Shoelace Operating Parameters:
Freq.: 40-300 kHz, 2 full triangle-wave sweeps
Amp.: Ramp amplitude down at higher frequencies to avoid trip: Build_Signal([1.,1.,.5,.5,1.,1.,.5,.5,1.,1.] * 240., *, [-.1,.6167,.7167,.7833,.8833,1.1167,1.2167,1.2833,1.3833,4.])
Result:
0.65< NL04<0.7
1.2 cm < RGAP < 1.6 cm
Shoelace antenna ran cleanly.
Next:
Try to reduce RGAP down to 0.5 cm
Transfer functions of Shoelace antenna current with some Mirnov coils
Same as last:
Freq.: 40-300 kHz, 2 full triangle-wave sweeps
Amp.: Ramp amplitude down at higher frequencies to avoid trip: Build_Signal([1.,1.,.5,.5,1.,1.,.5,.5,1.,1.] * 240., *, [-.1,.6167,.7167,.7833,.8833,1.1167,1.2167,1.2833,1.3833,4.])
Shoelace ran cleanly.
RGAP starts out around 1.6 cm and comes down to below 0.25 cm - not a bad RGAP scan.
q95 around 4
NL04 around 0.7
Next:
Try to have level RGAP flattop at 0.5 cm between 0.5 and 1.5 cm
Try NL04 at 0.4
Increase Ip to 650 kA
Transfer functions:
Same as last:
Freq.: 40-300 kHz, 2 full triangle-wave sweeps
Amp.: Ramp amplitude down at higher frequencies to avoid trip: Build_Signal([1.,1.,.5,.5,1.,1.,.5,.5,1.,1.] * 240., *, [-.1,.6167,.7167,.7833,.8833,1.1167,1.2167,1.2833,1.3833,4.])
RGAP: down at 0.5 cm by 0.61 s and stays there for rest of flattop - good.
NL04: around 0.5 during flattop
Ip: hits around 650 kA
q95: from 3.8-3.9
Next:
Bring Ip up to 800 kA, hold density. If that works, it will be the first shot of our density scan.
Transfer functions:
Same as last:
Freq.: 40-300 kHz, 2 full triangle-wave sweeps
Amp.: Ramp amplitude down at higher frequencies to avoid trip: Build_Signal([1.,1.,.5,.5,1.,1.,.5,.5,1.,1.] * 240., *, [-.1,.6167,.7167,.7833,.8833,1.1167,1.2167,1.2833,1.3833,4.])
RGAP: between 0.25 and 0.5 cm for most of flattop
NL04: around 0.4-0.5; there is a kick in density around 0.606 s which is synchronized with a dip in Shoelace antenna current and an increase in antenna loading. Ohmic EDA H-mode?
Weaker signal on Mirnov coils - q95, rgap, density to blame?
Next: Increse NL04 to 0.6; otherwise, same
Transfer functions:
Freq.: 40-300 kHz, 2 full triangle-wave sweeps
Amp.: Ramp amplitude down at higher frequencies to avoid trip: Build_Signal([1.,1.,.5,.5,1.,1.,.5,.5,1.,1.] * 240., *, [-.1,.6167,.7167,.7833,.8833,1.1167,1.2167,1.2833,1.3833,4.])
Density went up, as desired
Next: do a dynamic gap scan to see if this affects the signal level seen on different Mirnov coils
Run a fixed frequency of 150 kHz on Shoelace antenna, and modulate amplitude at 100 Hz (amp_wave_w levels railing between 0 and 240)
Freq.: Fixed frequency at 150 kHz
Amp.: amplitude modulation at about 100 Hz, amp_wave_w 0 to 240
Result: we got the gap scan. No very noticeable change in Mirnov coil pickup of the Shoelace signal.
Next: Current scan from 800 to 400 kA; NL04 at 0.6, RGAP constant at 0.5 cm
Freq.: Fixed frequency at 150 kHz
Amp.: amplitude modulation at about 100 Hz, amp_wave_w 0 to 240
Result: Signal on plunging probe with magnetic head comes in some time through downward current scan. Are we getting the right q95? Does seeing the signal on the probe mean that the probe is picking up more fluctuations from the current driven in the edge by the plasma, or that the background turbulence is smaller?
Next: Same plasma parameters, increase Shoelace frequency to 200 kHz to see if the signal comes on the plunging probe at the same time
Freq.: Fixed frequency at 200 kHz
Amp.: amplitude modulation at about 100 Hz, amp_wave_w 0 to 180
Look to see whether plunging probe starts seeing signal from antenna at same time as in Shot 10
Result: antenna signal does come in at same time as on Shot 10 - this may point to picking the right q95 for seeing signal on this diagnostic
Next: try a field scan - fix current at 700 kA and ramp up B_T from 3.5 to 6.5 T. Look for sweet-spot in plunging probe response and stay there for remainder of day. Same Shoelace operating parameters.
Shoelace Operating Parameters:
Freq.: Fixed frequency at 200 kHz
Amp.: amplitude modulation at about 100 Hz, amp_wave_w 0 to 180
Field scan. Notice how signal comes in and out of plunging probe response as field scans, as though field lines connecting cells from the antenna are moving past probe.
Lesson learned! q95~=4.8 seems to give a good response on plunging probe, as found from field and plasma current scans.
Next: Proceed with density scan at B_T=4.8 T, Ip=700 kA, q95=4.8
Freq.: Scan frequency in two triangle wave cycles from 40 to 300 kHz
Amp.: two amplitude modulation envelopes: 1 railing between max and 0 at 100 Hz, and the other lowering the envelope at higher frequency at 2 Hz, following frequency scan.
Had to rush, so 2 Hz amplitude envelope is an offset cosine function
Result: we see a signal on the scanning probe - second frequency cycle sees less signal, but still there.
Next: increase density to 0.8, marching along in our scan. Tweak field a bit.
Freq.: Scan frequency in two triangle wave cycles from 40 to 300 kHz
Amp.: two amplitude modulation envelopes: 1 railing between max and 0 at 100 Hz, and the other lowering the envelope at higher frequency at 2 Hz, following frequency scan.
This time, 2 Hz envelope is same as original envelope with linear slopes, instead of Cinf continuous ones.
Result: we had an injection in this shot around 0.3 s.
Alex Tronchin-James notes an increased heat flux on GH limiter around 0.7 s, and two hot spots on GH limiter present during flattop.
Next: March along on density scan to 1.0 - all else is same
Density up to 1.0
Next: density to 1.2
Next: Try again.
Next: punt on high density - go for target of NL04=0.4 density, and maybe the density ramp that we get as we come down will accomplish our density scan.
Fixed Shoelace frequency at 100 kHz, right in the peak of the broadband activity seen on magnetics and, in particular, GPI. Modulate antenna amplitude at 100 Hz. Perhaps we will see something on GPI upon post-processing after the run (need to adjust GPI analysis software for Shoelace amplitude modulation).
Next: Try again
Next: Try again
Next: Try again
Shoelace Operating Parameters:
Freq.: Constant frequency at 100 kHz
Amp.: Amplitude modulation at 100 Hz, Modulate between amp_wave_w=0,240
Went through the peak in the GPI spectrum.
Next: Drop frequency down to be off-peak in GPI spectrum, so effect of antenna may be more clear in GPI analysis. Same plasma parameters.
Freq.: Constant frequency at 50 kHz - try to go off-peak on GPI spectrum to see more cleary whether we have an effect
Amp.: Amplitude modulation at 100 Hz, Modulate between amp_wave_w=0,260 (push amplitude a little higher from last shot)
Result: Got over 80 A in the antenna. We'll see whether GPI shows anything.
Next: Staircase frequency at 50, 100 and 150 kHz; scan the scanning probe in at each of those three frequencies.
Freq.: Staircase frequency at 50, 100, and 150 kHz during flattop
Amp.: Amplitude modulation at 100 Hz, Modulate between amp_wave_w=0,240
Actually, originally, we didn't want amplitude modulation on the Shoelace signal. And timing was off a bit on scanning probe. But this shot should be useful for GPI - we have three frequencies with AM.
Next: No 100 Hz AM on antenna power, but do have slight staircase down, starting at amp_wave_w=260 and dropping to 250, then 240, as we step up in frequency. Same frequency steps. Change scanning probe timing and go a bit deeper. Drop density a bit.
Freq.: Staircase frequency at 50, 100, and 150 kHz during flattop
Amp.: No 100 Hz AM, amp_wave_w steps down from 260 to 250 to 240 as frequency steps up
Result: See a signal on the scanning probe.
Next: increase frequency range to 100, 150, and 200 kHz
Freq.: Staircase frequency at 100, 150, and 200 kHz during flattop
Amp.: No 100 Hz AM, amp_wave_w steps down from 260 to 245 to 230 as frequency steps up
Result: See a signal on the scanning probe.
Next: Same Shoelace parameters; increase RGAP to 1.0 cm so that we get a wider scan of probe with position - help pin down k_perp
Shoelace Operating Parameters:
Freq.: Staircase frequency at 100, 150, and 200 kHz during flattop
Amp.: No 100 Hz AM, amp_wave_w steps down from 260 to 245 to 230 as frequency steps up
Result: RGAP was 0.8 cm - a little under the 1.0 cm target but still good. See a smaller signal on BP_EF_TOP than on last shot, which is what we would expect with bigger RGAP. Scanning probe went very deep given smaller-than-expected RGAP - it's okay, and it looks like we got a great scan.
Next: Increase RGAP another 0.4 cm. Same Shoelace parameters.
Shoelace Operating Parameters:
Freq.: Staircase frequency at 100, 150, and 200 kHz during flattop
Amp.: No 100 Hz AM, amp_wave_w steps down from 260 to 245 to 230 as frequency steps up
Result: RGAP around 1.4 cm; signal on Mirnov coils even smaller - Shots 25, 26, and 27 make a good RGAP scan on the static Mirnov coils to compare with the scanning probe scan.
Next: Increase density to NL04=0.8, bring RGAP back to 0.8 cm, as in Shot 26. Change order of frequency steps so that they step down (200, 150, and 100 kHz), since NINJA puff for GPI comes on around 1.0 s, and only samples two out of three frequencies.
Last shot - thanks, all.