Stephen Harrison

The superconducting magnet system of AMS-02 - a particle physics detector to be operated on the International Space Station

The Alpha Magnetic Spectrometer (AMS) is a particle detector designed to search for anti-matter, dark matter and the origin of cosmic rays in space. The detector will be assembled at ETH Zurich and installed on the International Space Station (ISS) in 2004. The planned duration of the experiment is 3 years. The magnetic dipole field is achieved by an arrangement of 14 superconducting coils. The magnet system consists of a pair of large Helmholtz coils together with two series of six racetrack coils, circumferentially distributed between them. This arrangement was mainly chosen to minimize the stray field outside of the magnet and to minimize the magnetic dipole moment. It generates a magnetic field of 0.87 T in the center of the magnet with a bending power of 0.78 Tm/sup 2/. All superconducting coils are wound from a high purity aluminum-stabilized mono-strand NbTi conductor with rectangular shape of 1.55 mm /spl times/ 2.00 mm. The coils are located inside a toroidal-shaped vacuum vessel. They are indirectly cooled by superfluid helium at 1.8 K. This cooling loop is thermally connected with a 2500 l vessel for superfluid helium which serves as a cold reservoir. In order to ensure the 3 year endurance without refilling, the magnet design was optimized with respect to very low heat losses. This paper describes the main features of the AMS superconducting magnet including the manufacturing process of the conductor and the principle concept of the cryogenic system.

Loss of vacuum experiments on a superfluid helium vessel

The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment for use on the International Space Station (ISS). At the heart of the detector will be a large superconducting magnet cooled to a temperature of 1.8 K by superfluid helium. The helium is contained in a toroidal vessel with a volume of approximately 2500 liters. From ground safety and flight safety considerations, the system must be safe in the event of a sudden catastrophic loss of insulating vacuum. A test facility has been designed and built by the magnet designer and fabricator, Space Cryomagnetics Ltd. of Culham, England. This facility allows a sudden, total loss of vacuum event in a small (12 liter) superfluid helium vessel to be triggered and monitored, so that venting rates and heat fluxes can be calculated. This paper describes the design of the test facility and the results of experiments to determine the heat flux to the superfluid helium. Test results are given for a completely uninsulated vessel, and for a vessel insulated with a thin coating of a special, lightweight insulating material.

Cryogenic system for a large superconducting magnet in space

The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment for use on the International Space Station (ISS). At the heart of the detector will be a large superconducting magnet cooled to a temperature of 1.8 K by 2500 liters of superfluid helium. The magnet and cryogenic system are currently under construction by Space Cryomagnetics Ltd of Culham, England. This paper describes the cryogenic system for the magnet, designed for the unusual challenges of operating a superconducting system in space. Results from experiments demonstrating some of the new techniques and devices developed for the magnet cryogenics are also presented.

Design, manufacture, and test of an adiabatic demagnetization Refrigerator Magnet for use in space

The proposed European Space Agency (ESA) XEUS mission will use an adiabatic demagnetization refrigeration (ADR) system to cool X-ray detectors to a temperature of less than 0.1 K. The superconducting magnet for the flight standard prototype is currently under construction by Space Cryomagnetics Ltd of Culham, England. The magnet is subject to tight constraints on its mass, stray field, and power consumption. This paper describes the design, manufacture and test of the magnet.

Design and manufacture of high temperature superconducting magnets for an electron cyclotron resonance ion source

The use of superconducting magnets in ECR ion sources has the potential for large power savings compared with resistive magnets. High temperature superconductors (HTS) offer further advantages including compactness, efficiency, and a simplification of the overall system. Space Cryomagnetics Ltd has designed and manufactured a pair of HTS magnets for an ion source for Pantechnik. In this paper we describe the design, manufacture, and test results of these magnets.

Chapter 145 – Testing the coils of the superconducting magnet for the Alpha Magnetic Spectrometer

Publisher Summary This chapter explores the Alpha Magnetic Spectrometer (AMS), which is a particle physics experiment module for use on the International Space Station (ISS). The AMS experiment is designed to examine the fundamental physics of the universe, in particular through the search of antimatter and dark matter. At the heart of the detector is a large superconducting magnet system cooled to a temperature of 1.8 K by 2500 liters of superfluid helium: both the magnet and cryogenic systems are currently under construction by Space Cryomagnetics Ltd of Culham, England. The magnet consists of 14 superconducting coils arranged around the 1 m diameter warm bore. A special test facility has been designed and constructed which allows the AMS superconducting magnet coils to be tested individually in a cryogenic environment which approximates to conditions on the International Space Station. The twelve racetrack (flux return) coils have been tested at currents exceeding the assembled magnet current, to simulate the mechanical loadings in service. Quench testing has also been performed on each coil to check the operation of the quench heaters and the stability of the coils.

The Cryogenic System of the Superconducting Magnet for the Alpha Magnetic Spectrometer

The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment based on the International Space Station (ISS). Its mission is to study cosmic rays in space, using a large superconducting magnet to deflect charged particles which can then be identified by a set of advanced detectors. This paper describes the design of the magnet cryogenic system, and the status of manufacture and testing.

Status of the superconducting magnet for the Alpha Magnetic Spectrometer

The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment based on the International Space Station (ISS). At the heart of the detector is a large superconducting magnet, cooled to a temperature of 1.8 K by superfluid helium. The magnet and cryogenic system are currently under construction by Space Cryomagnetics Ltd of Culham, England. This paper describes the current status of the design and manufacture of the magnet system-including test results from the fourteen superconducting coils-and outlines the remaining work required to complete the project.

High-temperature Superconducting magnets for use in electron Cyclotron resonance ion sources

Ion sources using electron cyclotron resonance (ECR) require magnets to generate a particular field profile. High temperature superconducting (HTS) magnets offer advantages in power density, efficiency and the overall simplicity of the system. Space Cryomagnetics Ltd of Culham, England, has designed and manufactured HTS magnets for an ion source for Pantechnik in France, and is currently developing a second, more powerful system for the Laboratoire de Physique Subatomique et de Cosmologie (LPSC) in Grenoble, France. This paper describes the design, manufacture and test results of the first of these systems, and the current status of the design and manufacture of the second.

Design and manufacture of a low-current ADR magnet for a space application

Publisher Summary Adiabatic demagnetization refrigerator (ADR) systems offer a convenient method for achieving temperatures below 50 mK. The magnet system described in this chapter is a key component of the ADR engineering and qualification model for the proposed European Space Agencys (ESA) XEUS mission, in which the ADR will be used to cool x-ray detectors. A low-operating current ADR magnet has been constructed as part of the development of the XEUS x ray observatory satellite. The components of the magnet system are designed and developed with emphasis on the satellite requirements, and on constraints on the overall length and the interactions between the two ADR stages. The leads—which supply current to the magnet coils—operate in vacuum, and therefore have to be thermally anchored to the 4.5 K stage of the cryocooler. However, the cooling power available from the cryocooler is very limited, so it is vital to minimize the heat load from the current leads. For this reason, the magnet has been designed to operate at very low current, using very small NbTi superconducting wire, running at 60% of its short sample performance. For quench protection, the solenoids and coils are subdivided into sections with resistor and diode protection circuits. The magnet system consists of two major solenoid coils and eight secondary coils. All are cooled by conduction through heat shunts to the 4.5 K stage cryocooler: there are no liquid cryogens. Thermal modelling and eddy current analysis have been used to determine the optimum geometry for the heat shunts.