Flow-cooled magnet system

Abstract

A flow-cooled magnet system comprising a magnet for generating a magnetic field in a target region and a cooling system comprising a flow path for a coolant fluid. The flow path has a first part arranged in thermal communication with the magnet and a second part in thermal communication with the target region. Each of the magnet and target region are cooled by the flow of coolant in the first and second parts of the cooling system.

1 . A flow-cooled magnet system comprising: —
 a magnet for generating a magnetic field in a target region;    a cooling system comprising a flow path for a coolant fluid, the flow path having (i) a first part arranged in thermal communication with the magnet; and (ii) a second part in thermal communication with the target region such that each of the magnet and target region are cooled by the flow of coolant in the first and second parts of the cooling system.    
     
     
         2 . A magnet system according to  claim 1 , wherein the first part is upstream of the second part.  
     
     
         3 . A magnet system according to  claim 1 , wherein the target region is adapted to retain a sample when in use.  
     
     
         4 . A magnet system according to  claim 1 , wherein the magnet is contained within a cryostat comprising at least one radiation shield, wherein the flow path further comprises a third part in thermal communication with the at least one radiation shield, and wherein the flow path divides from a common path within which the first part is located, into at least two separate paths, within one of which is located the second part and another one of which is located the third part.  
     
     
         5 . A magnet system according to  claim 4 , wherein the flow path is divided such that some of the coolant flows through the second part and some through the third part.  
     
     
         6 . A magnet system according to  claim 4 , further comprising current leads for supplying electrical current to the magnet, and wherein the third part is in thermal communication with the current leads so as to cool the current leads when in use.  
     
     
         7 . A magnet system according to  claim 4 , further comprising a flow controller adapted to provide a predetermined flow of coolant within one or more of the first, second and third parts of the system.  
     
     
         8 . A magnet system according to  claim 7 , wherein the flow controller comprises a variable flow impedance or a static localised flow impedance.  
     
     
         9 . A magnet system according to  claim 1 , wherein the second part comprises a heat exchanger with which a sample is in thermal communication.  
     
     
         10 . A magnet system according to  claim 1 , wherein a heater is provided within the target region such that the heat produced, in combination with the cooling effect of the coolant in the second part of the cooling system, allows the target region to be held at a predetermined temperature.  
     
     
         11 . A magnet system according to  claim 10 , wherein the predetermined temperature lies in a range from the coolant temperature to ambient temperature.  
     
     
         12 . A magnet system according to  claim 9 , wherein the target region further comprises a temperature sensor and a temperature controller is provided for controlling the heater in response to signals received from the temperature sensor.  
     
     
         13 . A magnet system according to  claim 1 , wherein the magnet is located within a cryostat having a vacuum chamber, and wherein a sample vacuum chamber is provided as a target region for containing the second part of the coolant system and, when in use, a sample to be monitored, and wherein the sample vacuum chamber is independent of the cryostat vacuum chamber.  
     
     
         14 . A magnet system according to  claim 13 , wherein the temperature and pressure of the sample vacuum chamber are each controllable independently of the temperature and pressure within the cryostat vacuum chamber.  
     
     
         15 . A magnet system according to  claim 1 , wherein the magnet is a solenoid magnet having a bore and wherein the target region is located within the bore.  
     
     
         16 . A magnet system according to  claim 1 , further comprising at least a first window positioned to allow electromagnetic radiation to be transmitted and/or received from a sample when located in the target region.  
     
     
         17 . A magnet system according to  claim 16 , further comprising a second window located on the opposite side of the sample with respect to the first window so as to allow electromagnetic radiation to be received by the sample through the first window, to pass through the sample and then pass through the second window for monitoring.  
     
     
         18 . A magnet system according to  claim 1 , further comprising mountings for fitment of the system to an optical bench.  
     
     
         19 . A magnet system according to  claim 1 , wherein the system is defined by a nominal axis and the system is adapted to be operational with the axis orientated substantially vertically and substantially horizontally.  
     
     
         20 . A magnet system according to  claim 1 , wherein the system is a continuous flow system adapted such that the coolant flows through the cooling system continually when in use.  
     
     
         21 . A magnet system according to  claim 1 , wherein the magnet is cooled by thermal conduction.  
     
     
         22 . A magnet system according to  claim 21 , wherein the magnet is separated from the coolant by a high thermal conductivity member through which heat flows from the magnet.  
     
     
         23 . A magnet system according to  claim 22 , wherein the magnet is surrounded by an annular chamber comprising the first part of the cooling system through which the coolant flows when in use.  
     
     
         24 . A magnet system according to  claim 1 , wherein the target region further comprises a sample support for receiving a sample holder within which a sample is retained.  
     
     
         25 . A magnet system according  claim 1 , wherein the coolant is supplied to the flow path from a coolant reservoir.  
     
     
         26 . A magnet system according to  claim 1 , wherein the cooling system is a closed loop system such that, after passing through the flow path, the coolant is refrigerated and recirculated repeatedly through the flow path.  
     
     
         27 . A magnet system according to  claim 26 , further comprising a mechanical refrigerator for refrigerating the coolant for recirculation.  
     
     
         28 . A magnet system according to  claim 1 , wherein the coolant is a cryogenic fluid.  
     
     
         29 . A magnet system according to  claim 28 , wherein the coolant is a gas.  
     
     
         30 . A magnet system according to  claim 29 , wherein the coolant is helium or nitrogen gas.