HINS Superconducting Lens and Cryostat Performance

Abstract

Abstract-Fermi National Accelerator Laboratory is involved in the development of a 60 MeV superconducting linac. This linac is part of the High Intensity Neutrino Source (HINS) R&D Program. The initial beam acceleration in the front end section of the linac is achieved using room temperature spoke cavities, each of which is combined with a superconducting focusing solenoid. These solenoid magnets are cooled with liquid helium at 4.5K, operate at 250 A and have a maximum magnetic field strength of 7.5 T. A prototype solenoid cryostat was built and tested at the Fermilab Magnet Test Facility. This paper discusses the test results of the prototype and compares the measured and estimated performance of the cryostat. We also present the methods and results for measuring and fiducializing the axis of the solenoid lens.

Certification of Superconducting Solenoid-Based Focusing Lenses

“…3 illustrates the quench behavior at 1 A/s ramp rate of HCHB01 along with those Type-2 solenoids re-tested at MTF, and with a temperature-dependence prediction. The HCH-P-001 data are shown as well (scaled by 245/260A, due to the different solenoid design and higher maximum quench current): this was the only other device tested at 4.6 K in a cryostat, and it showed very little dependence on ramp rate [5].…”

“…A prototype Type-1 cryostat was built using one of the prototype R&D solenoids, and early test results were previously reported [5]. This prototype assembly used a pair of vapor-cooled leads, rather than HTS leads which were not yet available at the time; also, unlike the production design, it did not have a cold valve for LN 2 control.…”

“…The first Type-2 lens has been tested [7] at the Fermilab Magnet Test Facility (MTF) using a specially designed cryogenic interface to one of the Tevatron magnet test stands, as was done with the prototype cryostat [5]. The interface provides insulating vacuum, 90 K liquid nitrogen for thermal shields, and 4.3-4.6 K liquid helium for the superconducting coils.…”

“…As with the prototype cryostat solenoid [5], alignment measurements were made using Single Stretched Wire (SSW) techniques, which allow wire positioning control at the level of 1 micron. A Vibrating Wire (VW) technique [8] was developed and tested on the prototype.…”

Test Results for HINS Focusing Solenoids at Fermilab

“…Re-testing at Fermilab of approximately one in four of the production magnets is planned as a quality assurance step prior to installation into production cryostats. CH_01-1 was mounted in a prototype cryostat and the assembly has been tested [13].…”