EP4024415A1 - Système d'aimant supraconducteur et procédé pour faire fonctionner le système - Google Patents

Système d'aimant supraconducteur et procédé pour faire fonctionner le système Download PDF

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Publication number
EP4024415A1
EP4024415A1 EP21150247.1A EP21150247A EP4024415A1 EP 4024415 A1 EP4024415 A1 EP 4024415A1 EP 21150247 A EP21150247 A EP 21150247A EP 4024415 A1 EP4024415 A1 EP 4024415A1
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EP
European Patent Office
Prior art keywords
superconducting
current
temperature
mpcs
superconducting magnet
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP21150247.1A
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German (de)
English (en)
Inventor
Cornelis Leonardus Gerardus Ham
Gerardus Bernardus Jozef Mulder
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Koninklijke Philips NV
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Koninklijke Philips NV
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Priority to EP21150247.1A priority Critical patent/EP4024415A1/fr
Publication of EP4024415A1 publication Critical patent/EP4024415A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/006—Supplying energising or de-energising current; Flux pumps
    • H01F6/008—Electric circuit arrangements for energising superconductive electromagnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/06—Coils, e.g. winding, insulating, terminating or casing arrangements therefor
    • H01F6/065—Feed-through bushings, terminals and joints
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F6/00—Superconducting magnets; Superconducting coils
    • H01F6/04—Cooling

Definitions

  • the invention relates to the field of superconducting magnets, and in particular to medical imaging devices like magnetic resonance examination systems and other systems employing superconducting magnet systems.
  • the invention also relates to a method for controlling a ramp-up or ramp-down process for a superconducting magnet system.
  • the invention further relates to a magnetic resonance examination system, the magnetic resonance examination system comprising such a superconducting magnet system.
  • the invention also relates to a method for energizing a superconducting magnet system and an associated computer program product.
  • the present invention refers to MRI magnets, but is not limited to those magnets and is therefore not limited to the use of superconducting magnets in medical systems. Nevertheless modern MR systems have a superconducting magnet made from NbTi. Once the magnet has been ramped-up to field, the current is running in persistent mode. The superconducting coil forms a closed loop without electrical resistance and the current runs forever without the need to add power to it.
  • a magnet persistent mode switch (MPCS) is added, which can be opened during the ramp up or ramp down procedure.
  • MPCS magnet persistent mode switch
  • the MPCS is actually an amount of superconducting wire with a heater to make that specific part of the superconducting wire to become normal and having an electrical resistance.
  • the magnet coil is actually a huge self-inductance.
  • the magnet power supply to energize the magnet delivers for instance a constant voltage and in combination with the high self-inductance the current increases linearly.
  • a typical ramp voltage is 5V.
  • the duration to bring the a typical MRI magnet to field is less than 1 hour for a 1.5T magnet up to about 3 hours for a 3T magnet.
  • Magnet for spectroscopy may have different dimensions and may have a different duration to ramp-up or ramp-down.
  • Conventional magnets have their superconducting coils in a bath of liquid helium.
  • the temperature of those coils is equal to that of the helium bath and is about 4.2K (liquid helium at atmospheric pressure i.e., ⁇ 1bar).
  • the pressure may vary within a (small) pressure range but might also be controlled around a pressure set point. Since the boiling point of helium is a function of the gas pressure, the helium temperature is also within a (small) range or might even be fixed (e.g., 4.2K).
  • a 1.5T magnet loses typically 30L of liquid helium per ramp cycle (ramp-up and ramp-down) and a 3T magnet typically 100L of liquid helium.
  • the magnet power supply may deliver its power with a fixed voltage, in first order leading to a linear increase of the current as function of time (more or less constant dl/dt).
  • the voltage at the magnet itself is lower because of the ohmic voltage losses over the ramp cables.
  • This ohmic voltage increases when the current increases, leading to a lower dl/dt.
  • this magnet power supply could have been programmed for other voltage (or current) profiles as a function of time.
  • the sealed magnet is an example of magnet types where the superconducting coils are not sitting in a bath of liquid material.
  • This can for instance be magnets with superconducting coils made from LTS materials like NbTi as used for conventional magnets, but also from other materials, such as Nb 3 Sn, MgB2, or even more exotic HTS materials.
  • LTS materials like NbTi as used for conventional magnets, but also from other materials, such as Nb 3 Sn, MgB2, or even more exotic HTS materials.
  • These magnets do not be limited to MRI. It can also be used for (high field) spectroscopy, trains, accelerators, etc.
  • the term sealed magnet is mentioned, this must be read as the above described generalization.
  • the energize process is started at a sufficiently low temperature T energize .
  • the ⁇ T (T AutoDischarge - T energize ) must be large enough to deal with the dissipation during the energize process, with dissipation contributions due to eddy currents, hysteresis and dissipation in the MPCS. Therefore the magnet may have a higher critical temperature than a conventional magnet and/or be cooled to a lower temperature than a conventional magnet. This is achieved by adding more superconducting wire to the magnet design.
  • There are two problems involved with the previously described sealed magnet with ⁇ T is: The magnet first needs to be cooled to a pretty low temperature T energize where the cold head has little cooling power. This takes a lot of time to reach that temperature. This can be seen in Fig. 5 described later in the description.
  • the critical temperature of the superconducting coils at the end of the energization process must have a sufficiently large margin compared to the temperature at the end of the energize process (T AutoDischarge ) in order to avoid a Loss of Field (quench).
  • T AutoDischarge the temperature at the end of the energize process
  • a higher critical temperature is achieved by adding more superconductor wire to the coils and this is expensive.
  • a superconducting magnet system comprising: a superconducting coil with a least a superconducting coil winding for generating a magnetic field, wherein the superconducting coil winding is located in a first temperature region, an electrical current lead assembly for transferring electrical current to the superconducting coil winding, a power supply for providing an electrical current to the electrical current lead assembly, the electrical current lead assembly comprising:
  • the first temperature region having a temperature below a critical temperature of a low temperature superconductor, LTS.
  • the second temperature region having a temperature below a critical temperature of a high temperature superconductor, HTS.
  • At least a part of the high temperature superconducting, HTS material of the magnet persistent current switch, MPCS and/or the high temperature superconducting current leads connecting the MPCS with the superconducting coil winding comprises additional electrically conductive material preferred a metal, more preferred copper, wherein the additional electrically conductive material is cladded to the HTS material or embedded as filaments into the HTS material.
  • additional electrically conductive material is cladded to the HTS material or embedded as filaments into the HTS material.
  • the superconducting magnet system comprises a circuit with a contactor, wherein the circuit is arranged in parallel to the MPCS between the first electrical current lead and the second electrical current lead in a third temperature region.
  • the third temperature region has a normal temperature around room temperature or has the same temperature as the first temperature region or as the second temperature region.
  • the high temperature superconducting material, HTS of the magnet persistent current switch, MPCS has a high resistance in normal state. It is advantageous if the copper cladding/filaments do not form one long conductor, in order to achieve a high resistance in normal state.
  • the high temperature superconducting material, HTS of the magnet persistent current switch, MPCS is made of a ceramic material.
  • the high temperature superconducting material, HTS of the magnet persistent current switch, MPCS has a resistance suitable to minimize dissipation when energizing the superconducting magnet coil.
  • Most of the high temperature superconducting materials are ceramic materials having a very high resistance in normal state. In case the HTS material of the MPCS becomes normal, its resistance becomes very high. In that case the dissipation due to the energize process is very low, apart from the heater to keep it in the normal state. In normal operation, i.e., when the magnet is in persistent mode, the magnet current runs through the MPCS. This is also the case for the HTS MPCS.
  • MPCS has a resistance suitable to minimize dissipation when energizing the superconducting magnet coil to prevent an excessive heat in the HTS material that leads to electrical arcing and most probably to a damage of the magnet to a level that it needs to be replaced.
  • the high temperature superconducting, HTS current leads and the high temperature superconducting, HTS magnet persistent current switch, MPCS are separate components.
  • HTS current leads and the high temperature superconducting, HTS magnet persistent current switch, MPCS are integrated components forming one long high temperature superconducting, HTS lead. This has the advantage that unnecessary contacts and welds are avoided.
  • the invention further relates to a magnetic resonance examination system, the magnetic resonance examination system comprising a superconducting magnet system as described above.
  • the invention also relates to a method for controlling a ramp-up process for a superconducting magnet system, the method comprising the following steps:
  • the invention also relates to a method for controlling a ramp-down process for a superconducting magnet system, the method comprising the following steps:
  • the invention also relates to a method for energizing a superconducting magnet system, the method comprising the following steps:
  • the current I remains below a max I(T) including a margin to Ic(T), wherein Ic(T) is the maximum current that can be carried by the superconducting magnet coil without generating a Loss of Field.
  • an energizing speed dI/dT is determined by the speed of cooling down of the superconducting magnet coil.
  • the method for energizing a superconducting magnet system can be used independently of the superconducting magnet system described above. In an embodiment of the invention, however, it may be provided that the superconducting magnet system is a previously described superconducting magnet system with a magnet persistent current switch as described above.
  • the step of providing a superconducting magnet system comprises the step of providing a superconducting magnet system, wherein the MPCS is made of a high temperature superconductor, HTS.
  • the invention also relates to a computer program product comprising instructions which, when the program is executed by a computer, cause the computer to carry out the steps of the method for energizing a superconducting magnet system as described above.
  • Fig. 1 schematically depicts a superconducting magnet system 1 with a magnet persistent mode switch 8 in a first temperature region and a magnet power supply 4 according to the state of the art.
  • the superconducting magnet system 1 comprises a cryostat, including a cooling system for cooling different regions 5, 6, 7 of the superconducting magnet system to different temperatures.
  • the system further comprising a vessel 19 in which the different temperature regions 5, 6, 7 are arranged and a superconducting coil 2 with at least a superconducting coil winding 3 for generating a magnetic field.
  • the coil winding 3 is located in a first temperature region 5, the first temperature region 5 having a temperature below a critical temperature of a low temperature superconductor (LTS). This part of the cryostat is therefore cooled to a temperature of about 4K (2 nd stage of cold head).
  • LTS low temperature superconductor
  • the system further comprises an electrical current lead assembly 9 for transferring electrical current to the superconducting coil winding 3, wherein the assembly comprises a first current lead 10 and a second current lead 11, wherein each lead 10, 11 is electrically connected with the superconducting coil winding 3.
  • the current leads 10, 11 run all the way up to the outside of the magnet cryostat to a region that is close to room temperature (300K) and are connected to a power supply 4.
  • a second temperature region 6 is cooled to about 40K (1 st stage of the cold head).
  • the superconducting magnet system 1 further comprises a magnet persistent current switch 8 (MPCS) located in the first temperature region 5 having a temperature below a critical temperature of a low temperature superconductor (LTS).
  • MPCS magnet persistent current switch 8
  • the MPCS 8 is arranged between the first electrical current lead 10 and the second electrical current lead 11 and the MPCS 8 being adapted to switch between an open state and a closed state of the superconducting magnet coil 2.
  • the MPCS 8 in Fig. 1 is drawn in its open state, i.e., where the superconductor of the MPCS 8 has been warmed up to become normal.
  • the energize or discharge procedure is quite simple.
  • the energize procedure starts with the magnet persistent mode switch 8 (MPCS): the superconducting persistent current loop has to be opened by heating a part of this closed loop.
  • MPCS magnet persistent mode switch 8
  • the magnet power supply 4 can apply voltage to the selfinductance of the superconducting coil 2, but the resistive part of the circuit 8 (MPCS) is connected in parallel of this.
  • the applied voltage leads to a current increase in this magnet self inductance.
  • a part of the current is running through the normal wire of the MPCS 8 and dissipates energy and this keeps the MPCS at a sufficiently high temperature to keep it normal.
  • the heating element is usually not needed at this phase of the process.
  • Fig. 2 schematically depicts a superconducting magnet system 1 with a magnet persistent mode switch 8 (MPCS) in a high temperature superconducting (HTS) temperature region 6 and a circuit 14 with a contactor 15 parallel to the MPCS 8 according to an embodiment of the invention.
  • Fig. 2 shows a superconducting coil 2 with a least a superconducting coil winding 3 for generating a magnetic field.
  • the superconducting coil winding 3 is located in a first temperature region 5 wherein the first temperature region 5 has a temperature below a critical temperature of a low temperature superconductor, LTS.
  • the superconducting magnet system 1 comprises an electrical current lead assembly 9 for transferring electrical current to the superconducting coil winding 3.
  • the electrical current lead assembly 9 consists of a first current lead 10, 12 and a second current lead 11, 13, wherein each current lead 10, 11 is electrically connected with the superconducting coil winding 3.
  • the first current lead 12 and the second current lead 13 are made of a high temperature superconductor, HTS.
  • the superconducting magnet system 1 shown in Fig. 2 further comprises a magnet persistent current switch 8, MPCS made of a high temperature superconductor, HTS, and thermally connected to a second temperature region 6.
  • the second temperature region 6 has a temperature below a critical temperature of a high temperature superconductor, HTS.
  • the region is e.g., cooled to about 40K.
  • the superconducting magnet system 1 further comprises a circuit 14 with a contactor 15, wherein the circuit 14 is arranged in parallel to the MPCS 8 between the first electrical current lead 10 and the second electrical current lead 11 in a third temperature region 7. Wherein a third temperature region is a region that is close to room temperature (300K).
  • the superconducting magnet system 1 comprising a power supply 4 for providing an electrical current to the electrical current lead assembly 9.
  • the first electrical current lead 10 and the second electrical current lead 11 each comprising a contactor 16, 17 wherein the contactors 16, 17 are arranged in the third temperature region 7 between the power supply 4 and the circuit 14 with the contactor 15.
  • the normal temperature of the parallel contactor 15 may only be the case during the energize/discharge process. Depending where it is connected to the current leads 10,11 (above or below contactors 16, 17), the parallel contactor 15 is at the third temperature region 7 (normal temperature) or at the second temperature region 6 ( ⁇ 40K).
  • the high temperature superconducting material is a copper-oxide based high temperature superconducting material.
  • the high temperature superconducting material, HTS of the magnet persistent current switch 8, MPCS has a resistance suitable to minimize dissipation when energizing the superconducting coil 2.
  • HTS current leads 12, 13 connecting the MPCS 8 with the superconducting coil winding 3 comprises metal especially copper.
  • high temperature superconductor filaments can be embedded in a copper matrix.
  • Figs. 3 a) and 3 b) schematically depicts electrical current lead assemblies 9 of a superconducting magnet system 1 according to an embodiment of the invention.
  • the high temperature superconducting current leads 12, 13 and the high temperature superconducting magnet persistent current switch 8 are separate components as shown in Fig. 3 a) .
  • Fig. 3 b) an alternative is shown where the high temperature superconducting current leads 12, 13 and the high temperature superconducting magnet persistent current switch 8 are integrated components forming one long high temperature superconducting lead. This has the advantage that unnecessary contacts and welds are avoided.
  • Fig. 4 shows two flow charts of a method for controlling a ramp-up process shown in Fig. 4 a) and for controlling a ramp-down process shown in Fig. 4 b) of a superconducting magnet system 1 according to an embodiment of the invention.
  • a zero boil-off (ZBO) magnet current leads are inserted prior to the actual energize or discharge procedure and removed after it.
  • the energize procedure starts with the magnet persistent mode switch 8, MPCS: the superconducting persistent current loop has to be opened by heating a part of this closed loop.
  • MPCS the superconducting persistent current loop has to be opened by heating a part of this closed loop.
  • the magnet power supply 4 can apply a voltage to the self-inductance of the magnet coil 2, but the resistive part of the circuit (MPCS) is connected in parallel of this.
  • the applied voltage leads to a current increase in this magnet self-inductance.
  • a part of the current is running through the normal wire of the MPCS 8 and dissipates energy and this keeps the MPCS 8 at a sufficiently high temperature to keep it normal.
  • the heating element 18 is usually not needed at this phase of the process.
  • the current is kept constant (dissipation in MPCS 8 stops) and if the heating element 18 would still be needed, this is switched off.
  • the MPCS 8 is cooling down and is getting superconducting again, the magnet coil 2 is energized.
  • the discharge process is similar, but at the start of this process the current from the magnet power supply 4 has to be at a similar level as the current in the magnet coil 2.
  • the method for controlling a ramp-up process for a superconducting magnet system 1 starts with step 400 by providing a superconducting magnet system 1 according to claim 1 of the invention.
  • Fig. 4 a) describes the ramp-up process starting at zero current.
  • the magnet whould have been discharged partially, e.g., for shimming the magnet, the energizing process looks a bit different. Then the current from the power supply 4 must be set at the right level before opening the MPCS 8, similar to the first part of the ramp-down process.
  • step 410 the contactor 15 of the circuit 14 arranged in parallel to the magnet persistent current switch 8, MPCS in the third temperature region 7, is opened.
  • the MPCS 8 is opened by switching on the heating element 18 of the MPCS 8.
  • step 430 the contactors 16, 17 of the first current lead 10 and the second current lead 11 are closed. Since at the start of the ramp-up process there is no current in the superconducting coil 2, the order of steps 410 to 430 does not matter.
  • the contactors 16, 17 are implemented in the third temperature region 7.
  • the third temperature region can be e.g., a third temperature region around 300 K.
  • the contactors 16, 17 can be implemented at the second temperease 6 region at 40K as well.
  • the practical limitation is that the contactors 16, 17 are preferably placed in a low-field area and that is close to the outside of the cryostat.
  • step 440 the superconducting magnet coil 2 is energized until full current.
  • step 450 the contactor 15 of the circuit 14 arranged in parallel to the MPCS 8 in the third temperature region 7 is closed.
  • the MPSC 8 is closed by switching off the heating element 18 of the MPSC 8.
  • step 470 the current from the power supply 4 is set to zero.
  • step 480 the contactors 16, 17 in the third temperature region 7 of the first current lead 10 and the second current lead 11 are opened. The superconducting magnet system 1 is now ramped-up.
  • Fig. 4 b shows a flow chart of a method for controlling a ramp-down process for a superconducting magnet system 1.
  • the method starts in step 500 with providing a superconducting magnet system 1 according to claim 1 of the invention.
  • step 510 the contactors 16, 17 of the first current lead 10 and the second current lead 11 are closed.
  • the contactors 16, 17 are implemented in the third temperature region 7.
  • the third temperature region can be e.g., a temperature region around 300K.
  • the contactors 16, 17 can be implemented at the second temperautre region at 40K as well.
  • the practical limitation is that the contactors 16, 17 are preferably placed in a low-field area and that is close to the outside of the cryostat.
  • step 520 closing the contactor 15 of the circuit 14 arranged in parallel to the magnet persistent current switch 8, MPSC in the third temperature region 7 is closed.
  • step 530 a current from the power supply 4 is set to the same current as in the superconducting coil 2.
  • step 540 the MPSC 8 is opened by switching on the heating element 18 of the MPSC 8.
  • step 550 the superconducting magnet coil 2 is discharged until zero current.
  • step 560 the MPSC 8 is closed by switching off the heating element 18 of the MPSC 8.
  • step 570 the contactor 15 of the circuit 14 arranged in parallel to the MPSC 8 is closed.
  • step 580 opening the contactors 16, 17 in the third temperature region 7 of the first current lead 10 and the second current lead 11 are opened. Since the current is zero the order of steps 560 to 580 does not matter.
  • the superconducting magnet system 1 is now ramped down.
  • Fig. 5 shows a diagram of the temperature and the current plotted against the time in seconds according to the state of the art.
  • the critical temperature of the superconducting coil 2 at the end of the energization process must have a sufficiently large margin compared to the temperature at the end of the energize process (T AutoDischarge ) in order to avoid a Loss of Field (quench).
  • T AutoDischarge the temperature at the end of the energize process
  • a higher critical temperature is achieved by adding more superconductor wire to the coils and this is expensive.
  • the energize may start when the temperature drops below 7K, i.e., where the maximum allowed current becomes >0.
  • the maximum allowed current increases further and the energize current can be increased to the maximum allowed value.
  • the additional energize current is kind of "titrated" to the magnet, based on the actual temperature and the related maximum allowed current.
  • Fig. 6 shows a diagram of a critical current and a simplified curve for maximum allowed current as function of temperature according to an embodiment of the invention.
  • Fig. 7 shows a flow chart of a method for energizing a superconducting magnet system 1 according to another embodiment of the invention.
  • the method starts with step 700 by providing a superconducting magnet system 1 wherein the superconducting magnet system 1 comprises a superconducting coil 2 with at least a superconducting coil winding 3 for generating a magnetic field, wherein the superconducting coil 2 is in thermal contact with a first temperature region 5 having a temperature below a critical temperature of a low temperature superconductor, LTS, the system further comprising a power supply 4 and a magnet persistent current switch 8, MPCS, wherein the MPCS 8 is arranged to switch between an open state and a closed state of the superconducting magnet coil 2.
  • MPCS magnet persistent current switch
  • the method for energizing a superconducting magnet system 1 can be used independently of the superconducting magnet system 1 as described in claim 1. In an embodiment of the invention, however, it may be provided that the superconducting magnet system 1 is a previously described superconducting magnet system 1 with a magnet persistent current switch (MPCS) 8 as claimed in claim 1.
  • MPCS magnet persistent current switch
  • a current generated by the power supply 4 is set to an initial current value.
  • step 720 the MPCS 8 is activated to its open position and connecting the superconducting magnet coil 2 and the power supply 4, when the actual temperate T actual of the superconducting coil winding 3 falls below the superconducting critical temperature T c (I) at the actual electrical current density minus a safety margin ⁇ T which is higher than the ultimate operating temperature T op .
  • step 730 the superconducting magnet coil 2 is energized with a current, wherein the current and the energizing speed dl/dt is adjusted according to the temperature decrease during cooling of the superconducting coil winding 3, while keeping the actual temperature within the safety margin.
  • the step of energizing the superconducting magnet coil 2 with a current takes place at a higher temperature than the superconducting critical temperature T c (I) at full current.
  • the MPCS 8 is activated to its close position when the target magnetic field strength is reached, thereby placing the superconducting magnet coil 2 in a closed circuit.
  • Fig. 8 shows a diagram of the temperature and current as function of time for a method for energizing a superconducting magnet system according to the state of the art compared with the temperature and current as function of time for a method for energizing superconducting magnet system 1 according to an embodiment of the invention.
  • the ramp speed is now a function of the cool down speed and is in general much lower than based on according to the 5V output of the magnet power supply.
  • Fig. 9 shows a diagram of the temperature and current as function of time for a method for energizing a superconducting magnet system according to the state of the art compared with the temperature and current as function of time for a method for energizing superconducting magnet system 1 with reduced T AutoDischarge according to an embodiment of the invention.
  • Fig. 9 is similar to Fig. 8 , but with a 1K lower T AutoDischarge . Even for this situation the magnet is faster on field than with the existing energize procedure and with the original T AutoDischarge . This is the case when less superconductor would be used. That is the big (financial) advantage of using this energize idea.
  • Fig. 10 shows a diagram of the temperature and current as function of time for a method for energizing a superconducting magnet system according to the state of the art compared with the temperature and current as function of time for a method for energizing superconducting magnet system 1 according to an embodiment of the invention.
  • Advantages that can be seen in Fig. 10 are shorter shim iterations and a faster taking the magnet back to field after a turn off of the magnetic field by initiating an automated ramp-up, minimizing operational downtime. This is the situation of faster shimming (discharge and faster energize again). You do not have to wait with cooling down until T energize has been reached. Furthermore, a shorter installation time and major cost down on superconductors can be achieved.
EP21150247.1A 2021-01-05 2021-01-05 Système d'aimant supraconducteur et procédé pour faire fonctionner le système Withdrawn EP4024415A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023144247A1 (fr) 2022-01-27 2023-08-03 Koninklijke Philips N.V. Commutateur de courant persistant pour un électroaimant supraconducteur

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645830A1 (fr) * 1993-09-20 1995-03-29 Hitachi, Ltd. Commutateur à courant permanent et système magnétique supraconducteur
WO1998000848A1 (fr) * 1996-07-02 1998-01-08 American Superconductor Corporation Aimants supraconducteurs ameliores et sources d'alimentation pour dispositifs supraconducteurs
WO2017178560A1 (fr) * 2016-04-12 2017-10-19 Koninklijke Philips N.V. Conducteur et coupure thermique destinés à la montée en tension d'un mri ou d'un autre aimant supraconducteur
WO2020254158A1 (fr) * 2019-06-20 2020-12-24 Koninklijke Philips N.V. Protection contre la transition de conducteurs supraconducteurs à haute température (hts)

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0645830A1 (fr) * 1993-09-20 1995-03-29 Hitachi, Ltd. Commutateur à courant permanent et système magnétique supraconducteur
WO1998000848A1 (fr) * 1996-07-02 1998-01-08 American Superconductor Corporation Aimants supraconducteurs ameliores et sources d'alimentation pour dispositifs supraconducteurs
WO2017178560A1 (fr) * 2016-04-12 2017-10-19 Koninklijke Philips N.V. Conducteur et coupure thermique destinés à la montée en tension d'un mri ou d'un autre aimant supraconducteur
WO2020254158A1 (fr) * 2019-06-20 2020-12-24 Koninklijke Philips N.V. Protection contre la transition de conducteurs supraconducteurs à haute température (hts)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023144247A1 (fr) 2022-01-27 2023-08-03 Koninklijke Philips N.V. Commutateur de courant persistant pour un électroaimant supraconducteur

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