Numerical simulation research of a high-current ion source extraction system for nuclear fusion

We have studied beam optical characteristics of a high-current ion source extraction system for nuclear fusion research by means of numerical simulation. The effect of ion source plasma parameters (plasma density, electron, and ion temperature) on initial emission conditions is taken into account, and the effect of stray electrons from the source plasma and the effect of ion space charge nonlinear force in the beam on the beam optical characteristic are also taken into account in an improved calculation program. For a 55 keV high-current ion extraction system, the calculation results show: the matched ion current density of hydrogen and deuterium is 0.22 and 0.155 Acm-2, respectively, when the ion temperature is increased, the beam optical characteristic is degraded, and the effect of first-electrode geometry on the beam optics is the most sensitive. Attention should be paid to the design and manufacture of the electrode. Those results are essentially in agreement with experimental measurements. copyright 1996 American Institute of Physics