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Title: Penning discharge ion source with self-cleaning aperture

Abstract

An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode (24) with an exit aperture (12) in a position opposite a first dynode 10a, from which the ions are sputtered, two opposing cathodes (14, 16), each with an anode (18, 20) for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. Anmore » extractor (22) immediately outside the exit aperture of the second dynode is maintained at ground potential during this entire period of sputtering while the anode, dynode and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. In that manner, material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam. Atoms sputtered from the second dynode which do not become ionized and exit through the slit will be redeposited on the first dynode, and hence recycled for further ion beam generation during subsequent operating cycles.« less

Inventors:
 [1];  [2];  [3]
  1. (Berkeley, CA)
  2. (Richmond, CA)
  3. (El Cerrito, CA)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
864304
Patent Number(s):
4344019
Assignee:
United States of America as represented by United States (Washington, DC) LLNL
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
penning; discharge; source; self-cleaning; aperture; type; provided; dynode; 24; exit; 12; position; opposite; 10a; sputtered; opposing; cathodes; 14; 16; anode; 18; 20; accelerating; electrons; emitted; cylindrical; space; defined; support; gas; maintained; ionized; supplied; negative; pulse; emit; -300; attract; atoms; plasma; time; voltage; respect; -5; tuning; miniscus; optimum; extraction; geometry; terminated; driven; strongly; -600; allowing; heavy; sputtering; period; remove; virtually; deposited; material; extractor; 22; immediately; outside; ground; potential; entire; cathode; reference; positive; kv; 30; accelerated; manner; add; beam; slit; redeposited; hence; recycled; generation; subsequent; operating; cycles; ionized gas; space defined; ground potential; reference voltage; electrons emitted; exit aperture; support gas; self-cleaning aperture; penning discharge; discharge type; /315/204/250/313/

Citation Formats

Gavin, Basil F., MacGill, Robert A., and Thatcher, Raymond K. Penning discharge ion source with self-cleaning aperture. United States: N. p., 1982. Web.
Gavin, Basil F., MacGill, Robert A., & Thatcher, Raymond K. Penning discharge ion source with self-cleaning aperture. United States.
Gavin, Basil F., MacGill, Robert A., and Thatcher, Raymond K. Fri . "Penning discharge ion source with self-cleaning aperture". United States. https://www.osti.gov/servlets/purl/864304.
@article{osti_864304,
title = {Penning discharge ion source with self-cleaning aperture},
author = {Gavin, Basil F. and MacGill, Robert A. and Thatcher, Raymond K.},
abstractNote = {An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode (24) with an exit aperture (12) in a position opposite a first dynode 10a, from which the ions are sputtered, two opposing cathodes (14, 16), each with an anode (18, 20) for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. An extractor (22) immediately outside the exit aperture of the second dynode is maintained at ground potential during this entire period of sputtering while the anode, dynode and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. In that manner, material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam. Atoms sputtered from the second dynode which do not become ionized and exit through the slit will be redeposited on the first dynode, and hence recycled for further ion beam generation during subsequent operating cycles.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1982},
month = {1}
}

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