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Title: Oscillatory instability development in extraction system of a negative ion source

Conditions of oscillatory instability development in the extraction system of a negative hydrogen ion source based on a volume-produced plasma are studied. Such an ion source is characterized by the presence of the parent gas in the extraction system due to the leakage from the gas-discharge chamber. The secondary electrons in the area of the ion-optical system become the reason of oscillation appearance and possible beam current modulation. Analytically the range of the stable beam propagation is found. The instability increment is shown to be rather small. Maximum increment of the oscillations corresponds to the beam velocity equal to the thermal velocity of plasma electrons. The group velocity of the oscillations is close to the beam velocity so the oscillations are convective. Simulation of the low energy beam propagation is performed in COMSOL Multiphysics, the beam current modulation being observed.
Authors:
 [1] ;  [2]
  1. National Research Nuclear University MEPhI, Kashirskoye sh. 31, Moscow 115409 (Russian Federation)
  2. State Scientific Center “All-Russian Electrotechnical Institute (VEI),” Krasnokazarmennaya St. 12, Moscow 111250 (Russian Federation)
Publication Date:
OSTI Identifier:
22482860
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 87; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ANIONS; BEAM CURRENTS; BEAMS; ELECTRONS; HYDROGEN IONS; INSTABILITY; LEAKS; MODULATION; OPTICAL SYSTEMS; OSCILLATIONS; PLASMA; SIMULATION; VELOCITY