Effective hard x-ray spectrum of a tabletop Mather-type plasma focus optimized for flash radiography of metallic objects

Abstract

Effective hard x-ray spectrum of a tabletop Mather-type plasma focus optimized for flash radiography of metallic objects The effective spectrum of the hard x-ray output of a Mather-type tabletop plasma focus device was determined from attenuation data on metallic samples using commercial radiographic film coupled to a Gd 2 O 2 S : Tb phosphor intensifier screen. It was found that the radiation has relevant spectral components in the 40-150 keV range, with a single maximum around 60− 80 keV. The radiation output allows for 50 ns resolution, good contrast, and introspective imaging of metallic objects even through metallic walls. A numerical estimation of the induced voltage on the focus during the compressional stage is briefly discussed.

Update on the Scientific Status of the Plasma Focus

“…This method provides a correlation between K and the x-ray energy [241]. Using filters with different materials and mm thickness the method has been used to obtain an effective mean energỹ 70 ± 10 keV [242] in a kJ device. In the PF-400J device it was found to be~90 ± 5 keV [243], using the Curix ST-G2 AGFA system as recording media.…”

Radiographic method for measuring the continuum hard X-ray output spectrum of a Plasma Focus device

“…where A is the total amount of hard X-rays photons reaching the screens per unit area, η(E) is the screen conversion efficiency [3,10] and S(E) is the continuum part of the unknown hard X-ray spectrum. Expression (1) considers that the intensity of each spectral component exponentially decays as it penetrates matter.…”

“…Plasma Focus devices are intense sources of polychromatic hard X-ray pulses with extremely short wavelength components (∼ 10 pm) and a very short pulse duration (∼ 50 ns FWHM) [1], that make them specially suited for a number of important applications [2]. Nanosecond resolution radiographies of metallic pieces hidden behind metallic walls that involved 100 keV photons, were reported among them [3]. The development and enrichment of such imaging applications, as well as the understanding of many Plasma Focus pinch phenomena, benefit with the knowledge of the hard X-ray source spectral characteristics.…”

“…Photon energies between 5 and 45 keV were reported, and about 40 shots were required to improve the signal-to-noise ratio. More recently, an effective, single shot, Plasma Focus hard X-ray spectrum was determined from attenuation data on metallic samples [3] following a method that allows for comparisons between measurements made on different devices, provided that the same type of hard X-ray detector is used.…”

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

“…Comparing with isotopic neutron sources, PF have unique qualities as sources of X-ray/neutron pulses, emitting only on operator demand, with low risk of radiation contamination and low cost of operation and maintenance. PF devices are also interesting for industrial applications [23], ranging from tailored soft X-ray sources [24]- [26], and soft X-ray microlithography [27] to hard X-ray introspective imaging of metallic pieces [28]- [31], neutron production and applications [10], [12]- [14], [32], [33], detection of substances [34], plasma thrusters [35], materials testing [36], nanotechnologies [37], among others.…”