Pressure dependence of an ion beam accelerating structure in an expanding helicon plasma

We present measurements of the parallel ion velocity distribution function and electric field in an expanding helicon source plasma plume as a function of downstream gas pressure and radial and axial positions. The ion beam that appears spontaneously in the plume persists for all downstream pressures investigated, with the largest parallel ion beam velocities obtained for the lowest downstream pressures. However, the change in ion beam velocity exceeds what would be expected simply for a change in the collisionality of the system. Electric field measurements confirm that it is the magnitude of the potential structure responsible for accelerating the ion beam that changes with downstream pressure. Interestingly, the ion density radial profile is hollow close to the end of the plasma source for all pressures, but it is hollow at downstream distances far from the source only at the highest downstream neutral pressures.

[1]  E. Scime,et al.  Spatial Structure of Ion Beams in an Expanding Plasma , 2017 .

[2]  A. Fruchtman.  Neutral gas depletion in low temperature plasma , 2017 .

[3]  Å. Fredriksen,et al.  RFEA Measurements of High-Energy Electrons in a Helicon Plasma Device with Expanding Magnetic Field , 2017, Front. Phys..

[4]  D. Bora,et al.  Transition from single to multiple axial potential structure in expanding helicon plasma , 2017 .

[5]  Y. Takao,et al.  Modifications of plasma density profile and thrust by neutral injection in a helicon plasma thruster , 2016 .

[6]  I. Hutchinson.  Electron Holes in phase-space: what they are and why they matter , 2016 .

[7]  Å. Fredriksen,et al.  A comparison of ion beam measurements by retarding field energy analyzer and laser induced fluorescence in helicon plasma devices , 2015 .

[8]  Kazunori Takahashi,et al.  Characterization of Helicon Plasma Thruster Performance Operated for Various Rare Gas Propellants , 2015 .

[9]  A. Sasoh,et al.  Electrostatic acceleration of helicon plasma using a cusped magnetic field , 2014 .

[10]  C. Charles,et al.  Transport of ion beam in an annular magnetically expanding helicon double layer thruster , 2014 .

[11]  T. Lafleur.  Helicon plasma thruster discharge model , 2014 .

[12]  E. Scime,et al.  Instability limits for spontaneous double layer formation , 2013 .

[13]  S. Pottinger,et al.  Helicon double layer thruster operation in a low magnetic field mode , 2012 .

[14]  S. Markidis,et al.  Numerical simulations of separatrix instabilities in collisionless magnetic reconnection , 2012 .

[15]  E. Scime,et al.  Threshold for formation of a stable double layer in an expanding helicon plasma , 2010 .

[16]  C. Charles.  High density conics in a magnetically expanding helicon plasma , 2010 .

[17]  E. Scime,et al.  Time-resolved measurements of double layer evolution in expanding plasma , 2010 .

[18]  C. Charles,et al.  Oblique double layers: a comparison between terrestrial and auroral measurements. , 2009, Physical Review Letters.

[19]  E. Scime,et al.  One- and two-dimensional laser induced fluorescence at oblique incidence , 2009 .

[20]  E. Scime,et al.  Comparison of gridded energy analyzer and laser induced fluorescence measurements of a two-component ion distribution. , 2008, The Review of scientific instruments.

[21]  C. Charles,et al.  Ion beam formation in a low-pressure geometrically expanding argon plasma , 2007 .

[22]  C. Charles,et al.  The magnetic-field-induced transition from an expanding plasma to a double layer containing expanding plasma , 2007 .

[23]  R. Ergun,et al.  Double layers and ion phase-space holes in the auroral upward-current region. , 2006, Physical Review Letters.

[24]  M. Lieberman,et al.  A theory for formation of a low pressure, current-free double layer , 2006, Physical review letters.

[25]  F.F. Chen.  Nonlinear effects and anomalous transport in RF plasmas , 2006, IEEE Transactions on Plasma Science.

[26]  Francis F. Chen.  Physical mechanism of current-free double layers , 2006 .

[27]  C. Charles,et al.  The ion velocity distribution function in a current-free double layer , 2005 .

[28]  C. Charles,et al.  Observations of ion-beam formation in a current-free double layer. , 2005, Physical review letters.

[29]  Liang Zhao,et al.  Solar Wind Origin in Coronal Funnels , 2005, Science.

[30]  Xuan Sun,et al.  Parallel velocity and temperature of argon ions in an expanding, helicon source driven plasma , 2004 .

[31]  Christine Charles,et al.  Current-free double-layer formation in a high-density helicon discharge , 2003 .

[32]  J. Kline,et al.  Parametric decay instabilities in the HELIX helicon plasma source , 2003 .

[33]  E. Scime,et al.  Frequency dependent effects in helicon plasmas , 1997 .

[34]  C. Charles,et al.  Measurement and modeling of ion energy distribution functions in a low pressure argon plasma diffusing from a 13.56 MHz helicon source , 1992 .

[35]  A. V. Phelps,et al.  Cross Sections and Swarm Coefficients for Nitrogen Ions and Neutrals in N2 and Argon Ions and Neutrals in Ar for Energies from 0.1 eV to 10 keV , 1991 .

[36]  G. Ganguli,et al.  Kinetic theory for electrostatic waves due to transverse velocity shears , 1988 .

[37]  N. Omidi,et al.  The ion-ion acoustic instability , 1987, Journal of Plasma Physics.