Generation Of Ultrahigh Magnetic Fields Research Articles

Inductive Voltage of Insert HTS Coils Due to Coil Deformation for Ultra-High Magnetic Field Generation

Inductive Voltage of Insert HTS Coils Due to Coil Deformation for Ultra-High Magnetic Field Generation

Ternary Molybdenum Chalcogenide Superconducting Wires for Ultrahigh Field Applications

Regarding the generation of ultrahigh magnetic fields, Ternary Molybdenum Chalcogenide (TMC) superconducting wires may be considered as an attractive alternative to high temperature superconductors (HTS). For instance, the price per kilogram is almost one order of magnitude lower than that of HTS. TMC superconducting wires were developed and studied in academia and industry, i.e., Mitsubishi (Japan), Alstom (France), and Plansee (Austria), until the mid-1990s. Although TMC's are low temperature superconductors (T c ≤ 15 K), upper critical fields are up to 60 T. They are nearly isotropic and can be manufactured with round or rectangular cross section in kilometer's lengths. The yield strength, R p0.2 , at 4.2 K is about 860 MPa, much higher than other superconducting wires. An additional advantage is that a TMC wire does not require any reaction heat treatment. Supposing that the effective upper critical field, B* c2 , can be improved by the proposed new manufacturing process and which is at present limiting the critical current density, specifications for the Future Circular Collider project at CERN, either for the 16 T or the 20 T version, will be met. In this contribution, TMC superconducting wires are reviewed and the potential for achieving improved critical currents is discussed.

On Ultrahigh Magnetic-Field Generation Using Solid-State Liner System

A scheme of a device intended for amplification of an axial magnetic field by a system of solid-state cylindrical liners is described in this paper. A 1-D magnetohydrodynamic model used in this paper is stated briefly. Calculation results of ultrahigh magnetic-field generation using one-, two-, and three-stage liner systems are presented.

Experimental Design of a Magnetic Flux Compression Experiment

Generation of ultrahigh magnetic fields is an interesting topic of high-energy-density physics, and an essential aspect of Magnetized Target Fusion (MTF). To examine plasma formation from conductors impinged upon by ultrahigh magnetic fields, in a geometry similar to that of the MAGO experiments, an experiment is under design to compress magnetic flux in a toroidal cavity, using the Shiva Star or Atlas generator. An initial toroidal bias magnetic field is provided by a current on a central conductor. The central current is generated by diverting a fraction of the liner current using an innovative inductive current divider, thus avoiding the need for an auxiliary power supply. A 50-mm-radius cylindrical aluminum liner implodes along glide planes with velocity of about 5 km/s. Inward liner motion causes electrical closure of the toroidal chamber, after which flux in the chamber is conserved and compressed, yielding magnetic fields of 2–3 MG. Plasma is generated on the liner and central rod surfaces by Ohmic heating. Diagnostics include B-dot probes, Faraday rotation, radiography, filtered photodiodes, and VUV spectroscopy. Optical access to the chamber is provided through small holes in the walls.

2-D Modeling of Electromagnetic Flux-Compression in<tex>$theta$</tex>-Pinch Geometry

A major research program underway at Loughborough University involves the generation of ultrahigh magnetic fields up to 300 T (3 MG) by means of magnetic flux-compression. A high pulsed current is discharged into a single-turn driving coil surrounding a liner, with various aspects of the associated practical work being presented in a companion paper. This paper explains the two-dimensional filamentary modeling technique that is used to provide detailed prediction of the liner implosion, driving coil dynamics and magnetic field diffusion through all the metallic elements of the arrangement. The main typical results from numerical experiments are presented and experimental data are compared with theoretical predictions.

VNIIEF achievements on ultra-high magnetic fields generation

A brief review of the achievements on ultra-high magnetic field generation at VNIIEF is given. The cascade MC-1 generators for the 10 and 20 MG magnetic field ranges are described. Investigations in ultra-high fields provided by cascade MC-1 generators are an example of extended international collaboration.

MHD instabilities and the generation of ultrahigh magnetic fields

Methods are proposed for generating magnetic fields in connection with the intentional generation and development of force instabilities of a current-carrying plasma channel.

Mc generators. Selection of optimal experimental conditions

Many experiments on generation of ultrahigh magnetic fields in the range 1-15 mG have been performed by rapid compression of a magnetic flux by a conducting shell. The experiments were arranged in various conditions. Different schemes of introduction of initial magnetic flux, techniques of acceleration of a liner, its materials and design, etc. have been tested. In the present paper we systematize published results on generation of ultrahigh magnetic fields. A technique for selecting the initial magnetic field parameters is proposed, which allows one to choose optimal experimental conditions in a few steps.

Self-similar solutions for the supersonic implosion of a screw-pinch plasma

Self-similar solutions are obtained for the supersonic compression of a plasma containing an axial current and an entrained axial magnetic field (screw pinch). These solutions represent a complete generalization of previous works done on the Z-pinch and Θ-pinch schemes. The solutions presented herein represent a screw-pinch plasma with a diffuse current profile. Three separate plasma implosion modes are identified. These modes differ qualitatively from the Z-pinch and Θ-pinch schemes. They are comprised of the plasma annulus implosion, a converging transverse magnetohydrodynamic shock, and the propagation of fast magnetosonic waves toward the axis (weak discontinuity). These modes are chosen on the basis of their ability to achieve magnetic field cumulation during the course of the implosion. Analytic expressions describing the asymptotic behavior of the hydromagnetic profiles are obtained for each of the three implosion modes. Numerical examples for selected boundary conditions, representing realistic plasma parameters for the purpose of ultrahigh magnetic field generation, are presented.