Took initial OH and VF vacuum shots going in increments up to typical maximun runtime voltages (e.g. Wednesday January 22 05 26 Maurerē6606-36619 shake-downįinished getting the machine back in order(insulation, TF cooling oil, etc.) today after installation of majority of VF feeback coils during the past two weeks. The OH has been dismantled to facilitate installing the lower 21 turn coil. The lower 12 turn coil has been installed. They should be ready for experiments when we run again. Since the machine will not be running next week we took the opportunity to pump on and bake the Mach and Biased probe bellows and opened them up to the chamber. He also stated he has made progress on fixing the systematic errors in the measurement through calibration improvements. Steve expects a factor of roughly 4 increase in collected light. Steve Paul was in today and reinstalled a new fiber optic bundle and optics to carry light from the machine to the screen room, as a consequence of that and some work on TS triggering we did not run today.
The other thing: I forgot to put in the last shot number of the day. We just discovered that by mistake, we ran today with the 10% helium mixture instead of the 20% hydrogen. Thursday December 19 05 43 -36603 ICRH Addendum We did not make significant progress on the triple probe, for lack of time, mostly. Nonetheless, Q was only observed to dip during inboard disruptions.
The calibration factors have all been worked into the MDSPlus tree, so the f_bprobe tag now directly reflects the RF B-field in Gauss.Ĭory developed some good discharges that would hang around 92-91 cm for a couple of milliseconds. vacuum B fields were basically the same as those when the plasma was around. The RF B field at the probe is about 1 Gauss, within expectations for vacuum. On the bright side, the RF B probe is now absolutely calibrated. However, today, we took several non-plasma shots, with and without banks firing, 36562, 36564, 36565, where the loop voltage clearly oscillated during the RF. Last week we had one shot, 36486, without plasma, and the loop voltage oscillation was absent. Today, in contrast to last week, the oscillation was there even in the absence of plasma. The shots typically disrupted at about 8 to 9ms (see shot #35642 as an example).ĭisappointingly, the large oscillations on the loop voltage now appear not to be related to the plasma after all. The q=2 surface goes out into the vacuum at ~ 4.5ms. The kink is of m/n=2/1 helicity instead of our more typical 3/1 variety.
These shots have an Ip ramp of 2 MA/sec during the first half of the shot and then Ip rolls over somewhat at ~15kA during the last half of the shot when the kink is excited. I was successful in bringing the q=2 surface external with a Ip ramp style shot. These plasmas were made with the Al shells inserted to suppress higher m/n=4/1 and 3/1 RWMs and 2/1 tearing type modes also. Wednesday December 18 05 32ē6514-36542ğB setup shotsĭeveloped a "long lived" saturated RWM target mode that lasts about 2 to (sometimes even) 3 ms near the end of the shot. Due to certain problems with the CAMAC racks and Crunch cabinet I didn't get much run time. I was trying to develope a model discharge that would be stable to low frequency 3/1 oscilations with the aluminum shells fully inserted and unstable when they're retracted. Wednesday December 18 03 58ē6492-36513Ğxternal Fieldĭuring the run I was working with 'high beta' shots that I usually use in my 3/1 experiments.
0 kommentar(er)
