Title :
A 35 GHz free electron laser amplifier operating with high guide magnetic field
Author :
Conde, M.E. ; Bekefi ; Wurtele, J.S.
Abstract :
Summary form only given, as follows. A free electron laser (FEL) has been operated as an amplifier at 35 GHz. The strong axial guide magnetic field (12 kG) places the electrons into the so-called group II orbits. In the regime of interest the expected efficiency is high because the space charge wave is unstable. The mildly relativistic beam (1 MeV) is generated by a Marx capacitor bank. The field-emission cathode yields about 360 A, with a beam radius of 2.54 mm. The bifilar helical wiggler has a period of 3.18 cm and provides a magnetic field of 1 kG. The FEL amplifies the TE11 mode in a circular wave-guide with a radius of 5.1 mm. The high-efficiency below-grazing regime, in which the beam resonance line falls slightly below the vacuum waveguide dispersion curve, is being investigated. Preliminary data show a gain of 30 dB/m. About 13 kW has been injected from a magnetron and an output of about 20 MW has been obtained, corresponding to an efficiency of approximately 6%
Keywords :
free electron lasers; magnetic field effects; masers; 1 MeV; 1 kG; 10.2 mm; 12 kG; 20 MW; 35 GHz; 360 A; 5.08 mm; 6 percent; Marx capacitor bank; TE11 mode; beam radius; beam resonance line; below-grazing regime; bifilar helical wiggler; circular wave-guide; field-emission cathode; free electron laser amplifier; gain; group II orbits; guide magnetic field; magnetron; mildly relativistic beam; output; period; unstable space charge wave; vacuum waveguide dispersion curve;
Conference_Titel :
Plasma Science, 1990. IEEE Conference Record - Abstracts., 1990 IEEE International Conference on
Conference_Location :
Oakland, CA, USA
DOI :
10.1109/PLASMA.1990.110842
