In this paper,a new carbon fiber based cathode — a low-outgassing-rate carbon fiber array cathode — is investigated experimentally,and the experimental results are compared with those of a polymer velvet cathode.The carbon fiber array cathode is constructed by inserting bunches of carbon fibers into the cylindrical surface of the cathode.In experiment,the diode base pressure is maintained at 1 × 10-2 Pa-2× 10-2 Pa,and the diode is driven by a compact pulsed power system which can provide a diode voltage of about 100 kV and pulse duration of about 30 ns at a repetition rate of tens of Hz.Real-time pressure data are measured by a magnetron gauge.Under the similar conditions,the experimental results show that the outgassing rate of the carbon fiber array cathode is an order smaller than that of the velvet cathode and that this carbon fiber array cathode has better shot-to-shot stability than the velvet cathode.Hence,this carbon fiber array cathode is demonstrated to be a promising cathode for the radial diode,which can be used in magnetically insulated transmission line oscillator (MILO) and relativistic magnetron (RM).