How the Performance of a Superconducting Magnet Is Affected by the Connection Between a Small Cooler and the Magnet

Green, M.A.

doi:10.1109/tasc.2006.871294

Cited by 9 publications

(13 citation statements)

References 5 publications

(6 reference statements)

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“…Simply immersing the cold head of the cooler into a bath of liquid cryogen does not work if one wants a low temperature drop between the source of the heat and the cold head. A recondensing gravity thermal siphon circuit shown in FIGURE 1 will have a much lower ∆T between the magnet and the cooler cold head than any other method of connecting the cold head to the load [3]. Excellent vibration isolation can be achieved because the distance from the load to the cold head can be increased and the elements connecting the two can be flexible within the pressure constraints of the cooling circuit.…”

Section: Re-condensation Of Helium and Hydrogen Using A Coolermentioning

confidence: 99%

“…As a result, the coolers must be located some distance (~0.3 to 0.5 meters) from the magnet module being cooled. The coolers will be connected to the magnet cold mass through a two-phase helium thermal siphon cooling system [3], where the liquid helium is around the magnet cold mass. Thus the re-condensation of helium is of great importance.…”

Section: Introductionmentioning

confidence: 99%

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Re-Condensation and Liquefaction of Helium and Hydrogen Using Coolers

Green¹,

Weisend²

2010

AIP Conference Proceedings

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A helium liquefier using three 4 k pulse tube cryocoolers AIP Conference Proceedings 1434, 1640 (2012); 10.1063/1.4707096 RE-CONDENSATION AND LIQUEFACTION OF HELIUM AND HYDROGEN USING COOLERS M. A. GreenLawrence Berkeley National Laboratory Berkeley CA 94720, USA ABSTRACTCoolers are used to cool cryogen free devices at temperatures from 5 to 30 K. Cryogen free cooling involves a temperature drop within the device being cooled and between the device and the cooler cold heads. Liquid cooling with a liquid cryogen distributed over the surface of a device combined with re-condensation can result in a much lower temperature drop between the cooler and the device being cooled. The next logical step beyond simple re-condensation is using a cooler to liquefy the liquid cryogen in the device. A number of tests of helium liquefaction and re-condensation of helium have been run using a pulse tube cooler in the drop-in mode. This report discusses the parameter space over which re-condensation and liquefaction for helium and hydrogen can occur.

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Section: Re-condensation Of Helium and Hydrogen Using A Coolermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Re-Condensation and Liquefaction of Helium and Hydrogen Using Coolers

Green¹,

Weisend²

2010

AIP Conference Proceedings

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“…The tracker magnet will be kept cold with two or three 1.5 W coolers. The connection between the 4 K second stage of the coolers and the magnet cold mass is through thermal siphon heat pipes [7].…”

Section: The Tracker Magnet Coil Designmentioning

confidence: 99%

The Design Parameters for the MICE Tracker Solenoid

Green

Chen

Juang

et al. 2007

IEEE Trans. Appl. Supercond.

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Abstract-The first superconducting magnets to be installed in the muon ionization cooling experiment (MICE) will be the tracker solenoids. The tracker solenoid module is a five coil superconducting solenoid with a 400 mm diameter warm bore that is used to provide a 4 T magnetic field for the experiment tracker module. Three of the coils are used to produce a uniform field (up to 4 T with better than 1 percent uniformity) in a region that is 300 mm in diameter and 1000 mm long. The other two coils are used to match the muon beam into the MICE cooling channel. Two 2.94-meter long superconducting tracker solenoid modules have been ordered for MICE. The tracker solenoid will be cooled using two-coolers that produce 1.5 W each at 4.2 K. The magnet system is described. The decisions that drive the magnet design will be discussed in this report.

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“…The connection between the cooler second-stage and the cold mass will be made using a natural convection thermal siphon type of circuit that condenses helium gas from the magnet and distributes the liquid helium back to the magnet cold mass [12], [13]. The system should be designed to minimize the temperature drop between the magnet hot spot and the second stage cold heads [14]. This improves the temperature margin of the superconducting magnets.…”

Section: Introductionmentioning

confidence: 99%

“…The third ΔT is along the copper plate to the ring around the cooler first stage. Arrangement A in Figure 1 has been discussed in References [12] through [14]. This configuration permits on to feed the condensed liquid to the bottom of the helium tank while feeding the boil-off helium to the space just above the condenser.…”

Section: Introductionmentioning

confidence: 99%

Results from the Cooler and Lead Tests

Green¹

2010

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The report presents the results of testing MICE spectrometer magnet current leads on a test apparatus that combines both the copper leads and the high temperature superconducting (HTS) leads with a single Cryomech PT415 cooler and liquid helium tank. The current is carried through the copper leads from 300 K to the top of the HTS leads. The current is then carried through the HTS leads to a feed-through from the vacuum space to the inside of a liquid helium tank. The experiment allows one to measure the performance of both cooler stages along with the performance of the leads. While the leads were powered we measured the voltage drops through the copper leads, through the HTS leads, through spliced to the feed-through, through the feed-through and through the low-temperature superconducting loop that connects one lead to the other.Measurements were made using the leads that were used in spectrometer magnet 1A and spectrometer magnet 2A. These are the same leads that were used for Superbend and Venus magnets at LBNL. The IL/A for these leads was 5.2x10 6 A m -1 . The leads turned out to be too long. The same measurements were made using the leads that were installed in magnet 2B. The magnet 2B leads had an IL/A of 3.3x10 6 A m -1 . This report discusses the cooler performance and the measured electrical performance of the lead circuit that contains the copper leads and the superconducting leads. All of the HTS leads that were installed in magnet 2B were current tested using this apparatus.

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How the Performance of a Superconducting Magnet Is Affected by the Connection Between a Small Cooler and the Magnet

Cited by 9 publications

References 5 publications

Re-Condensation and Liquefaction of Helium and Hydrogen Using Coolers

Re-Condensation and Liquefaction of Helium and Hydrogen Using Coolers

The Design Parameters for the MICE Tracker Solenoid

Results from the Cooler and Lead Tests

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