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Title: Negative ion source

Abstract

A method and apparatus for providing a negative ion source accelerates electrons away from a hot filament electron emitter into a region of crossed electric and magnetic fields arranged in a magnetron configuration. During a portion of the resulting cycloidal path, the electron velocity is reduced below its initial value. The electron accelerates as it leaves the surface at a rate of only slightly less than if there were no magnetic field, thereby preventing a charge buildup at the surface of the emitter. As the electron traverses the cycloid, it is decelerated during the second, third, and fourth quadrants, then reeccelerated as it approaches the end of the fourth quadrant to regain its original velocity. The minimum velocity occurs during the fourth quadrant, and corresponds to an electron temperature of 200.degree. to 500.degree. for the electric and magnetic fields commonly encountered in the ion sources of magnetic sector mass spectrometers. An ion source using the above-described thermalized electrons is also disclosed.

Inventors:
 [1]
  1. Idaho Falls, ID
Issue Date:
Research Org.:
EXXON NUCLEAR IDAHO CO
OSTI Identifier:
866175
Patent Number(s):
4649279
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
DOE Contract Number:  
AC07-79ID01675
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
negative; source; method; apparatus; providing; accelerates; electrons; hot; filament; electron; emitter; region; crossed; electric; magnetic; fields; arranged; magnetron; configuration; portion; resulting; cycloidal; path; velocity; reduced; below; initial; value; leaves; surface; rate; slightly; field; preventing; charge; buildup; traverses; cycloid; decelerated; third; fourth; quadrants; reeccelerated; approaches; quadrant; regain; original; minimum; occurs; corresponds; temperature; 200; degree; 500; commonly; encountered; sources; sector; mass; spectrometers; above-described; thermalized; disclosed; electron emitter; mass spectrometers; mass spectrometer; magnetic field; magnetic fields; hot filament; commonly encountered; reduced below; electron velocity; sector mass; magnetic sector; electron temperature; crossed electric; /250/315/

Citation Formats

Delmore, James E. Negative ion source. United States: N. p., 1987. Web.
Delmore, James E. Negative ion source. United States.
Delmore, James E. Thu . "Negative ion source". United States. https://www.osti.gov/servlets/purl/866175.
@article{osti_866175,
title = {Negative ion source},
author = {Delmore, James E},
abstractNote = {A method and apparatus for providing a negative ion source accelerates electrons away from a hot filament electron emitter into a region of crossed electric and magnetic fields arranged in a magnetron configuration. During a portion of the resulting cycloidal path, the electron velocity is reduced below its initial value. The electron accelerates as it leaves the surface at a rate of only slightly less than if there were no magnetic field, thereby preventing a charge buildup at the surface of the emitter. As the electron traverses the cycloid, it is decelerated during the second, third, and fourth quadrants, then reeccelerated as it approaches the end of the fourth quadrant to regain its original velocity. The minimum velocity occurs during the fourth quadrant, and corresponds to an electron temperature of 200.degree. to 500.degree. for the electric and magnetic fields commonly encountered in the ion sources of magnetic sector mass spectrometers. An ion source using the above-described thermalized electrons is also disclosed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {1}
}

Patent:

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