A safe, low current, high gradient, superconducting quadrupole magnet for high energy physics beam transport

A superconducting quadrupole magnet has been fabricated and tested that generates a gradient of 60 T/m at a peak operating current of 1100 amperes. The cold bore of the magnet is 12.7 cm in diameter and 2.8 m long, and the unwanted field multipoles sum to 4 parts per thousand of the quadrupole field at a bore radius of 5.0 cm. The magnet operates safely without quench protection and peak coil temperatures following quenches deliberately induced at full field do not exceed 50 K. Testing at the design gradient of 50 T/m indicates a beam energy deposition quench threshold of approximately 5 mJ/cm
³
.