The Design and Construction of the MICE Spectrometer Solenoids

Wang, B.; Wahrer, B.; Taylor, C.; Xu, Limin; Chen, J.Y.; Wang, M.; Juang, T.; Zisman, Michael S.; Virostek, Steve; Green, M.A.

doi:10.1109/tasc.2009.2018057

Cited by 16 publications

(12 citation statements)

References 9 publications

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“…In both case the stored energy of these coils is low (less than 0.5 MJ) [5]. Because the stored energy is low, the peak voltage to ground is also low.…”

Section: B Quench Protection Of the Long Solenoidmentioning

confidence: 95%

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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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“…In both case the stored energy of these coils is low (less than 0.5 MJ) [5]. Because the stored energy is low, the peak voltage to ground is also low.…”

Section: B Quench Protection Of the Long Solenoidmentioning

confidence: 95%

“…1 [5]. This magnet consists of two match coils M1 and M2 and three-coil spectrometer section (E1, C, and E2).…”

Section: A Long Solenoid Parametersmentioning

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.

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“…The magnet was trained to seventy percent of full operating in August of 2008 [13]. There were a number of problems uncovered during the cool down and testing of the magnet.…”

Section: Tests Of the First Mice Spectrometer Magnetmentioning

confidence: 99%

Preliminary Test Results for the MICE Spectrometer Superconducting Solenoids

Virostek

Green

et al. 2009

IEEE Trans. Appl. Supercond.

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Abstract-This report describes the MICE spectrometer solenoids as built. Each magnet consists of five superconducting coils. Two coils are used to tune the beam going from or to the MICE spectrometer from the rest of the MICE cooling channel. Three spectrometer coils (two end coils and a long center coil) are used to create a uniform 4 T field (to ±0.3 percent) over a length of 1.0 m within a diameter of 0.3 m. The three-coil spectrometer set is connected in series. The two end coils use small power supplies to tune the uniform field region where the scintillating fiber tracker is located. This paper will present the results of the preliminary testing of the first spectrometer solenoid. Index Terms-Superconducting Solenoid and 4 K Coolers

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“…In the highest current coils in MICE (the tracker solenoid coils), the heat produced in the joints at 275 A would be about 0.76 mW. The tracker solenoids have ten joints [2]. These joints are in liquid helium.…”

Section: Theoretical Calculations Of Mice Coil Joint Resistancementioning

confidence: 99%

The Calculated and Measured Resistance for Splices between Conductors in a MICE Superconducting Coil

Green¹,

Dietderich²,

Higley³

et al. 2009

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The resistance of superconducting joints within MICE coils is an important issue particularly for the coupling coils. The MICE tracker solenoids have only two superconducting joints in the three spectrometer set (end coil 1, the center coil and end coil 2). The AFC magnets may have only a single joint within the coil. The coupling coils may have as many as fifteen joints within the coil, due to relatively short piece lengths of the superconductor. LBNL and ICST looked at three types of coil joints. They are; 1) cold fusion butt joints, 2) side-by-side lap joints, and 3) up-down lap joints. A theoretical calculation of the joint resistance was done at LBNL and checked by ICST. After looking at the theoretical resistance of the three types of joints, it was decided that the cold welded butt joint was not an attractive alternative for joints within a MICE superconducting magnet coil. Side-by-side and up-down lap joints were fabricated at ICST using two types of soft solder between the conductors. These conductor joints were tested at LBNL at liquid helium temperatures over a range of magnetic fields. The joint resistance was compared with the theoretical calculations. Measurements of splice strength were also made at 300 K and 77 K.

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The Design and Construction of the MICE Spectrometer Solenoids

Cited by 16 publications

References 9 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

Preliminary Test Results for the MICE Spectrometer Superconducting Solenoids

The Calculated and Measured Resistance for Splices between Conductors in a MICE Superconducting Coil

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