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In accordance with an embodiment of the invention, there is provided a system for cooling a load. The system comprises a closed loop primary refrigeration system comprising: a primary compressor taking in a primary refrigerant at a low pressure and discharging the primary refrigerant at a high press

In accordance with an embodiment of the invention, there is provided a system for cooling a load. The system comprises a closed loop primary refrigeration system comprising: a primary compressor taking in a primary refrigerant at a low pressure and discharging the primary refrigerant at a high pressure; an insulated enclosure comprising an inlet receiving the primary refrigerant at the high pressure from the primary compressor and an outlet returning the primary refrigerant at the low pressure to the primary compressor; at least one heat exchanger within the insulated enclosure receiving the primary refrigerant at the high pressure and cooling the primary refrigerant using a secondary refrigerant from a secondary refrigeration system, the secondary refrigerant being in heat exchange relationship with the primary refrigerant in the at least one heat exchanger; an expansion unit within the insulated enclosure receiving the primary refrigerant at the high pressure from the at least one heat exchanger and discharging the primary refrigerant at the low pressure; and a supply line delivering the primary refrigerant at the low pressure to the load and a return line returning the primary refrigerant from the load to the primary refrigeration system. The system further comprises the secondary refrigeration system, wherein the secondary refrigeration system comprises at least one secondary cryogenic refrigerator. A system control unit controls operation of at least one of the primary refrigeration system and the secondary refrigeration system to provide a variable refrigeration capacity to the load based on at least one of: a pressure of the primary refrigerant delivered to the load, and at least one temperature of the load.

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1. A system for cooling a load, the system comprising: a closed loop primary refrigeration system comprising a primary compressor taking in a primary refrigerant at a low pressure and discharging the primary refrigerant at a high pressure;an insulated enclosure comprising an inlet receiving the prim

1. A system for cooling a load, the system comprising: a closed loop primary refrigeration system comprising a primary compressor taking in a primary refrigerant at a low pressure and discharging the primary refrigerant at a high pressure;an insulated enclosure comprising an inlet receiving the primary refrigerant at the high pressure from the primary compressor and an outlet returning the primary refrigerant at the low pressure to the primary compressor;at least one heat exchanger within the insulated enclosure receiving the primary refrigerant at the high pressure and cooling the primary refrigerant using a secondary refrigerant from a secondary refrigeration system, the secondary refrigerant being in heat exchange relationship with the primary refrigerant in the at least one heat exchanger;an expansion unit within the insulated enclosure receiving the primary refrigerant at the high pressure from the at least one heat exchanger and discharging the primary refrigerant at the low pressure;a supply line delivering the primary refrigerant at the low pressure to the load and a return line returning the primary refrigerant from the load to the primary refrigeration system;the secondary refrigeration system, wherein the secondary refrigeration system comprises at least one secondary cryogenic refrigerator, and wherein the secondary refrigeration system comprises a first channel delivering cooling to at least one heat transfer surface of the load and a second channel delivering the secondary refrigerant to the at least one heat exchanger; anda system control unit controlling operation of at least one of the primary refrigeration system and the secondary refrigeration system to provide a variable refrigeration capacity to the load based on at least one of: a pressure of the primary refrigerant delivered to the load, and at least one temperature of the load;the system control unit further comprising a control unit configured to control operation of the secondary refrigeration system to avoid either undercooling of the load or overcooling of the load, based on (i) a measured pressure or a measured temperature of the primary refrigerant returned from the load or (ii) a measured pressure or a measured temperature of the primary refrigerant entering the load. 2. The system according to claim 1, wherein the at least one temperature of the load comprises a temperature of from about −80 C to about −250 C. 3. The system according to claim 1, wherein the at least one heat transfer surface transfers heat to cool at least a portion of the load to a temperature in the range of from about −40 C to about −100 C. 4. The system according to claim 1, wherein the at least one heat transfer surface comprises at least a portion of a chamber to receive a semiconductor substrate to be processed by a system of the load. 5. The system according to claim 1, wherein the secondary refrigeration system comprises a mixed gas refrigeration system. 6. The system according to claim 5, wherein the mixed gas refrigeration system comprises more than one heat exchanger and at least one phase separator. 7. The system according to claim 1, wherein the secondary refrigeration system comprises a reverse Brayton refrigeration system. 8. The system according to claim 1, wherein the load comprises at least one of a pre-cool cryogenic interface module, a pre-cool chamber, a cold pad cryogenic interface module, a platen, an electrostatic chuck and two separate loads. 9. The system according to claim 1, further comprising an electrical interface control unit in electronic communication with the load. 10. The system according to claim 9, wherein the electrical interface control unit receives an electronic signal indicating at least one temperature of the load. 11. The system according to claim 9, wherein the electrical interface control unit receives an electronic signal indicating at least one set-point temperature of the load. 12. The system according to claim 9, wherein the electrical interface control unit outputs an electrical signal to control operation of the secondary refrigeration system to control at least one temperature of the load. 13. The system according to claim 12, wherein the at least one temperature of the load controlled by the electrical interface control unit comprises a temperature of at least one heat transfer surface of the load. 14. The system according to claim 1, wherein the system control unit comprises a control unit to control the providing of the variable refrigeration capacity to the load based on at least the pressure of the primary refrigerant delivered to the load. 15. The system according to claim 1, wherein the system control unit comprises a control unit to control a discharge rate of the primary compressor. 16. The system according to claim 1, wherein the system control unit comprises a control unit to control at least one of a high pressure, a low pressure and a pressure differential of the primary compressor. 17. The system according to claim 1, wherein the system control unit comprises a control unit to control a heat source to supply heat to be delivered to the primary refrigerant. 18. The system according to claim 1, wherein the expansion unit comprises an adjustable throttle, and wherein the system control unit comprises a control unit to control operation of the adjustable throttle. 19. The system according to claim 1, wherein the system control unit comprises a control unit to control flow of the primary refrigerant to bypass at least a portion of the at least one heat exchanger. 20. The system according to claim 1, wherein the system control unit comprises a control unit to control flow of the primary refrigerant to bypass at least a portion of the primary refrigeration system. 21. The system according to claim 1, wherein the system control unit comprises a control unit to control a rate of flow of the primary refrigerant. 22. The system according to claim 1, wherein the system control unit comprises a control unit to control a rate of flow of the secondary refrigerant. 23. The system according to claim 1, wherein the system control unit comprises a control unit to control a set point temperature of the secondary refrigeration system. 24. The system according to claim 1, wherein the system control unit comprises a control unit to control a heat source to supply heat to be delivered to the secondary refrigerant. 25. The system according to claim 1, wherein the system control unit comprises a control unit to control flow of the secondary refrigerant to bypass at least a portion of the secondary refrigeration system. 26. The system according to claim 1, wherein the system control unit comprises a control unit to control flow of at least a portion of the primary refrigerant to warm at least a portion of the load. 27. The system according to claim 1, wherein the system control unit comprises a control unit to control flow of at least a portion of the secondary refrigerant to warm at least a portion of the load. 28. A system according to claim 1, wherein the insulated enclosure is integrated into at least a portion of the secondary refrigeration system. 29. The system according to claim 1, wherein the at least one heat exchanger comprises a condenser. 30. The system according to claim 1, wherein the system control unit comprises a control unit to adjust the speed of the at least one secondary cryogenic refrigerator. 31. The system according to claim 1, wherein the system control unit comprises a control unit to turn off at least one of the at least one secondary cryogenic refrigerators. 32. The system according to claim 1, wherein the system control unit controls operation of at least one of the primary refrigeration system and the secondary refrigeration system to vary a proportion of the primary refrigerant that is flowed to the load in a liquid phase versus a gaseous phase. 33. The system according to claim 1, wherein the system control unit controls operation of at least one of the primary refrigeration system and the secondary refrigeration system to maintain a substantially constant temperature of the at least one temperature of the load. 34. The system according to claim 1, wherein the system control unit comprises a control unit to route at least a portion of the primary refrigerant to a warmer surface in the system to reduce refrigeration applied to the load. 35. The system according to claim 1, wherein the system control unit comprises a control unit to permit at least one of variable speed operation of the primary compressor, and pulsed operation of the primary compressor. 36. The system according to claim 1, wherein the control unit configured to control operation of the secondary refrigeration system is configured to control operation of the secondary refrigeration system to avoid undercooling of the load by: determining a calculated boiling point of the primary refrigerant returned from the load based on a measured pressure of the primary refrigerant returned from the load;comparing a measured temperature of the primary refrigerant returned from the load with the calculated boiling point; andif the measured temperature is more than a predetermined temperature difference above the calculated boiling point, controlling the secondary refrigeration system to increase available refrigeration to the load. 37. The system according to claim 1, wherein the control unit configured to control operation of the secondary refrigeration system is configured to control operation of the secondary refrigeration system to avoid undercooling of the load by: monitoring a temperature of the primary refrigerant returning from the load at a first temperature sensor downstream of the load;controlling a small heater, downstream of the first temperature sensor, to turn on if the temperature at the first temperature sensor has reached a predetermined assumed saturation temperature point;monitoring a temperature of the primary refrigerant at a second temperature sensor, downstream of the small heater; andif the turning on of the small heater raises the temperature of the primary refrigerant, controlling the secondary refrigeration system to increase available refrigeration to the load. 38. The system according to claim 1, wherein the control unit configured to control operation of the secondary refrigeration system is configured to control operation of the secondary refrigeration system to avoid overcooling of the load by: monitoring a temperature of the primary refrigerant returning from the load at a first temperature sensor downstream of the load;controlling a small heater, downstream of the first temperature sensor, to turn on if the temperature at the first temperature sensor has reached a predetermined assumed saturation temperature point;monitoring a temperature of the primary refrigerant at a second temperature sensor, downstream of the small heater; andif the turning on of the small heater raises the temperature of the primary refrigerant, determining the magnitude of the heat provided by the small heater and, based on the magnitude, determining whether to control the secondary refrigeration system to decrease available refrigeration to the load. 39. The system according to claim 1, wherein the system control unit comprises a control unit to adjust a variable heater on the at least one secondary cryogenic refrigerator. 40. The system according to claim 1, wherein the system control unit comprises a control unit to control a setpoint temperature of the at least one secondary cryogenic refrigerator. 41. The system according to claim 1, wherein the primary refrigerant comprises a nitrogen stream. 42. The system according to claim 1, wherein the primary refrigerant comprises at least one of argon, xenon, krypton, helium and a mixed gas refrigerant. 43. The system according to claim 1, wherein the primary refrigerant comprises at least one refrigerant component having a boiling temperature that is higher than a boiling temperature of a refrigerant used in the secondary refrigeration system. 44. The system according to claim 43, wherein the primary refrigerant comprises at least one of argon, nitrogen, xenon and krypton, and wherein the secondary refrigerant comprises at least one of helium and neon. 45. The system according to claim 1, wherein the primary refrigerant comprises a refrigerant having a boiling temperature that is lower than a boiling temperature of at least one refrigerant used in the secondary refrigeration system. 46. The system according to claim 45, wherein the primary refrigerant comprises at least one of argon, nitrogen, xenon, krypton and helium, and wherein the secondary refrigerant comprises a mixed gas refrigerant. 47. The system according to claim 1, further comprising a recuperative heat exchanger within the insulated enclosure and exchanging heat between the primary refrigerant at the high pressure flowing from the inlet of the insulated enclosure and the primary refrigerant returned from the load, the recuperative heat exchanger discharging the primary refrigerant at the high pressure to a condenser. 48. The system according to claim 47, further comprising a bypass valve permitting bypassing of the recuperative heat exchanger such that the primary refrigerant at the high pressure flowing from the inlet of the insulated enclosure does not exchange heat with the primary refrigerant returned from the load. 49. The system according to claim 47, wherein the control unit configured to control operation of the secondary refrigeration system is configured to control operation of the secondary refrigeration system to avoid undercooling of the load by: monitoring a temperature in at least one of an intermediate point in the recuperative heat exchanger and an end point of the recuperative heat exchanger; andif the monitored temperature falls below a predetermined temperature, controlling the secondary refrigeration system to decrease available refrigeration to the load. 50. The system according to claim 1, wherein the load comprises an electrostatic chuck. 51. The system according to claim 50, wherein the electrostatic chuck is a portion of an ion implantation system to manufacture a semiconductor device. 52. The system according to claim 51, further comprising a pre-cooling chamber to receive the semiconductor device prior to its handling by the electrostatic chuck. 53. The system according to claim 1, wherein the load comprises at least one of: at least a portion of a system for cooling a semiconductor wafer, at least a portion of an ion implantation system, and at least a portion of a physical vapor deposition system. 54. The system according to claim 1, wherein the at least one secondary cryogenic refrigerator comprises a Gifford-McMahon cycle refrigerator. 55. A system according to claim 54, wherein the Gifford-McMahon cycle refrigerator comprises a helium refrigerator. 56. The system according to claim 1, wherein the at least one secondary cryogenic refrigerator comprises a pulse tube refrigerator. 57. The system according to claim 1, wherein the at least one secondary cryogenic refrigerator comprises at least one of a reverse Brayton cycle refrigerator, a Stirling cycle refrigerator and a Joule-Thomson cycle refrigerator. 58. A system according to claim 1, wherein the at least one secondary cryogenic refrigerator comprises a refrigerator using a single refrigerant. 59. The system according to claim 1, wherein the at least one secondary cryogenic refrigerator comprises a refrigerator using a mixed gas refrigerant. 60. The system according to claim 1, wherein the primary compressor of the primary refrigeration system comprises a variable speed compressor. 61. A system according to claim 1, further comprising a cryopumping surface to create a vacuum within the insulated enclosure. 62. A system according to claim 61, wherein the cryopumping surface comprises a second stage of cooling of the at least one secondary cryogenic refrigerator. 63. The system according to claim 1, further comprising a bypass valve permitting the primary refrigerant to bypass the supply line that delivers the primary refrigerant to the load and the return line that returns the primary refrigerant from the load. 64. The system according to claim 1, wherein the expansion unit comprises at least one of a capillary tube, a valve with a variable flow area, a spring biased valve, a piston expander and a turbine expander. 65. The system according to claim 1, further comprising: a pressure regulator regulating flow of the primary refrigerant between a source of the primary refrigerant and the primary refrigerant at the low pressure taken in by the primary compressor; anda pressure control unit to control the pressure regulator to regulate the flow of the primary refrigerant into the system. 66. The system according to claim 1, further comprising an isolation valve connected to a pressure gauge on the insulated enclosure, the isolation valve preventing flow of the primary refrigerant into the inlet of the insulated enclosure if the pressure gauge on the insulated enclosure detects a pressure above a predetermined maximum safe pressure. 67. The system according to claim 1, further comprising: a thermal sensor connected to monitor the temperature of the primary refrigerant returning from the insulated enclosure to the primary compressor; anda safety control unit connected to discontinue operation of the secondary refrigeration system if the temperature of the primary refrigerant returning from the insulated enclosure is less than a predetermined touch hazard minimum temperature. 68. The system according to claim 1, wherein at least a portion of each of the supply line and the return line extend within a vacuum insulated transfer line. 69. The system according to claim 1, wherein the at least one heat exchanger converts at least a substantial portion of the primary refrigerant to a liquid phase. 70. The system according to claim 1, wherein the at least one heat exchanger substantially does not convert the primary refrigerant to a liquid phase. 71. The system according to claim 70, wherein the expansion unit converts at least a substantial portion of the primary refrigerant to a liquid phase. 72. The system according to claim 1, wherein the supply line delivers the refrigerant at the low pressure to the load through a transfer line out of the insulated enclosure, and wherein the return line returns the refrigerant from the load to the insulated enclosure through the transfer line. 73. The system according to claim 1, wherein the load is within the insulated enclosure. 74. The system according to claim 1, wherein the load comprises at least one of: a semiconductor substrate, a fluid stream for cryogenic separation, a gas to be liquefied, a biological sample, a chemical process, material property analysis equipment, a water vapor trap, an article in a manufacturing process, an imaging device, a subatomic particle detector, a photonic detector, chemical analysis equipment, a superconducting cable, and a superconducting device. 75. A method for cooling a load, the method comprising: compressing a primary refrigerant in a primary compressor of a closed loop primary refrigeration system, the primary compressor taking in the primary refrigerant at a low pressure and discharging the primary refrigerant at a high pressure;transferring the primary refrigerant at the high pressure from the primary compressor to an inlet of an insulated enclosure, and returning the primary refrigerant at the low pressure from the insulated enclosure to the primary compressor;transferring the primary refrigerant at the high pressure to at least one heat exchanger within the insulated enclosure, and cooling the primary refrigerant in the at least one heat exchanger using heat exchange with a secondary refrigerant from a secondary refrigeration system, the secondary refrigeration system comprising at least one secondary cryogenic refrigerator;expanding the primary refrigerant using an expansion unit within the insulated enclosure, the expansion unit receiving the primary refrigerant at the high pressure from the at least one heat exchanger and discharging the primary refrigerant at the low pressure;delivering the primary refrigerant at the low pressure to the load and returning the primary refrigerant from the load to the primary refrigeration system;controlling operation of at least one of the primary refrigeration system and the secondary refrigeration system to provide a variable refrigeration capacity to the load based on at least one of: a pressure of the primary refrigerant delivered to the load, and at least one temperature of the load;controlling operation of the secondary refrigeration system to avoid either undercooling of the load or overcooling of the load, based on (i) a measured pressure or a measured temperature of the primary refrigerant returned from the load or (ii) a measured pressure or a measured temperature of the primary refrigerant entering the load; anddelivering cooling from the secondary refrigeration system to at least one heat transfer surface of the load through a first channel of the secondary refrigeration system, and delivering the secondary refrigerant to the at least one heat exchanger through a second channel of the secondary refrigeration system. 76. The method according to claim 75, further comprising controlling the providing of the variable refrigeration capacity to the load based on at least the pressure of the primary refrigerant delivered to the load. 77. The method according to claim 75, further comprising controlling at least one of a high pressure, a low pressure and a pressure differential of the primary compressor. 78. The method according to claim 75, further comprising controlling a heat source to supply heat to be delivered to the primary refrigerant. 79. The method according to claim 75, wherein the expansion unit comprises an adjustable throttle, the method further comprising controlling operation of the adjustable throttle. 80. The method according to claim 75, further comprising controlling flow of the primary refrigerant to bypass at least a portion of the at least one heat exchanger. 81. The method according to claim 75, further comprising controlling flow of the primary refrigerant to bypass at least a portion of the primary refrigeration system. 82. The method according to claim 75, further comprising controlling a rate of flow of the primary refrigerant. 83. The method according to claim 75, further comprising controlling a rate of flow of the secondary refrigerant. 84. The method according to claim 75, further comprising controlling a set point temperature of the secondary refrigeration system. 85. The method according to claim 75, further comprising controlling a heat source to supply heat to be delivered to the secondary refrigerant. 86. The method according to claim 75, further comprising controlling flow of the secondary refrigerant to bypass at least a portion of the secondary refrigeration system. 87. The method according to claim 75, further comprising controlling flow of at least a portion of the primary refrigerant to warm at least a portion of the load. 88. The method according to claim 75, further comprising controlling flow of at least a portion of the secondary refrigerant to warm at least a portion of the load. 89. The method according to claim 75, comprising delivering the refrigerant at the low pressure to the load through a transfer line out of the insulated enclosure, and returning the refrigerant from the load to the insulated enclosure through the transfer line. 90. The method according to claim 75, wherein the load is within the insulated enclosure. 91. The method according to claim 75, wherein the load comprises at least one of: a semiconductor substrate, a fluid stream for cryogenic separation, a gas to be liquefied, a biological sample, a chemical process, material property analysis equipment, a water vapor trap, an article in a manufacturing process, an imaging device, a subatomic particle detector, a photonic detector, chemical analysis equipment, a superconducting cable, and a superconducting device. 92. The method according to claim 75, further comprising moving an object or fluid to be cooled from a heat transfer surface of the load to another portion of the load. 93. The system according to claim 1, wherein the first channel of the secondary refrigeration system comprises a separate refrigeration channel from the second channel of the secondary refrigeration system. 94. The method according to claim 75, wherein the first channel of the secondary refrigeration system comprises a separate refrigeration channel from the second channel of the secondary refrigeration system.