Abstract: A cryogenic vacuum pump includes, in an integral assembly, temperature sensors and heaters associated with the first and second stages of the cryopumping array, a roughing valve and a purge valve. An electronic module removably coupled in the assembly responds to all sensors and controls all operations of the cryopump including regeneration thereof. System parameters are stored in a nonvolatile memory in the module. Included in the regeneration procedures are an auto-zero of the pressure gauge, heating of the array throughout rough pumping, and a change in pressure rate test to determine stall in rough pumping. The electronic module also restarts the system after power failure, limits use of a pressure gauge to safe conditions, provides warnings before allowing opening of the valves while the cryopump is operating and stores sensor calibration information. Control through a control pad on the pump may be limited by a password requirement. Password override is also provided.

Abstract: The refrigerator of a cryopump is positioned within an insulating vacuum and the two stages of the refrigerator are selectively thermally coupled to first and second stage cryopanels. After initial rough pumping by an air ejector, rough pumping is completed during startup by coupling the cold first stage of the refrigerator to a first stage adsorption cryopanel. The second stage of the refrigerator is thereafter coupled to the second stage cryopanel. Thermal coupling of the refrigerator to the cryopanels is by means of spring biased thermal contacts brought into position by movement of the refrigerator. The thermal contact elements are provided with sufficiently large thermal masses to handle the large thermal loads of system startup.

Abstract: An oil free vacuum system 10 which comprises a high thermal capacitance cryopump 12 and air ejector 38. The air ejector 38 is used to reduce load lock chamber 16 pressure to an intermediate vacuum. Cryopump 12 further evacuates chamber 12 to the operating vacuum of a work chamber 14. The work chamber 14 is maintained at high vacuum by a main cryopump 20. The main cryopump can be started in an oil free manner through the use of air ejector 38 and high thermal capacitance cryopump 12. A high themal capacitance, high thermal conductance cryopanel is formed of a lead/copper sandwich.

Abstract: In a cryopump, condensation of gases such as argon, oxygen and nitrogen on surfaces other than the second stage array 38, 40 is avoided to prevent cross over hang up and pressure instability. To prevent condensation of argon, oxygen and nitrogen on the frontal cryopumping array 46, that array is held to a temperature of at least 50.degree. K. A heat load to the first stage increases as the temperature of the first stage drops. That heat load is provided by a high emissivity radiation shield 44 or by a thermal switch 56, 58. Condensation of argon and other gases on the second stage refrigerator cylinder 32 is avoided by a close fitting sleeve 52 positioned over the refrigerator cylinder 32 in thermal contact with the second stage heat sink 30 but out of thermal contact with the cylinder 32.

Abstract: A time delay relay has a switch assembly, a spring terminal assembly, and an electrical resistance heater unit of an inexpensive construction held together in a reliable and economical manner by a pair of easily mounted metal spring clips.

Abstract: An equal input output learning device that can be added to or built into any musical instrument facilitating the teaching and improvisation of music and muscial theory using the musical instrument itself which device consists of a plurality of 12 switches representing the equal tempered 12 tone Chromatic scale, and which switches can be easily activated and changed by the player, as desired, using switches separately or in any combination, and, which switches when activated show all notes of the pitch classes chosen by indicators on the musical instrument together with indicators on the switches themselves.