Research in ultrahigh magnetic field physics

Abstract

The history of the achievements of the All-Russian Research Institute of Experimental Physics (VNIIEF in Russ. abbr. )i n the field of ultrahigh magnetic field (UHMF) generation and applications in fundamental physical studies begins in 1952, when Andrey D Sakharov put forward the idea of magnetic cumulation as one of the possible methods for achieving a controlled thermonuclear reaction [1]. He also proposed two types of magnetocumulative generators of UHMFs (MC-1) and energy (MC-2) [1, 2]. In the first of them, a special device produces the initial axial magnetic field flux in the cavity of a cylindrical metal shell (liner). A converging detonation wave is initiated in a circular explosive charge surrounding the liner so that it arrives at the external boundary of the liner at the instant of time when the initial magnetic field in the liner achieves a maximum. Under the action of pressure of the detonation products, the liner collapses to the center, compressing the initial magnetic flux. If the compression is rapid enough,the magnetic flux inthe cavity is preserved, and themagnetic fieldstrengthonthelineraxisincreasesinversely proportionally to the squared radius of the liner, achieving a few megagausses. The chemical energy of the explosive is transformed into the magnetic field energy through the kinetic energy of the liner. Extensive attempts made in many countries to reproduce UHMFs by the explosive compression of a magnetic flux revealed unexplainable difficulties in obtaining magnetic fields exceeding 3 MG, which resulted in the termination of work in this field. 2. MC-1 cascade generator A group of researchers at VNIIEF headed by A I Pavlovskii proposed and realized a number of concepts supplementing and developing the magnetic cumulation idea and solved the problem of the reproducible generation of UHMFs. First, it was proposed to make the shells of the MC-1 generator from a material with a controllable electrical conduction. Such a material in the initial state is either completely nonconducting or conducts current only in one direction. At the required instant, a shock wave is passed through the material, making it conducting in all directions. For example, such a material can be produced from closely packed parallel isolated copper wires glued with an epoxy compound. Second, unique solenoids of the initial magnetic field in