ELECTRON-ION HYBRID INSTABILITY IN LASER-PRODUCED PLASMA EXPANSIONS ACROSS MAGNETIC-FIELDS

High-intensity laser irradiation of hollow glass cylinders immersed in a magnetic field results in plasma expansions strongly collimated in the direction transverse to both the initial flow and the magnetic field, but jetlike in the direction parallel to the initial flow. Magnetic fields from B = 0 kG to B = 10 kG produced plasmas with markedly different geometrical features. Fast framing camera photographs show the plasmas propagating across magnetic field lines and undergoing structuring indicative of transverse velocity shear-driven instabilities. Comparison is made between the observed instability characteristics and predictions of Rayleigh-Taylor, classical Kelvin-Helmholtz, and the electron-ion hybrid instabilities. Only the electron-ion hybrid instability is consistent with the experimental results.