Cooling System, Method for Operating the Same, and Plasma Processing System Using Cooling System

Abstract

In a cooling system, a compressor ( 1 ), a heat source ( 2 ), a heat exchanger ( 3 ), and a buffer tank ( 4 ) are connected in that order by piping ( 5 ) to constitute a closed circuit. In the closed circuit, nitrogen serving as a refrigerant is circulated without contacting open air. Any gas except for the air may be used as the refrigerant as long as the gas absorbs heat from the heat source ( 2 ) and dissipates the heat to the outside in the heat exchanger ( 3 ) when the gas is circulated in the closed circuit without being liquefied.

1 . A cooling system comprising:
 a compressor to compress a gas refrigerant except air to a degree in which the gas refrigerant is not liquefied and to deliver the gas refrigerant;   a heat source to be cooled by said gas refrigerant when the gas refrigerant delivered from said compressor passes therethrough;   a heat exchanger in which said gas refrigerant dissipates heat to an outside after absorbing the heat from said heat source;   a buffer tank in which said gas refrigerant is temporarily accumulated after dissipating the heat to the outside in said heat exchanger; and   piping to couple said compressor, said heat source, said heat exchanger, and said buffer tank in that order to constitute a closed circuit, said gas refrigerant being circulated through the closed circuit.   
   
   
       2 . The cooling system according to  claim 1 , further comprising another buffer tank between said compressor and said heat source to temporarily accumulate said gas refrigerant therein. 
   
   
       3 . The cooling system according to  claim 1 , wherein a volume of said buffer tank is not lower than an amount of said gas refrigerant discharged by said compressor within a time necessary to circulate said gas refrigerant once in said closed circuit. 
   
   
       4 . The cooling system according to  claim 1 , further comprising:
 replenishing piping connected to said buffer tank to replenish said gas refrigerant from the outside; and   discharging piping connected to said buffer tank to discharge said gas refrigerant to the outside.   
   
   
       5 . The cooling system according to  claim 1 , wherein said compressor has an ability to discharge an amount of said gas refrigerant larger than a circulating amount of said gas refrigerant necessary to cool said heat source to a target temperature. 
   
   
       6 . The cooling system according to  claim 1 , wherein said gas refrigerant contains nitrogen, oxygen, carbon dioxide, or inert gas. 
   
   
       7 . The cooling system according to  claim 1 , wherein said piping acts as a cooling tube in said heat source, and a surface area of said cooling tube is in a range of 20 cm 2  to 750 cm 2  per 1 m 3  of the heat source. 
   
   
       8 . The cooling system according to  claim 1 , wherein pressure loss of gas in said heat exchanger is not more than one-tenth of pressure loss of gas in said entire closed circuit. 
   
   
       9 . The cooling system according to  claim 1 , further comprising a refrigerant supply path aside from said closed circuit, said refrigerant supply path supplying said gas refrigerant having an amount discharged by said compressor to said compressor until said gas is circulated once in said closed circuit since said compressor is started up. 
   
   
       10 . The cooling system according to  claim 1 , further comprising:
 an exhaust valve to automatically exhaust said gas refrigerant in said buffer tank when a pressure of said gas refrigerant in said buffer tank is substantially equal to an upper limit of a suction pressure of said compressor; and   a suction valve to automatically suck said gas refrigerant into said buffer tank when the pressure of said gas refrigerant in said buffer tank is substantially equal to a lower limit of the suction pressure of said compressor.   
   
   
       11 . A plasma processing system comprising:
 a compressor to compress a gas refrigerant except air to a degree in which the gas refrigerant is not liquefied and to deliver the gas refrigerant;   a plasma processing apparatus to generate heat when a predetermined process is performed using a plasma processing gas, the apparatus being cooled by said gas refrigerant when the gas refrigerant delivered from said compressor passes therethrough;   a heat exchanger in which said gas refrigerant dissipates heat to an outside after absorbing the heat from said heat source;   a buffer tank in which said gas refrigerant is temporarily accumulated after dissipating the heat to the outside in said heat exchanger; and   piping to couple said compressor, said heat source, said heat exchanger, and said buffer tank in that order to constitute a closed circuit, said gas refrigerant being circulated through the closed circuit,   wherein said gas refrigerant includes one or more gases which does not react with said plasma processing gas.   
   
   
       12 . A method for operating the cooling system according to  claim 1 , the method comprising the steps of:
 sucking said gas refrigerant into said buffer tank by a decrease in pressure of said gas refrigerant in said buffer tank when said compressor is started up; and   maintaining a pressure of said gas in said buffer tank at a value of a degree in which said compressor is not broken, after a time longer than a time necessary to circulate said gas refrigerant once in said closed circuit elapses.