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Title: Improved 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 reaccelerated 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 to 500/sup 0/C 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:
Issue Date:
OSTI Identifier:
6107421
Application Number:
ON: TI85006445
Assignee:
Dept. of Energy EDB-85-040662
DOE Contract Number:  
AC07-79ID01675
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ION SOURCES; DESIGN; ANIONS; CROSSED FIELDS; ELECTRIC FIELDS; MAGNETIC FIELDS; CHARGED PARTICLES; IONS; 640301* - Atomic, Molecular & Chemical Physics- Beams & their Reactions

Citation Formats

Delmore, J.E. Improved negative ion source. United States: N. p., 1984. Web.
Delmore, J.E. Improved negative ion source. United States.
Delmore, J.E. Tue . "Improved negative ion source". United States.
@article{osti_6107421,
title = {Improved negative ion source},
author = {Delmore, J.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 reaccelerated 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 to 500/sup 0/C 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 = {1984},
month = {5}
}