Abstract Cesium evaporator filled with a mixed powder of a silicon and cesium chromate and/or cesium bichromate for depositing cesium vapor on the face plate of a photoelectric tube, the silicon powder has such a particle size distribution that the average particle size is 30 to 80 microns, with particles larger than 100 microns or those smaller than one micron constituting not more than 30 weight percent, and the cesium chromate or cesium bichromate powder has such a particle size distribution that the average particle size is 3 to 10 microns with particles larger than 25 microns constituting not more than 30 weight percent and those smaller than 0.5 micron constituting not more than 40 weight percent.
preparing a powder of at least one cesium compound selected from the group consisting of cesium chromate and cesium bichromate, said powder having a particle size distribution such that the average particle size ranges between 3 and 10 microns and not more than 30 percent of the mixture by weight consists of particles larger than 25 microns and not more than 40 percent of the mixture by weight consists of particles smaller than 0.5 micron, by repeatedly pulverizing and drying said cesium compound powder until a mixture having the stated particle size distribution is obtained; subjecting said powder to a first sieving operation through a relatively coarse mesh screen to break up any large aggregates of powder in said mixture; and then subjecting said screened powder to a second sieving operation through a relatively fine screen;
Claim 2
Dependent Claim
30 words
mixing the silicon powder obtained in (1) with the cesium compound powder obtained in (2) to form a mixture consisting of said silicon powder and said cesium compound powder; and
Claim 3
Dependent Claim
20 words
drying and sieving the mixture so obtained to produce a mixture from which cesium is evaporated at a uniform rate.