Enhancing the performance of a high-gain free electron laser operating at millimeter wavelengths

Conference · Thu Oct 25 00:00:00 EDT 1984

OSTI ID:6199243

Barletta, W A; Anderson, B; Fawley, W M; Neil, V K; Orzechowski, T J; Prosnitz, D; Scharlemann, E T; Yarema, S M; Paul, A C; Hopkins, D

A high-gain, high extraction efficiency, free electron laser (FEL) amplifier operating at the Experimental Test Accelerator (ETA) at 34.6 GHz has demonstrated a small signal gain of 13.4 dB/m. With a 30 kW input signal, the amplifier has produced a saturated output of 80 MW and a 5% extraction efficiency. Comparison of these results with a linear model at small signal levels indicates that the amplifier can deliver saturated output starting from noise, if the brightness of the electron beam is sufficiently high. The brightness of the ETA is far below that possible with optimized choice of practical design characteristics such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. In particular, the measured brightness of the ETA injector is limited by plasma effects from the present cold, plasma cathode. As part of a coordinated theoretical and experimental effort to improve injector performance, we are using the EBQ gun design code to explore the current limits of gridless, relativistic, Pierce columns with moderate current density (>50 A/cm/sup 2/) at the cathode. The chief component in our experimental effort is a readily modified electron gun that will allow us to test many candidate cathode materials, types, and electrode geometries at field stresses up to 1 MV/cm. 8 references, 5 figures.

• Research Organization: Lawrence Livermore National Lab., CA (USA); Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098; W-7405-ENG-48
• OSTI ID: 6199243
• Report Number(s): UCRL-91123; CONF-8409163-1; ON: DE85000862
• Resource Relation: Conference: Workshop on coherent and collective properties of relativistic E-beams and electromagnetic radiation, Villa Olmo, Como, Italy, 13 Sep 1984
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
43 PARTICLE ACCELERATORS
FREE ELECTRON LASERS
PERFORMANCE
BEAM EMITTANCE
BEAM EXTRACTION
BEAM OPTICS
BRIGHTNESS
ELECTRON BEAMS
ELECTRON GUNS
KILO AMP BEAM CURRENTS
LINEAR ACCELERATORS
MEV RANGE 01-10
OPTIMIZATION
ACCELERATORS
BEAM CURRENTS
BEAMS
CURRENTS
ENERGY RANGE
LASERS
LEPTON BEAMS
MEV RANGE
OPTICAL PROPERTIES
PARTICLE BEAMS
PHYSICAL PROPERTIES
420300* - Engineering- Lasers- (-1989)
430200 - Particle Accelerators- Beam Dynamics
Field Calculations
& Ion Optics
430301 - Particle Accelerators- Ion Sources