Chapter 3 Baking; Outline - Ulvac CRYO-U Series Instruction Manual

CRYO-U Bakeable Type Cryopump Instruction Manual
®
3.1 Outline ············································································ 3-1
3.2 Baking Method ·································································· 3-2
3.1

Outline

In order to obtain high vacuum quickly, it is necessary to degas the cryopump and the
vacuum chamber by baking. Prior bake-out is essential to obtain extreme high vacuum
in particular.
For bake-out of cryopump itself, pressure inside the pump should be lowered as much
as possible before starting cool-down in order to achieve lower ultimate pressure.
Thereby installing auxiliary vacuum system (roughing vacuum system), which is able
to exhaust at least 0.1Pa or less, is required.
Procedure for baking the cryopump is explained below with an example of vacuum
system using a turbo molecular pump and a drypump
Bake-out is performed while the cryopump in operation. Please carefully read
CRYO-U Cryopump Instruction Manual beforehand and prepare the cryopump to be
®
able to start. ※ Drypump is recommended for rough pumping as it does not cause back
diffusion of oil.
PiG2
IG2
IG1
H PV
2
H PV: Hydrogen Vapor Pressure Gauge
2
PiG1 : Cryopump Pirani Gauge
IG1 : Cryopump Ionization Gauge
PiG2 : Vacuum Chamber Pirani Gauge
IG2 : Vacuum Chamber Ionization Gauge
PiG3 : Turbo Molecular Pump Pirani Gauge
Figure 3-1
3. BAKING
Vacuum
Chamber
Cryopump
PiG1
Example of Baking Vacuum System
ULVAC CRYOGENICS INCORPORATED
(Figure 3-1).
※
RV2
Turbo Molecular Pump
V1
PiG3
RV3
RV5
RV1
V1 : Main Valve
RV1 : Cryopump Roughing Valve
RV2 : Vacuum Chamber Roughing Valve
RV3 : Turbo Molecular Pump Valve
RV4 : Turbo Molecular Pump Roughing Valve
RV5 : Bypass Valve
RV4
Drypump
3-1