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• Introduction
• What is the Vacuum ?
• Pressure & Gas Flow in the Vacuum
• A sort of Vacuum Pumps & Property
• About the Gauge
What is the Vacuum?
• 일 정 한 공 간 에 존 재 하 는 공 기 를 제 거 한 상 태 를 의미한다 .
• 왜 진공 상태가 필요한가 ?
Rough vacuum pump: 10-3~760 torr
High vacuum pump: 10-8~10-3 torr
Ultrahigh high vacuum pump: 10-12~10-8 torr
Pressure & Gas Flow in the Vacuum
P = F / A
Partial Pressure
• Pressure
• Gas Flow Viscous Flow
Molecular Flow
A sort of Vacuum Pumps & Property
Roughing PumpsRoughing Pumps
Rotary Vane, Oil-Sealed Mechanical Pump
Sorption Pump
sorption pump 는 내 부 쪽 으 로 돌 출 된 Heat Transfer Fin 으 로 된 알류미늄 Body 를 가지고 있으며 , Molecular Sieve 로 채워져 있다 . -196℃ 까지 냉각시키기 위해 Pump 는 액체 질소 (LN2) 를 포함하고 있는 Dewar 속에 자리잡고 있다 .
1) Cryocondensation
2) Crysorption
How the pump works
Gases are trapped on cold surfaces in two ways
Cryocondensation is the trapping of gases that are condensable at liquid nitrogen temperature(-196 ). The cold tra℃pping surfaces in the pump are the molecular sieve material.
Crysorption is the trapping of gases not readily condensed or pumped at LN2 temperature. Cryosorbed gases are trapped in the pump’s molecular sieve material. The molecular sieve material is porous. Gases that are not readily condensed at LN2 temperature bounce around within the sieve, losing heat. They are finally trapped.
Venturi Pump
속도 증가 → 압력증가
Venturi Pump 는 Sorption Pump 의 역할의 일부를 부담한다 .
Pump 의 수증기 포화상태는 쉽게 일어나지 않는다 .
High Vacuum PumpsHigh Vacuum Pumps
Oil Diffusion Pump
Heating → Jet Assembly → Cryotrap → Foreline( 배출 )
Fractionation
Mechanical Cryopump
Components
기체헬륨 compressor,
Baffle Pump body, HV Valve
LN Cryotrap
Helium 압축 → Cold Head → 기체 Pumping
Cryocondensation & Cryosorption
Ultra-high Vacuum PumpUltra-high Vacuum Pump Titanium Sublimation Pump
Sublimation ( solid → gas )
Chemical Reaction
Titanium Hydride, Oxide, Nitride
SurfaceTemperature
H2 N2 O2 CO CO2 H2O
20 ℃ 20 30 60 60 50 20
-196℃ 65 65 70 70 60 90
Typical Pumping Speeds Per Square
Because the sticking coefficient
Vacuum System 용례
Ion Pump
collision between free electron
and neutron
Electronic Devices do not use
moving part and oil
How to work the Ion Pump Ion Pump Schematics and
Mechanism
Thermocouple Gauge
Use rough vacuum range
TC gauge 는 온도 측정하여
압력으로 변화
Pirani Gauge
TC gauge 와 비슷하게 작동
Gauge 에서 온도변화가 Filament 의 저항변화를 일으킨다 .
Bridge Circuit 전류흐름변화를 측정
Ion Gauge
원자나 분자에 Energy 를 가하면 전자를 잃고 전하를 띄게 된다 . 이 전하를
띤 이온들이 다시 중성이 되기 위해 전자를 얻을 때 count 가 된다 .
Using the High Vacuum