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Time-resolved compression of a laser-driven solid deuterated plastic sphere with a cone was measured with flash Kα x-ray radiography. A spherically converging shockwave launched by nanosecond GEKKO XII beams was used for compression while a flash of 4.51 keV Ti Kα x-ray backlighter was produced by a high-intensity, picosecond laser LFEX (Laser for Fast ignition EXperiment) near peak compression for radiography. Areal densities of the compressed core were inferred from two-dimensional backlit x-ray images recorded with a narrow-band spherical crystal imager. The maximum areal density in the experiment was estimated to be 87 ± 26 mg/cm2. The temporal evolution of the experimental and simulated areal densities with a 2-D radiation-hydrodynamics code is in good agreement.

We investigate the nonlinear characteristics of space‐charge waves, which propagate along a relativistic electron beam drifting near the surface of a semi‐infinite Kerr‐like medium, under the condition that the drift velocity of the electron beam does not exceed the Cherenkov threshold. On the basis of the linear fluid model for the electron beam and the stationary wave analysis, we obtain some interesting features for the nonlinear space‐charge waves such as power dependence of wave numbers and hysteresis characteristics.

The effect of beam thickness in a two‐dimensional Cherenkov laser is investigated on the basis of the fluid model for the electron beam. In the analysis, the transverse variation of the drift velocity for the electron beam is taken into account. The numerical simulation shows that there exists an optimum beam thickness for an efficient use of the electron beam in the Cherenkov laser.

A possibility to realize an isotropic left handed material up to optical frequencies is theoretically investigated. The proposed homogeneous structure consists of dielectric spheres embedded randomly in a negative permittivity host medium. While the effective permittivity of the structure is negative over a wide frequency range due to the host medium, the negative effective permeability is obtained by spherical magnetic resonances of the dielectric spheres. Since this structure utilizes only magnetic resonance, both analytical and numerical simulation results show that it has higher fabrication tolerance, larger bandwidth and potentially less propagation loss than the previously proposed structure, i.e., the dielectric spheres embedded in the dielectric host.