During the working period of the ion source of a Neutral Beam Injector (NBI) for plasma heating, the temperature of its transmission line inserted in its snubber rises rapidly. This is because the heating current of the filament and arc reaches over 10 kA for over 100 s, which accumulates large amounts of energy on the line. Rapidly ageing of the wire insulation will occur as the temperature rises. More importantly, an electrical fire could occur in a case of poor design. In this paper, the heat transfer performance of a neutral beam transmission line is analysed using Computational Fluid Dynamics (CFD) software, which is operated by the mode of repetitive pulse. The temperature distribution of the transmission line, inserted in the snubber, is obtained after a number of pulse cycles by numerical simulation and the results provide a reliable basis for the design of Experimental Advanced Superconductor Tokamak (EAST) NBI power transmission lines.

Simulation of heat transfer performance of NBI transmission line

When the transmission lines of ion source is inserted into the high voltage snubber, the temperature of the transmission lines is rising as transmission wire accumulated a large amount of electric power, so the balance temperature of transmission line will be important basis for the safety operation of ion source and the choice of the insulation material. In this paper, the heat transfer performance of neutral beam transmission line is analyzed with CFD (computational fluid dynamics) software. The temperature of the transmission lines inserted in the snubber is obtained after numbers of pulse cycle using the numerical simulation model, and the result would provide a reliable basis for modification of NBI power transmission lines design.

http://ieeexplore.ieee.org/iel7/6516158/6518655/06518851.pdf

The numerical simulation of the heat transfer performance of NBI power transmission line

The four Neutral Beam Injectors (NBI) on the TFTR Tokamak Test Cell (TTC) floor require twelve transmission lines to carry arc and filament power to the twelve ion sources from the basement. Also, the Neutral Beam Test Cell (NBTC) requires three lines but on the same floor through a wall. The same basic specifications apply: (1) center bundle operates at 120 kV with respect to the outer cables, (2) filament circuits at 6000 A, (3) arc circuits at 3000 A, (4) gradient grid, (5) accel grids in a quadrupole configuration, (6) multi wire control cable, (7) SF/sub 6/ environment, (7) flexible, (8) 36'' centerline bend radius and (9) hi-pot to 200 kV.

/pdf/fabrication-and-testing-of-the-flexible-transmission-line-to-1u2db6rtwz.pdf

K. Lou

Papers

Fabrication and testing of the flexible transmission line to the TFTR neutral beam ion sources