Development of Langmuir Probes on Divertor Cassettes in JT-60SA

Abstract

Langmuir probes installed in the lower divertor region under high heat flux have been developed and manufactured for JT-60SA. A probe electrode with a head having a rooftop shape is made of a carbon fiber composite and can withstand heat fluxes of up to 10 MW/m 2 for 5 s and 1 MW/m 2 for 100 s. This has been achieved by increasing the volume of the probe electrode that is not directly exposed to the plasma. To minimize the reduction of the heat removal performance of the divertor, the Langmuir probes are installed in toroidal gaps with widths of 10 mm between the divertor cassettes, without embedding them in the divertor tiles. Aluminum oxide coatings have been applied to insulate the probe electrodes from the divertor cassettes and to limit the toroidal thickness to 8 mm. Brazing of the nickel connectors to the probe electrodes has reduced the toroidal thickness of the Langmuir probes. A minimum spatial resolution of 13.5 mm has been achieved to the Langmuir probes installed on the inner and outer divertor targets.

A new electromagnetic probe array diagnostic for analyzing electrostatic and magnetic fluctuations in EAST plasmas

“…In fusion plasma research, magnetic probes are widely used for taking stationary and fluctuating magnetic field measurements, such as in DIII-D [1,2], Alcator C-Mod [3], NSTX-U [4], JET [5], ASDEX Upgrade [6,7], MAST [8], TCV [9], WEST [10], EAST [11,12], T-10 [13], HL-2A [14], J-TEXT [15,16], KTX [17], SUNIST [18,19], KSTAR [20], W7-X [21], LHD [22], and H-1NF [23], etc. The electrostatic probes are also frequently employed to provide the plasma potential, electron density and temperature and many other physical parameter measurements in the scape-off layer or divertor region [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38].…”

Upgrade of an integrated Langmuir probe system on the closed divertor target plates in the HL-2A tokamak

“…WEST [5], JET [6], DIII-D [7], ASDEX-Upgrade [8], KSTAR [9], JT-60SA [10] and NSTX [11,12]. The above divertor Langmuir probe systems almost have similar design, the pyrolytic graphite with high heat conductivity is chosen as the material of probe tips, and the probe bodies are embedded into the gaps between the divertor cassettes.…”