Presentation materials
AWE conducts hydrodynamic trials as part of its continual mission to maintain the UK nuclear deterrent. The trials utilise flash x-ray radiography as a key diagnostic for studying explosively driven experiments. Future trials will use a Self-Magnetic Pinch diode on the Merlin Inductive Voltage Adder as one of the radiographic sources.
This body of work presents predictions of the...
X-Ray flash radiography is a useful diagnostic for investigating the structural response of matter during hydrodynamic experiments. Intense pulsed X-ray sources are required to freeze the motion during these experiments and hence, produce sharp images. For this purpose, Linear Induction Accelerators (LIA) provide high flux X-rays pulses [1-2]. In order to optimize the electron beam transport,...
Experiments have been carried out at the Naval Research Laboratory to measure the air response to an intense electron beam created using a 4 kA, 100 kV, 50 ns pulsed-power source. The electron beam is extracted through a pair of thin foils and injected directly into an 11-cm-long, 17.8-cm-diameter, gas-filled chamber. The properties of the plasma produced by the rapidly varying electron-beam...
We are pursuing the development of 0.5-4 MV, 40-120 J/cm2 electron beams to benchmark and validate models of dynamic material response. Large-area sources at low impedance can be achieved using multiple parallel ring diodes, whose multiple current returns keep the local self-magnetic field below the threshold for pinching, thus alleviating the need for an external magnetic field. We report...
Experimental study of system-generated electromagnetic pulse effect requires large area hard x-ray source with the average energy of photons less than 100 keV and few electrons. Compared with the single diode, the bremsstrahlung reflex triode can generate hard x-ray more efficiently to meet the demand of experiment. Reflex triode applies two face-to-face cathodes to reflex the electrons. The...
The plasma filled rod pinch diode (aka PFRP) offers a small radiographic spot size and a high brightness source. it operates in a very similar way to plasma opening switches and dense plasma focus devices - with a plasma prefill supplied by a number of simple coaxial plasma guns, being snowploughed along a thin rod anode before detaching at the end.
The aim of this study is to model the PFRP...
A large selection of materials have been investigated as electron beam producing repetitively pulsed cold cathodes. The cathodes were tested at 200 kV to 500 kV, 100 A to 110 kA, with cathode cross-sections ranging from 5 cm2 to 3000 cm2, and pulse widths from 50 ns to 300 ns. Cathode turn-on time and emission uniformity were measured, and cathode longevity was estimated...
Performance of flash radiography system requires high spatial resolution. To produce point-like source of x-ray radiation electron beams focused on high-Z material are used. The target material is strongly heated by an electron beam with power deposition about of 1 kJ/mm^3. Dense plasma is formed that affects the beam via neutralization by fast ions and ionic instabilities. In this work we...
Well diagnosed measurements of electrical breakdown between metal electrodes in vacuum have been made using a 1-MV, 50-ns pulse-generator-based test stand [1]. Results with bare, as-machined electrodes showed that cathode surface finish and material have little to no effect on the breakdown electric field. However, changing the AK gap did affect the breakdown field level, suggesting that the...
