Modeling of electron temperature in H^- ion source

The equation of electron temperature is included in a two point numerical code for a high power hydrogen negative ion source. The calculated results of the electron temperature are in good agreement with Japan Atomic Energy Research Institute (JAERI)'s experimental results. The scaling law of electron temperature is estimated as a function of input power and gas pressure. Energy input by arc discharge, energy loss by ionization, dissociation and loss on the wall are considered in the electron energy equation. The leak width on the wall at the cusp magnet is also calculated numerically. Energy loss on the wall is dominant, and is larger than the ionization loss. In a similarly enlarged JAERI's Kamaboko source, electron density increases and electron temperature decreases under a constant energy input per unit volume. In this situation, H^- extraction current increases despite the decrease in H^- density because of the enlargement of the H^- extraction area.