Enhanced modified faraday cup for determination of power density distribution of electron beams

Patent · Mon Jan 01 04:00:00 EST 2001

OSTI ID:874046

Elmer, John W ^[1]; Teruya, Alan T ^[2]

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1. Danville, CA
2. Livermore, CA

An improved tomographic technique for determining the power distribution of an electron or ion beam using electron beam profile data acquired by an enhanced modified Faraday cup to create an image of the current density in high and low power ion or electron beams. A refractory metal disk with a number of radially extending slits, one slit being about twice the width of the other slits, is placed above a Faraday cup. The electron or ion beam is swept in a circular pattern so that its path crosses each slit in a perpendicular manner, thus acquiring all the data needed for a reconstruction in one circular sweep. The enlarged slit enables orientation of the beam profile with respect to the coordinates of the welding chamber. A second disk having slits therein is positioned below the first slit disk and inside of the Faraday cup and provides a shield to eliminate the majority of secondary electrons and ions from leaving the Faraday cup. Also, a ring is located below the second slit disk to help minimize the amount of secondary electrons and ions from being produced. In addition, a beam trap is located in the Faraday cup to provide even more containment of the electron or ion beam when full beam current is being examined through the center hole of the modified Faraday cup.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• DOE Contract Number: W-7405-ENG-48
• Assignee: Regents of University of California (Oakland, CA)
• Patent Number(s): US 6300755
• OSTI ID: 874046
• Country of Publication: United States
• Language: English

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acquired
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addition
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beam
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beam profile
beam trap
beams
below
center
chamber
circular
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containment
coordinates
create
crosses
cup
current
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eliminate
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metal
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minimize
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orientation
path
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perpendicular
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placed
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provide
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refractory
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