Term
| What are the types of pumps? |
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Definition
1]mechanical pump
2]turbomolecular pump
3]diffusion pump
4]ion pump
5]sublimation pump
6]cryo pump |
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Term
| What are the pressure regions and associated pressure range? |
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Definition
Region A [760 to 10^-4 Torr]
Region B [10^-4 to10^-8 Torr]
Region C [10^-8 to 10^-11 Torr]
Region D [10^-11 to 10^-15 Torr] |
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Term
| What pump(s) are required to reach Region A (760 to 10^-4 Torr)? |
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Definition
| Mechanical pump (Roughing pump) |
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Term
| What pump(s) are required to reach region B [10^-4 to10^-8 Torr] |
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Definition
| Combination of heat and mechanical pump in addition to either a turbo pump or diffusion pump. |
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Term
| What pump(s) are required to reach region C [10^-8 to 10^-11 Torr]? |
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Definition
| Requires heating to 200C+ in addition to a mechanical pump plus a turbo or diffusion pump and an ion, sublimation or cryo pump. |
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Term
| What pumps are required to reach region D Region D [10^-11 to 10^-15 Torr]? |
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Definition
| Requires a combination of cryo and sublimation pumps in addition to other specialized pumps. |
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Term
| How does a rough (rotary) pump work? |
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Definition
| A vane sweeps out the volume as the pump rotates pushing the gas through an outlet and into oil. The gas from the chamber comes back into the pump at the inlet and it is swept away and so on. |
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Term
| How does an oil diffusion pump work? |
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Definition
| Molecules of a gas being pumped diffuse in to a jet of hot diffusion pump oil, which carries them along by viscous flow inside a condenser in which the vapor is gradually condensed into a liquid of low vapor pressure. |
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Term
| How does a turbo molecular pump work? |
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Definition
| A turbine like rotar rotates ata aspeed that exceeds the mean molecular speed of all ordinary components of air. The rotars smash into the molecules being pumped and remove them. |
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Term
| How does an Ion pump work? |
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Definition
| Ionization of atoms/molecules forcing them to a cathode. Ionized atoms/molecules smash into a titanium wall and imbed in it. |
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Term
| How does a sublimation pump work? |
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Definition
| Titanium is heated until it vaporizes. The Ti vapor pick up gas molecules/atoms. the Ti-gas vapor condenses on the container wall and traps the gas. |
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Term
| How does a cryo pump work? |
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Definition
| A large surface area chilled to liquid He temp (4.2K) adsorbs the gas molecules to be pumped. |
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Term
| What are the gauges that measure pressure and what ranges do the cover? |
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Definition
1] Mercury manometer [1000 to 1 Torr]
2] Oil manometer [10 to 0.03 Torr]
3]Thermocouple Gauge [760 to 10^-3 Torr]
4] Pirani Gauge [10-10^-4 Torr]
5]Capacitance manometer [1000-10^-4 Torr]
6]McLeod Gauge [1-10^-5 Torr]
7] Ionization Gauge [10^-3 to 10^-12 Torr] |
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Term
| How does a mercury manometer [1000 to 1 Torr] work? |
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Definition
| Works on the principle of Boyle’s Law and compression of a known volume. Boyle’s Law: Volumelow x Pressurelow = Volumehigh x PressureHigh. High and low can be replaced with final and initial if need be. |
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Term
| How does an oil manometer [10 to 0.03 Torr] work? |
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Definition
| Works on the principle of Boyle’s Law and compression of a known volume. Boyle’s Law: Volumelow x Pressurelow = Volumehigh x PressureHigh. High and low can be replaced with final and initial if need be. |
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Term
| How does a Thermocouple Gauge [760 to 10^-3 Torr] Work? |
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Definition
| Measures the temperature of a filament as the thermal conductivity of a gas changes with pressure |
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Term
| How does a Pirani Gauge [10 to 10^-4 Torr] work? |
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Definition
| Measure the resistance of a filament as its temperature changes due to a change in the thermal conductivity of a gas with changing pressure. |
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Term
| How does a Capacitence Manometer [1000-10^-4 Torr] work? |
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Definition
| Changes in pressures cause deflections in a capacitor membrane. Pressure readings made based on change in capacitance. |
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Term
| How does a McLeod Gauge [1-10^-5 Torr] work? |
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Definition
| Works on the principle of Boyle’s Law and compression of a known volume. Boyle’s Law: Volumelow x Pressurelow = Volumehigh x PressureHigh. High and low can be replaced with final and initial if need be. |
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Term
| How Does an Ionization Gauge [10^-3 to 10^-12 Torr] work? |
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Definition
| Molecules and atoms are ionized. The ion current of the resulting ions is indicative of the pressure. |
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Term
| What is conductivity with regard to pumping? |
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Definition
| A given segment, i, of a pumping apparatus conducting the gas, may be said to have conductance Ci which is the flux, Q, in the gas through it divided by the pressure difference: Ci = Q/ (P1i – P2i) |
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