2009/3/3us high gradient research collaboration workshop 1 design studies of an x-band multi- beam...
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2009/3/3 US High Gradient Research Collaboration Workshop
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Design Studies of an X-band Multi-beam Klystron
S. Fukuda
KEK
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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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 budg
et, we want to develop an X-band mbk.
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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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 .
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Project and Parameters (1)
Required parameters:
• Vbeam =50kV• Prf out =2MW• P rf in < 50W• Loading of the cathode should be no more than 7A/cm2
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Parameters (2)Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Sketch of whole MBKAccelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Gun Simulation
Micro-perv. of a beam-let=1.25Current of a beam-let=14A
Bz=2.5kG, Bz/Bb=2
Focusing by 2-lenses compensation of transverse Field, less than 0.005Bz
Magnetic field is a key point.
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Cavity simulation
TM410 Mode is used.6 cavities system
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Electromagnet Design
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Klystron simulation : one dimensional and Magic simulationAccelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Design Difficulties and Drawback
Hot dimension of the cathode Different expansion factors between copper an
d iron for magnetic lens High perveance of 10 microperv. can lead the i
nstability, 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 hig
h microperv of a beam-let.
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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More high power version: Larionov’s approachMagnetically compression for MBK
More larger cathodes are possibly used.( more beam intensity)
Number of the cathodes (i.e. beamlets) are possibly used.
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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10.3MW
10.1MW
9.8MW
Accelerator Laboratory, KEK
2009/3/3 US High Gradient Research Collaboration Workshop
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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.
Accelerator Laboratory, KEK