We deal with a new type ceramic emitter which is used in a cleanroom ionizer system and is composed of a needle-shaped silicon and a rod-shaped silicon carbide ceramics. The discharge test was carried out to investigate the particle generation from the emitter and the degradation of the emitter. As a result, it was found that the ceramic emitter had practically higher performance than a conventional tungsten emitter.

Effect of annealing on electrical conductivity of sintered silicon carbide containing boron carbide and carbon was investigated. The silicon carbide was sintered at the temperature range of 1650-2150 for 0.5 hr in vacuum. Samples sintered at above 1980 were annealed in argon at 1750 to 2000 for 0.5 hr to 5 hrs. The electrical conductivity was measured for both non-annealed and annealed silicon carbide, and following results were obtained.(1) The electrical conductivity was reduced about one order of magnitude by annealing for silicon carbide sintered at above 2050.(2) The effect to annealing on electrical conductivity was maximum at 1950 of annealing temperature, and is saturated at 3 hrs of annealing time.