Helix Technology Corporation

Other

Philip A Lessard

Allen J Bartlett

Thomas J Dunn

Bruce R Andeen

Stephen J Yamartino

John T Harvell

Alan L Weeks

Paul E Dresens

Gary S Ash

Stephen R Matte

Maureen C Buonpane

James A O'Neil

Mark A Stira

Douglas F Aitken

John F Peterson

Robert M Patterson

Steven A Michaud

Roland P Graham

Karen J Manning

Alan C Brightman

Timothy M Pulling

Fred F Chellis, Deceased

Marshall J Smith

Robert D Bradford

A cryopump is regenerated by roughing the cryopump during purging. Purging and roughing is carried out in first a high temperature mode and then a lower ambient temperature mode. In the lower temperature mode, the cryogenic refrigerator is turned on. If the system fails a rough test after roughing at the lower temperature, it is repurged with the rough valve open.

Purge and rough cryopump regeneration process, cryopump and controller

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.

High conductance water pump

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.

Cryogenic waterpump

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.

Cryopump with improved second stage passageway

A cryopump having at least two temperature stages for pumping gases at their optimal temperatures. A first embodiment has a third temperature stage that is surrounded by and separated from the second temperature stage which is surrounded by and separated from the first temperature stage. Adsorbent placed on the second and third stages are operated at different temperatures to prevent gases with higher critical mobility temperatures from becoming immobilized at the entrance of pores and wells along the surface of the adsorbent. Another embodiment has at least a second stage, a temperature sensor, and a heater to maintain the second stage temperature at optimal level for the gas being pumped.

Optimally staged cryopump

A cryopump which has three temperature stages for pumping gas. The third temperature stage is surrounded by and separated from the second temperature stage which is surrounded by and separated from the first temperature stage. Adsorbent placed on the second and third stage are operated at different temperatures to prevent gases with higher critical mobility temperatures from becoming immobilized at the entrance of pores and wells along the surface of the adsorbent.

In a vacuum system having a load lock cooperating with a work chamber, a flow line is connected between the cryopump of the load lock and the work chamber. The flow line passes noncondensible gases which are not absorbed by the cryopump of the load lock to the work chamber 12 for absorption by the cryopump of the work chamber. Alternatively, the flow line is connected between the load lock cryopump and the cryopump of the work chamber for directly passing the noncondensible gases to the work chamber cryopump. The flow line prevents buildup of noncondensible gases within the cryopump of the load lock. The flow line may include baffles to damp pressure surges during cryopumping of the load lock. A control valve connected to the flow line allows operator control of the passing of noncondensible gases from the load lock cryopump to the work chamber or to the work chamber cryopump through the flow line. The dimensions of the flow line provide molecular flow of the noncondensible gases.

Vacuum system with molecular flow line

A recondenser cycles a working volume of cryogen gas through a remote cold box and a coaxial recondensing, heat exchanger transfer line which is inserted into a cryostat. The working volume of gas is compressed to a high pressure and cooled through cooling means which include a mechanical refrigerator of the regenerator-displacer type. The cooled gas is expanded through a first JT valve to a medium pressure and further cooled. The further cooled medium pressure gas is transferred in a closed coaxial transfer line to a cryostat in which boil-off is recondensed. A second JT valve in the cryostat end of an inner tube coaxially positioned in an outer tube forming the transfer line expands the gas to a lower pressure and forms a liquid-gas mixture. The liquid-gas mixture is passed in heat exchange relation with the boil-off from an inner tube to an outer tube of a coaxial recondensing heat exchanger. The outer surface of the outer tube at the cryostat end of the transfer line has burrs which provide the necessary surface area on which to recondense the boil-off. The gas is transferred back to the cooling means through intermediate channels formed between the outer tube and the coaxially positioned inner tube.

Cryogenic recondenser with remote cold box

A cryopump with quicker adsorption of non-condensible gases is disclosed. The second stage cryopanel of this cryopump is comprised of an array of discs spaced along an axis perpendicular to the frontal cryopanel, and in close thermal contact with the second stage heat sink. Each disc of the array is bent toward the frontal cryopanel at the outer edge of the disc and is flat radially inward from the bend. Each disc is coated with adsorbent material on the surface away from the frontal cryopanel radially inward from the bend in the disc.

Cryopump with quicker adsorption

In an expansion engine used in cryogenic refrigeration, a stepped inlet valve 10 and a stepped exhaust valve 11 are fluid activated to control high pressure gas such as helium into and out of the engine. Clearance seals in the stepped valve are achieved by sizing a small diameter of a stepped piston to a small bore and by sizing a sleeve 16 to a larger diameter of the stepped piston. The sleeve 16 fits loosely within a large bore, and is fixed into position by placing a wire of soft metal 9 between the sleeve and the wall of the cylinder.

High pressure stepped clearance seal valve in a cryogenic refrigeration

To control the temperature of one or more heat sinks of a cryogenic refrigerator in a cryopump, refrigerant gas to the refrigerator is diverted through heat exchangers associated with the refrigerator heat sinks. The diverted refrigerant gas may be used to maintain the temperature of the first stage cryopumping surfaces above some level to avoid cross over hangup. The second stage cryopumping surfaces may be warmed by the diverted refrigerant to some temperature level for partial regeneration. Both heat sinks may be warmed for full regeneration of the cryopump. Bleed flow of refrigerant gas cooled by the first stage of the refrigerator can be directed past a thermal mass to cool that mass. By reversing the flow of refrigerant gas during cooldown of the system, the thermal mass can be used to more rapidly cool the refrigerator. The thermal mass is thermally isolated from the refrigerator heat sinks and is positioned within the vacuum vessel of the cryopump adjacent to the first stage of the refrigerator.

Temperature control of cryogenic systems

A cryopump 20 with increased adsorptive capacity comprising a honeycomb adsorption structure 46 positioned within a second stage chevron assembly 40. Multiple chambers 58 of the honeycomb are covered with adsorbent charcoal 68. The entire structure 46 is attached to a second stage 52 of a cryogenic refrigerator 45.

Cryopump with improved adsorption capacity

Valves for controlling process gas at the cold end of an expansion engine are fluid actuated. The actuating fluid is controlled by a solenoid actuated spool valve positioned at ambient temperature. The fluid is cooled in a thermally regenerative flow path extending between the solenoid actuated valve and the fluid actuated valve.

Fluid actuator for cryogenic valve

The invention discloses a cryopump comprising a primary cryopanel 67 associated with a low temperature heat sink 60 having means for adsorbing a first low boiling point gas and a secondary cryopanel 80 associated with heat sink 60 and a higher temperature heat sink 48 having means for condensing a higher boiling point gas. There are means 90 for selectively conducting heat to the primary cryopanel to raise the temperature of the cryopanel above that which is necessary to cause said first gas to become desorbed from said cryopanel while having minimal effect on the capacity of the higher temperature heat sink.

Growing community of inventors

Acton, MA, United States of America

Philip A Lessard