Transient electrical discharges in small devices

Abstract

Fundamental and applied research on plasmas with high energy density that are unstable and radiate can be done at a relatively low cost with small plasma pinches. In this paper we discuss three experiments using small pinch devices: a capillary discharge, a Z-pinch driven by a small generator, and a low energy plasma focus. The experiments were complemented by magnetohydrodynamics numerical calculations in order to assist the design and physical interpretation of the experimental data. The diagnostics used in the experiments include current and voltage monitors, multipinhole camera, holographic interferometry, and vacuum ultraviolet spectroscopy.

Research on pinch plasma focus devices of hundred of kilojoules to tens of joules

“…If the value of (I/a) is increased, speed will increase with (I/a), and T will increase with (I/a) 2 . In the present range of operation of plasma focus (∼ 1keV when is used D 2 ), increase in T will lead to increase in fusion cross section σv proportional to T ν , with ν ∼ 4, thus σv ∼ (I/a) 8 [23]. Thus in the limit, if a is keeping constant whilst increasing I, Y b−t ∝ I 3 and Y th ∝ I 8 .…”

“…As first stage of a program to design a repetitive pulsed radiation generator for industrial applications we constructed two very small plasma focus operating at an energy level of the order of a) tens of joules (PF-50J, 160nF capacitor bank,20 − 35kV , 32 − 100J, ∼ 150ns time to peak current) [8][9][10] and b) hundred of joules (PF-400J, 880nF , 20 − 35kV , 176 − 539J, ∼ 300ns time to peak current) [11]. 2.1 Design criteria.…”

“…In fact, we can question if good focussing can be achieved below 1 kJ, and if so which are the appropriate design criteria and scaling laws in this energy region. Experimental research with a plasma focus driven by a capacitor bank of tens to hundred of joules would allow to extend the theoretical models to the region of low energy [8][9][10]. Moreover, a capacitor bank under the kilojoule has a small size in comparison with banks in the kilojoules range, thus it would be easier to operate in a repetitive regime from Hz to kHz, since the power requirements and the spark-gap erosion are consequently lower.…”

Construction and experimental study of a 2.5kJ, simply configured, mather type plasma focus device

“…The detector is placed on the top of plasma chamber perpendicular to the axis of focus tube ( fig.2 no. 22) and is connected to a counter via an inverter, counting fusion neutrons with a calibration constant of 1.6 4 …”

Palm top plasma focus device as a portable pulsed neutron source

“…Several successful attempts have been made to develop miniature and portable PF devices operated with bank energy in the ranges of tens to hundreds of joules. The pinching evidence has been observed in the PF devices operated at very low bank energies of 50 J, 6 50-70 J, 7 ≈100 J, 8 and 32-102 J, 9 leading to the generation of neutrons from a) E-mail: niranjan@barc.gov.in such devices. A battery (12 V DC, 400 Ah) powered transportable PF device working at 125 J of bank energy has been shown 10 to produce 10 5 to 10 6 neutrons/pulse but only in 30% of the PF discharges.…”