Alcator C-Mod Run 1050225 Information

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Miniproposals
Miniproposal:364
Date Filed:11/14/2003
Title:Measurement of wall pumping on Alcator C-Mod
First Author:Bruce Lipschultz
Session Leader:Bruce Lipschultz (shots 1-14)

Operators
Session leader(s):Bruce Lipschultz
Physics operator(s):Jim Irby
Engineering operator(s):Bill Cochran

Engineering Operator Run Comment
Shot Cycle Gas System Tests

Session Leader Plans
Entered: Feb 25 2005 08:22:38:847AM
Author: Bruce Lipschultz
MP364 - sort of.

The idea is to check out the RGA and other data (MKS gauges, IGT, IGP gauges, valves statuses) in terms of their archiving as part of the before/after shot deposition in the tree. We also hope to check whether the trend data, archived each midnight is also being archived properly.

The plan is to inject both Ar and D2 into the machine at the time of the shot and keep the gate valves closed for the standard time - 5 minutes. Intitially, we will have the gate valves closed for 6 minutes and see whether that is enough.

Physics Operators Plans
Entered: Feb 25 2005 07:37:02:830AM
Author: Jim Irby

Overnight ECDC in D2, bake at 60C

Engineering setup:

Gas setup:
-----------

> fill B-side lower with 10 psi Ar Hybrid enabled (PG1)
> fill (former) C-side with 30 psi D2 Hybrid Enabled (PG3)

Torvac Setup:
--------------
GV1 closed, Bypass to RGA open at 180 clicks
Torus gate valves closed in Pulse for 5min after shot

Session Leader Summaries
Entered: Feb 25 2005 03:53:06:230PM
Author: Bruce Lipschultz
1050225 - trying to undestand the before/after data

We made progress today. The before and after data appears to be being written. The issues we encccountered are:

1) When the dwell time of the rga/mass is reduced to 15 ms (standard during a run) we continually get 'checksum' errors indicating a communication error from the RGA in the cell to the PC in the control room. This checksum error apparently forces the spectrum to start over again. Thus, if it occurs before the end of a spectrum trace continually one never gets the higher masses (e.g 40 as we were injecting Ar and D2). The solution was to lengthen the dwell to 120 ms. This seemed to reduce the error frequency, but not to zero frequency. The spectra took longer, somewhere between 1.5 and 2 minutes. This necessitated moving the triggers to far enough after the shot (5 minutes) and before (at check, but with 4 minutes of gate valve closing before pulse to allow for 2 full scans). We are assuming 2 full scans are needed becasue if the pulse (or gate valve closure before the shot) occurs near the beginning of a scan, we will want to wait for that scan to finish and a full one before acquiring the data.

2) The files are reversed. We do see that the filenames appearing on the PC have names - TRIGG000.DAT and TRIGG001.DAT. Today it looks like the after data was appearing in the 000 file. This correlates with the reversal in the tree. This may be due to the MDS storage occurring before the after data is taken. Thus, the after data sits around till the next shot and is paired with the before daata of that shot. We need to make sure that the MDS archiving is timed properly. In addition it would be good if the MDS archiving checked the times of the files and deleted the files before the shot (at INIT). This also might eliminate something that Jim Irby has noticed - namely that there are 2 mass spectra, instead of 2, for the 1st shot of the day.

3) The pressure data has some minor issues. It turns out that the mantissa of the IGP and IGT data is being stuck into both the mantissa and exponent when stored in the tree. We have comunicated with TWF about this and have suggested a solution. There is also an issue wwith offsets in the MKS data injected by the AFOLs. The amount, approx. .206 V, translates into 2.06 mT for G-side (multiply the voltage by 10 to get mT) and 20.6 mT for B_Bot MKS (x 100 to get mT). We can live with this for now but it would be good to get this fixed.

4) Potential probblem with other processes going on. During runs the standard RGA archiving ('midnight' data) is set to occur every minute. This could be leading to further confusing of the RGA. For now I recommend that this be stopped or kept at 15 minute intervals, during the run. More tests could be run.

In any case it would be good to see if the checksum errors could be reduced to 0. That might help considerably.

Physics Operator Summaries
Entered: Feb 25 2005 03:21:46:310PM
Author: Jim Irby
Found many problems with RGA triggering and gatevalve operation. Shots 12 and 14 seem to have the
correct before/after data but reversed in the expected order:

m(0, 0:100) gives the after data
m(1, 0:100) gives the before data

Looks like we will have to manually close the gatevalves to get the right before data.


See session leader summary for more details.

Session Leader Comments
Feb 25 2005 08:22:35:127AM1050225001Bruce Lipschultzshot 1: D2 and Ar puffed. But bypass valve too far open - 180. Gate valves may have opened too soon as well. Closing the bypass to 180. Setting the gate valve closure to 6 minutes after the shot for the next shot.
Feb 25 2005 08:36:16:800AM1050225002Bruce Lipschultzshot 2: D2 and Ar puffed. Bypass valve ok but GV2 open. Try again.
Feb 25 2005 09:40:13:703AM1050225003Bruce Lipschultzshot 3: D2 and Ar puffed. Bypass valve ok GV2 ok

Mass 2: 9.9e-9
Mass 3: 2.71e-9
Mass 3: 1.36e-6
Mass 40: 2.8e-8
TC2 pressure: 26.5 mT
B_bot pressure: 32.7 mT
G_side pressure: 26.2

Note - B_bot and G_side have offsets of 8.4 and 2.44 mT respectively

RGA data appearing in MDS deos not look right:-(

Need to check the pressure data.
Feb 25 2005 09:39:49:720AM1050225004Bruce Lipschultzshot 4: D2 and Ar puffed. Bypass valve ok GV2 ok

Mass 2: 1.4e-8
Mass 3: 3.8e-9
Mass 3: 1.6e-6
Mass 40: 1.97e-7
TC2 pressure: 29.6 mT
B_bot pressure: 32.3 mT
G_side pressure: 30.8

Note - B_bot and G_side have offsets of 8.4 and 2.44 mT respectively

There appears to be a problem with the ionization gauge data the mantissa is being put into both the mantissa and exponent in the tree.

Next shot turn off the RGA archiving so we can look directly at the RGA data before it is put in the tree.
Feb 25 2005 03:20:44:433PM1050225014Bruce Lipschultzshot 14: D2 and Ar puffed. Bypass valve ok GV2 ok

The data seemed to be taken correctly with this setup of:

dwell time = 120 ms
before trigger - aat check
after trigger - 5 minutes after pulse
gate valves closed 2 minutes before init
gate valves opened 6 minutes after pulse

Physics Operator Comments
Feb 25 2005 08:35:01:830AM1050225001Jim Irbypuff D2 from 0 to 200 ms at 80% (pg3)

puff argon from 800 to 1000 ms at 100% (pg1)

got large puff

sv4 was too open at 180 clicks: mass 4 to 2e-5

gatevalve toggle was not enabled

vessel at 60C
RGA dwell at 15 ms
Data transfers every minute
Feb 25 2005 08:38:56:017AM1050225002Jim Irbysv4 to 160 clicks
gatevalves enabled for 360 s

nice puff --- but still no gatevalve toggle!
gv1 was closed but not gv2



Feb 25 2005 08:53:57:610AM1050225003Jim Irbytry again with gatevalve toggle --- getting up to 20 mTorr in vessel

big puff --- about 24 mTorr

gatevalve toggle did work --- see both D2 and Ar

Bruce wants more argon for next shot

Feb 25 2005 09:16:42:500AM1050225004Jim IrbyArgon pressure to 30 psi

Argon puff from 600 to 1000 ms (from 800 to 1000 ms on last shot)

29 mTorr on TC3

Argon increased from 9e-8 to 2e-7 on the RGA mass 40

before/after rga data still not working properly
Feb 25 2005 11:52:56:500AM1050225005Jim IrbyNo changes except before/after data store disabled by Steve Wolfe so we can
look at the PLC files before they are deleted.

mks pressures about 29 mTorr

still having problems with before/after
Feb 25 2005 12:32:48:377PM1050225006Jim Irbygatevalve toggle delay set to 600 s --- give more time for the RGA data to be transfered.
Joe Bosco has added extra delay to the transfer time also.

before/after may be okay!

reading from RGA console:

m40 1.7e-7
m04 1.4e-6
m03 3.7e-9
m02 1.1e-8
Feb 25 2005 12:42:20:127PM1050225007Jim Irbyrepeat

no rga data?

Feb 25 2005 12:57:03:970PM1050225008Jim Irbytry again

got rga before/after: low mass okay, but mass 40 screwed up

Feb 25 2005 03:23:32:920PM1050225009Jim Irbyrepeat

note that big board shot number is wrong

before/after screwed up again --- consultation with Joe

Feb 25 2005 03:15:17:390PM1050225012Jim Irbybefore/after data range okay, but before and after arrays reversed:
mass(0,*) after
mass(1,*) before

Feb 25 2005 03:15:27:577PM1050225013Jim Irbyno before/after data
Feb 25 2005 03:17:11:530PM1050225014Jim Irbybefore/after = mass(1,*)/mass(0,*) again

Engineering Operator Comments
ShotTimeTypeStatusComment
108:08:18:907AMTestOk
208:30:17:097AMTestOk
308:39:30:907AMTestOk
408:57:11:270AMTestOk
509:39:55:720AMTestOk
612:13:05:657PMTestOk
712:28:19:487PMTestOk
812:42:47:457PMTestOk
912:57:39:830PMTestOk
1001:13:42:143PMTestOk
1101:52:28:800PMTestOk
1202:19:58:720PMTestOk
1302:39:53:627PMTestOk
1402:56:28:970PMTestOk