In his letter “Tales of the Soviet hydrogen bomb” (Physics Today, January 2018, page 13), Lars-Erik De Geer refers to “Soviet experiments in which extremely strong magnetic fields had been used to compress fusion materials.” That approach, which may have originated with Andrei Sakharov, has been continued over five decades by his followers and has recently involved official rather than de facto cooperation between the US and Russia. Indeed, a Russian monograph on such work was published by Los Alamos National Laboratory.1 An experimental test of one approach to using megagauss magnetic fields for controlled fusion was even carried out jointly at a secure site at Los Alamos.2
More recently the US Department of Energy has sponsored a program to enable low-cost fusion research for the development of imploding-liner technology, which would allow repeated application of megagauss fields to compress fusion plasma.3 By combining conventional magnetic and inertial confinement approaches, magneto-inertial fusion may significantly reduce the cost of controlled fusion. So Sakharov—and, independently, Enrico Fermi—may have been right half a century ago to suggest high magnetic fields for fusion energy.
