A study of the effects of the cathode configuration on the plasma kinetics and neutron emission of plasma-focus discharges in deuterium

Abstract

The differences in performance of a 1.9 kJ plasma-focus device PACO assembled with three different cathode configurations are experimentally qualified. In particular, the current sheath kinetics and the neutron yield operating with deuterium gas are systematically studied for the whole range of neutron-producing pressures, and the measurements are analyzed searching for relations between relevant physical magnitudes. The pinching time was found correlated with the dimensionless driver parameter, and this feature was found statistically independent of the cathode. The variation of the inductance jump associated with the radial collapse stage is used to estimate the effective pinch length, ( )  7.3 1.6 mm, and radius, ( )  3.6 2.1 mm. The maximum production in a single shot was registered for the smallest cathode radius, 41 mm, whereas the intermediate cathode radius, 45 mm, scored better in average. In all configurations, the neutrons per deuteron pair correlates fairly well with an estimation of the effective equilibrium temperature of the pinch, which suggests a prevalence of thermonuclear neutrons measured perpendicularly to the focus axis.

Dense plasma focus: different cathode geometries and their influence on the hard x-ray production

“…This work evaluates only experiments where neutrons and hard x-ray emissions are present simultaneously. This study is based on the same experience set analyzed in a previous work where other aspects of the phenomenon were studied [41].…”

“…The scintillator trace shows two peaks, the first one corresponds to the hard x-ray, and the second one is the neutrons burst. Both pulses are time separated since the neutrons are much slower than of the x-ray photons [41].…”

Bayesian inference of spectrometric data and validation with numerical simulations of plasma sheath diagnostics of a plasma focus discharge

“…Several studies have been presented in connection with the impact of the rundown and the pinch formation providing preliminary insights of the sheath characteristics: Zakaullah et al 17 used a -source at the bottom of the insulator in order to improve neutron production by enhancing the ionization during breakdown of a Plasma Focus discharge; Veloso et al 18 compared the detachment time and plasma sheath thickness with the neutron emission in a 400J Plasma Focus discharge; Barbaglia et al 19 , considered different cathode configurations on the PACO device (1.9 kJ) in order to study the influence of the geometrical dimensions to the neutron production and also its effect on the drive parameter. Ultrafast photographic visualization and electrical signal processing are amongst the popular techniques used to measure the shape and velocity of the sheath.…”

Experimental study of the effect of circuit inductance on pinch-time in plasma focus MTPF2.5 KJ .

“…The dependence of hard x-rays on the design parameters of a PF, especially the geometry of the electrodes, has been studied by M. *. Corresponding Author name: M. Akbari Nasaji E-mail address: mnasaji2353@gmail.com Barbaglia, [1]. There is an optimum value for Lo below corresponding to each plasma focus capacitance of Co, which performance in terms of Ipinch and Yn does not improve.…”