Design of ion beam source for a sample tokamak neutral beam injection heating system

Abstract

In this paper, the design and simulation of ion source based on a helicon plasma generator and its corresponding extraction system for design of the neutral beam injection heating system of a sample tokamak like Damavand tokamak using COMSOL software have been investigated. Based on our previous calculations, to increase the electron temperature of this tokamak to 300 eV and the ion temperature to 150 eV, it requires a neutral beam injection system with energy 4.5 KeV, 6.7 A current, and 30.15 kW power. In this regard, in the present model, a dense helicon plasma source with an electron density of 5.51×1018 m-3, an electron temperature of 2.8 eV and an extraction system with 280 holes (3.5 mm in diameter) and 7 A ion beam for this heating system were designed, simulated and presented. Also, in this design, all the optical issues of the ion beam such as divergence, space charge, and beam size which can affect the beam quality are investigated.

Keywords

• nbi system
• ion source
• beam extraction
• tokamak
• space charge