CN102751699B - Nuclear magnetic resonance superconducting magnetic quenching protection device - Google Patents
Nuclear magnetic resonance superconducting magnetic quenching protection device Download PDFInfo
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- CN102751699B CN102751699B CN201210202216.7A CN201210202216A CN102751699B CN 102751699 B CN102751699 B CN 102751699B CN 201210202216 A CN201210202216 A CN 201210202216A CN 102751699 B CN102751699 B CN 102751699B
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Abstract
A nuclear magnetic resonance superconducting magnetic quenching protection device consists of a plurality of main coil divided circuits (3) and a compensation coil divided circuit (4). Each main coil divided circuit (3) is formed by serially joining a diode pair (2) with a compensation coil heater (R2). The compensation coil divided circuit (4) is formed by serially joining a diode pair (2) and a heater assembly (6) which is formed by serially joining all main coil heaters (R1a to R1d). Two ends of each main coil (L1a to L1d) are respectively connected with one main coil divided circuit (3) in parallel. Two ends of a compensation coil (L2) of a superconducting magnetic body (1) are connected with one compensation coil divided circuit (4) in parallel.
Description
Technical field
The present invention relates to a kind of protective device for superconducting magnet quench, particularly for the not impaired protective device when quench of the superconducting magnet in the nuclear magnetic resonance imaging system of highfield.
Background technology
Superconductor for superconducting magnet only could embody superconducting characteristic when meeting specified conditions (as temperature, magnetic field, current density).Once condition is destroyed, will there is quench in superconductor.The sub-fraction of superconductor is no longer superconducting state, and enters resistance states.Any electric current flowing through this active component all can cause local joule to be generated heat.This will cause the neighbouring part quench of this superconductor, and result forms larger resistance volume, and this causes again further joule heat.
The quench process of superconducting magnet is the electromagnetic energy thermotropism transformation of energy process be stored in superconductor.If heat energy evenly discharges in whole magnet after superconducting magnet quench, the temperature rise of hot spot caused is more much lower during the release of local in superconducting magnet than heat energy, therefore once detect in superconducting magnet and occur Signal of quench, the energy that should superconducting magnet be made as far as possible to store in whole magnet evenly release or by loop by its energy ezpenditure in external resistance.In fact the quench of superconducting magnet always from local, i.e. so-called some disturbance.The quench event of superconducting magnet has very large randomness, and quench propagation is very complicated physical process.
Highfield superconducting magnet of NMR refers generally to central magnetic field and is greater than 7T.Usually central field is called highfield nmr magnet higher than the nmr magnet of 7T.Highfield superconducting magnet of NMR, generally by organizing main coil and one group of bucking coil forms, often organizes coil winding on same coil rack more.Many groups main coil coaxially fits together from inside to outside, and bucking coil coaxial package is at the outermost layer of main coil.Have very strong electromagnetic coupled between each group of coil of highfield superconducting magnet of NMR, but each thermal coupling organized between coil is very poor.When highfield superconducting magnet of NMR runs, the energy storage density of its inside is very high.The most effective guard method is exactly avoid the heat be harmful to concentrate by expansion quench process, and heat is as far as possible evenly consumed in whole superconducting magnet.If superconducting magnet, after the locally generation quench of a certain coil, expands to whole superconducting magnet rapidly, cause whole quench, just mean that neither one part can reach dangerous temperature.
Highfield superconducting magnet of NMR is that the hot(test)-spot temperature after effectively reducing quench generally uses sectionalised protection.Highfield superconducting magnet of NMR forms by being separated from each other many group coil coaxial combination, between each group coil except electromagnetic coupled, do not have thermal coupling.Therefore in the middle of, a certain deactivation coil time-out may produce contiguous coil current and increases fast, the energy of its quench coil is quickly transferred in non-quench coil, the electromagnetic stress causing adjacent coils to produce increases fast, make one section of coil quench that the electric current increase of superconducting coil is higher, coil is burned because heat does not evenly discharge.Sharply raise to overcome this electric current, the mechanical instability of coil and heat is caused too to concentrate the problem burning out coil, make superconducting coil shift to an earlier date quench at each group of coil surface mounting heater, the energy even of superconducting magnet is released among whole superconducting magnet.
In traditional segmentation quench protection system, the heater that each group coil surface is installed is connected in a certain segmentation loop or certain several segmentation loop respectively.There is provided energy by the shunt current in segmentation loop to heater, make heater generate heat thus trigger corresponding coil quench.Because the appearance of quench has randomness, in each segmentation loop, occur that the time of shunt current and size can be different and have greatly changed with the coil that quench occurs at first.Therefore respectively organize the be triggered sequential of quench of coil and just there is randomness, be difficult to control.Respectively organize electromagnetic coupled between coil for highfield superconducting magnet of NMR very strong, and energy storage density is very high, it is excessive that this uncontrolled quench accelerator still can cause certain to organize coil-induced electric current, or temperature rise is too high.
Summary of the invention
The object of the invention is to overcome known quench protection system to be applied in the superconducting magnet of NMR protection of highfield produce above-mentioned defect, a kind of new quenching protection device is proposed.
The present invention the superconducting magnet that is suitable for by organizing main coil and one group of bucking coil is composed in series more, all main coils of superconducting magnet and one group of bucking coil be radially arrangement and do not have thermo-contact coaxially.Superconducting magnet two ends are parallel with main superconducting switch, run with the persistent mode realizing superconducting magnet.
Quenching protection device of the present invention is made up of multichannel main coil shunt circuit and a road bucking coil shunt circuit.Wherein the quantity of main coil shunt circuit is identical with the set of main coils number in superconducting magnet, an often group main coil two ends main coil shunt circuit in parallel of superconducting magnet.A bucking coil two ends bucking coil shunt circuit in parallel of superconducting magnet.
The often group coil of superconducting magnet is all equipped with the heater of close thermal contact, can by pasting at the outer surface often organizing coil of superconducting magnet the close thermal contact that heater realizes coil and heater.Wherein, the outer surface often organizing main coil of superconducting magnet pastes a heater respectively, and these heaters are called main coil heater, and all main coil heater connected in electrical series form heater assembly together.Bucking coil outer surface pastes the heater with set of main coils number equal number, and these heaters are called bucking coil heater.
The main coil shunt circuit that the present invention proposes is made up of a diode pair bucking coil heater of connecting.The heater assembly of bucking coil shunt circuit described in a diode pair is connected forms.Two diodes that described diode pair is connected by inverse parallel mode back-to-back form.
When any main coil quench of superconducting magnet, along with the increase of normal region resistance, this main coil circulation electric current by branching part in main coil shunt circuit.Bucking coil heater in this main coil shunt circuit will generate heat, thus triggers bucking coil quench.After bucking coil quench, bucking coil circulation electric current by branching part in bucking coil shunt circuit.All main coil heaters will flow through the identical electric current of size simultaneously, will trigger respective main coil quench respectively after the heating of these main coil heaters.Its heating power can be changed by the size changing each main coil heater, thus control it and trigger corresponding main coil quench required time.Therefore quenching protection device of the present invention can to control in superconducting magnet each group coil wittingly and to be triggered the priority sequential of quench.
Accompanying drawing explanation
Fig. 1 is the quenching protection device schematic diagram of the embodiment of the present invention, in figure: 1 superconducting magnet, L1a-L1d main coil, L2 bucking coil, 2 diode pairs, 3 main coil shunt circuits, 4 bucking coil shunt circuits, R1a-R1d main coil heater, R2 bucking coil heater, 5 main superconducting switchs, 6 heater assemblies.
Embodiment
The present invention is further illustrated below in conjunction with the drawings and specific embodiments.
The present invention the superconducting magnet 1 that is suitable for be composed in series by organizing main coil L1a-L1d and group of bucking coil L2 more, all main coil L1a-L1d and groups of bucking coil L2 of superconducting magnet 1 are radially arrangement and do not have thermo-contact coaxially.Superconducting magnet 1 two ends are parallel with main superconducting switch 5, run with the persistent mode realizing superconducting magnet 1.
Quenching protection device of the present invention is made up of multichannel main coil shunt circuit 3 and a road bucking coil shunt circuit 4.The quantity of described main coil shunt circuit 3 is identical with the group number of the main coil L1a-L1d in superconducting magnet 1, often organizes each main coil shunt circuit 3 in parallel in main coil L1a-L1d two ends.A bucking coil L2 two ends bucking coil shunt circuit 4 in parallel of superconducting magnet 1.
The all coils of superconducting magnet 1, comprises the heater that main coil L1a-L1d and bucking coil L2 is equipped with close thermal contact, can by pasting at the outer surface often organizing coil of superconducting magnet 1 close thermal contact that heater realizes coil and heater.The outer surface often organizing main coil pastes a heater respectively, and these heaters are called main coil heater R1a-R1d.The outer surface of main coil L1a pastes main coil heater R1a, and the outer surface of main coil L1b pastes main coil heater R1b, by that analogy.All main coil heater R1a-R1d connected in electrical series form heater assembly 6 together.Bucking coil L2 outer surface pastes the heater with main coil L1 group number equal number, and these heaters are called bucking coil heater R2.
The main coil shunt circuit 3 that the present invention proposes is made up of a diode pair 2 bucking coil heater R2 that connects.The heater assembly 6 that bucking coil shunt circuit 4 is connected described by a diode pair 2 forms.Two diodes that described diode pair 2 is connected by inverse parallel mode back-to-back form
When any main coil quench of superconducting magnet 1, along with the increase of normal region resistance, this main coil circulation electric current by branching part in the main coil shunt circuit 3 of correspondence.Bucking coil heater R2 in this main coil shunt circuit 3 will generate heat, thus triggers bucking coil L2 quench.After bucking coil L2 quench, bucking coil L2 circulate electric current by branching part in bucking coil shunt circuit 4.All main coil heater R1a-R1d will flow through the identical electric current of size simultaneously, and these main coil heaters R1a-R1d will trigger respective main coil L1a-L1d quench after generating heat respectively.Its heating power can be changed by the size changing main coil heater R1a-R1d, thus control it and trigger corresponding main coil L1a-L1d quench required time.Therefore quenching protection device of the present invention can to control in superconducting magnet 1 each group coil wittingly and to be triggered the priority sequential of quench.
Claims (1)
1. a superconducting magnet of NMR quenching protection device, described superconducting magnet (1) by organizing main coil (L1a-L1d) and one group of bucking coil (L2) is composed in series more, superconducting magnet (1) main coil (L1a-L1d) and the coaxial radially arrangement of bucking coil (L2) and there is no thermo-contact; Superconducting magnet (1) two ends are parallel with main superconducting switch (5); Described quenching protection device is made up of multichannel main coil shunt circuit (3) and road bucking coil shunt circuit (4); It is identical that number organized by the quantity of described main coil shunt circuit (3) and the main coil (L1a-L1d) in described superconducting magnet (1), often organizes each main coil shunt circuit (3) in parallel in two ends of main coil (L1a-L1d); Bucking coil (L2) two ends bucking coil shunt circuit (4) in parallel of superconducting magnet (1),
It is characterized in that: the outer surface often organizing main coil of superconducting magnet (1) pastes a main coil heater; Main coil heater (R1a-R1d) connected in electrical series forms heater assembly (6) together; Bucking coil (L2) outer surface is pasted with the bucking coil heater (R2) organizing number equal number with main coil (L1a-L1d); Described every road main coil shunt circuit (3) is made up of diode pair (2) series connection bucking coil heater (R2); The heater assembly (6) of bucking coil shunt circuit (4) described in a diode pair (2) is connected forms; Two diodes that described diode pair is connected by inverse parallel mode back-to-back form.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201210202216.7A CN102751699B (en) | 2012-06-15 | 2012-06-15 | Nuclear magnetic resonance superconducting magnetic quenching protection device |
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| CN201210202216.7A CN102751699B (en) | 2012-06-15 | 2012-06-15 | Nuclear magnetic resonance superconducting magnetic quenching protection device |
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| CN102751699B true CN102751699B (en) | 2015-05-13 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE102018211511A1 (en) * | 2018-07-11 | 2020-01-16 | Bruker Biospin Gmbh | Superconducting magnetic coil system |
| CN112908608B (en) * | 2021-01-27 | 2021-11-19 | 华中科技大学 | Superconducting magnet system quench protection circuit based on distributed heater network |
| CN114217252B (en) * | 2021-12-14 | 2023-09-29 | 中国科学院合肥物质科学研究院 | Same-winding compensation coil and quench detection system with same |
| CN114221298B (en) * | 2021-12-15 | 2023-11-14 | 中国科学院电工研究所 | Quench protection circuit of high-field high-uniformity superconducting magnet |
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| CN102361318A (en) * | 2011-09-09 | 2012-02-22 | 中国科学院电工研究所 | Superconducting magnet quench protective device with auxiliary superconductive switch |
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| US6717781B2 (en) * | 2001-09-25 | 2004-04-06 | Ge Medical Systems Global Technology Company, Llc | Balanced quench protection circuit |
| JP4933034B2 (en) * | 2004-06-10 | 2012-05-16 | 株式会社日立製作所 | Superconducting coil protection device, NMR device and MRI device |
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| CN102361318A (en) * | 2011-09-09 | 2012-02-22 | 中国科学院电工研究所 | Superconducting magnet quench protective device with auxiliary superconductive switch |
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