RESUMO
The simplest way to produce high density hydrogen plasmas is to form an arc between the arcing electrode and the plasma chamber (cathode). For arc-based hydrogen plasma generation, a pulsed power supply that delivers 2 ms-long constant current pulse has been developed. This pulsed power supply employs a high frequency buck converter topology with a nonlinear filter inductor. This paper describes the development and testing of a constant current pulsed power supply that operates at 50 A and 550 V with a pulse width of 2 ms and a pulse repetition rate of 2 Hz. By changing the arc current, the arc impedance and the positive hydrogen ion current were also measured. The extraction of positive hydrogen ions was carried out using a three-electrode extraction design, which results in a current of 80 mA of positive hydrogen ions at an energy of 50 keV.
RESUMO
A multicusp-free external antenna based radio frequency (RF) negative hydrogen (H-) ion source was developed to produce 16 mA of H- ion current at -50 kVDC accelerating voltage operated with a pulse width of 2 ms at 2 Hz repetition rate. A pulsed RF igniter system is devised for generating the initial electron and ion pairs required to generate the main plasma in the pulsed mode. This pulsed RF igniter reliably starts ignition with a hydrogen gas flow rate in the range of 18-50 standard cubic centimeter per minute (SCCM). This system eliminates the need of igniter in continuous operation although it is operated in low power mode. This source operating at a low average power and without any moving parts can be expected to have a superior lifetime. This paper describes the development and operational characteristics of the pulsed RF ignited H- ion source.