Alcator C-Mod Run 970620 Information

Miniproposals

Miniproposal: 149a

Date Filed: 7/23/1996

Title: ICRF Reversed Shear Mode

First Author: Miklos Porkolab

Session Leader: Miklos Porkolab (shots 1-37)

Session Leader: Yuichi Takase (shots 1-37)

Operators
Session leader(s):	Miklos Porkolab,Yuichi Takase
Physics operator(s):	John Goetz
Engineering operator(s):	Vinny Bertolino,Dave Terry

Engineering Operator Run Comment
mp149a/Terry/Cochran/Bertolino/Goetz/setup as for 970617033

Session Leader Plans

Physics Operators Plans

Session Leader Summaries

Entered: Jul 7 2004 03:49:16:977PM

Author: To Be Determined

M.P. 149A. ICRF Reversed Shear Mode
SL: M. Porkolab
PO: J. Goetz

The purpose of the experiment is to explore the possibility of achieving the
enhanced reversed shear (ERS) mode of operation in Alcator C-Mod by early
ICRF heating. We will start with a shot which is similar to last year's
960223047. For ease of startup, we will start with a similar shot to 970617031.
The goal is to ramp the current slowly to a value of 800 kA , and keep the line
average density to about 1xe10(20 m-3). The magnetic field will be at 5.3 T,
and the hydrogen minority will be kept at a minimum value ( no H puff
initially). Experimental procedure will be as follows: 1. Establish
reproducible shots with slow current ramp, and ultimately with at least 2 MW
ICRF power (ramped slowly, or better, in 2 steps, step 1 at 1.0 MW for 50 -100
ms, followed by a 2.0 MW step (RS mode)). After successful tuning and
coupling, shorten the 1 MW first step to last for 50 ms only, namely at times
0.05-0.10 sec, followed by the 2.0 MW step at 0.1 sec onward. If successfull,
ramp the power at 0.15 sec toward the 3.0 MW level to achieve the ERS mode.
Estimate 20 shots to achieve this phase . Critical measurements during this
phase: Monitor ECE GPC channels to look for MHD modes ( similar to last
year's). Also, look at the MHD signals with magnetic loops at times the ECE
channels show MHD activity. FInally, look for rotation during ICRF injection.
Monitor sawtooth delay at all times. 2. Scan the magnetic field for off-axis
heating to see if this would result in a better RS/ERS mode.3. Inject Li pellet
to combine RS/PEP mode to achieve ERS mode ( pressure profile control).

Summary of achievements: Only part of (1) was achieved, with D-port antenna
(transmitter 1) operating only. Transmitter 2 did not operate properly all day.
After many fizzles, good plasmas were formed by late morning and we were able
to couple up to 1.5 MW of power into the ramping phase of the discharge.
Evidence of RS profiles were seen already in the ohmic heating phase and with
low RF power. As the RF power was increased to 1.5 MW, temperatures of order 3
keV were achieved before sawtooth phenomena occured. Interesting MHD
oscillations were seen on shots 32,33. These were even better than last year's
best shot, which was studied in great detail with the MARS code. These modes
were identified as single layer tearing modes and were used to bracket
q-profiles. We should be able to do even better with the present data. We
attempted (2) but after two fizzles stopped near the end of the day. Step (3)
was not attempted. The H/D minority concentration was 3% in the morning and
increased during the day to 12 %, satisfactory for minority heating. Details of
the shots can be found in the shot-log. The last shot of the day (37) was
used to identify the problem with transmitter 2, which turned out to be
noise on the input signal to the power feedback circuit.

Physics Operator Summaries

Entered: Jul 7 2004 04:36:57:800PM

Author: To Be Determined

Physics operator summary for 970620

EO: Terry/Bertolino
PO: Goetz
SL: Porkolab/Takase

Run 970620 was in support of Mini-Proposal #149A - Optimize Reverse Shear Mode
The goals for today are to try and produce good plasmas and obtain the reverse
shear mode from last run campaign. After that, twiddle things like current rise
ramp rate, outer gap, etc. to optimize the mode.

The goals were not reached today. Good plasmas were made today, but the RF was
having trouble with E-port antenna, so much of the plan could not be carried out.
See the Session Leader's report for the physics results.

More plasmas today than fizzles - which is pretty good for this week. No non-
power supply duds today.

Once the fill and the Br were determined, breakdowns were at 6msec. This
was from shot 4 through 23. After that the breakdown time began to drift
later and the fizzle frequency increased. The breakdown time could be affected
by fill pressure.

It seemed that Br, as calculated, liked to be about .002T. Breakdowns usually
happened on negative swings of the Br.

All plasmas moved in after formation. A plasma/fizzle was determined by
when this movement occured; the later the movement the better. Gas puffs
were suspected at first as to the cause of the plasma moving in. Changing the
proportional gain relative to the derivative gain on the RCUR controller in
the first 10's of milliseconds did seem to help make the movement time later, but
this fix needed to be fixed further as the day went on. A drastic change in the
RCUR offset was NOT attempted and is recommended as an avenue of exploration in
the future.

The startup is still not robust and needs work.

Engineering, computing, and diagnostics today: CAMAC troubles with the magnetics early in
the run. Joe Bosco threatened the highway and the errors retreated. One magnet
resistance fault. OH2 and TF crowbars on the last shot of the day.

Scorecard: 37 shots = 20 plasmas + 16 fizzles + 1 dud

Shot summary for Run 970620:

Load 970617033
coldstart hybrid - all matrices respond
IP = -800000
NL04 = 6e19
PG4 = 24msec

Shot change result
____ _____ ______
1 see above fizzle; breakdown @ 7ms; null looks o.k.

2 PG4=28ms fizzle; breakdown @ 6.5ms; not enough Br

3 BR_0=.008; PG4=30ms fizzle; breakdown @ 10ms; too much Br

4 BR_0 offset = .007 plasma; b.d. @ .006; good shot; disrupts @ 0.2MA
some e-heating and neuts

5 RCUR=.669 @ 0.3s fizzle; b.d. @ .006; Bz not in fast enough

6 RCUR offset = 6800 plasma; b.d. @ .006; disrupts @ 0.2MA; plenty
of H-modes, e-heating, neuts but only one transmitter

7 RCUR = .62 @ 0 to match actual plasma; b.d. @ .006; nice shot

8 no changes fizzle; b.d. @ .006; Bz not in fast enough??

9 RCUR offset = 7000 fizzle; b.d. @ .006; plasma moves in; correlates
with first gas puff from K-side

10 PG3 starts @ .03s plasma; b.d. @ .006; good current rise; no hesitation

11 no changes fizzle; b.d.@ .006; CII light = .004; moves in; gas
not the culprit

12 lower RCUR P gain to 5 from 10 plasma; b.d.@ .006; slight hesitation; good plasma

13 RCUR=.669 @ .25 plasma; b.d.@ .006; no hesitation; good plasma

14 PG2=[40msx90V] @ .7s plasma; b.d. @ .006; slight hesitation; o.k. plasma

15 RCUR=.669 @ .28s; bring current fizzle; b.d. @ .006; not enough current for the Bz
down faster

16 lower P gain of RCUR to fizzle; b.d. @ .006; moves in @ .016
3.5 @ .006

17 PG4 = 28msec plasma; b.d. @ .006; moves in @ .032; right gap very small early

18 RCUR=.669 @ .29s; PG2 = plasma; b.d. @ .006; moves in @ .035; right gap 1cm; o.k.
[.05sx100V] @ .7s

19 slow down current ramp down plasma; b.d. @ .006; moves in @ .03;
PG2 = [.06sx100V] @ .7s

20 CLEARIN=-.005 @ .25; RCUR=.669 plasma; b.d.@.006; moves in @ .033; diverts earlier and reduced gap
@ 0.27s

21 CLEARIN=-.005 @.225; plasma; b.d. @ .0065; moves in @ .03; right gap is
RCUR=.66 @.14 reduced to 1cm by .15s

22 PG2=[.08sx100V] @ .7s plasma; b.d. @ .0065; moves in @ .035; diverts by .18s;

23 PG2=[0.2sx100V] @ .7s with plasma; b.d. @ .006; moves in @ .028; good shot
vacuum - not enabled

24 CLEARIN=-.005 @ 0.2s; PG2 = plasma; b.d. @ .007; lucky to make it
[1.3sx100V] @ 0.1 with vacuum

25 PG4=27msec fizzle; b.d. @ .007; moves in at 18ms; should have made it

26 BR_0 offset = .0067 fizzle; b.d. @ .008; moves in at 16ms

27 BR_0 offset = .0075 fizzle; b.d. @ .008; moves in at 13ms; terrible discharge

28 BR_0 offset = .007; PG4=28ms plasma; b.d. @ .006; moves in @ .029s; good shot!

29 PG2=[.05sx100V] @ .7s with plasma; b.d. @ .007; moves in @ .03s; o.k. shot
4psi of neon

30 PG2=[.07sx100V] @ .7s fizzle; b.d. @ .007; moves in @ .013

31 PG4 =25ms fizzle; b.d. @ .008; bad fizzle

32 PG4=31ms; IC_EF4=-1335A plasma; b.d. @ .0065; moves in after 30ms; nice shot

33 PG4=32ms; PG2=[.08x100V] @ .7 plasma; b.d. @ .0065; moves in after 30ms

34 PG2=[.09sx100V] @ .7; TF dud; magnet resistance fault
current = -130500 -> 4.7T

35 try again fizzle; b.d. @ .01s; too much curvature

36 IC_EF1x = -6350 @ t=0 fizzle; b.d. @ .008s; too much curvature

37 reload 970620033 plasma; b.d. @ .007s; TF and OH2 crowbar

Session Leader Comments

Jun 20 1997 09:22:06:430AM Miklos Porkolab M.P. 149A. ICRF Reversed Shear Mode

The purpose of the experiment is to explore the possibility of achieving the enhanced reversed
shear (ERS) mode of operation in Alcator C-Mod by early ICRF heating. We will
start with a shot which is similar to last year's 960223047. For ease of startup, we will
start with a similar shot to 970617031. The goal is to ramp the current slowly to a value
of 800 kA , and keep the line average density to about 1xe10(20 m-3). The magnetic field
will be at 5.3 T, and the hydrogen minority will be kept at a minimum value ( no H puff
initially). Experimental procedure will be as follows:
1. Establish reproducible shots with slow current ramp, and ultimately with at least
2 MW ICRF power (ramped slowly, or better, in 2 steps, step 1 at 1.0 MW for 50 -100 ms,
followed by a 2.0 MW step (RS mode)). After successful tuning and coupling, shorten the 1 MW
first step to last for 50 ms only, namely at times 0.05-0.10 sec, followed by the 2.0 MW step
at 0.1 sec onward. If successfull, ramp the power at 0.15 sec toward the 3.0 MW level to
achieve the ERS mode. Estimate 20 shots to achieve this phase . Critical measurements during
this phase: Monitor ECE PCE channels to look for MHD modes ( similar to last year's). Also,
look at the MHD signals with magnetic loops at times the ECE channels show MHD activity.
FInally, look for rotation during ICRF injection. Monitor sawtooth delay at all times.
2. Scan the magnetic field for off-axis heating to se

Jun 20 1997 09:22:50:580AM 970620001 Miklos Porkolab Fizzle.

Jun 20 1997 09:26:51:060AM 970620002 Miklos Porkolab Fizzle

Jun 20 1997 09:27:21:410AM 970620003 Miklos Porkolab Fizzle

Jun 20 1997 09:28:39:200AM 970620004 Miklos Porkolab First plasma shot. Still tuning.

Jun 20 1997 09:29:11:090AM 970620005 Miklos Porkolab Fizzle.

Jun 20 1997 09:47:54:280AM 970620006 Miklos Porkolab Good plasma shot. RF power around 1-1.5 MW. Still tuning.

Jun 20 1997 09:54:45:450AM 970620007 Miklos Porkolab Good plasma shot. RF power around 1-1.5 MW. Still tuning.

Jun 20 1997 10:05:33:120AM 970620008 Miklos Porkolab Fizzle.

Jun 20 1997 10:33:42:590AM 970620009 Miklos Porkolab Fizzle.

Jun 20 1997 10:34:44:020AM 970620010 Miklos Porkolab Good shot. Trying to move RF to earlier times, to delay sawtooth time.

Jun 20 1997 10:46:52:330AM 970620010 Miklos Porkolab Good shot. Trying to move RF to earlier times, to delay sawtooth time.
Do not believe EFIT data on this shot. Corrupted magnetics data on this shot.

Jun 20 1997 10:47:48:600AM 970620011 Miklos Porkolab Fizzle. Stop for "cell access" to fix interferometer.

Jun 20 1997 11:40:31:530AM 970620012 Miklos Porkolab Resumed shots after cell break. Good shot. Up to 0.2 sec, Prf=0.2 MW only.
Then power is raised to 1 MW but sawteeth show up.

Jun 20 1997 12:14:34:850PM 970620013 Miklos Porkolab Shot OK.

Jun 20 1997 12:15:18:060PM 970620014 Miklos Porkolab Shot OK.

Jun 20 1997 12:15:48:470PM 970620014 Miklos Porkolab Shot OK.

Jun 20 1997 12:17:23:160PM 970620015 Miklos Porkolab Fizzle.

Jun 20 1997 12:31:13:190PM 970620016 Miklos Porkolab Fizzle.

Jun 20 1997 12:50:16:020PM 970620017 Miklos Porkolab Good shot. Plasma resting against E port antenna. Decent electron
heating between 0.20 and 0.23 sec, when sawteeth show up and Te plunges.

Jun 20 1997 12:54:17:920PM 970620018 Miklos Porkolab Good shot. Sawteeth come in at 0.23 sec; Prf=.7 MW after 0.20 sec.
Low power before.

Jun 20 1997 12:55:49:890PM 970620018 Miklos Porkolab Good shot. Sawteeth come in at 0.23 sec; Prf=.7 MW after 0.20 sec.
Low power before. Prf=0.15 MW between 0.10 and 0.20 sec.

Jun 20 1997 01:15:11:510PM 970620019 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power limited to 0.6-1.0 MW.

Jun 20 1997 01:39:49:400PM 970620020 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power limited to 0.6-1.0 MW.

Jun 20 1997 01:46:04:290PM 970620021 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power limited to 0.6-1.0 MW.

Jun 20 1997 02:03:31:290PM 970620022 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power limited to 0.2 MW at times 0.10-0.15 sec, and 1.0 MW
after 0.15 sec. No sign of MHD on this shot.

Jun 20 1997 02:29:50:260PM 970620023 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power now up to 1.5 MW on D port early into the pulse,
0.15 sec.

Jun 20 1997 02:52:15:400PM 970620024 Miklos Porkolab Good shot. E port and D port still not coupling together.
Power now up to 1.5 MW on D port early into the pulse,
0.10sec.

Jun 20 1997 02:54:46:530PM 970620025 Miklos Porkolab Fizzle.

Jun 20 1997 02:55:02:930PM 970620026 Miklos Porkolab Fizzle.

Jun 20 1997 03:21:50:070PM 970620027 Miklos Porkolab Fizzle.

Jun 20 1997 03:36:28:190PM 970620027 Miklos Porkolab Fizzle.

Jun 20 1997 03:38:08:300PM 970620028 Miklos Porkolab Good shot. High Rf power early into the discharge,
1.5 MW from D port. Fairly high Te before sawteeth at 0.23 sec.

Jun 20 1997 03:38:36:020PM 970620029 Miklos Porkolab Good shot. High Rf power early into the discharge,
1.5 MW from D port. Fairly high Te before sawteeth at 0.23 sec.

Jun 20 1997 03:44:10:430PM 970620030 Miklos Porkolab Fizzle.

Jun 20 1997 03:45:47:140PM 970620031 Miklos Porkolab Fizzle.

Jun 20 1997 04:10:53:170PM 970620032 Miklos Porkolab High power RF early on in the discharge. Shot is a "gold-mine" for MHD !
Large internal tearing modes at 0.11-0.12 sec during high power RF,
as well as earlier during the OH phase around 0.06-0.07 sec. In addition,
when high power RF turns on, we see internal sawtooth crash like phenomena.
Reserve this shot for later MHD studies !

Jun 20 1997 04:19:28:380PM 970620033 Miklos Porkolab High power RF early on in the discharge. Shot is also good for MHD !
Large internal tearing modes at 0.11-0.12 sec during high power RF,
Somewhat similar to previous shot, but perhaps not as spetacular.

Jun 20 1997 04:31:36:950PM 970620034 Miklos Porkolab Set B-field to 4.7 Tesla ( off axis heating attempt).
No plasma, engineering error.

Jun 20 1997 04:32:12:080PM 970620035 Miklos Porkolab Set B-field to 4.7 Tesla ( off axis heating attempt).
Fizzle.

Jun 20 1997 04:44:16:160PM 970620036 Miklos Porkolab Set B-field to 4.7 Tesla ( off axis heating attempt).
Fizzle.

Jun 20 1997 05:16:52:480PM 970620037 Miklos Porkolab Returned to 5.3 Tesla for RF transmitter test. It was concluded that
port-E transmitter is faulty, hence the lack of performance all day.
Got 1.5 MW in early on from D-port antenna as earlier.

Physics Operator Comments

Jun 20 1997 08:33:14:750AM John Goetz Run 970620
MiniProposal 149A - Optimize Reverse Shear Mode

Obtain Reverse Shear plasmas and try to optimize by
heating early, fiddling with the current rise ramp
rate, outer gap, etc.

Start with a load of 970617033 and make the following changes:
draw Ip to 0.8MA
draw nl04 to 0.6e20
draw PG4 to 24msec

Jun 20 1997 08:51:45:200AM John Goetz Shot 970620001:
Load 970617033
IP = -800000
NL04 = 6e19
PG4 = 24msec

Results:
fizzle; breakdown @ .007
fields don't look too bad

Jun 20 1997 08:52:22:040AM 970620001 John Goetz Shot 970620001:
Load 970617033
IP = -800000
NL04 = 6e19
PG4 = 24msec

Results:
fizzle; breakdown @ .007
fields don't look too bad

Jun 20 1997 09:01:06:770AM 970620002 John Goetz Shot 970620002:
PG4 = 28msec

Results:
fizzle
breakdown @ .0065; CII light = .004
radial field not positive enough?

Jun 20 1997 09:10:13:150AM 970620003 John Goetz Shot 970620003:
PG4 = 30msec
BR_0 offset = .008

Results:
fizzle
late breakdown @ .01
too much radial field now

Jun 20 1997 09:25:10:230AM 970620004 John Goetz Shot 970620004:
BR_0 offset = .007

Results:
Plasma
breakdown @ .006; likes to breakdown on a negative Br swing
some electron heating and neutrons during the RF pulses

Jun 20 1997 09:35:32:550AM 970620005 John Goetz Shot 970620005:
RCUR = .669 @ .3s to make the right gap smaller sooner

Results:
fizzle
breakdown @ .006
bounces; Bz not coming in fast enough?

Jun 20 1997 09:48:38:260AM 970620006 John Goetz Shot 970620006:
RCUR offset = 6800 to bring in Bz faster
RCUR = .669 @ .3s to make the right gap smaller sooner

Results:
plasma
breakdown @ .006; CII = .004; don't know if the RCUR offset makes a difference
plenty of H-modes; electron heating and neuts

Jun 20 1997 10:13:25:770AM 970620008 John Goetz Shot 970620008:
no changes

Results:
fizzle;
breakdown @ .006; CII light = .005; Bz not in fast enough??

Jun 20 1997 10:21:23:480AM 970620009 John Goetz Shot 970620009:
RCUR offset = 7000

Results:
fizzle
breakdown @ .006; CII light = .004
plasma moves in; movement corresponds with the first gas puff from K-side

Jun 20 1997 10:32:34:760AM 970620010 John Goetz Shot 970620010:
first non-zero PG3 point @ .03s

Results:
plasma
breakdown @ .006; disrupts @0.2MA
good current rise - no hesitation - first gas puff doesn't come until .035s
nice plasma - but only one transmitter

Jun 20 1997 11:04:13:400AM 970620011 John Goetz Shot 970620011:
no changes

Results:
fizzle
breakdown @ .006; CII light = .004; plasma moves in
looks like the gas puff was not the culprit in pushing the plasma in.

Jun 20 1997 11:36:19:910AM 970620012 John Goetz Shot 970620012:
lower RCUR P gain @ .006s to 5 from 10 (control system thinks plasma is outside
and pulls it in on all these fizzles)
45 minute wait for cell access

Results:
plasma
breakdown @ .006; slight current rise hesitation
nice shot; still having RF problems

Jun 20 1997 11:56:02:720AM 970620013 John Goetz Shot 970620013:
RCUR = .669 @ .25 sec

Results:
Plasma
breakdown @ .006; good current rise
good shot; bad RF; magnetics errors - no EFIT

Jun 20 1997 12:05:48:160PM 970620014 John Goetz Shot 970620014:
PG2 = 40msx90V @ .7s and enable for neon puff

Results:
plasma
breakdown @ .006; CII light = .005; plasma stays out until .03sec
heating and neutrons have disappeared
right gap is very small during RF pulses

Jun 20 1997 12:17:32:830PM 970620015 John Goetz Shot 970620015:
RCUR = .669 @ .28sec
bring current down faster before the EF2's run out of oomph

Results:
fizzle
breakdown @ .006; moves in at around 15msec

Jun 20 1997 12:27:28:140PM 970620016 John Goetz Shot 970620016:
drop P gain of RCUR to 3.5 @ .006

Results:
fizzle
breakdown @ .006; moves in beginning around 16msec

Jun 20 1997 12:43:10:550PM 970620017 John Goetz Shot 970620017:
PG4 to 28msec

Results:
plasma
breakdown @ .006; doesn't move in until .03s
right gap still going to zero; plasma rubbing off on E-port antenna
not allowing it to run

Jun 20 1997 12:53:42:210PM 970620018 John Goetz Shot 970620018:
RCUR = .669 @ .29s
PG2 = .05sx100V @ .7s

Results:
plasma
breakdown @ .006; no hesitation in current rise; moves in @ .035
right gap now 1 cm; doesn't go to zero
disrupts @ 0.3MA

Jun 20 1997 01:09:44:380PM 970620019 John Goetz Shot 970620019:
PG2 = .06sx100V @ .7s
slow down current ramp down

Results:
plasma
b.d. @ .006; moves in beginning @ .03s
better target for RF
disrupts @ 0.2MA

Jun 20 1997 01:33:38:010PM 970620020 John Goetz Shot 970620020:
CLEARIN = -.005 @ .25s for earlier divertor
RCUR = .669 @ .27 for smaller gap earlier

Results:
plasma
breakdown @ .006; begins to move in @ .033;
disrupts @ 0.2MA
diverts a bit earlier and the right gap shrinks earlier

Jun 20 1997 01:47:07:590PM 970620021 John Goetz Shot 970620021:
CLEARIN = -.005 @ .225s for earlier divertor
RCUR = .66 @ .14 for smaller right gap earlier

Results:
plasma
b.d. @ .0065; moves in @ .03
disrupts @ 1.2; vertical oscillation and some other demand on EF2 lower
RF trips out early

Jun 20 1997 02:00:30:630PM 970620022 John Goetz Shot 970620022:
PG2 = .08sx100V @ 0.7

Results:
plasma
breakdown @ 0.006; begins to move in around .036s
disrupts @ 0.3MA
diverts about .18sec - right gap ~1cm at same time

Jun 20 1997 02:21:08:540PM 970620023 John Goetz Shot 970620023:
PG2 = 0.2sx100V @ .7s with vacuum but not enabled

Results:
plasma
breakdown @ .006; moves in at .028s; no hesitation
D-port @ 1.5MW for 0.3s
disrupts @ 0.3MA

Jun 20 1997 02:39:25:330PM 970620024 John Goetz Shot 970620024:
PG2 = 1.3sx100V @ .1s with vacuum
CLEARIN = -.005 @ 0.2s

Results:
plasma
breakdown @ .007; current hesitation; lucky to get this one
good shot after that

Jun 20 1997 02:44:23:590PM 970620025 John Goetz Shot 970620025:
PG4 = 27msec

Results:
fizzle
breakdown @ .007; moves in at around 18msec; should have made it

Jun 20 1997 02:54:34:480PM 970620026 John Goetz Shot 970620026:
BR_0 offset = .0067

Results:
fizzle
breakdown @ .008!!; moves in at .016

Jun 20 1997 03:06:07:270PM 970620027 John Goetz Shot 970620027:
BR_0 offset = .0075

Results:
fizzle
terrible fizzle; breakdown @ .008; moves in @ .013

Jun 20 1997 03:15:26:380PM 970620028 John Goetz Shot 970620028:
BR_0 offset = .007
PG4 = 28msec

Results:
Plasma
breakdown @ .006; moves in at about .029sec
diverted and small right gap by about .15-.16sec

Jun 20 1997 03:30:29:400PM 970620029 John Goetz Shot 970620029:
PG2 = .05sx100V @ .7 with 4psi Ne

Results:
plasma
breakdown @ .007; moves in @ .03
diverted by about .15sec

Jun 20 1997 03:49:37:820PM 970620031 John Goetz Shot 970620031:
PG2 = .07sx100V @ .7 with 4psi Ne

Results:
fizzle
breakdown @ .008; wimpy fizzle
moves in at about 15msec

Jun 20 1997 04:01:36:750PM 970620032 John Goetz Shot 970620032:
PG4 = 30msec
IC_EF4 = -1335A

Results:
plasma
breakdown @ .0065; moves in after 30msec; good current rise
disrupts @ 0.3MA
RF early, not late

Jun 20 1997 04:13:50:170PM 970620033 John Goetz Shot 970620033:
PG4 = 32msec
PG2 = .08sx100V @ 0.7s

Results:
plasma
breakdown @ .0065; moves in after 30msec; good current rise
disrupts @ 0.2MA
not too bad

Jun 20 1997 04:25:47:920PM 970620034 John Goetz Shot 970620034:
PG2 = .09sx100V @ 0.7s
TF current = -130500A -> 4.7T breakdown

Results:
dud - magnet resistance fault

Jun 20 1997 04:36:05:370PM 970620035 John Goetz Shot 970620035:
PG2 = .09sx100V @ 0.7s
TF current = -130500A -> 4.7T breakdown

Results:
fizzle
breakdown @ .0095; too much curvature

Jun 20 1997 04:45:38:220PM 970620036 John Goetz Shot 970620036:
IC_EF1x = -6350 at t=0 (to compensate for the single-turn change in TF)

Results:
fizzle; b.d. @ .008; too much curvature still

Jun 20 1997 05:21:03:140PM 970620037 John Goetz Shot 970620037:
reload 970620033

Results:
plasma
b.d. @ .007; but a good current rise
disrupts @ 0.4MA accompanied by TF and OH2 crowbars
RF group pinned the troubles on the E-port transmitter with this shot
and not on any plasma related problems

Engineering Operator Comments

Shot Time Type Status Comment

1 08:41:17:080AM Plasma Bad no plasma

2 08:53:30:350AM Plasma Ok

3 09:03:56:790AM Plasma Ok

4 09:12:11:070AM Plasma Ok

5 09:26:22:480AM Plasma Ok

6 09:37:49:600AM Plasma Ok

7 09:51:45:690AM Plasma Ok

8 10:03:18:570AM Plasma Ok

9 10:13:45:760AM Plasma Ok

10 10:23:36:030AM Plasma Ok no faults/plasma

11 10:37:01:380AM Plasma Ok

12 11:22:50:850AM Plasma Ok

13 11:40:39:180AM Plasma Ok

14 11:56:07:580AM Plasma Ok

15 12:10:07:950PM Plasma Ok

16 12:19:20:760PM Plasma Ok

17 12:29:04:620PM Plasma Ok

18 12:43:19:790PM Plasma Ok

19 12:58:45:270PM Plasma Ok

20 01:15:58:730PM Plasma Ok

21 01:34:43:020PM Plasma Ok

22 01:48:07:600PM Plasma Ok

23 02:11:34:570PM Plasma Ok

24 02:26:33:810PM Plasma Ok

25 02:38:08:660PM Plasma Ok

26 02:47:34:850PM Plasma Ok

27 02:58:36:130PM Plasma Ok

28 03:07:57:230PM Plasma Ok

29 03:21:55:410PM Plasma Ok

30 03:33:43:270PM Plasma Ok

31 03:43:36:070PM Plasma Ok

32 03:54:17:830PM Plasma Ok

33 04:06:16:410PM Plasma Ok

34 04:21:50:250PM Plasma Ok

35 04:29:30:690PM Plasma Ok

36 04:38:33:640PM Plasma Ok

37 04:49:20:140PM Plasma Ok

Session Leader Comments
Jun 20 1997 09:22:06:430AM		Miklos Porkolab	M.P. 149A. ICRF Reversed Shear Mode The purpose of the experiment is to explore the possibility of achieving the enhanced reversed shear (ERS) mode of operation in Alcator C-Mod by early ICRF heating. We will start with a shot which is similar to last year's 960223047. For ease of startup, we will start with a similar shot to 970617031. The goal is to ramp the current slowly to a value of 800 kA , and keep the line average density to about 1xe10(20 m-3). The magnetic field will be at 5.3 T, and the hydrogen minority will be kept at a minimum value ( no H puff initially). Experimental procedure will be as follows: 1. Establish reproducible shots with slow current ramp, and ultimately with at least 2 MW ICRF power (ramped slowly, or better, in 2 steps, step 1 at 1.0 MW for 50 -100 ms, followed by a 2.0 MW step (RS mode)). After successful tuning and coupling, shorten the 1 MW first step to last for 50 ms only, namely at times 0.05-0.10 sec, followed by the 2.0 MW step at 0.1 sec onward. If successfull, ramp the power at 0.15 sec toward the 3.0 MW level to achieve the ERS mode. Estimate 20 shots to achieve this phase . Critical measurements during this phase: Monitor ECE PCE channels to look for MHD modes ( similar to last year's). Also, look at the MHD signals with magnetic loops at times the ECE channels show MHD activity. FInally, look for rotation during ICRF injection. Monitor sawtooth delay at all times. 2. Scan the magnetic field for off-axis heating to se
Jun 20 1997 09:22:50:580AM	970620001	Miklos Porkolab	Fizzle.
Jun 20 1997 09:26:51:060AM	970620002	Miklos Porkolab	Fizzle
Jun 20 1997 09:27:21:410AM	970620003	Miklos Porkolab	Fizzle
Jun 20 1997 09:28:39:200AM	970620004	Miklos Porkolab	First plasma shot. Still tuning.
Jun 20 1997 09:29:11:090AM	970620005	Miklos Porkolab	Fizzle.
Jun 20 1997 09:47:54:280AM	970620006	Miklos Porkolab	Good plasma shot. RF power around 1-1.5 MW. Still tuning.
Jun 20 1997 09:54:45:450AM	970620007	Miklos Porkolab	Good plasma shot. RF power around 1-1.5 MW. Still tuning.
Jun 20 1997 10:05:33:120AM	970620008	Miklos Porkolab	Fizzle.
Jun 20 1997 10:33:42:590AM	970620009	Miklos Porkolab	Fizzle.
Jun 20 1997 10:34:44:020AM	970620010	Miklos Porkolab	Good shot. Trying to move RF to earlier times, to delay sawtooth time.
Jun 20 1997 10:46:52:330AM	970620010	Miklos Porkolab	Good shot. Trying to move RF to earlier times, to delay sawtooth time. Do not believe EFIT data on this shot. Corrupted magnetics data on this shot.
Jun 20 1997 10:47:48:600AM	970620011	Miklos Porkolab	Fizzle. Stop for "cell access" to fix interferometer.
Jun 20 1997 11:40:31:530AM	970620012	Miklos Porkolab	Resumed shots after cell break. Good shot. Up to 0.2 sec, Prf=0.2 MW only. Then power is raised to 1 MW but sawteeth show up.
Jun 20 1997 12:14:34:850PM	970620013	Miklos Porkolab	Shot OK.
Jun 20 1997 12:15:18:060PM	970620014	Miklos Porkolab	Shot OK.
Jun 20 1997 12:15:48:470PM	970620014	Miklos Porkolab	Shot OK.
Jun 20 1997 12:17:23:160PM	970620015	Miklos Porkolab	Fizzle.
Jun 20 1997 12:31:13:190PM	970620016	Miklos Porkolab	Fizzle.
Jun 20 1997 12:50:16:020PM	970620017	Miklos Porkolab	Good shot. Plasma resting against E port antenna. Decent electron heating between 0.20 and 0.23 sec, when sawteeth show up and Te plunges.
Jun 20 1997 12:54:17:920PM	970620018	Miklos Porkolab	Good shot. Sawteeth come in at 0.23 sec; Prf=.7 MW after 0.20 sec. Low power before.
Jun 20 1997 12:55:49:890PM	970620018	Miklos Porkolab	Good shot. Sawteeth come in at 0.23 sec; Prf=.7 MW after 0.20 sec. Low power before. Prf=0.15 MW between 0.10 and 0.20 sec.
Jun 20 1997 01:15:11:510PM	970620019	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power limited to 0.6-1.0 MW.
Jun 20 1997 01:39:49:400PM	970620020	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power limited to 0.6-1.0 MW.
Jun 20 1997 01:46:04:290PM	970620021	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power limited to 0.6-1.0 MW.
Jun 20 1997 02:03:31:290PM	970620022	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power limited to 0.2 MW at times 0.10-0.15 sec, and 1.0 MW after 0.15 sec. No sign of MHD on this shot.
Jun 20 1997 02:29:50:260PM	970620023	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power now up to 1.5 MW on D port early into the pulse, 0.15 sec.
Jun 20 1997 02:52:15:400PM	970620024	Miklos Porkolab	Good shot. E port and D port still not coupling together. Power now up to 1.5 MW on D port early into the pulse, 0.10sec.
Jun 20 1997 02:54:46:530PM	970620025	Miklos Porkolab	Fizzle.
Jun 20 1997 02:55:02:930PM	970620026	Miklos Porkolab	Fizzle.
Jun 20 1997 03:21:50:070PM	970620027	Miklos Porkolab	Fizzle.
Jun 20 1997 03:36:28:190PM	970620027	Miklos Porkolab	Fizzle.
Jun 20 1997 03:38:08:300PM	970620028	Miklos Porkolab	Good shot. High Rf power early into the discharge, 1.5 MW from D port. Fairly high Te before sawteeth at 0.23 sec.
Jun 20 1997 03:38:36:020PM	970620029	Miklos Porkolab	Good shot. High Rf power early into the discharge, 1.5 MW from D port. Fairly high Te before sawteeth at 0.23 sec.
Jun 20 1997 03:44:10:430PM	970620030	Miklos Porkolab	Fizzle.
Jun 20 1997 03:45:47:140PM	970620031	Miklos Porkolab	Fizzle.
Jun 20 1997 04:10:53:170PM	970620032	Miklos Porkolab	High power RF early on in the discharge. Shot is a "gold-mine" for MHD ! Large internal tearing modes at 0.11-0.12 sec during high power RF, as well as earlier during the OH phase around 0.06-0.07 sec. In addition, when high power RF turns on, we see internal sawtooth crash like phenomena. Reserve this shot for later MHD studies !
Jun 20 1997 04:19:28:380PM	970620033	Miklos Porkolab	High power RF early on in the discharge. Shot is also good for MHD ! Large internal tearing modes at 0.11-0.12 sec during high power RF, Somewhat similar to previous shot, but perhaps not as spetacular.
Jun 20 1997 04:31:36:950PM	970620034	Miklos Porkolab	Set B-field to 4.7 Tesla ( off axis heating attempt). No plasma, engineering error.
Jun 20 1997 04:32:12:080PM	970620035	Miklos Porkolab	Set B-field to 4.7 Tesla ( off axis heating attempt). Fizzle.
Jun 20 1997 04:44:16:160PM	970620036	Miklos Porkolab	Set B-field to 4.7 Tesla ( off axis heating attempt). Fizzle.
Jun 20 1997 05:16:52:480PM	970620037	Miklos Porkolab	Returned to 5.3 Tesla for RF transmitter test. It was concluded that port-E transmitter is faulty, hence the lack of performance all day. Got 1.5 MW in early on from D-port antenna as earlier.

Physics Operator Comments
Jun 20 1997 08:33:14:750AM		John Goetz	Run 970620 MiniProposal 149A - Optimize Reverse Shear Mode Obtain Reverse Shear plasmas and try to optimize by heating early, fiddling with the current rise ramp rate, outer gap, etc. Start with a load of 970617033 and make the following changes: draw Ip to 0.8MA draw nl04 to 0.6e20 draw PG4 to 24msec
Jun 20 1997 08:51:45:200AM		John Goetz	Shot 970620001: Load 970617033 IP = -800000 NL04 = 6e19 PG4 = 24msec Results: fizzle; breakdown @ .007 fields don't look too bad
Jun 20 1997 08:52:22:040AM	970620001	John Goetz	Shot 970620001: Load 970617033 IP = -800000 NL04 = 6e19 PG4 = 24msec Results: fizzle; breakdown @ .007 fields don't look too bad
Jun 20 1997 09:01:06:770AM	970620002	John Goetz	Shot 970620002: PG4 = 28msec Results: fizzle breakdown @ .0065; CII light = .004 radial field not positive enough?
Jun 20 1997 09:10:13:150AM	970620003	John Goetz	Shot 970620003: PG4 = 30msec BR_0 offset = .008 Results: fizzle late breakdown @ .01 too much radial field now
Jun 20 1997 09:25:10:230AM	970620004	John Goetz	Shot 970620004: BR_0 offset = .007 Results: Plasma breakdown @ .006; likes to breakdown on a negative Br swing some electron heating and neutrons during the RF pulses
Jun 20 1997 09:35:32:550AM	970620005	John Goetz	Shot 970620005: RCUR = .669 @ .3s to make the right gap smaller sooner Results: fizzle breakdown @ .006 bounces; Bz not coming in fast enough?
Jun 20 1997 09:48:38:260AM	970620006	John Goetz	Shot 970620006: RCUR offset = 6800 to bring in Bz faster RCUR = .669 @ .3s to make the right gap smaller sooner Results: plasma breakdown @ .006; CII = .004; don't know if the RCUR offset makes a difference plenty of H-modes; electron heating and neuts
Jun 20 1997 10:13:25:770AM	970620008	John Goetz	Shot 970620008: no changes Results: fizzle; breakdown @ .006; CII light = .005; Bz not in fast enough??
Jun 20 1997 10:21:23:480AM	970620009	John Goetz	Shot 970620009: RCUR offset = 7000 Results: fizzle breakdown @ .006; CII light = .004 plasma moves in; movement corresponds with the first gas puff from K-side
Jun 20 1997 10:32:34:760AM	970620010	John Goetz	Shot 970620010: first non-zero PG3 point @ .03s Results: plasma breakdown @ .006; disrupts @0.2MA good current rise - no hesitation - first gas puff doesn't come until .035s nice plasma - but only one transmitter
Jun 20 1997 11:04:13:400AM	970620011	John Goetz	Shot 970620011: no changes Results: fizzle breakdown @ .006; CII light = .004; plasma moves in looks like the gas puff was not the culprit in pushing the plasma in.
Jun 20 1997 11:36:19:910AM	970620012	John Goetz	Shot 970620012: lower RCUR P gain @ .006s to 5 from 10 (control system thinks plasma is outside and pulls it in on all these fizzles) 45 minute wait for cell access Results: plasma breakdown @ .006; slight current rise hesitation nice shot; still having RF problems
Jun 20 1997 11:56:02:720AM	970620013	John Goetz	Shot 970620013: RCUR = .669 @ .25 sec Results: Plasma breakdown @ .006; good current rise good shot; bad RF; magnetics errors - no EFIT
Jun 20 1997 12:05:48:160PM	970620014	John Goetz	Shot 970620014: PG2 = 40msx90V @ .7s and enable for neon puff Results: plasma breakdown @ .006; CII light = .005; plasma stays out until .03sec heating and neutrons have disappeared right gap is very small during RF pulses
Jun 20 1997 12:17:32:830PM	970620015	John Goetz	Shot 970620015: RCUR = .669 @ .28sec bring current down faster before the EF2's run out of oomph Results: fizzle breakdown @ .006; moves in at around 15msec
Jun 20 1997 12:27:28:140PM	970620016	John Goetz	Shot 970620016: drop P gain of RCUR to 3.5 @ .006 Results: fizzle breakdown @ .006; moves in beginning around 16msec
Jun 20 1997 12:43:10:550PM	970620017	John Goetz	Shot 970620017: PG4 to 28msec Results: plasma breakdown @ .006; doesn't move in until .03s right gap still going to zero; plasma rubbing off on E-port antenna not allowing it to run
Jun 20 1997 12:53:42:210PM	970620018	John Goetz	Shot 970620018: RCUR = .669 @ .29s PG2 = .05sx100V @ .7s Results: plasma breakdown @ .006; no hesitation in current rise; moves in @ .035 right gap now 1 cm; doesn't go to zero disrupts @ 0.3MA
Jun 20 1997 01:09:44:380PM	970620019	John Goetz	Shot 970620019: PG2 = .06sx100V @ .7s slow down current ramp down Results: plasma b.d. @ .006; moves in beginning @ .03s better target for RF disrupts @ 0.2MA
Jun 20 1997 01:33:38:010PM	970620020	John Goetz	Shot 970620020: CLEARIN = -.005 @ .25s for earlier divertor RCUR = .669 @ .27 for smaller gap earlier Results: plasma breakdown @ .006; begins to move in @ .033; disrupts @ 0.2MA diverts a bit earlier and the right gap shrinks earlier
Jun 20 1997 01:47:07:590PM	970620021	John Goetz	Shot 970620021: CLEARIN = -.005 @ .225s for earlier divertor RCUR = .66 @ .14 for smaller right gap earlier Results: plasma b.d. @ .0065; moves in @ .03 disrupts @ 1.2; vertical oscillation and some other demand on EF2 lower RF trips out early
Jun 20 1997 02:00:30:630PM	970620022	John Goetz	Shot 970620022: PG2 = .08sx100V @ 0.7 Results: plasma breakdown @ 0.006; begins to move in around .036s disrupts @ 0.3MA diverts about .18sec - right gap ~1cm at same time
Jun 20 1997 02:21:08:540PM	970620023	John Goetz	Shot 970620023: PG2 = 0.2sx100V @ .7s with vacuum but not enabled Results: plasma breakdown @ .006; moves in at .028s; no hesitation D-port @ 1.5MW for 0.3s disrupts @ 0.3MA
Jun 20 1997 02:39:25:330PM	970620024	John Goetz	Shot 970620024: PG2 = 1.3sx100V @ .1s with vacuum CLEARIN = -.005 @ 0.2s Results: plasma breakdown @ .007; current hesitation; lucky to get this one good shot after that
Jun 20 1997 02:44:23:590PM	970620025	John Goetz	Shot 970620025: PG4 = 27msec Results: fizzle breakdown @ .007; moves in at around 18msec; should have made it
Jun 20 1997 02:54:34:480PM	970620026	John Goetz	Shot 970620026: BR_0 offset = .0067 Results: fizzle breakdown @ .008!!; moves in at .016
Jun 20 1997 03:06:07:270PM	970620027	John Goetz	Shot 970620027: BR_0 offset = .0075 Results: fizzle terrible fizzle; breakdown @ .008; moves in @ .013
Jun 20 1997 03:15:26:380PM	970620028	John Goetz	Shot 970620028: BR_0 offset = .007 PG4 = 28msec Results: Plasma breakdown @ .006; moves in at about .029sec diverted and small right gap by about .15-.16sec
Jun 20 1997 03:30:29:400PM	970620029	John Goetz	Shot 970620029: PG2 = .05sx100V @ .7 with 4psi Ne Results: plasma breakdown @ .007; moves in @ .03 diverted by about .15sec
Jun 20 1997 03:49:37:820PM	970620031	John Goetz	Shot 970620031: PG2 = .07sx100V @ .7 with 4psi Ne Results: fizzle breakdown @ .008; wimpy fizzle moves in at about 15msec
Jun 20 1997 04:01:36:750PM	970620032	John Goetz	Shot 970620032: PG4 = 30msec IC_EF4 = -1335A Results: plasma breakdown @ .0065; moves in after 30msec; good current rise disrupts @ 0.3MA RF early, not late
Jun 20 1997 04:13:50:170PM	970620033	John Goetz	Shot 970620033: PG4 = 32msec PG2 = .08sx100V @ 0.7s Results: plasma breakdown @ .0065; moves in after 30msec; good current rise disrupts @ 0.2MA not too bad
Jun 20 1997 04:25:47:920PM	970620034	John Goetz	Shot 970620034: PG2 = .09sx100V @ 0.7s TF current = -130500A -> 4.7T breakdown Results: dud - magnet resistance fault
Jun 20 1997 04:36:05:370PM	970620035	John Goetz	Shot 970620035: PG2 = .09sx100V @ 0.7s TF current = -130500A -> 4.7T breakdown Results: fizzle breakdown @ .0095; too much curvature
Jun 20 1997 04:45:38:220PM	970620036	John Goetz	Shot 970620036: IC_EF1x = -6350 at t=0 (to compensate for the single-turn change in TF) Results: fizzle; b.d. @ .008; too much curvature still
Jun 20 1997 05:21:03:140PM	970620037	John Goetz	Shot 970620037: reload 970620033 Results: plasma b.d. @ .007; but a good current rise disrupts @ 0.4MA accompanied by TF and OH2 crowbars RF group pinned the troubles on the E-port transmitter with this shot and not on any plasma related problems

Engineering Operator Comments
Shot	Time	Type	Status	Comment
1	08:41:17:080AM	Plasma	Bad	no plasma
2	08:53:30:350AM	Plasma	Ok
3	09:03:56:790AM	Plasma	Ok
4	09:12:11:070AM	Plasma	Ok
5	09:26:22:480AM	Plasma	Ok
6	09:37:49:600AM	Plasma	Ok
7	09:51:45:690AM	Plasma	Ok
8	10:03:18:570AM	Plasma	Ok
9	10:13:45:760AM	Plasma	Ok
10	10:23:36:030AM	Plasma	Ok	no faults/plasma
11	10:37:01:380AM	Plasma	Ok
12	11:22:50:850AM	Plasma	Ok
13	11:40:39:180AM	Plasma	Ok
14	11:56:07:580AM	Plasma	Ok
15	12:10:07:950PM	Plasma	Ok
16	12:19:20:760PM	Plasma	Ok
17	12:29:04:620PM	Plasma	Ok
18	12:43:19:790PM	Plasma	Ok
19	12:58:45:270PM	Plasma	Ok
20	01:15:58:730PM	Plasma	Ok
21	01:34:43:020PM	Plasma	Ok
22	01:48:07:600PM	Plasma	Ok
23	02:11:34:570PM	Plasma	Ok
24	02:26:33:810PM	Plasma	Ok
25	02:38:08:660PM	Plasma	Ok
26	02:47:34:850PM	Plasma	Ok
27	02:58:36:130PM	Plasma	Ok
28	03:07:57:230PM	Plasma	Ok
29	03:21:55:410PM	Plasma	Ok
30	03:33:43:270PM	Plasma	Ok
31	03:43:36:070PM	Plasma	Ok
32	03:54:17:830PM	Plasma	Ok
33	04:06:16:410PM	Plasma	Ok
34	04:21:50:250PM	Plasma	Ok
35	04:29:30:690PM	Plasma	Ok
36	04:38:33:640PM	Plasma	Ok
37	04:49:20:140PM	Plasma	Ok