CHARGING OF A SPHERICAL HIGH-VOLTAGE TERMINAL BY PARTICLE BEAM

Recently, the accelerator complex for custom examinations had been discussed. The complex consists of RF electron linac and the direct-voltage proton accelerator. The 2-MeV electron beam used for the X-ray generation is also utilized for electrostatic charging of the high-voltage terminal of a proton accelerator. Highvoltage terminal can be constructed as a large sphere to minimize peak electric field stress. In this report, the charging process of the spherical target by electron beam is studied. The particle motion is described by the classical Coulomb scattering in the field of the charged sphere. The effects of secondary emission and resistive divider are included as leakage currents. The differential equation for the time-derivative of the sphere charge is derived in a non-relativistic approach. The timedependences for the charge accumulated on sphere and the energy of hitting electrons are obtained analytically. The final values of the sphere potential and the energy of hitting electrons depend on total value of leakage current. The numerical model for studying relativistic effects is outlined. The simulations are performed under conditions of negligible leakage currents.