| 摘要 |
<p>A pulse tube refrigerator 200 comprises a pedestal head 5a and at least one cooled stage. The at least one cooled stage is mounted on a distal end from the pedestal head by a regenerator tube and pulse tube that together provide pressurised coolant gas to the at least one cooled stage. The displacements of the distal ends of the tubes in response to cyclical changes in coolant pressure are the same when the refrigerator is in use. Ideally the refrigerator comprises a first cooled stage 12 having respective first regenerator 6 and pulse 9 tubes and a second cooled stage 15 having a respective second regenerator 7 and pulse 10 tubes. The displacements of the distal ends of the tubes may be kept the same by forming all the regenerator and pulse tubes from the same material and forming all the regenerator and pulse tubes so as to have an inner radius (ri, figure 3) and outer radius (ro, figure 3) whereby the ratio of the square of the inner radius to the difference of the squares of the outer and inner radiuses is the same for each tube. The refrigerator can be used to cool magnetic resonance systems.</p> |
