Generation of Intense Magnetic Fields

Abstract

The advent of high-field superconducting magnets has made magnetic fields above 30 kG available to the entire scientific community. Small diameter coils to 60 kG cost considerably less than conventional 12-in. iron magnet systems. Fields to 80 kG, and in a few recent instances to 100 kG, even in multicentimeter bores, are now economically within the reach of most research budgets. The current and future status of superconducting magnets, their economic advantages and associated problems are presented. Other methods of generating fields, such as water-cooled continuous magnets, millisecond pulse magnets, and long-pulse cryogenic magnets, will find their principal use in reaching even higher fields, supplementing superconducting magnets, or in circumventing problems which preclude the use of superconductors. Pulse magnets are presented as a relatively simple and inexpensive method of producing millisecond fields up to 500 kG and long pulses to 250 kG. Relationships between energy, time, and volume are given for pulse magnets. The current and future status, and the problems associated with conventional continuous field magnets in the 100 to 250 kG range are given and the availability of such magnets at the National Magnet Laboratory discussed. New critical current—critical field data for niobium—tin materials measured in continuous fields up to 180 kG is presented.