMs, the EDA H-mode could be a highly favorable
regime for a tokamak reactor - if we can understand the underlying
physics sufficiently to extrapolate into new regimes. The key to
understanding EDA seems to be in the quasi-coherent fluctuations which
have been observered by the reflectometer, PCI, and probes. These
fluctuations seem always to accompany EDA and have been shown to
drive significant particle flux. We want to understand the
relationship between the mode and the local pedestal profiles
allowing us to evaluate the micro and macro-stability. The first
step will be to localize the mode relative to the density and
temperature pedestals. We will try to correlate both mode amplitude
and convected flux with the local gradients.

We want to run ohmic EDA H-modes at the lowest possible power levels
to allow the deepest penetration of the scanning probe. The goals
are to:

1 Verify the extent and radial structure of the quasi-coherent
fluctuation and its relation to density and temperature profiles
2 Compare particle (and energy) flux convected by the
fluctuation with the local particle and power balance.
3 Improve on k$_{\theta}$ resolution from previous campaign.

The new wrinkle here is the new probe head on ASP. This restores
the 6 mm spacing. We will also try some puffing with FSP to look
for flows during H-mode.
Sep 28 2000 09:33:59:700AM1000928002Martin GreenwaldOhmic H-mode
Good confinement
no fluctuation data yet
Sep 28 2000 09:38:58:950AM1000928003Martin GreenwaldDisrupts at about 1. sec
brief h-mode
Sep 28 2000 10:03:18:547AM1000928004Martin GreenwaldGood ohmic h-mode
signs of weak eda startin at about 1.18 sec
Sep 28 2000 10:14:59:983AM1000928005Martin Greenwalddud
Sep 28 2000 10:28:43:233AM1000928006Martin Greenwalddud
Sep 28 2000 11:33:17:733AM1000928009Martin GreenwaldGood shot after series of duds
no h-mode

Sep 28 2000 11:58:57:420AM1000928010Martin Greenwaldslightly deeper sweep in Bt
Good H-mode at about 1.sec
QC fluctuations seen beginning about 1.05
sharp change in slope of Wmhd and Prad at about 1.1
after 1.1 dW/dt and dPrad/dt = 0 => strong EDA
strong density peaking seen too
Sep 28 2000 12:27:51:653PM1000928011Martin GreenwaldGood ohmic H-mode
QC fluctuations seen with PCI and Reflt
just beginning to be seen with probes
Sep 28 2000 12:26:42:357PM1000928012Martin GreenwaldAnother good Ohmic H-mode
EDA fluctuations seen on all diagnostics

Sep 28 2000 12:36:28:123PM1000928013Martin GreenwaldGood shot though disrupts at 1.45 sec
maybe an injection early in the h-mode phase
Sep 28 2000 01:02:10:577PM1000928014Martin GreenwaldLasts longer
injection at 1.3 sec ELMfree afterwards
Good data from fsp
Sep 28 2000 01:15:45:933PM1000928016Martin GreenwaldGood shot
both probe scans during EDA
differences in phase seen between scans
and between asp and fsp
Sep 28 2000 01:28:59:373PM1000928016Martin GreenwaldGood shot
clear EF/EDA transition at 1.18 sec - early shots were more gradual
Sep 28 2000 01:44:52:107PM1000928017Martin GreenwaldDisrupts early, 1.26 sec
Sep 28 2000 01:53:59:873PM1000928018Martin Greenwaldprobe in a bit too deep - injecting impurities
never develops good eda
Sep 28 2000 02:25:59:623PM1000928019Martin Greenwaldfizzle
Sep 28 2000 02:26:10:107PM1000928020Martin Greenwaldfizzle
Sep 28 2000 02:52:13:217PM1000928021Martin GreenwaldGood shot
nice signals on the scanning probes
Sep 28 2000 03:42:43:780PM1000928022Martin GreenwaldGood shot
Sep 28 2000 03:16:47:437PM1000928023Martin GreenwaldGood H-mode
Disrupts early
only one probe scan
Sep 28 2000 03:35:45:233PM1000928024Martin GreenwaldDisrupts early, but first scan good
just barely into eda
Sep 28 2000 03:53:16:593PM1000928025Martin GreenwaldDisrupts early again
Sep 28 2000 04:21:14:857PM1000928026Martin GreenwaldBetter,
Good data with both plunges
ASP may go in too far - mode disappears before deepest insertion
FSP sees mode throughout
Sep 28 2000 05:21:09:763PM1000928028Martin GreenwaldGood Shot
Sep 28 2000 05:20:37:183PM1000928029Martin GreenwaldGood shot

Physics Operator Comments
Sep 28 2000 07:51:03:513AMBill RowanEngineering Setup for Thursday, Sept 28

MP#253 Low-Power Ohmic H-Mode EDA
SL: Greenwald
PO: Rowan

Engineering setup:
-------------------
Overnight ECDC in D2, stopping 1-2 hours before run.

Run begins 9:00 and ends at 17:00

Power System Setup: Same as on 1000622022

Gas setup - fill B-top with 6 psi of D2 Hybrid enabled
fill B-side lower with 1 psi of Ar Hybrid DISABLED
fill B-side upper with 35 psi of D2 Hybrid DISABLED, available ECDC
fill C-side with 30 psi of D2 Hybrid enabled
leave J-bottom as is Hybrid DISABLED

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

DNB gate valve will be disabled.


Run Plan
-------------------
Continuation of MP 253 Low-Power Ohmic H-Mode EDA
The main new thing will be the wider spacing on the a-side scanning probe.
The aim is to get more data on the k spectrum and particle transport driven by the
quasi-coherent mode. We also hope to get better data on the ionization source
(Ly_alpha) than last time. We're interested in getting the best data we can
on edge profiles and fluctuations.
Sep 28 2000 08:17:11:717AMBill Rowan
Started pcs and loaded shot 1000622022
Load at 28-Sep-2000 08:08:50.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done


Did a coldstart. Last few lines:
rtnode -- data loaded, A matrix responds
rtnode -- data loaded, M matrix responds
rtnode -- data loaded, PID matrix responds
RT_NODE Done
28-SEP-2000 08:12:50.87 doing TCL command TYPE *************** END COLD
START ******************
*************** END COLDSTART ******************

Sep 28 2000 09:16:03:437AM1000928001Bill Rowan
001. Fizzle
BR_0 was negative with respect to the last shot yesterday (1000927013) and with
respect to the reference shot (1000622022)
Imported segment 01 from shot 1000927013.
Pressure and BZ_0 look okay to me.
Sep 28 2000 09:37:26:623AM1000928003Bill Rowan002. Plasma.

Next shot: no changes
Sep 28 2000 09:47:42:513AM1000928003Bill Rowan003. Plasma. Disruption at 0.99s.
Not sure about this disruption. Small indication on 2pi bolometer.
Also ramping the field. With regard to this disruption, will try again
and see if it happens at the same time.

Next shot: Change TF rampup from 1.3 s to 1.15 s to avoid disruption that
we expect to develop at late times based on the reference shots.
Sep 28 2000 09:58:33:843AM1000928004Bill Rowan004. Plasma. Disruption on the current rampdown.
Sep 28 2000 10:13:20:543AM1000928004Bill Rowan004. Plasma. Disruption on the current rampdown.

Next shot: Changes in the magnetic field after 1 s to move the ramp
Sep 28 2000 10:22:50:280AM1000928005Bill Rowan005. Dud. Gas is low. It started low this morning and has not come up
shot by shot as I thought that it might.

Next shot. add 2 ms of gas to the prefill
Sep 28 2000 10:37:25:280AM1000928006Bill Rowanl006. Dud. Prefill pressure dropped.

Next shot. Added 2 ms of gas to the prefill. Expecting 24 ms prefill
Verified load/clean
Load at 28-Sep-2000 10:32:45.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done
Sep 28 2000 10:50:16:373AM1000928007Bill Rowan007. Dud. Prefill pressure increased to 0.05 mT to 0.06 mT

Next shot. Added 1 ms of gas to the prefill.
Verified load/clean
Load at 28-Sep-2000 10:48:58.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done
Sep 28 2000 11:09:17:920AM1000928008Bill Rowan008. Dud.
Returning to what worked before.
Increased sparker voltage to 800
Starting ECDC for 15 minutes between shots.
Sep 28 2000 11:37:24:373AM1000928009Bill Rowan009. Plasma.

Next shot: Small change in field ramp after 1 s.
Verified load:
Load at 28-Sep-2000 11:33:00.00
Open tree SCRATCH_DISK:[ROWAN] -1
Open tree done
Sep 28 2000 12:01:57:107PM1000928010Bill Rowan
Next shot. Moved ZXL lower by approximately 7 mm after 1 s
Sep 28 2000 12:13:05:060PM1000928011Bill Rowan011. Plasma
On this shot zxl was ramped from 1 s to 1.3 s for probes.

Next shot. Increased the ramp so that zxl is lower by 3 mm at 1.3 s
Sep 28 2000 12:33:01:293PM1000928012Bill Rowan012. Plasma.

Next shot. No changes.
Sep 28 2000 12:44:18:873PM1000928013Bill Rowan013. Plasma. Disruption just before 1.5 s.

Next shot. No changes.
Sep 28 2000 12:58:19:310PM1000928014Bill Rowan014. Plasma. Disruption just after 1.5 s.
This and the previous disruption appear to be related to an
impurity injection

Next shot. No changes.
Sep 28 2000 01:13:14:937PM1000928015Bill Rowan015. Plasma. Disruption just after 1.6 s IP ramp down starts at 1.5 s

Next shot. No change in plasma setup.
Sep 28 2000 01:13:55:230PM1000928015Bill RowanPlume probe in operation
Sep 28 2000 01:28:14:153PM1000928016Bill Rowan016. Plasma.

Next shot. No changes.
Sep 28 2000 01:39:57:217PM1000928017Bill Rowan017. Plasma. Disruption at 1.26 s.

Next shot. No changes
Sep 28 2000 01:54:29:373PM1000928018Bill Rowan018. Plasma. Disruption at 1.45 s

Next shot. No changes.
Sep 28 2000 02:11:33:560PM1000928019Bill Rowan019. Fizzle.

ECDC for 15 minutes before the next shot.

Next shot. No changes in pcs. Plume probe off.
Sep 28 2000 02:34:33:217PM1000928020Bill Rowan020. Fizzle. Late breakdown.

Next shot. Reduced prefill by 2 ms.
Sep 28 2000 02:45:39:857PM1000928021Bill Rowan021. Plasma.

Next shot. No changes in pcs. Burping probe back on.
Sep 28 2000 03:04:41:513PM1000928022Bill Rowan022. Plasma.

Next shot. No changes in pcs
Sep 28 2000 03:17:04:060PM1000928023Bill Rowan023. Plasma.

Next shot. No changes in pcs
Sep 28 2000 03:39:19:200PM1000928024Bill Rowan024. Plasma. Disruption at 1.4 s.

Next shot. Adjusted zxl for probe at 1.4 s
Sep 28 2000 03:55:24:873PM1000928025Bill Rowan025. Plasma. Disrupted at 1.2 s.

Next shot. No changes in pcs.
Sep 28 2000 04:12:04:780PM1000928026Bill Rowan026. Plasma. Disrupted at 1.5 s.

Next shot. No changes in pcs.
Sep 28 2000 04:29:33:903PM1000928027Bill Rowan027. Plasma.

Next shot. No changes in pcs.
Sep 28 2000 04:58:31:000PM1000928028Bill Rowan028. Plasma.

Next shot. No changes in pcs.

Sep 28 2000 05:05:25:967PM1000928028Bill Rowan028. Plasma.

Next shot. No changes in pcs.



Sep 28 2000 05:05:53:530PM1000928029Bill Rowan029. Plasma.

Last shot.



Engineering Operator Comments
ShotTimeTypeStatusComment
109:03:39:640AMPlasmaOk
209:20:56:030AMPlasmaOk
309:34:19:280AMPlasmaOk
409:47:51:107AMPlasmaOk
510:10:54:577AMPlasmaOk
610:25:52:547AMPlasmaOk
710:40:53:750AMPlasmaOk
810:53:56:810AMPlasmaOk
911:25:27:547AMPlasmaOk
1011:45:55:437AMPlasmaOk
1112:03:57:297PMPlasmaOk
1212:17:00:687PMPlasmaOk
1312:30:41:637PMPlasmaOk
1412:45:30:263PMPlasmaOk
1501:00:02:640PMPlasmaOk
1601:14:59:903PMPlasmaOk
1701:29:49:623PMPlasmaOk
1801:43:26:030PMPlasmaOk
1901:56:41:607PMPlasmaOk
2002:24:13:450PMPlasmaOk
2102:37:19:153PMPlasmaOk
2202:50:45:683PMPlasmaOk
2303:05:28:030PMPlasmaOk
2403:23:08:827PMPlasmaOk
2503:42:08:200PMPlasmaOk
2603:57:19:250PMPlasmaOk
2704:15:22:433PMPlasmaOk
2804:47:47:687PMPlasmaOk
2905:01:32:390PMPlasmaOk