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A MONTE CARLO CALCULATION OF ION EMISSION SYSTEM WITH A LIQUID METAL ION SOURCE |
Liu Chang①②; Chu Xuanwen①; Shen Qinggai① |
Zhejing University Hangzhou |
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Abstract The emission characteristics of liquid metal ion source are simulated by Monte Carlo method. The initial positions and velocities of emitted ions are given by random sampling with random numbers. Trajectory calculations including the effect of discrete space charge are carried out with fourth order auto-variable-step Runge-Kutta method. In order to accelerate the convergence of Poisson field, the total emission current is kept constant in the iterative process, and we assume the quantity of voltage variation between two succesive iterations as the iterion
of convergence. Finally, the emission characteristics of the ion source such as angular current intensity, energy spread, beam divergence, virtual source size and its position are given.
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Received: 23 June 1988
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