"Effects of RF heat on edge/SOL poloidal velocities"
This follows two previous half days devoted to this MP; the
others took place on 1110127 (with normal field) and
1110218 (with reversed field, but with no J antenna operation)
Note that this run is with REVERSED field (and Ip) direction.
We desire normal ECDC preparation in D2.
NINJA with 10 PSI He4
We are examining the strong changes in the edge/SOL profiles
of the phase velocities of the fluctuations brought
about by the application of ICRF power above a threshold of
~0.6 MW. These changes are measured by the outboard midplane GPI.
Critical diagnostics:
Midplane GPI
A port scanning probe - to probe when PRF<1 MW
Emissive probe on S3
The run plan is:
Load (reversed field) shot 1110218001.
Ip=0.8 MA
Bt=5.4 T (-->q95=4.7)
LSN
adjust NL04 of the target plasma to 0.7e20 m-2
adjust outer gap to 2.0 cm
adjust D & J RF waveforms be the following:
This provides a J antenna power scan followed by a
D & J power scan at q_95=4.7
Puff the NINJA so that the puff hits the plasma at 0.98 s
Perform 4 shot q_95 scan (with Bt=5.4 T) in order to vary the mapping from
GPI to the D & J antennas (Bt=5.4 T)
Ip=0.8 MA (NL04=0.8e20) (-->q95=4.7)
Ip=0.6MA (NL04=0.7e20) (--> q95=9.5)
Ip=1.0MA (NL04=0.8e20) (--> q95=3.8)
Ip=1.2MA (NL04=1.3e20) (--> q95=3.16)
Reload the first successful (q_95, Ip=0.8, Bt=5.4 T) shot from this run.
Change SSEP programming so that SSEP sweeps from -2 cm at 1.05 s to
+1.5 cm at 1.40 s and hold SSEP at +1.5 cm until 1.45 s. Thus we
sweep from LSN, through DN, to USN.
The RF power is at 1.0 MW from J only.
3 good shots
Change heating scheme and gyro-radius by loading shot 1110218018 with Bt=2.7 T
Bt=2.7T, Ip=0.4MA (-->q95=4.7) NL04=0.4e20 m-2 (2nd harmonic H minority)
The RF waveform (J only) will be stepped in three steps (0.6, 1.0, 1.4 MW)
with the 1st step starting at 1.05 s and each step lasting 0.1 s.
This may take a few shots to get the RF tuning
Total of 8-10 shots
MP 610: - Investigate Thomson/ECE Discrepancy in High Temperature Discharges
Session leaders: A. White, Y. Lin, A. Hubbard, J. Hughes, S. Wukitch
TS: Y. Ma, PCI: P. Ennever
March 10th, 2011 Thursday
Goal of MP 610: Run as many shots as possible with Te(0) > 9 keV
for making detailed TS/ECE comparisons to study discrepancy seen on TFTR/JET. Optimize MC heating via adjustment of He3 puff length to vary He3 concentration. We will run +90 degree phase for J antenna (waves in the counter-Ip direction), because previously this phase resulted in a longer sawtooth period... and higher Te. Expect minor tweaks to Bt to shift ECE locations to overlap better with core TS points.
NOTE: Extended Run
11 am �- 6 pm
- Use reference LSN shot from an 8 T day, e.g. 1110216 per PO suggestion, or if it looks better, use a LSN from the day before.
- B_T = 8.0 T, I_p = 1 MA, nL04 = 0.5e20
- He3 puff starting with 150 ms and adjusting to get good MC heating on axis
Required sub-systems:
ICRF (D,E,J) at max power, 8 T, w/He3 puffing for MC heating
GPC1 and GPC2 with gratings for 8 T, Michelson (may need to adjust aperture to avoid saturation, which would require us to recalibrate with the reduced aperture), HIREX, PCI (for He3 concentration monitoring), McPherson helium monitor
Shot Plan: 8 T partial day, expect total of 10-14 shots
1) 1-3 shots, bring machine up to 8 T:
(See PO plan)
2) 2-3 shots, modulated RF to determine MC layer location
If we have whole day, then perform this step. If we have only a half day, then skip this step and go to step 3.
Use modulated RF to determine MC layer location. He3 puff is set to 150 ms. RF programming, all antennas, (or just one or two antennas, per RF group guidance), power modulated (40 on, 60 off) from t = 0.6 - 1.3 s
Monitor GPC channels to observe prompt break in slope as ICRF power is modulated. This tells us location of mode conversion. Monitor He3 concentration with PCI. We can run Yijun�??s analysis using as input the He3 concentration, the Bt, the wave frequency and the plasma density profile to calculate the MC layer location. Repeat with an adjusted He3 puff length (100 or 200 ms depending on how we need to move MV layer.)
3) 3 shots, steady RF pulse, scan of He3 concentration to maximize Te on axis
B_T = 8.0 T, I_p = 1 MA, nL04 = 0.5e20
We want to adjust the 3He puff length (He3 concentration) shot by shot to get the MC layer as close to on-axis and produce as High Te as possible, as informed by step 2 (if there was time for step 2) .
If we did step 2, then scan as follows: He3 Puff length first of 50 ms, then 200 ms, then then 150 ms
If we skipped step 2, then scan as follows: He3 Puff length first of 150 ms, then 50 ms, then 200 ms
Use phasing of antennas (per Yijun's guidance) in counter current direction to lengthen the sawtooth period. This is done in an attempt to sustain for longer time the higher core Te before sawtooth crash.
Use steady RF pulse, with all three antennas (D, E and J at 78-80 MHz) on steady to get maximum power entire L-mode time of interest. RF Demand would be something similar to this:
D: t = [0.6, 1.3] sec, 1.30 MW, 80.5 MHz
E: t = [0.6, 1.3] sec, 1.00 MW, 80.0 MHz
J3: t = [0.6, 1.3] sec, 1.25 MW, 78.0 MHz
J4: t = [0.6, 1.3] sec, 1.25 MW, 78.0 MHz
4) 6 shots, Repeat High Te shot with TS, GPC and Michelson data obtained
B_T = 8.0 T, I_p = 1 MA, nL04 = 0.5e20
Using whatever He3 puff length gave maximum Te on axis in part 3), now just repeat that set-up to gather as much high Te TS and ECE data. Steady RF power t = 0.6-1.3 s.
Diagnostics and plasma issues to keep an eye out for: saturation of signals, offset in magnetic axis position, timing and quality of TS data, position of LSN strike points and occurrence of injections.
