Design Studies of an X-band Multi-beam Klystron

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Design Studies of an X-band Multi-beam Klystron

• S. Fukuda
• KEK

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Motivation to develop x-band MBK

• X-band compact linac are desired for the medical
  use and non-destructive inspection ex.
  Cyber-knife machine, handy X-ray inspection for
  chemical plant.
• We have developed the compact linac of 900keV
  collaborating between KEK and Tokyo university.
  RF source was a commercial magnetron.
• It is desired to develop a mbk for the next
  stage.
• If we are succeeded in obtaining the competitive
  budget, we want to develop an X-band mbk.

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Achieving goal of MBK design

• Lower applied voltage not to use the insulation
  oil or to use a small insulation oil cup.
• Output Power (1) Output power of 2 MW.
• (2) Output power of a10 MW or more.
• Two approach
• (1) usual multi-gun assemblies for MBK and
• (2) magnetic compression gun for MBK (more high
  power version).
• Designs were performed by Russians of BINP Dr.
  Vladimir Teryaev and Dr. Alexsander Larionov at
  KEK .

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Project and Parameters (1)

• Required parameters
• Vbeam 50kV
• Prf out 2MW
• P rf in lt 50W
• Loading of the cathode should be no more than
  7A/cm2

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Parameters (2)
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Sketch of whole MBK
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Gun Simulation
Bz2.5kG, Bz/Bb2
Focusing by 2-lenses compensation of transverse
Field, less than 0.005Bz Magnetic field is a
key point.
Micro-perv. of a beam-let1.25 Current of a
beam-let14A
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Cavity simulation
TM410 Mode is used. 6 cavities system
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Electromagnet Design
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Klystron simulation one dimensional and Magic
simulation
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Design Difficulties and Drawback

• Hot dimension of the cathode
• Different expansion factors between copper and
  iron for magnetic lens
• High perveance of 10 microperv. can lead the
  instability, and beam tester is required.
• Collector is also possible source of instability
  and model test is required.
• Drawback low efficiency of 40 due to a high
  microperv of a beam-let.

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More high power version Larionovs
approachMagnetically compression for MBK
More larger cathodes are possibly used. (
more beam intensity) Number of the cathodes
(i.e. beamlets) are possibly used.
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(No Transcript)
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10.3MW
10.1MW
9.8MW
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Summary

• X-band mbk is desired for an application of a
  compact linac such as medical use and
  non-destructive inspection use.
• Design attempts of X-band mbk in KEK are shown.
• Features of low applied voltage to the klystron
  around 50-60kV are achieving goal of these
  designs.