Magnetic valve and system including magnetic valve

A magnetic resonance (MR) imaging system comprising:

• (i) superconducting magnet system configured to provide an MR magnetic field to enable MR imaging, the superconducting magnet system comprising:
• a plurality of magnet coils configured to generate the MR magnetic field in a superconducting state,
• a magnet persistent current switch (PCS) configured to enter a normal state during ramping of the plurality of magnet coils to an operating current in the superconducting state, wherein a temperature of the magnet PCS increases in the normal state, and
• a cryostat configured to provide a cryogenic temperature to the plurality of magnet coils and the magnet PCS, wherein the cryostat includes a first loop tube for circulating a coolant at the cryogenic temperature through the plurality of magnet coils and a second loop tube for circulating the coolant at the cryogenic temperature through the magnet PCS;
• (ii) a magnetic valve integrated with the second loop tube and configured to selectively couple and decouple the magnet PCS to and from the second loop tube, the magnetic valve comprising:
• a first diode and a first solenoid connected between a first terminal and a second terminal,
• a second diode and a second solenoid connected between the first terminal and the second terminal in parallel with the first diode and the first solenoid, wherein the second diode is arranged antiparallel to the first diode, and
• a ferromagnetic ball configured to move between an open position and a closed position, wherein the open position enables flow of the coolant through the second loop tube at the magnet PCS to thermally couple the magnet PCS to the second loop tube, and wherein the closed position blocks flow of the coolant through the second loop tube at the magnet PCS to thermally decouple the magnet PCS from the second loop tube;
• and
• (iii) a control circuit configured to apply a control signal having a first polarity to the first and second terminals of the magnetic valve when the magnet PCS is in a closed state and to apply the control signal having a second polarity to the first and second terminals of the magnetic valve when the magnet PCS is in the normal state, wherein the first polarity is opposite the second polarity,
• wherein the first solenoid is configured to generate a first magnetic field in response to the control signal having the first polarity, causing the ferromagnetic ball to move toward the first solenoid into the open position enabling the flow of the coolant to lower the temperature of the magnet PCS, and
• wherein the second solenoid is configured to generate a second magnetic field in response to the control signal having the second polarity, causing the ferromagnetic ball to move toward the second solenoid into the closed position blocking the flow of the coolant to prevent the magnet PCS from increasing a temperature of the coolant in the first loop tube.

A system for controlling temperature of a magnet persistent current switch (PCS) operating in a superconducting magnet system, the system comprising:

• a heat exchanger configured to disperse heat to a cryocooler;
• a loop tube configured to enable flow of coolant to convectively transfer thermal energy generated by the magnet PCS and a plurality of magnet coils to the heat exchanger;
• a control circuit configured to generate a control signal having a first polarity or a second polarity opposite the first polarity;
• and
• a magnetic valve comprising:
• a first diode and a first solenoid connected between a first terminal and a second terminal;
• a second diode and a second solenoid connected between the first terminal and the second terminal in parallel with the first diode and the first solenoid, wherein the second diode is arranged antiparallel to the first diode;
• and
• a ferrous ball configured to move between an open position, enabling flow of the fluid through the loop tube, and a closed position, blocking flow of the fluid through the loop tube,
• wherein the first solenoid is configured to generate a first magnetic field in response to the control circuit applying the control signal having the first polarity to the first and second terminals, causing the ferrous ball to move toward the first solenoid into the open position, and
• wherein the second solenoid is configured to generate a second magnetic field in response to the control circuit applying the control signal having the second polarity to the first and second terminals, causing the ferrous ball to move toward the second solenoid into the closed position.