渍制钪酸盐钡钨阴极脉冲性能的研究

本文对渍制钪酸盐钡钨阴极的脉冲性能作了下述几方面的研究。(1)脉冲发射水平和逸出功分布;(2)脉冲运用下的电子初速分布;(3)脉冲工作比效应;(4)强场下的非常肖特基效应。 本阴极在Tk=850℃下能提供的脉冲发射电流密度大于20A/cm2;平均逸出功=1.7eV;发射的不均匀性与国外报道的M型阴极的相近;在脉冲运用下,电子速度的分散值低于氧化物阴极的。本阴极在场强高于1104V/cm时,出现非常肖特基效应,本文用S值来表征。本阴极的S值明显高于渍制铝酸盐钡钨阴极和L阴极的。造成非常肖特基效应的主要原因是表面逸出功不均匀。在脉冲工作比f=510-3410-2范围内,支取8.8A/cm2时,本阴极有良好的平坦f特性,所以适用于长脉冲、大功率毫米波器件。 最后结合国内外对这种阴极的表面分析结果,对本文的实验结果进行了讨论,这些讨论有助于阐明本阴极的发射机制。

AN INVESTIGATION ON PULSE PROPERTIES OF IMPREGNATED BARIUM SCANDATE DISPENSER CATHODES

The impregnated barium scandate dispenser cathode used in microwave tulbes, especially in gyrotrons, has been investigated in following aspects: (1) pulse emission property and work function distribution; (2) electron initial velocity distribution in pulse operation; (3) the effect of pulse duration ratio; (4) anomalous Schottky effect under high electric field. Some useful results are obtained: the pulse emission current density is higher than 20 A/cm2 (when t=850℃) ; the anomalous Schottky effect is observed when the electric field is higher than 104V/cm; the cathode has a flat Ja-f property when the pulse duration ratio is in the range of 510-3--410-2 and an emission current density of 8.8A/cm2 is drawn. In the end, the obtained results are discussed in relation to the surface analysis of the cathode.