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Ultrafast photoemission from a nanostructured Si-cathode array comprised of nano-sharp tips (∼5 nm radius of curvature) was studied. Total current yield and electron spectra indicate a transition from multiphoton to strong-field emission followed by virtual cathode formation.
Emission from an array of dissimilar field emitters are known to produce non-uniform patterns that affect space charge forces within the electron beam produced, with consequences on emittance and transit time effects. To model variation, a semi-analytical Point Charge Model (PCM) gives rapid and analytical representations of tip current, variation, and emission statistics to be used in the MICHELLE...
Space-charge neutralization is required to compress and focus a pulsed high-current ion beam on a target for warm dense matter physics or heavy ion fusion experiments. We describe an approach to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary space-charge compensating electrons....
An analytical formula of the emittance of and space charge effects on a sharply curved emitter surface is given. The 3D formulation makes use of the Point Charge Model (PCM) of a unit cell emitter coupled with a trajectory analysis to follow electrons to an evaluation plane where emittance is determined. The single tip theory extended to an array predicts the emittance of a Field Emitter Array 0.2...
Summary form only given. L-3 Communications continues development and testing of a moderate power helix TWT incorporating a new low-voltage high-transconductance field emitter array cold cathode developed by SRI International. The TWT employs a custom electron gun required to control the high beam space charge density created in the acceleration region between the HV cathode surface and the grounded...
L-3 Communications continues development and testing of a moderate power helix TWT incorporating a new low-voltage high-transconductance field emitter array cold cathode developed by SRI International. The TWT employs a custom electron gun required to control the high beam space charge density created in the acceleration region between the HV cathode surface and the grounded input TWT helix. A custom...
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