Filament heater current modulation for increased filament lifetime

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Description

The surface conversion H-minus ion source employs two 60 mil tungsten filaments which are approximately 17 centimeters in length. These filaments are heated to approximately 2,800 degrees centigrade by 95--100 amperes of DC heater current. The arc is struck at a 120 hertz rate, for 800 microseconds and is generally run at 30 amperes peak current. Although sputtering is considered a contributing factor in the demise of the filament, evaporation is of greater concern. If the peak arc current can be maintained with less average heater current, the filament evaporation rate for this arc current will diminish. In the vacuum ... continued below

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6 p.

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Paul, J.D. & Williams, H.E. III June 1, 1996.

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Description

The surface conversion H-minus ion source employs two 60 mil tungsten filaments which are approximately 17 centimeters in length. These filaments are heated to approximately 2,800 degrees centigrade by 95--100 amperes of DC heater current. The arc is struck at a 120 hertz rate, for 800 microseconds and is generally run at 30 amperes peak current. Although sputtering is considered a contributing factor in the demise of the filament, evaporation is of greater concern. If the peak arc current can be maintained with less average heater current, the filament evaporation rate for this arc current will diminish. In the vacuum of an ion source, the authors expect the filaments to retain much of their heat throughout a 1 millisecond (12% duty) loss of heater current. A circuit to eliminate 100 ampere heater currents from filaments during the arc pulse was developed. The magnetic field due to the 100 ampere current tends to hold electrons to the filament, decreasing the arc current. By eliminating this magnetic field, the arc should be more efficient, allowing the filaments to run at a lower average heater current. This should extend the filament lifetime. The circuit development and preliminary filament results are discussed.

Physical Description

6 p.

Notes

INIS; OSTI as DE96009219

Source

  • Power modulator conference, Boca Raton, FL (United States), Jul 1996

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  • Other: DE96009219
  • Report No.: LA-UR--96-1249
  • Report No.: CONF-960799--1
  • Grant Number: W-7405-ENG-36
  • Office of Scientific & Technical Information Report Number: 251382
  • Archival Resource Key: ark:/67531/metadc667862

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • June 1, 1996

Added to The UNT Digital Library

  • June 29, 2015, 9:42 p.m.

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  • Feb. 29, 2016, 3:07 p.m.

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Paul, J.D. & Williams, H.E. III. Filament heater current modulation for increased filament lifetime, article, June 1, 1996; New Mexico. (digital.library.unt.edu/ark:/67531/metadc667862/: accessed August 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.