Physics of a magnetic filter for negative ion sources. I. Collisional transport across the filter in an ideal, 1D filter

Magnetic filters are used in negative ion sources for neutral beam injection in fusion devices to reduce the electron temperature in the extraction region in order to limit negative ion destruction by fast electrons. The drop in electron temperature through the filter is due to the enhanced residence time and collisional energy losses of electrons trapped in the magnetic field. The mechanisms controlling particle and energy transport through the magnetic filter in negative ion sources of the ITER type are still not clear and the aim of this paper is to clarify and quantify these mechanisms. A particle-in-cell Monte Carlo simulation is used to revisit and analyze the role and operation of the magnetic filter in an “ideal” one-dimensional configuration and to study the stability of the one-dimensional solution in a two-dimensional configuration with periodic boundary conditions. The roles of collisions and instabilities on electron transport through the filter are discussed. The influence of a more realisti...

[1]  K. Tarnev,et al.  Magnetic filter operation in hydrogen plasmas , 2007 .

[2]  A. Lichtenberg,et al.  Two-dimensional particle-in-cell simulations of transport in a magnetized electronegative plasma , 2010 .

[3]  S. Mattoo,et al.  Plasma diffusion across inhomogeneous magnetic fields , 2002 .

[4]  G. Ganguli,et al.  Electron–ion hybrid mode due to transverse velocity shear , 1988 .

[5]  J. Adam,et al.  Study of stationary plasma thrusters using two-dimensional fully kinetic simulations , 2004 .

[6]  A. Holmes.  Electron flow through transverse magnetic fields in magnetic multipole arc discharges , 1982 .

[7]  U. Fantz,et al.  Laser photodetachment on a high power, low pressure rf-driven negative hydrogen ion source , 2009 .

[8]  J. Boeuf,et al.  Particle-in-cell with Monte Carlo collision modeling of the electron and negative hydrogen ion transport across a localized transverse magnetic field , 2009 .

[9]  A. Holmes.  A one-dimensional model of a negative ion source , 1996 .

[10]  G. Bonhomme,et al.  Low-frequency instabilities in a laboratory magnetized plasma column , 2004 .

[11]  T. Klinger,et al.  Radially propagating turbulent structures in a linear helicon plasma device , 2007 .

[12]  B. Chaudhury,et al.  Physics of a magnetic filter for negative ion sources. II. E × B drift through the filter in a real geometry , 2012 .

[13]  B. Heinemann,et al.  Plasma grid design for optimized filter field configuration for the NBI test facility ELISE , 2009 .

[14]  N. Oudini,et al.  Plasma transport across magnetic field lines in low-temperature plasma sources , 2011 .

[15]  C. Martens,et al.  Physical performance analysis and progress of the development of the negative ion RF source for the ITER NBI system , 2009 .

[16]  U. Fantz,et al.  A Langmuir probe system for high power RF-driven negative ion sources on high potential , 2009 .

[17]  J. Verboncoeur.  Particle simulation of plasmas: review and advances , 2005 .

[18]  R. S. Hemsworth,et al.  Status of the ITER heating neutral beam system , 2009 .

[19]  A. Phelps.  Energetic ion, atom, and molecule reactions and excitation in low-current H2 discharges: model. , 2009, Physical review. E, Statistical, nonlinear, and soft matter physics.

[20]  G. Fubiani,et al.  Physics of a magnetic barrier in low-temperature bounded plasmas: insight from particle-in-cell simulations , 2012 .

[21]  Charles K. Birdsall,et al.  Particle-in-cell charged-particle simulations, plus Monte Carlo collisions with neutral atoms, PIC-MCC , 1991 .

[22]  G. Ganguli,et al.  Nonlinear evolution of a strongly sheared cross‐field plasma flow , 1993 .

[23]  M. A. Henderson,et al.  Progress on the heating and current drive systems for ITER , 2009 .

[24]  J. Boeuf,et al.  Modeling a high power fusion plasma reactor-type ion source: Applicability of particle methods , 2012 .

[25]  C. Martens,et al.  Overview of the RF source development programme at IPP Garching , 2006 .

[26]  T. Shirai,et al.  ANALYTIC CROSS SECTIONS FOR COLLISIONS OF H+, H2+, H3+, H, H2, AND H− WITH HYDROGEN MOLECULES , 2000 .

[27]  L. Lea,et al.  The suppression of electrons extracted from a negative‐ion source , 1990 .