Dynamics and Density Measurements in a Small Plasma Focus of Tens-of-Joules-Emitting Neutrons

Abstract

Abstract-Dynamics in the radial phase and plasma conditions in the pinch phase have been studied using interferometry in a plasma focus device that operates in the range of tens of joules of stored energy in the capacitor bank and tens of kiloamperes, PF-50J. The results of these experiments using deuterium as filling gas, together with the simultaneous measurements of neutron production, are reported in this paper. The results show that the typical dynamics, pinch conditions, and electron density observed in larger machines are also present in this experiment operated at only tens of joules.Index Terms-Neutron emission, pinch plasma density, plasma focus (PF).

Statistical characterization of the reproducibility of neutron emission of small plasma focus devices

“…33 It was also demonstrated that this device reproduces the dynamics and high density scenarios observed in machines operated at energies several orders of magnitude higher. 7,22,23 Notwithstanding the systematic research already done in PF-50J, the neutron emission of this PF has not been studied in detail. In comparison to other devices, PF-50J is an extremely fast and low energy plasma focus.…”

Influence of the Anode Length on the Neutron Emission of a 50 J Plasma Focus: Modeling and Experiment

“…As is defined in (14), ξ R can be interpreted as the fraction of deuterons initially contained in a cylinder of length h and radius r 1 that effectively contributes to the reaction process in the pinch. Interferometric measurements of the electron density performed in the device PF-50 J indicate that the mass trapped in the pinch is ∼25% of the mass initially contained in the cylindrical volume [18]. Hence, the calibrated value ξ R ∼ 0.01 suggests that only ∼4% of the deuterons of the pinch contributes to the reaction.…”

“…The experiments were performed at the Chilean Nuclear Energy Commission in the compact PF device PF-50 J, which is a very-low energy PF device operating in the range of tens of Joules designed to produce fast discharges (quarter of period ∼150 ns) in H2 or D2 [11], [12], [18]- [20], [38]. The capacitor bank consisted in four units (40 nF, 20 nH, each) connected in parallel around a spark-gap.…”

Numerical Simulation of the Inductance Variation of a Plasma Focus Based in a Two-Dimensional Model

“…The variable part of the circuit inductance depends on the CS profile as a function of time, particularly during the imploding stage. This dynamics of the CS has been shown to play an important role in the performance of PF devices [4]- [6]. For this reason, theoretical models of the CS cinematic that compare well with measurements of the timevarying component of the inductance have a better experimental support.…”