High-power and long-pulse injection with negative-ion-based neutral beam injectors in the Large Helical Device

Abstract

A negative-ion-based neutral beam injection (NBI) system has been operated reliably in the Large Helical Device (LHD) since it was operational in 1998. The injection power achieved is 13.1 MW with three injectors. In one injector with modified ion sources with the multi-slotted grounded grid, the injection power reached 5.7 MW with an energy of 184 keV, both of which exceed the designed values of 180 keV-5 MW. The individual control of the arc-discharge with the divided arc and filament power supplies is effective to improve the beam uniformity. The injection duration is extended to 120 sec with a reduced power of 0.2-0.3 MW using one ion source with the cooled plasma grid. The performance of the negative-NBI in LHD is reviewed with regard to the progress of the negative ion sources.

Cs-doped Mo as surface converter for H−/D− generation in negative ion sources: First steps and proof of principle

“…For example, in the frame of neutron therapy [1], for spallation neutron sources [2] as well as for neutral beam injection (NBI) systems on LHD [3]. For ITER, H -/D -NBI systems based on the small [4,5] and "half-size" [6,7] IPP prototype sources will be used.…”

Computer simulation of cylindrical plasma target trap with inverse magnetic mirrors

“…This is especially important for reactions with small energy yield. Various types of neutralizing targets (gas, plasma, photon) are developed in a number of laboratories at present [1], [2], [3]. The concept of the high-energy negative ion beam neutralization by the low-temperature plasma target has been proposed and developed at BINP [4].The yield of neutral atoms has reached 85% in a plasma target, and high rates of plasma confinement were obtained.…”

Research progress on ionic plasmas generated in an intense hydrogen negative ion source

“…Then, high-intensity hydrogen/deuterium negative-ion sources are inevitable because of the high neutralization efficiency of the negative ions at such high beam energies. We have been developing high-current hydrogen negative ion sources for negative-ion-based NBI systems [1][2][3][4][5] on the Large Helical Device (LHD) [6,7], which is the world's largest superconducting fusion device. Three injectors are now in operation, injecting high-power hydrogen beams of 16MW of the total injection power with 180keV of the injection energy [2][3][4][5].…”