Title :
Prepulse Suppression on a High-Power Electron Beam Accelerator Using a Dielectric Cathode Holder
Author :
Roy, Amitava ; Mitra, Sabyasachi ; Menon, Rakhee ; Kumar, D. Durga Praveen ; Kumar, Senthil ; Sharma, Archana ; Mittal, K.C. ; Nagesh, K.V. ; Chakravarthy, D.P.
Author_Institution :
Accel. & Pulse Power Div., Bhabha Atomic Res. Centre, Mumbai
Abstract :
Intense gigawatt relativistic electron beam generation studies were carried out with a Perspex cathode holder. Purpose of the dielectric cathode holder was to minimize the prepulse voltage across the diode. The typical electron beam parameter was 180 kV, 26 kA, 100 ns, with a few hundreds of ampere per square centimeter current density. It was found that corrugated Perspex of length ges35 mm can eliminate the prepulse voltage but affects the rise time of the diode voltage. The diode voltage and current waveforms were analyzed with the bipolar space-charge limited flow model. The anode and cathode plasma expansion velocities were calculated using the perveance data. The plasma expands at 5.1 cm/mus for 18-mm anode-cathode gap and the plasma velocity increases for larger gap. Inserting a dielectric at the cathode holder could be a very effective method to reduce prepulse voltage at the electron beam diode, but it increases the rise time of the diode voltage and reduces the effective electron beam pulsewidth. The prepulse voltage reduces significantly (les10%) when an inductance is added to the charging circuit of the Blumlein line.
Keywords :
anodes; arcs (electric); cathodes; flashover; plasma applications; plasma flow; relativistic electron beam tubes; relativistic electron beams; Blumlein line; Perspex cathode holder; anode plasma expansion velocitiy; bipolar space charge limited flow model; cathode plasma expansion velocitiy; corrugated Perspex; current 26 kA; dielectric cathode holder; diode current waveform; diode voltage waveform; distance 18 mm; electron beam diode; gigawatt relativistic electron beam generation; high power electron beam accelerator; prepulse suppression; time 100 ns; velocity 51000 m/s; voltage 180 kV; Anodes; Cathodes; Current density; Dielectrics; Diodes; Electron accelerators; Electron beams; Plasma density; Plasma waves; Voltage; Electron beam diode; perveance; plasma expansion; surface flashover;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2008.2006473