NIFS-378

FULL TEXT (PDF, 639 KB)


Author(s):

K. Akaishi

Title:

Theoretical Consideration for the Outgassing Characteristics of an Unbaked Vacuum System

Date of publication:

Oct. 1995

Key words:

outgassing rate, gas desorption model, sticking probability, Freundlich isotherm, Temkin isotherm, extended Temkin isotherm

Abstract:

Recently the outgassing rate of an unbaked vacuum chamber has been measured with a variable orifice pumping by the author, and it has been shown that the outgassing rate q obeys the power law of pumping time t as q = q_0 (t_1/t)^x, 0.8 &It; x &It; 1.1 and the initial outgassing rate q_0 is dependent on the pumping speed S of orifice as q_0 propt S^m, 0 &It; m &It;1. This paper describes the theoretical verification for the outgassing characteristics in the light of absorption - desorption of molecules on the wall surface and the pump-down of gas phase molecules out of the chamber.

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