Effects of neutral interactions on velocity-shear-driven plasma waves

In a laboratory experiment, we demonstrate the substantial effects that collisions between charged and neutral particles have on low-frequency (Ωi ≪ ω ≪ Ωe) shear-driven electrostatic lower hybrid waves in a plasma. We establish a strong (up to 2.5 kV/m) highly localized electric field with a length scale shorter than the ion gyroradius, so that the ions in the plasma, unlike the electrons, do not develop the full E × B drift velocity. The resulting shear in the particle velocities initiates the electron-ion hybrid (EIH) instability, and we observe the formation of strong waves in the vicinity of the shear with variations in plasma densities of 10% or greater. Our experimental configuration allows us to vary the neutral background density by more than a factor of two while holding the charged particle density effectively constant. Not surprisingly, increasing the neutral density decreases the growth rate/saturation amplitude of the waves and increases the threshold electric field necessary for wave format...

[1]  L. Rudakov,et al.  Generation of electromagnetic waves in the very low frequency band by velocity gradient , 2014 .

[2]  G. Ganguli,et al.  Plasma response to a varying degree of stress. , 2013, Physical review letters.

[3]  G. Ganguli,et al.  Spontaneous electromagnetic emission from a strongly localized plasma flow. , 2010, Physical review letters.

[4]  G. Ganguli,et al.  Laboratory investigation of boundary layer processes due to strong spatial inhomogeneity , 2003 .

[5]  J. Jackson,et al.  Observations of low frequency oscillations due to transverse sheared flows , 2003 .

[6]  J. Peñano,et al.  Generation of electromagnetic ion cyclotron waves in the ionosphere by localized transverse dc electric fields , 2002 .

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

[8]  Takao Tanikawa,et al.  Anomalous Cross-Field Transport of Electrons Driven by the Electron-Ion Hybrid Instability Due to the Velocity Shear in a Magnetized Filamentary Plasma , 2000 .

[9]  J. Peñano,et al.  Generation of ELF electromagnetic waves in the ionosphere by localized transverse dc electric fields: Subcyclotron frequency regime , 2000 .

[10]  J. Peñano,et al.  IONOSPHERIC SOURCE FOR LOW-FREQUENCY BROADBAND ELECTROMAGNETIC SIGNATURES , 1999 .

[11]  J. Peñano,et al.  Velocity shear-driven instabilities in a rotating plasma layer , 1998 .

[12]  G. Ganguli,et al.  Velocity‐shear‐driven ion‐cyclotron waves and associated transverse ion heating , 1998 .

[13]  Duncan,et al.  Plasma Response to Strongly Sheared Flow. , 1996, Physical review letters.

[14]  G. Ganguli,et al.  Velocity‐shear‐induced ion‐cyclotron turbulence: Laboratory identification and space applications , 1995 .

[15]  M. Koepke,et al.  Observation of ion‐cyclotron turbulence at small values of magnetic‐field‐aligned current , 1994 .

[16]  Carroll,et al.  Experimental verification of the inhomogeneous energy-density driven instability. , 1994, Physical review letters.

[17]  G. Ganguli,et al.  Coupling of microprocesses and macroprocesses due to velocity shear: An application to the low-altitude ionosphere , 1994 .

[18]  G. Ganguli,et al.  Relaxation of the stressed plasma sheet boundary layer , 1994 .

[19]  G. Ganguli,et al.  Small‐scale plasma irregularities produced during electron attachment chemical releases , 1994 .

[20]  G. Ganguli,et al.  Electron–ion hybrid instability in laser‐produced plasma expansions across magnetic fields , 1992 .

[21]  Y. C. Lee,et al.  Electron–ion hybrid instabilities driven by velocity shear in a magnetized plasma , 1992 .

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

[23]  G. Ganguli,et al.  Simulation of ion‐cyclotron‐like modes in a magnetoplasma with transverse inhomogeneous electric field , 1988 .

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

[25]  Y. C. Lee,et al.  Electrostatic ion cyclotron instability due to a nonuniform electric field perpendicular to the external magnetic field , 1985 .