Plasma dynamics in PF-1000 device under full-scale energy storage: I. Pinch dynamics, shock-wave diffraction, and inertial electrode

Abstract

This paper (paper I) presents the first part of results obtained with the PF-1000 facility for the first time at its upper energy limit (≈1 MJ). Special attention is paid here to plasma (‘pinch’) dynamics, which was investigated in relation to its electro-technical and radiation (especially neutron) characteristics with the help of a number of diagnostics, both time-integrated and with nanosecond temporal resolution. In these methods we utilized a Rogowski coil for the routine electro-technical measurements, visual multi-frame and streak cameras, soft x-ray pin-hole multi-frame cameras, PIN-diode assembly and PM tubes with scintillators for soft and hard x-rays as well as for neutron investigations together with a set of activation counters. In particular, the temporal cross correlation of different phenomena taking place during the discharge was investigated. The pinch's longevity appears to be 10–15 times larger than the ideal magnetohydrodynamic growth time (ratio of the pinch radius to the ion thermal velocity). It is demonstrated how the ‘target’ dynamics (pinch plasma of the dense plasma focus (DPF)) depends on and may be controlled by the electrode's size and the geometry of the chamber in this large-scale device. Diffraction of a shock wave together with a current sheath on an obstacle made at the DPF anode cap opens an opportunity for an inertial electrode to be used in future at larger DPF devices.

The experimental and theoretical investigations of damage development and distribution in double-forged tungsten under plasma irradiation-initiated extreme heat loads

“…It is known that changing the distance between the anode and the sample (see Fig. 1) allows one to change plasma parameters on the sample surface [16,17] (see also [18,19] for an overview of PF-1000 and [10] for PF-12).…”

“…Thus, the power fl ux density of slow plasma is almost the same for all the samples those were placed at the same distance from the anode. The power fl ux density of slow plasma (E ~ 0.1-1 keV) and fast ions (E ~ 100 keV) was calculated considering initial conditions and plasma properties (velocity of a plasma shock wave and the current rise time) for working PF devices [16,18,19]. The power fl ux density of non-homogeneous slow plasma (E ~ 0.1-1 keV) varied from 5 × 10 7 to 5 × 10 9 W/cm 2 with interaction time equal to 50-100 ns depended on samples' positions.…”

“…Plasma and ion fl ux parameters generated at the PF-1000 were measured by different direct methods (see e.g. [18,19]). It was estimated that hot plasma power fl ux density was 10 9 to 10 10 W/cm 2 at the pulse duration 100 ns.…”

Investigation of Effective Parameters on Metal Nitride Deposition by Plasma Focus Device: Number of Shots and Substrate Axial and Angular Positions

“…Among the different methods, plasma assisted methods have recently become promising candidate because of its wide range of energy and intensity spectra. Plasma focus (PF) [1,2] method is a simple process that generates a magnetic field to compress the plasma to a high density of *10 25 -10 26 m -3 and high temperature (*1-2 keV) for a short period of time (*10 -7 s) [2,3]. This device is a potential candidate for soft and hard X-rays, neutrons, relativistic electrons and energetic ions irradiation [4,5].…”

Scaling the plasma focus for fusion energy considerations

“…A big machine such as the PF1000 typically produces 10 11 neutrons per shot [3]. Gribkov et al [4] had pointed out that Y n 5 10 13 in Deuterium is a desired landmark to achieve in a plasma focus device; from the point of view of possible exploitation as a powerful source of fusion neutrons for testing of prospective materials for the first wall components and construction elements in magnetic confinement fusion and also in inertial confinement fusion reactors. Converting such a plasma focus yield to operation in D-T, with Y n 5 10 15 could produce, during a 1-year run, an overall fluenceaffecting materials to the order of 0.1-1.0 displacements per atom (DPA) (1 DPA is equal to a mean neutron flux of 4.5 Â 10 16 neutrons m À2 s À1 for 1 year) for such testing purposes, at a very low cost relative to other methods currently being considered.…”