Title :
Characterizing the photon spectrum in the DARHT Axis-I diode
Author :
Coleman, J.E. ; Johnson, J.B. ; McCuistian, B.T. ; Moir, D.C. ; Crawford, M.T.
Author_Institution :
Los Alamos Nat. Lab., Los Alamos, NM, USA
Abstract :
An array of photon diagnostics have been deployed on a high power relativistic electron beam diode. Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are accelerated through a 17.8 cm diode. This discharge is assumed to be a hydrocarbon mixture. A small portion of the off energy electrons (1-3 MeV) accelerated during the rise and fall of the 80 ns FWHM pulse impact the beam pipe and generate a Bremsstrahlung spectrum of 0.1-3 MeV photons. The principal objective of these experiments is to quantify the dynamics of the hard X-ray and γ-ray flux generated in the diode region, in addition to quantifying dynamics of the visible photons generated, and the ion species of the surface discharge on the velvet cathode. A qualitative comparison of different diagnostic results are presented, which include time resolved measurements with X-ray PIN diodes, a PMT, and CCD images. In addition initial visible spectroscopy measurements will also be presented.
Keywords :
X-ray spectra; bremsstrahlung; carbon fibres; cathodes; flashover; gamma-ray spectra; p-i-n diodes; relativistic electron beams; surface discharges; visible spectra; γ-ray flux; Bremsstrahlung spectrum; CCD images; DARHT axis-I diode; FWHM pulse; PMT; X-ray PIN diodes; beam pipe; carbon fiber velvet cathode; electron volt energy 0.1 MeV to 3 MeV; hard X-ray; high power relativistic electron beam diode; hydrocarbon mixture; off energy electrons; photon diagnostics array; photon spectrum; size 17.8 cm; surface discharge; surface flashover; time 80 ns; time resolved measurements; visible photons; visible spectroscopy measurements; Cathodes; Face; Logic gates; Photonics; Plasma measurements; Temperature measurement; Voltage measurement;
Conference_Titel :
Plasma Sciences (ICOPS) held with 2014 IEEE International Conference on High-Power Particle Beams (BEAMS), 2014 IEEE 41st International Conference on
Conference_Location :
Washington, DC
Print_ISBN :
978-1-4799-2711-1
DOI :
10.1109/PLASMA.2014.7012758