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Title: Design And Construction of a W-Band Sheet Beam Klystron

Abstract

The design and construction of a 100 kW peak power, 2% duty, PCM focused, Wband sheet beam klystron is discussed. The elliptical cross section beam is produced by a new electron gun design using a cylindrical cathode and a racetrack shaped focus electrode. The multi-gap cavities produce acceptable values of R/Q and are designed to produce a uniform electric field over the width of the 12:1 aspect ratio beam. The prototype cavities are produced using normal machining however, LIGA will be used to fabricate the cavities in production versions.

Authors:
;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
876449
Report Number(s):
SLAC-PUB-11688
TRN: US0600966
DOE Contract Number:
AC02-76SF00515
Resource Type:
Conference
Resource Relation:
Conference: 7th Workshop on High Energy Density and High Power RF, Kalamata, Greece, 6/13/2005-6/17/2005
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ASPECT RATIO; CATHODES; CAVITIES; CONSTRUCTION; CROSS SECTIONS; DESIGN; ELECTRON GUNS; ENERGY DENSITY; KLYSTRONS; PEAK LOAD; Accelerators,ACCPHY

Citation Formats

Scheitrum, G., and /SLAC. Design And Construction of a W-Band Sheet Beam Klystron. United States: N. p., 2006. Web.
Scheitrum, G., & /SLAC. Design And Construction of a W-Band Sheet Beam Klystron. United States.
Scheitrum, G., and /SLAC. Tue . "Design And Construction of a W-Band Sheet Beam Klystron". United States. doi:. https://www.osti.gov/servlets/purl/876449.
@article{osti_876449,
title = {Design And Construction of a W-Band Sheet Beam Klystron},
author = {Scheitrum, G. and /SLAC},
abstractNote = {The design and construction of a 100 kW peak power, 2% duty, PCM focused, Wband sheet beam klystron is discussed. The elliptical cross section beam is produced by a new electron gun design using a cylindrical cathode and a racetrack shaped focus electrode. The multi-gap cavities produce acceptable values of R/Q and are designed to produce a uniform electric field over the width of the 12:1 aspect ratio beam. The prototype cavities are produced using normal machining however, LIGA will be used to fabricate the cavities in production versions.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 14 00:00:00 EST 2006},
month = {Tue Feb 14 00:00:00 EST 2006}
}

Conference:
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  • Sheet beam devices provide important advantages for very high power, narrow bandwidth RF sources like accelerator klystrons [1]. Reduced current density and increased surface area result in increased power capabi1ity, reduced magnetic fields for focusing and reduced cathode loading. These advantages are offset by increased complexity, beam formation and transport issues and potential for mode competition in the ovennoded cavities and drift tube. This paper will describe the design issues encountered in developing a 100 kW peak and 2 kW average power sheet beam k1ystron at W-band including beam formation, beam transport, circuit design, circuit fabrication and mode competition.
  • With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat} {approx} {lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focusing field strengths.more » Initial simulations of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35% beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry.« less
  • An X band klystron using a sheet beam and wiggler focusing was simulated using the 2 + 1/2 dimensional particle in cell code MASK. Simulation of the rf cavities was by means of the port approximation used in modelling of standard klystrons. The wigglers, which would need permanent magnets to achieve the required field strengths, were modelled using an idealized analytic expression with an exponential rise and a linear taper superimposed on a sinusoidal variation. Cavity locations and tunings were varied for maximum output power. Beam voltage and current were also varied to explore the effect on efficiency. Both anmore » idealized laminar beam and a more realistic beam from a gun design code were studied. For a voltage of 200 kV and current of 20 amp per linear cm efficiencies of approximately 50% were calculated.« less
  • With the development of ever higher energy particle accelerators comes the need for compactness and high gradient, which in turn require very high frequency high power rf sources. Recent development work in W-band accelerating techniques has spurred the development of a high-power W-band source. Axisymmetric sources suffer from fundamental power output limitations (P{sub sat}{approximately}{lambda}{sup 2}) brought on by the conflicting requirements of small beam sizes and high beam current. The sheet beam klystron allows for an increase in beam current without substantial increase in the beam current density, allowing for reduced cathode current densities and focussing field strengths. Initial simulationsmore » of a 20:1 aspect ratio sheet beam/cavity interaction using the 3 dimensional particle-in-cell code Magic3D have demonstrated a 35{percent} beam-power to RF power extraction efficiency. Calculational work and numerical simulations leading to a prototype W-band sheet beam klystron will be presented, together with preliminary cold test structure studies of a proposed RF cavity geometry. {copyright} {ital 1999 American Institute of Physics.}« less