Session 8 February 2019, all new shots for Daniela Kropáčková

#Session goal

Perform a series of shots with the following parameters:

Bt capacitor voltage: 1300 V
CD capacitor voltage: 500 V
t_CD: 0 ms
Gas pressure: 20 mPa
Working gas: H
Preionization: Upper el. gun

Operating probes:

  • Tunnel probe: \(r = 60, 65, 70, 75, 80, 85, 90\) mm (this refers to the tunnel centre), all four electrode (two tunnels, two back plates) at -100 V (Isat regime)
    • Note: Honza Stöckel’s amplifier was used to supply the voltage
    • data acquisition system: Papouch Stockel
    • signal names: tp_t_limiter, tp_bp_limiter, tp_t_op_limiter, tp_bp_op_limiter
  • Double rake probe: \(r = 92\) mm (this refers to the pin deepest in the plasma), all 8 measuring pins (pin 9-16) at -143 V (Isat regime)
    • data acquisition system: Papouch Zacek
    • signal names: drppin01-drppin04, drppin09-droppin16
    • Note: throughout the session, pin 13 collects flat zero (probably bad contact somewhere) and pin 11 falls to zero at some point in the discharge (unknown reason)
    • also at random times, Papouch Zacek as a whole either collects flat zero, or doesn’t collect anything entirely (Vojtech Svoboda suggests that this is due to poor triggering and thinks that moving the data acquisition system further from the tokamak may reduce the interference in the trigger)
    • first pin position was measured as \(r=J-32\) mm, where \(J\) is the easiest distance to measure on the manipulator (refer to the DRP page)
    • as one of Sergei’s reports shows, the probe head is oriented in an awkward direction - now it makes sense why pin 12 measures significantly higher signal than pin 16; pin 16 (and the entire row, which is the one that provides the full profile) is toroidally shadowed by the probe head

Example of DRP signal time evolution. The y axis is proportional to \(I_{sat}\). Pins 16, 15 and 14 are in the SOL (probe connections shown in one of Sergei’s reports), the rest are within the port so they measure zero current.

  • Standard diagnostics
  • Bolometer array

The goal is to measure Mach number profile at clockwise and anticlockwise field orientation.

#Session discharges

In the morning, the chamber was baked and a hydrogen glow discharge was performed.

29459: Master test, vacuum shot

29450: Master test, plasma discharge

29451-29456: more tests, trying to achieve a reproducible discharge regime (#29455 - Papouch Zacek, housing DRP, collected no data, #29453 and #29454 - Papuch Zacek collected flat zero)

29457: \(r=90\) mm, CW

29458: \(r=85\) mm, CW, tunnel probe back plate and tunnel facing away from the limiter collected flat zero

29459: \(r=85\) mm, CW, tunnel probe worked, Papouch Zacek collected flat zero

29460: \(r=80\) mm, CW

29461: \(r=75\) mm, CW, Papouch Zacek collected flat zero

29462: \(r=70\) mm, CW, tunnel of the probe facing limiter shows two weird negative jumps in the collected current

29463: \(r=65\) mm, CW, tunnel probe facing away from the limiter collects poorly

29464: \(r=65\) mm, CW, beautiful shot lasting full 17 ms

29465: \(r=60\) mm, CW

29466: \(r=62.5\) mm, CW

29467: \(r=67.5\) mm, CW

29468: \(r=72.5\) mm, CW

29469: \(r=77.5\) mm, CW

29470: \(r=82.5\) mm, CW, tunnel probe facing away from the limiter collects poorly

29471: \(r=82.5\) mm, CW

29472: \(r=87.5\) mm, CW

29473: \(r=92.5\) mm, CW

29474: \(r=92.5\) mm, ACW, all probes work (as much as they do, anyway), but their signals are considerably lower - effect of plasma being higher?

29475: \(r=90\) mm, ACW, the shot is 2 ms longer than the previous shot (maybe effect of the reverse field configuration change)

29476: \(r=87.5\) mm, ACW

29477: \(r=85\) mm, ACW

29478: \(r=80\) mm, ACW

29479: \(r=75\) mm, ACW

29480: \(r=70\) mm, ACW

29481" \(r=65\) mm, ACW

29482, \(r=60\) mm, ACW, tunnel probe facing away from the limiter collects poorly, \(U_{loop}\) has a bump at the beginning

29483: \(r=60\) mm, ACW (this is the last shot for Daniela’s purposes, now the DRP is moved inside and the tunnel probe will be swept between approx -100 V and 20 V)

29484: \(r_{TP}=70\) mm, \(r_{DRP}=84\) mm, CW, only about 5 mPa instead of 8 mPa

29485: \(r_{TP}=70\) mm, \(r_{DRP}=84\) mm, CW, \(p_H=6\) mPa

29486: \(r_{TP}=70\) mm, \(r_{DRP}=73\) mm, CW, 19 ms shot, \(p_H=5\) mPa,

29487: \(r_{TP}=70\) mm, \(r_{DRP}=73\) mm, CW, half the DRP pins collected no data

29488: \(r_{TP}=70\) mm, \(r_{DRP}=61\) mm, CW, slightly shorter discharge (DRP is pretty deep inside…)

29489: \(r_{TP}=70\) mm, \(r_{DRP}=61\) mm, ACW

29490: \(r_{TP}=70\) mm, \(r_{DRP}=69\) mm, ACW

29491: \(r_{DRP}=82\) mm, ACW, tunnel probe turned off