Cryogenic Cooling System

Abstract

An improved cryogenic cooling system is disclosed. The cryogenic cooling system comprises a pressure sensing system disposed at or near the cryocooler to provide a more accurate representation of the pressure of the working gas within the cryocooler. By utilizing pressure measurements at the cryocooler, the thermal performance and net cooling capacity of the system may be improved. This may also improve the life of the cryocooler. Further, in some embodiments, pressure sensing systems are disposed at both the compressor and the cryocooler. In these embodiments, performance issues and potential failures may be monitored.

What is claimed is: 
     
         1 . A cryogenic cooling system, comprising:
 a compressor;   a cryocooler;   a supply conduit and a return conduit connecting the compressor and the cryocooler; and   a first pressure sensing system disposed at or proximate the cryocooler to measure at least one of:
 differential pressure between the supply conduit and the return conduit; 
 pressure of the supply conduit; and 
 pressure of the return conduit. 
   
     
     
         2 . The cryogenic cooling system of  claim 1 , further comprising a controller in communication with the first pressure sensing system. 
     
     
         3 . The cryogenic cooling system of  claim 2 , wherein the first pressure sensing system measures differential pressure between the supply conduit and the return conduit at or proximate the cryocooler. 
     
     
         4 . The cryogenic cooling system of  claim 3 , wherein the compressor is regulated based on the differential pressure between the supply conduit and the return conduit measured at or proximate the cryocooler. 
     
     
         5 . The cryogenic cooling system of  claim 3 , wherein the controller detects impending failures in the cryocooler based on the differential pressure between the supply conduit and the return conduit at or proximate the cryocooler. 
     
     
         6 . The cryogenic cooling system of  claim 5 , wherein the controller monitors the differential pressure over time to detect impending failures. 
     
     
         7 . The cryogenic cooling system of  claim 5 , wherein the controller monitors the differential pressure over time, creates a pressure vs. time curve and compares the pressure vs. time curve to a library of curves that represent different failure modes. 
     
     
         8 . The cryogenic cooling system of  claim 5 , further comprising a flow rate sensor to measure a flow rate of working gas in the supply conduit or the return conduit, and wherein the flow rate is used in conjunction with the differential pressure to detect an impending failure. 
     
     
         9 . The cryogenic cooling system of  claim 2 , further comprising a second cryocooler in communication with the supply conduit and the return conduit and having a first pressure sensing system disposed at or proximate the second cryocooler to measure at least one of:
 differential pressure between the supply conduit and the return conduit;   pressure of the supply conduit; and   pressure of the return conduit.   
     
     
         10 . The cryogenic cooling system of  claim 9 , wherein the compressor is regulated to achieve a minimum differential pressure between the supply conduit and the return conduit measured at or proximate the cryocooler and measured at or proximate the second cryocooler. 
     
     
         11 . The cryogenic cooling system of  claim 1 , wherein the cryocooler comprises a valving system in communication with the supply conduit, the return conduit and a cylinder within the cryocooler, and wherein the first pressure sensing system comprises a pressure sensor in communication with the cylinder, such that the pressure sensor measures the pressure within the supply conduit or the return conduit, based on a state of the valving system. 
     
     
         12 . A cryogenic cooling system, comprising:
 a compressor;   a cryocooler;   a supply conduit and a return conduit connecting the compressor and the cryocooler;   a first pressure sensing system disposed at or proximate the cryocooler to measure at least one of:
 differential pressure between the supply conduit and the return conduit; 
 pressure of the supply conduit; and 
 pressure of the return conduit; and 
   a second pressure sensing system disposed at or proximate the compressor to measure at least one of:
 differential pressure between the supply conduit and the return conduit; 
 pressure of the supply conduit; and 
 pressure of the return conduit. 
   
     
     
         13 . The cryogenic cooling system of  claim 12 , further comprising a controller in communication with the first pressure sensing system and the second pressure sensing system. 
     
     
         14 . The cryogenic cooling system of  claim 13 , wherein the first pressure sensing system and the second sensing system measure differential pressure between the supply conduit and the return conduit. 
     
     
         15 . The cryogenic cooling system of  claim 14 , wherein the controller estimates a pressure drop through the supply conduit or return conduit based on the differential pressure measured by the first pressure sensing system and the second pressure sensing system. 
     
     
         16 . The cryogenic cooling system of  claim 15 , wherein the controller performs an action if the pressure drop through the supply conduit or return conduit is greater than a predetermined value. 
     
     
         17 . The cryogenic cooling system of  claim 13 , wherein a pressure drop through the supply conduit or return conduit is determined based on measurements from the first pressure sensing system and the second pressure sensing system. 
     
     
         18 . The cryogenic cooling system of  claim 17 , wherein the controller performs an action if the pressure drop through the supply conduit or return conduit is greater than a predetermined value. 
     
     
         19 . The cryogenic cooling system of  claim 17 , wherein the controller monitors the pressure drop over time, creates a pressure vs. time curve and compares the pressure vs. time curve to a library of curves that represent different failure modes. 
     
     
         20 . An ion implantation system comprising:
 an ion source to generate an ion beam;   a processing chamber comprising a platen on which a workpiece may be disposed;   beam line components to guide the ion beam from the ion source to the processing chamber; and   a cryogenic cooling system in communication with the processing chamber, wherein the cryogenic cooling system comprises:
 a compressor; 
 a cryocooler; 
 a supply conduit and a return conduit connecting the compressor and the cryocooler; and 
 a first pressure sensing system disposed at or proximate the cryocooler to measure at least one of: 
 differential pressure between the supply conduit and the return conduit; 
 pressure of the supply conduit; and 
 pressure of the return conduit.