1996 Volume 39 Issue 7 Pages 346-351
We developed a novel evaporator (EPC), which can be used to maintain a pressure of 10-5 Pa in a bell jar without breaking vacuum, by using a novel exchangeable source electrode with a liquid contact and a substrate exchangeable via a pre-evacuation chamber. (1) The supercooled state of the liquid alloys Ga1-xCux was used as the electrical contact material in the exchangeable source electrode. A composition (x) in the range from 0.0005 to 0.02 is appropriate for a stable liquid state in the contact. (2) The optimum practical EPC design criteria were determined by calculating the equilibrium pressure in terms of the volume ratio (M) of the bell jar to the pre-evacuation chamber, the working pressure of the bell jar and the working pressure of the pre-evacuation chamber. The optimum value of M for practical use is chosen as 181, where the volume of the pre-evacuation chamber is 1.1l and that of the bell jar is 200 l. (3) The pumping time of EPC is markedly improved to 10s. The ratio of the pumping times of the EPC system and the conventional system is then 1/1800. (4) The amount of residual water vapor in EPC is much less than that in a conventional system.
