Objectives
Target Langmuir (electrostatic) probe array is a crucial diagnostics to measure target plasma parameters such as electron temperature (Te) and electron density (ne).
Profiles of ion saturation current (Isat), electron temperature (Te) and floating potential (Vf) at the divertor target are measured directly.
Studies of a cold and dense divertor and detached divertor plasmas have been accomplished. SOL/divertor plasma density and temperature are evaluated using an interpretative divertor code based on the Langmuir probe data. These SOL/divertor plasma data are also used for transport studies of neutrals and impurities such as carbon ions.
Specification
Langmuir probes are mounted on the divertor target tiles
Shape: All Dome-type, 6 mm diameter, 1.3(1.2~1.5) mm protruded.
Materials: Carbon Fiber Composite.
| Type: | (1) | Single-probe array (inboard 9 and outboard 9 poloidal locations): Is, Te, Vf profiles are provided routinely with 1-10ms time resolution (from 2003). |
| (2) | Single-probe array (inboard 6 and outboard 6 poloidal locations): Vf profiles are provided routinely with 0.01-0.1mstime resolution (from 2005). |
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| (3) | Single-probe array (8 Upper-Inner first wall): Is, Te, Vf profiles are provided with 2-20ms time resolution (from 2005), only in case that the plasma approaches the probe. |
Position: Between P-2and P-3 section (Feed through is located at U2 port, P3)
Spatial separation: 2.5-3.5 cm poloidally, 8-12cm toroidally(between arrays).
Operation: Data sampling and control systems were revised for long-pulse operation of JT-60U(from 2003)
Replacement of probe tips and insulators (all outer divertor, and 3/5 of inner divertor) were done (2005)
Replacement of WSs and Crate Controller were done to enhance the acquisition and analysis speed (2005)
Recorders: Two transient recorder systems (KS4020 for faster & low resolution, KS4008 for slower & high resol.)
| KS4020 system (14ch): | Is, Te, Vf measurements at 10 locations near strike points, V-scan period of typ. 1-20 ms with typ. 200-20kHz sampling. 512kwords/channel, signal resolution of 12bits (+-2048). Maximum 5 "Burst period" (faster sampling mode: up to 500kHz) is available. |
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| KS4008 system (32ch): | Is, Te, Vf measurements at 8 locations on upper divertor tiles, V-scan period of typ. 1-20 ms with typ. 200-20kHz sampling, 512kwords/channel, signal resolution of 16bits (+-32768). Maximum 5 "Burst period" (faster sampling mode: up to 130kHz) is available, and Vf measurements at 12 locations with 20-100kHz sampling, and Is, Te, Vf measurements at 8 locations on upper-inner first wall. |
* Major Development/Modification History is listed Here.
** Data PID for DAIDY: for New system and Previous system are Here.
