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Title: Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams

Abstract

An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.

Inventors:
 [1];  [1];  [1]
  1. Madison, WI
Issue Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
973142
Patent Number(s):
7498592
Application Number:
11/427,273
Assignee:
Wisconsin Alumni Research Foundation (Madison, WI)
Patent Classifications (CPCs):
H - ELECTRICITY H01 - BASIC ELECTRIC ELEMENTS H01J - ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
H - ELECTRICITY H05 - ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR H05H - PLASMA TECHNIQUE
DOE Contract Number:  
FG02-97ER54437
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Hershkowitz, Noah, Longmier, Benjamin, and Baalrud, Scott. Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams. United States: N. p., 2009. Web.
Hershkowitz, Noah, Longmier, Benjamin, & Baalrud, Scott. Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams. United States.
Hershkowitz, Noah, Longmier, Benjamin, and Baalrud, Scott. Tue . "Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams". United States. https://www.osti.gov/servlets/purl/973142.
@article{osti_973142,
title = {Non-ambipolar radio-frequency plasma electron source and systems and methods for generating electron beams},
author = {Hershkowitz, Noah and Longmier, Benjamin and Baalrud, Scott},
abstractNote = {An electron generating device extracts electrons, through an electron sheath, from plasma produced using RF fields. The electron sheath is located near a grounded ring at one end of a negatively biased conducting surface, which is normally a cylinder. Extracted electrons pass through the grounded ring in the presence of a steady state axial magnetic field. Sufficiently large magnetic fields and/or RF power into the plasma allow for helicon plasma generation. The ion loss area is sufficiently large compared to the electron loss area to allow for total non-ambipolar extraction of all electrons leaving the plasma. Voids in the negatively-biased conducting surface allow the time-varying magnetic fields provided by the antenna to inductively couple to the plasma within the conducting surface. The conducting surface acts as a Faraday shield, which reduces any time-varying electric fields from entering the conductive surface, i.e. blocks capacitive coupling between the antenna and the plasma.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2009},
month = {3}
}

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Works referenced in this record:

Neutral pumping in a helicon discharge
journal, August 1998


Helicons-the early years
journal, January 1997


Steady‐state ion pumping of a potential dip near an electron collecting anode
journal, August 1986


Non-ambipolr electron extraction from a weakly magnetized RF plasma
conference, January 2006


Sheaths: More complicated than you think
journal, May 2005


"Electrodeless" Plasma Cathode for Neutralization of Ion Thrusters
conference, June 2012


Helicons-the past decade
journal, January 1997