Use of a Secondary Current Sensor in Plasma during Electron-Beam Welding with Focus Scanning for Process Control

Figure 11

Functional diagram of the modified focus control system: 1, electron gun; 2, focus coil; 3, amplifier for the focus coil current; 4, electron collector; 5, modulation block; 6, bias voltage source; 7, load resistor; 8, high-frequency filter; 9, synchronous detection block for harmonic ; 10, control block; 11, synchronous detection block for harmonic ; 12, division block.