Divertor probes are renewed, WSs and Crate Controller are upgraded, KS4008 recorders are added for First Wall probe measurement.
I Probe replacement in 2005:
Probe tips (CFC) for all outboard divertor(36), 3/5 of inboard divertor(24), and most insulators were replaced.
- However, somel probes were not recovered due to wire break/short to VV.
We found that insulator damage became serious mostly due to 2003-2004 long-pulse discharges.
-> Operation plan: Vf-mode is selected IF NO REQUEST from USER, is continue in 2005-2006.
II System modifications in 2005
II-1) Two KS4008 (16ch) are added in KS4008 system to measure "first wall probes" and "floating potentials".
II-2) Workstations and Crate Controller were replaced to New WSs(Sun Blade 150 &1500) and Network CCs (Toyo Tech. CCnet) to enhance acquisition and analysis speed (about 10 times).
- -> 512k data/channel are sampled in routine operations, and analysis are completed much earlier.
III 8 First Wall probes (at upper inner wall) are routinely measured from 2005:
- Typical operation for V-scan-mode:
50kHz sampling/200Hz V-scan (15s), 20kHz sampling/100Hz V-scan(30s).
Probe operation: probe operation mode can be selected:
- (1) V-scan-mode for Is, Te, Vf (normally used),
(2) Is-mode for fast Is change measurement for ELM/fluctuation study,
(3) Vf-mode for fast Vf change measurement,
- Typical operation for the divertor probes (18-probe array):
For 15s discharge, 50kHz sampling/200Hz V-scan are used to cover 10s, or
100kHz sampling/500Hz V-scan to cover 5s (for ELM measurement).For Long-pulse (30s), 20kHz sampling/100Hz V-scan are used to cover 25s. "Burst mode" with Max. 5 Fast-sampling windows (e.g. 100-200kHz sampling/500Hz V-scan) is available to measure transient events such as ELM and detachment, Here, two types of recorders are assigned to the probe array (see figure below),
(1) KS4020 (Max. 500kHz, 12bit) and (2) KS4008 (Max. 132kHz, 16bit).
Sampling time is limited by the specifications.
Arrangement of transient recorders and power amp. for 18 probes.
