The plasma-filled rod-pinch diode: A new technique to concentrate MeV electron beams to ultra-high power and energy densities

The plasma-filled rod-pinch diode produces an MeV electron beam with ultra-high power density (∼30 TW/cm²) and energy density (600 MJ/cm³) at the tip of a tapered tungsten rod. Current flows through an injected plasma between the grounded cathode and the high-voltage anode rod. Once J×B forces translate the current to the tip, an e-beam is drawn across a vacuum gap that opens there. Intense e-beam deposition on the anode tip creates an ultra-bright x-ray source. The x-ray source distribution has a very narrow central part (0.4 mm FWHM) with large-scale (few mm) wings, attributed to expanding rod material. Despite the wings, resolution target data show the ability to resolve (with contrast ratio 1.2) 2.5 line-pairs per mm at 5× magnification, the same as would be obtained from a 0.42-mm diam, uniformly emitting disk source.