Experimental study of X-pinch in a submicrosecond regime

Abstract

International audienceX-pinch plasmas are known as point-like X-ray sources with the potential application for backlighting diagnostics. X-pinches are commonly driven by large pulsed power generators delivering high-voltage pulses with short rise-times, typically under 100 ns. When operating with slower capacitor banks, X-pinches become less reliable because of the arising X-ray pulse jitter and because of the appearance of two or more X-ray bursts coming from multiple hot spots. In this paper, a very compact inductance-capacitance (LC) generator with the current rise-time of 200 ns was used to drive molybdenum and tungsten wire X-pinches. A single peak, small shot-to-shot jitter emission of X-rays was obtained. Time-integrated penumbral imaging recorded the X-ray source dimension of less than 15 μm in the spectral region above 2.4 keV. The total yield of more than 80 mJ was registered with the radiation pulse duration as short as 1.5 ns. The appearance of single- or multiple-source core structures is discussed in correlation with used wire material and X-pinch torsion angle. The results confirm the possibility of using an X-pinch driven by a fast compact capacitor bank for backlighting applications

Étude spectrale d'un micro-plasma d'implosion X-pinch

“…On avait rapporté des mesures préliminaires de taille de la source X inférieures à 100 m (E > 1,5keV) par sténopé de diamètre 10 m [2]. La source étant ainsi définie, elle est convenable pour radiographier des objets de petite taille et peu absorbants.…”

“…Les configurations retenues sont principalement Al 20 m et 25 m, Cu 25 m, Mo 25 m et W 13 m et 18 m. Le fil, lesté de plombs de 2 à 6g, est croisé en 2 par rotation de 180 • de l'anode supérieure, plus un angle destiné à rattraper le jeu mécanique du fil dans les fentes des électrodes. Pour un angle de 15 • , un bon couplage de l'énergie se produit et on observe une émission X en montée du courant [2].…”

“…On avait aussi mesuré une durée JOURNAL DE PHYSIQUE IV d'émission du rayonnement dur (>1,5keV) assez brève, environ 1,5ns, présentant des indices de pics multiples [2]. Cependant la littérature rapporte des séries de 2 ou 3 impulsions plus brèves d'un facteur 10 [3,4].…”

Study of keV radiation properties of Mo and Ti X-pinch plasma sources using a pinhole transmission grating spectrometer

“…[1][2][3][4][5][6][7] The pulsed current electrically explodes the wires, leading to a complex pinch dynamics near the cross-point where one or more bright x-ray bursts in 1-10 keV may be produced. 2,8,9 In the past decades, X-pinch plasmas have aroused a lot of interests not only because they are excellent point x-ray sources ͓e.g., a source of ϳ1 m scale with subnanosecond duration in 3-5 keV ͑Ref.…”

“…14 The radiation properties of X-pinch plasma sources ͑e.g., source number and size, time duration, spectra, etc.͒ in keV region have been studied by many groups. 3,4,7,15 However, for the study of spectra of keV x-rays from these sources, most of the previous works are focused on diagnosing emission lines using crystal spectroscopy that is characterized by a high spectral resolution but a rather narrow band. 16,17 Few efforts have been made to measure the spectra in a broad band, which, in fact, is also very helpful to the understanding of the pinch dynamics and to the applications in backlighting radiography.…”