Development of a high-voltage power supply with ultra-low ripple of beam current on electron beam gun

Electron beam guns with grid-controlled electrodes and hot-cathodes are widely used in accelerator physics facilities, high-voltage electron beam welding machines, electron beam 3D additive manufacturing, x-ray sources, etc. The ripple of electron beam current is one of the most critical factors affecting beam quality, and the electron beam current ripple is generally more than 2% with traditional circuit topology. This paper presents the expression for beam current, high voltage, and bias voltage derived from experimental data on a certain electron beam gun. Furthermore, the main causes of affecting beam current ripple are analyzed, and a novel circuit topology is proposed. According to the ISO14744, Welding-Acceptance inspection of electron beam welding machines, a Faraday cup is used to collect the beam from the electron beam gun. In this paper, the ripple of the beam current of the electron gun driven by the traditional and proposed circuits is tested, respectively. The experimental results show that the ripple of beam current of the novel circuit topology can be achieved to within ±0.18% when the voltage is 150 kV and the beam current is 33 mA, lower than 10 percent of that of the traditional power supply. The stability of beam current is better than 5 μA at 150 kV and 3.3 mA.