Linear permittivity tapering in a Cerenkov microwave source with a pre-bunched beam
- Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523 (United States)
Cerenkov microwave sources use a dielectric-lined waveguide to reduce the velocity of the electromagnetic wave and provide efficient energy transfer between the wave and the driving electron beam. Tapering the permittivity of the dielectric to maintain synchronism between the beam and the wave as the beam loses energy can increase the efficiency of these devices. Here, we consider such a structure driven by an electron beam with a harmonic density perturbation. Particle-In-Cell (PIC) simulations and a macro-particle model based on the slowly varying envelope approximation are first used to examine an un-tapered baseline case. PIC simulations of the source with linear tapers over the entire amplifier length as well as over only a section of the amplifier where the beam executes synchrotron oscillations are examined. The efficiency for the baseline un-tapered source is 18%, while efficiencies up to approximately 48% are found using a taper in dielectric permittivity. Results of the best performing cases are presented. Detailed examination of longitudinal phase space, particle energy distributions, evolution of longitudinal wavenumber, and phase dynamics are presented from the PIC simulations.
- OSTI ID:
- 22130469
- Journal Information:
- Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 4 Vol. 20; ISSN PHPAEN; ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Transient Self-Amplified Cerenkov Radiation with a Short Pulse Electron Beam
Efficiency enhancement in a Cherenkov laser by a proper permittivity variation
Computer simulation of a Cerenkov interaction between obliquely propagating whistler mode waves and an electron beam
Journal Article
·
Wed Jan 21 23:00:00 EST 2009
· Physical Review Special Topics Accelerators and Beams, vol. 12, no. 8, August 24, 2009, pp. 080705-1 -080705-14
·
OSTI ID:1019062
Efficiency enhancement in a Cherenkov laser by a proper permittivity variation
Journal Article
·
Sun Nov 30 23:00:00 EST 1997
· Journal of Applied Physics
·
OSTI ID:550444
Computer simulation of a Cerenkov interaction between obliquely propagating whistler mode waves and an electron beam
Journal Article
·
Mon Dec 31 23:00:00 EST 1979
· Phys. Fluids; (United States)
·
OSTI ID:5540168