Performance of a 14-T CuNb/Nb 3 Sn Rutherford coil with a 300 mm wide cold bore

Proton therapy is a rapidly increasing modality to treat cancerous tumors, but large-scale implementation, and therefore widespread availability for patients, is hindered by the size and upfront investment for treatment facilities. Superconducting technology can enable more compact, and therefore more affordable treatment systems, by increasing the magnetic field in the magnets for the proton accelerator (typically a cyclotron) and in the beam guidance up, over, and into the patient (the gantry). In this article, we discuss research at Varian Medical Systems Particle Therapy GmbH on various superconducting technologies for potential application in future, more compact cyclotrons and gantries. We discuss which technologies are feasible, and to what extent. We demonstrate why certain conductor choices are made, and show the development of novel new conductor and magnet technologies that will be required to enable the next generation of cryogen-free, conduction-cooled compact treatment systems. We conclude that superconductivity is certainly required for the next generation of proton treatment systems, but also that the amount of compactness that can eventually be achieved is not solely determined by the magnetic field strength that is generated in the magnets.

Section: Conductor Optionsmentioning

confidence: 99%

Research at Varian on applied superconductivity for proton therapy

Godeke¹,

Alberty²,

Akcöltekin³

et al. 2020

“…RW forced-flow conductors have been used in several (fusion) coils in the past, e.g. in the Mirror Fusion Test Facility (Livermore, USA), Levitated Dipole Experiment (MIT, USA) and more recently in a 25 T cryogen-free magnet [146] at IMR (Tohoku University, Japan). The disappointing experience from the T-15 tokamak, where the TF coils became resistive with ohmic heating in the kW range right from the first operation in 1988, presumably due to handling during which bending strain reached ±0.8% [147], brought a lot of aversion to the RW technology.…”

Section: Drawbacks and Risks Of The Rw Conceptmentioning

confidence: 99%

Superconductors for fusion: a roadmap

Mitchell

Zheng

Vorpahl³

et al. 2021

110

With the first tokamak designed for full nuclear operation now well into final assembly (ITER), and a major new research tokamak starting commissioning (JT60SA), nuclear fusion is becoming a mainstream potential energy source for the future. A critical part of the viability of magnetic confinement for fusion is superconductor technology. The experience gained and lessons learned in the application of this technology to ITER and JT60SA, together with new and improved superconducting materials, is opening multiple routes to commercial fusion reactors. The objective of this roadmap is, through a series of short articles, to outline some of these routes and the materials/technologies that go with them.

“…All the Nb 3 Sn solenoid coils were made using a react-and-wind (R&W) method. In addition, we applied pre-bending to the reacted Rutherford Nb 3 Sn cables before winding [13][14][15][16]. The load factor of the L1 coil, which operates under the most severe conditions, is 49%.…”

Section: Lts Coilmentioning

confidence: 99%

First performance test of a 25 T cryogen-free superconducting magnet

Awaji

Watanabe

Oguro

et al. 2017

Self Cite

154

A 25 T cryogen-free superconducting magnet (25T-CSM) was developed and installed at the High Field Laboratory for Superconducting Materials (HFLSM), IMR, Tohoku University. The 25T-CSM consists of a high-temperature superconducting (HTS) coil and a low-temperature superconducting (LTS) coil. A high-strength CuNb/Nb3Sn Rutherford cable with a reinforcing stabilizer CuNb composite is adopted for the middle LTS section coil. All the coils were impregnated using an epoxy resin for conduction cooling. Initially, a GdBa2Cu3Oy (Gd123) coil was designed as the HTS insert coil, and then a Bi2Sr2Ca2Cu3Oy (Bi2223) coil was also developed. The HTS insert and the LTS (CuNb/Nb3Sn and NbTi) outsert coils are cooled by two 4K GM and two GM/JT cryocoolers, respectively. The LTS coils successfully generated a central magnetic field of 14 T at an operating current of 854 A without any training quench. The Gd123 coil generated 10.15 T at an operating current of 132.6 A in the absence of a background field. Subsequently, the operating current of the Gd123 insert was increased in a step-by-step manner under a background field of 14 T. The Gd123 coil could be operated up to 124.0 A stably, which corresponds to 23.55 T, but quenched at around 124.6 A (23.61 T). The Bi2223 insert coil using a Ni-alloy reinforced Bi2223 tape successfully generated 11.48 T at an operation current of 204.7A in a stand-alone test and 24.57 T in a background field of 14 T. The differences between the calculated and the measured values of the central magnetic fields are about 0.4 T for the Gd123 insert and 0.1 T for the Bi2223 insert around 24 T.