Low Temperature Closed Cooling System for MRI Magnets

In the past five years a considerable amount of clinical test results have become available from Magnetic Resonance Imaging (MRI) and/or Spectroscopy systems based on superconducting magnets with field strengths up to 4 T. This new technique has now proved to be an important diagnostic tool for physicians. Most of the superconducting magnet systems commercially available today are solenoid type magnets cooled by pool boiling of liquid helium surrounded by a liquid nitrogen cooled radiation shield. At DUT we reconsidered the design of the superconducting magnet and the cooling system to get a system that might be more acceptable for use in a clinical environment. We designed a compact 1.5 T double pair magnet system with low temperature cooling system for: a) two radiation shields, b) precooling of the magnet system to 20 K and c) recondensation of the evaporated helium from the coils. The design and first test results of this system will be discussed.