Ion source with improved primary arc collimation

Title: Ion source with improved primary arc collimation

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Abstract

An improved negative ion source is provided in which a self-biasing, molybdenum collimator is used to define the primary electron stream arc discharge from a filament operated at a negative potential. The collimator is located between the anode and the filament. It is electrically connected to the anode by means of an appropriate size resistor such that the collimator is biased at essentially the filament voltage during operation. Initially, the full arc voltage appears across the filament to collimator until the arc discharge strikes. Then the collimator biases itself to essentially filament potential due to current flow through the resistor thus defining the primary electron stream without intercepting any appreciable arc power. The collimator aperture is slightly smaller than the anode aperture to shield the anode from the arc power, thereby preventing the exposure of the anode to the full arc power which, in the past, has caused overheating and erosion of the anode collimator during extended time pulsed-beam operation of the source. With the self-biasing collimator of this invention, the ion source may be operated from short pulse periods to steady-state without destroying the anode.

Inventors:

Dagenhart, William K ^[1]

Oak Ridge, TN

Issue Date:: 1985-01-01

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

OSTI Identifier:: 865527

Patent Number(s):: 4531077

Assignee:: United States of America as represented by United States (Washington, DC)

Patent Classifications (CPCs):: H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01J - ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS

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H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01J - ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
H01J27/028 - {Negative ion sources}
H01J27/20 - using particle {beam} bombardment, e.g. ionisers

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DOE Contract Number:: W-7405-ENG-26

Resource Type:: Patent

Country of Publication:: United States

Language:: English

Subject:: source; improved; primary; collimation; negative; provided; self-biasing; molybdenum; collimator; define; electron; stream; discharge; filament; operated; potential; located; anode; electrically; connected; means; appropriate; size; resistor; biased; essentially; voltage; operation; initially; appears; strikes; biases; due; current; flow; defining; intercepting; appreciable; power; aperture; slightly; shield; preventing; exposure; past; caused; overheating; erosion; extended; time; pulsed-beam; pulse; periods; steady-state; destroying; electron stream; current flow; electrically connected; negative potential; pulse period; time pulse; primary electron; /315/250/313/

Citation Formats


                    Dagenhart, William K. Ion source with improved primary arc collimation.  United States: N. p., 1985. 
        Web.

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                    Dagenhart, William K. Ion source with improved primary arc collimation.  United States.

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                    Dagenhart, William K. Tue .  
        "Ion source with improved primary arc collimation".  United States.  https://www.osti.gov/servlets/purl/865527.

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@article{osti_865527,

  title        = {Ion source with improved primary arc collimation},

  author       = {Dagenhart, William K},

  abstractNote = {An improved negative ion source is provided in which a self-biasing, molybdenum collimator is used to define the primary electron stream arc discharge from a filament operated at a negative potential. The collimator is located between the anode and the filament. It is electrically connected to the anode by means of an appropriate size resistor such that the collimator is biased at essentially the filament voltage during operation. Initially, the full arc voltage appears across the filament to collimator until the arc discharge strikes. Then the collimator biases itself to essentially filament potential due to current flow through the resistor thus defining the primary electron stream without intercepting any appreciable arc power. The collimator aperture is slightly smaller than the anode aperture to shield the anode from the arc power, thereby preventing the exposure of the anode to the full arc power which, in the past, has caused overheating and erosion of the anode collimator during extended time pulsed-beam operation of the source. With the self-biasing collimator of this invention, the ion source may be operated from short pulse periods to steady-state without destroying the anode.},

  doi          = {},

  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {1985},

  month        = {1}

}

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