The role of quench back in quench protection of a superconducting solenoid

Green, M.A.

doi:10.1016/0011-2275(84)90034-1

Cited by 39 publications

(19 citation statements)

References 8 publications

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Section: Index Terms-magnet Quench-back Coil Sub-divisionmentioning

confidence: 99%

“…If it is in good thermal contact with the magnet winding, it will initiate further quenching-effectively increasing quench propagation velocity and therefore reducing the hot spot temperature. It is particularly effective in a situation where the normal zone hits boundaries rather early in the quenching process and thereafter spreads very slowly in the other dimension [1][2][3].Sub-division provides an alternative path for some of the current by connecting shunt resistors across sections of the magnet, and the shunt resistor can absorb some of the stored energy in the coil. So the hot spot temperature of the coil can This paper describes a passive quench protection system that may be applied to a long superconducting solenoid with sub-division.…”

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confidence: 99%

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The Role of Quench-Back in the Passive Quench Protection of Long Solenoids With Coil Sub-Division

Guo¹,

Green

Wang

et al. 2010

IEEE Trans. Appl. Supercond.

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Abstract-This paper describes how a passive quench protection system can be applied to long superconducting solenoid magnets. When a solenoid coil is long compared to its thickness, the magnet quench process will be dominated by the time needed for quench propagation along the magnet length. Quench-back will permit a long magnet to quench more rapidly in a passive way. Quenchback from a conductive (low resistivity) mandrel is essential for spreading the quench along the length of a magnet. The mandrel must be inductively coupled to the magnet circuit that is being quenched. Current induced in the mandrel by di/dt in the magnet produces heat in the mandrel, which in turn causes the superconducting coil wound on the mandrel to quench. Sub-division is often employed to reduce the voltages to ground within the coil. This paper explores when it is possible for quench-back to be employed for passive quench protection. The role of sub-division of the coil is discussed for long magnets. Index Terms-Magnet Quench-back, Coil Sub-division. INTRODUCTION uench-back is a widely used passive quench protection method that enhances the rate of propagation of the normal zone by using a coupled secondary circuit. As quenching proceeds, the secondary will heat up. If it is in good thermal contact with the magnet winding, it will initiate further quenching-effectively increasing quench propagation velocity and therefore reducing the hot spot temperature. It is particularly effective in a situation where the normal zone hits boundaries rather early in the quenching process and thereafter spreads very slowly in the other dimension [1][2][3].Sub-division provides an alternative path for some of the current by connecting shunt resistors across sections of the magnet, and the shunt resistor can absorb some of the stored energy in the coil. So the hot spot temperature of the coil can This paper describes a passive quench protection system that may be applied to a long superconducting solenoid with sub-division. The role of quench-back in the quench protection of such a solenoid is discussed. I. PASSIVE QUENCH PROTECTION OF A LONG SOLENOID A. Long Solenoid ParametersThe solenoid discussed in this paper is a spectrometer magnet used in the MICE project, shown in Fig. 1 [5]. This magnet consists of two match coils M1 and M2 and three-coil spectrometer section (E1, C, and E2). M1 and M2 are used to match the spectrometer section with the MICE cooling channel. The three-coil section produces a uniform magnetic field (±0.3 percent) within a region that is 1000 mm long and 300 mm in diameter. The uniform field section contains a fiveplane scintillating fiber detector for muon beam emittance analysis. The magnet has an Nb-Ti superconductor with a copper to superconductor ratio of four. The insulated conductor dimensions are 1.65 by 1.00 mm. All five coils are wound on a single 6061-T6-aluminum mandrel. The cryostat consists of 4.2 K helium vessel, an 80 K thermal shield, cold mass supports for 500 kN and a 300 K vacuum vessel. The spectrometer se...

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Section: Index Terms-magnet Quench-back Coil Sub-divisionmentioning

confidence: 99%

mentioning

confidence: 99%

The Role of Quench-Back in the Passive Quench Protection of Long Solenoids With Coil Sub-Division

Guo¹,

Green

Wang

et al. 2010

IEEE Trans. Appl. Supercond.

View full text Add to dashboard Cite

show abstract

“…In one magnet quench-back will initiate further quenching, thus effectively increasing quench propagation velocity. It is particularly effective in a situation where the normal zone hits boundaries early in the quench process and thereafter spreads very slowly in the other dimensions [3][4][5]. When magnets are connected in series, quench-back can potentially cause the other magnets to quench even if they are not inductively coupled [6] [7].…”

Section: Introductionmentioning

confidence: 99%

The Role of Quench-Back in the Passive Quench Protection of Uncoupled Solenoids in Series With and Without Coil Sub-Division

Guo

Green

Wang

et al. 2011

IEEE Trans. Appl. Supercond.

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Abstract-This paper is the final paper in a series of papers that discusses passive quench protection for high inductance solenoid magnets [1], [2]. This report describes how passive quench protection system may be applied to superconducting magnets that are connected in series but not inductively coupled. Previous papers have discussed the role of magnet sub-division and quench back from a conductive mandrel in reducing the hot-spot temperature and the peak coil voltages to ground. When magnets are connected in series, quench-back from a conductive mandrel can cause other magnets in a string to quench even without inductive coupling between magnets. The magnet mandrels must be well coupled to the magnet circuit that is being quenched. When magnet circuit sub-division is employed to reduce the voltages-to-ground within magnets, the resistance across the subdivision becomes the most important factor in the successful quenching of the magnet string.Index Terms-Quench-back, Sub-division quench protection

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“…where Ec is the energy that ends up in the coils and the mandrel; Eo is the total stored magnetic energy; and EoR is the magnetic energy extracted by the dump resistor with a resistance R 0 • One can estimate the amount of energy deposited in the dump resistor EoR (assuming an exponential decay with a time constant t1+t2 and very good coupling) using the following expression [2]:…”

Section: Introductionmentioning

confidence: 99%

The role of quench back in quench protection of a superconducting solenoid

Cited by 39 publications

References 8 publications

The Role of Quench-Back in the Passive Quench Protection of Long Solenoids With Coil Sub-Division

The Role of Quench-Back in the Passive Quench Protection of Long Solenoids With Coil Sub-Division

The Role of Quench-Back in the Passive Quench Protection of Uncoupled Solenoids in Series With and Without Coil Sub-Division

Calculation of the pressure rise in the cooling tube of a two-phase cooling system during a quench of an indirectly cooled superconducting magnet

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