Alcator C-Mod Run 1080111 Information

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Engineering Operator Run Comment

Session Leader Plans
Entered: Jan 10 2008 05:42:07:493PM
Author: Greg Wallace
Session leader plan for 1080111
Session leader: G. Wallace
Physics operator: S. Wolfe
MP 473: Lower Hybrid System Check-out and Initial operation

The purpose of this run will be to isolate the damage by ICRF on the LH launcher
and to find conditions under which we can operate both systems without causing
harm to either.

Plasma setup: Overnight ECDC. Starting shot will be 1080109002. No NINJA at
first.

LH setup: 2.5mm behind limiter, 90deg current drive phasing, 85kW per klystron
at 40kV beam voltage, firing from t=.7 to 1.3s. Be prepared to set launcher to
1.5, 2.5, 3.5, 4.5mm during the run. These values have been calculated and
written on the sheet in the cell.


(very rough) Shot plan:
1) Repeat of shot 1080109002, i.e. no NINJA, no ICRF, upper null, 1.5cm outer
gap, and ~500kW LH power. The launcher will be at 2.5mm behind limiter vs 1.5mm
behind limiter, though.

2) Same plasma as shot 1. Turn off LH and run 2MW on J from 0.7 to 0.9s, 1MW on
E from 0.9 to 1.1s, and 1MW on D from 1.1 to 1.3s. Look to see when/if glowing
appears on LH launcher.

3) Repeat shot 2 but add LH from 0.7 to 1.3s at 85kW per klystron.

4) If glowing is visible on shots 2-3, turn on ICRF antenna which causes
strongest glow from 1.0 to 1.3s at 1-2MW. Keep LH on from 0.7 to 1.3s.
Increase outer gap to 2.5cm.

or

Start stacking antennas and raising power until glowing starts.

5) If glow is still visible, increase outer gap to 3.5cm.

or

If coupling is degraded due to increased outer gap/ICRF, add 5psi NINJA puff
from 0.55 to 1.15s.

6) If increasing outer gap works, turn up RF and LH power until we see glowing
again. As glowing comes back try increasing outer gap again.

7) If increasing outer gap does not make the glowing go away, move launcher to
3.5mm behind the limiter.



8) Repeat steps 1-7 (roughly) in lower null. Start with equilibrium from
1071219015 but program density to 4e19 (or as low as possible). Decrease J to
1.5MW if we are going into H-mode.

Physics Operators Plans
Entered: Jan 10 2008 04:29:42:993PM
Author: Steve Wolfe
PO_PLAN for Friday, 1/11/2008
(second try)
MP#473: LH Stuff
maybe go to 518 depending on results
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Engineering Setup
-----------------

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

Power systems as on: 1080109002

Acoil: +Dtop -Dbot -Jtop +Jbot (standard) Hybrid Enabled

Gas setup:

Fill B-Top with 6 psi D2 Hybrid enabled (PG4)
fill B-side lower with 1 psi Ar Hybrid DISABLED (PG1)
leave B-side upper as is Hybrid DISABLED (PG2)
fill B-main (C-side) with 40 psi D2 Hybrid enabled (PG3)
fill NINJA with 10 psi D2 DISABLED

Enable gatevalves and shutters: ECE, VUV, DNB, Z-bolo

Torvac gatevalve toggle (yes/no): no

Boronization(yes/no): no
Overnight ECDC (yes/no): yes
ICRF(yes/no): yes
LH(yes/no): yes
DNB(yes/no): yes (not absolutely required)
Cryopump (yes/no): not required for first shot, maybe later in
the day if LHe arrives and we have a cell access

Vessel temperature: 35/35/35

------------------------------
ECDC Parameters (if requested)
------------------------------
gas and pressure: D2 at 2e-4 Torr
sweep: 44/45/103 cm
scan: 20/120 s

Plan:
-------

Start from 1080109002 (upper null, 1.5cm outer gap)
LH will start with launcher at 2.5mm
First they'll try different ICRF antennas to see which may be
causing the glowing on the grill. Then play it by ear with
NINJA, raising power, moving grill, etc.
If a cell access is required, for instance to move the launcher,
and LHe has been delivered, then install it for the cryo and perhaps
use cryo with NINJA puffs for the rest of the day. See SL_PLAN
for a possibly more coherent plan (still in development at this point).




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