New developments in paraxial radiographic diode technology for focusing intense relativistic electron beams

Locally conformal finite-difference time-domain techniques for particle-in-cell plasma simulation

“…In experiments, (see Ref. [32]) the leading surface of the emitter is partially covered with a low-emission-threshold paint that allows initiation of space-charged-limited (SCL) emission of electrons. The AK gap is set to keep the electric field stresses low enough to prevent plasma formation and SCL electron emission on the other region of the cathode.…”

“…The paraxial electron beam diode is an extended cathode emitter consisting of a $1 cm radius spherical conductor mounted on a long, thin ((1 cm) stalk and a planar anode [32][33][34]. The electron beam passes through a foil (anode) and enters a gas-filled transport cell where the beam is focused onto a high-atomic-number range-thin target to produce bremsstrahlung.…”

Science of nuclear warheads

“…AWE has been active since the early 1960s 7 in pioneering tools to investigate material compression and the transmission of shock waves through materials, using short pulses from high-energy X-ray machines. The largest radiographic machine generates a 10-MV electron beam of 30 kA with a duration of less than 100 ns, which is focused into a 5-mm tantalum target to produce the X-ray source necessary for flash radiography 8 .…”

Bernstein mode generated anomalous resistivity in a current carrying plasma focusing cell

“…[1][2][3] Pulsed-power diodes can reliably produce high doses with Ͼ1 cm spot sizes. In order to ballistically focus the intense beam down to ϳ1 mm spot sizes required for radiography, the beam self-fields must be largely neutralized.…”

“…Because of its simplicity, gas cell focusing has been the method of choice for several decades. 3,4 The electron beam enters the cell through a thin foil that separates the gas from the vacuum diode region. In the transport region the gas is broken down by beam impact ionization and electron avalanche driven by self-fields.…”