Abstract: An apparatus and method for monitoring the torque load condition of a cryopump motor includes a power transducer for monitoring the electrical power input to the cryopump motor. A preferred embodiment of the power transducer includes a Hall-effect multiplier which measures the instantaneous and average electrical power input to the cryopump motor to determine torque load. Another preferred embodiment includes a power transducer which measures the Power Factor of the electrical power input to the cryopump motor to determine torque load. The Power Factor transducer includes a phase detector which detects the phase difference between the input voltage and the input current applied to the cryopump motor.

Abstract: A cryogenic trap is shielded by a floating baffle array which is insulated from ambient temperature. The cryogenic trap includes a baffle array which is suspended by conductive braid from split cylinders. The split cylinders are cooled by respective closed cycle refrigerators.

Abstract: In a subatmospheric regeneration process, a relief valve and a roughing valve are coupled in parallel to a common roughing pump. During regeneration, the cryopump is warmed to release gases from cryopump stages. The relief valve opens at a first cryopump pressure level less than a predetermined maximum pressure. The maximum pressure is subatmospheric. The relief valve closes when the cryopump pressure drops below a second cryopump pressure level. Pressure in a line between the relief valve and the roughing pump is monitored to control the opening of the roughing valve to the roughing pump.

Abstract: A cryogenically cooled water pump traps water vapor with a high probability but is open to non-condensing gases for high conductance to a turbomolecular pump. The preferred array is a single cylinder, having a length to diameter ratio of between 0.5 and 1, concentric with and near to an ambient temperature conduit. A center baffle, preferably of closed frustoconical shape, may be positioned at the center of the array over the upper bearing plate of the turbomolecular pump where it results in minimal reduction in conductance to the pump.

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: A vacuum system comprises, as an integral assembly, a turbomolecular pump with drive motor, a vent valve, a purge valve, a roughing valve, a heater and an electronic control module. The control module has a programmed processor for controlling the motor and valves and is user programmable for establishing specific control sequences. The integral electronic control module is removable from the assembly and is connected to the other devices through a common connector assembly. Proper introduction of a purge gas through the purge valve is detected by detecting the current load on the pump drive or by detecting foreline pressure. To test the purge gas status, the purge valve may be closed and then opened as drive current or pressure is monitored. After power failure, the controller will continue normal drive of the turbomolecular pump so long as the speed of the pump has remained above a threshold value. Otherwise the vent valve will have been opened, and a start-up sequence must be initiated.

Abstract: In a fast partial regeneration process, the second stage of a cryopump is heated as purge gas is applied to the cryopump. In a test loop, the purge gas is turned off and the roughing valve is opened. If the cryopump is judged to be sufficiently empty of gases from the second stage by being roughed to a sufficiently low pressure in a short period of time the system proceeds to a reconditioning phase. If the system fails the test, however, it is repurged with a burst of warm purge gas and then retested. After passing the emptiness test, the pressure is further reduced by the roughing pump as heat is applied to the second stage. The heat is then turned off for cool down as the system continues to be rough pumped to a base pressure. At about the base pressure, the roughing valve is cycled to maintain the cryopump pressure at a level near to the base pressure.

Abstract: A secondary pressure relief valve assembly is coupled to a cryopump relief valve for reducing the gas load on the cryopump. The pressure relief valve assembly comprises a main housing mounted to a crypoump exhaust conduit enclosing that portion of the cryopump valve typically exposed to the external environment. A second relief valve is mounted to the main housing and operates in series with the cryopump valve to exhaust pressurized gases from the cryopump during regeneration. A pump is coupled to a port on the main housing and maintains a pressure within the main housing which is less than the pressure of the external environment. As such, the pressure differential across the cyropump valve is reduced. Since the leakage and permeation gas loads are linearly related to the pressure differential, they are correspondingly reduced.

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: A cryopump includes a sloped draining surface for receiving liquids released from cyropumping surfaces. The liquids are collected in an exhaust port and released outside the cryopump vacuum vessel. A pressure relief valve coupled to the exhaust port exhausts gases released by the pumping surfaces after warming. The cryopump further includes a drain filter assembly connected to the exhaust port for collecting debris and removing liquid that is released from the cryopumping surfaces. A purge gas tube facilitates the removal of large quantities of liquid in the cryopump.

Abstract: In a cryopump a frost concentrating device is affixed to a condensing cryopanel and provides surfaces for condensing gases which are cryopumped through an opening in the vacuum vessel. The surfaces of the frost concentrator extend towards the opening in the vacuum vessel and thus limit the amount of gases which condense on the surfaces of the condensing cryopanel facing the opening. The result is that the gap between the radiation shield and the condensing cryopanel does not become significantly narrowed by condensing gases, particularly in the area closest to the opening through which gases are cryopumped. This allows other gases to pass easily through the gap and condense on surfaces of the condensing cryopanel further away from the opening of the cryopump or to be adsorbed by an adsorbent material shielded by the condensing cryopanel.

Abstract: A network of cryopumps, each having an electronic regeneration controller, is coupled to a common rough pump. Each regeneration controller operates independently except that each is inhibited from opening its roughing valve to the common rough pump. Each regeneration controller only proceeds to open the roughing valve after it has received a token from a network interface terminal. The network interface terminal may control multiple groups of cryopumps coupled to respective common rough pumps. The regeneration controllers are removable modules connected to the cryopumps. A PROM is provided for each cryopump to the side of the connector opposite to the module. The PROM stores data specific to the cryopump and retains the data for the cryopump with replacement of the controller module.

Abstract: A cold trap includes a set of baffles cooled by the cold finger of a closed cycle refrigerator. The baffles are vertically disposed in a vertical fluid conduit with frustoconical and conical surfaces for directing liquid to a circular trough during regeneration. After the liquid is collected, it is blown from the trough through a pressure relief valve by a nitrogen purge. The trough is formed in the upper surface of a connecting flange at the lower end of the fluid conduit.

Abstract: A secondary pressure relief valve assembly is coupled to a cryopump relief valve for reducing the gas load on the cryopump. The pressure relief valve assembly comprises a main housing mounted to a cryopump exhaust conduit enclosing that portion of the cryopump valve typically exposed to the external environment. A second relief valve is mounted to the main housing and operates in series with the cryopump valve to exhaust pressurized gases from the cryopump during regeneration. A pump is coupled to a port on the main housing and maintains a pressure within the main housing which is less than the pressure of the external environment. As such, the pressure differential across the cyropump valve is reduced. Since the leakage and permeation gas loads are linearly related to the pressure differential, they are correspondingly reduced.

Abstract: A cryopump includes a sloped draining surface for receiving liquids released from cyropumping surfaces. The liquids are collected in an exhaust port and released outside the cryopump vacuum vessel. A pressure relief valve coupled to the exhaust port exhausts gases released by the pumping surfaces after warming. The cryopump further includes a drain filter assembly connected to the exhaust port for collecting debris and removing liquid that is released from the cryopumping surfaces. A purge gas tube facilitates the removal of large quantities of liquid in the cryopump.

Abstract: A cryopump is capable of pumping a process chamber at a process pressure and differentially pumping a second chamber such as an RGA independently at a substantially lower pressure. A member extends through the cryopump housing into a low pressure region disposed within the second stage array. The member comprises a port for accessing the low pressure region, thus providing an independent differential pumping source. No physical seal is required between the member and the main cryopump volume to maintain the pressure differential.

Abstract: A network of cryopumps, each having an electronic regeneration controller, is coupled to a common rough pump. Each regeneration controller operates independently except that each is inhibited from opening its roughing valve to the common rough pump. Each regeneration controller only proceeds to open the roughing valve after it has received a token from a network interface terminal. The network interface terminal may control multiple groups of cryopumps coupled to respective common rough pumps. The regeneration controllers are removable modules connected to the cryopumps. A PROM is provided for each cryopump to the side of the connector opposite to the module. The PROM stores data specific to the cryopump and retains the data for the cryopump with replacement of the controller module.

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: Condensation on a cryopump second stage refrigerator cylinder is prevented by arranging a passageway between a colder second stage cylinder shield in thermal contact with the coldest section of the second stage and a warmer radiation shield in thermal contact with the warmer first stage. This arrangement produces a uniform and significant temperature differential in the passageway. The passageway is arranged so that the ratio of its length, L, to its width, W, is ideally greater than five. This ensures molecular collisions with the cold surface of the cylinder shield so that gas molecules are tightly bound to the cylinder shield. As a result, condensation on the refrigerator cylinder and resultant pressure variations are prevented.

Abstract: A linear drive motor of a cryogenic refrigerator, where a reciprocating armature is coupled to a piston which alternately compresses and expands a gaseous fluid in a thermodynamic cycle. The piston has a clearance seal and is attached at one end to a flexible coupling to reduce cross-bearing loads exerted by the piston along the clearance seal. A displacer assembly of the cryogenic refrigerator employs a displacer piston that reciprocates along a clearance seal. The displacer piston is coupled to the displacer cylinder and/or the armature of a displacer drive motor by a flexible coupling that reduces radial forces exerted by the displacer piston on the clearance seal.