Observation of Collisionless Shocks in Laser-Plasma Experiments

The propagation in a rarefied plasma (n(e)less than or similar to 10(15) cm(-3)) of collisionless shock waves and ion-acoustic solitons, excited following the interaction of a long (tau(L)similar to 470 ps) and intense (I similar to 10(15) W cm(-2)) laser pulse with solid targets, has been investigated via proton probing techniques. The shocks' structures and related electric field distributions were reconstructed with high spatial and temporal resolution. The experimental results were interpreted within the framework of the nonlinear wave description based on the Korteweg-de Vries-Burgers equation.

The role of the relative voltage and phase for frequency coupling in a dual-frequency capacitively coupled plasma

Frequency coupling in multifrequency discharges is a complex nonlinear interaction of the different frequency components. An alpha-mode low pressure rf capacitively coupled plasma operated simultaneously with two frequencies is investigated and the coupling of the two frequencies is observed to greatly influence the excitation and ionization within the discharge. Through this, plasma production and sustainment are dictated by the corresponding electron dynamics and can be manipulated through the dual-frequency sheath. These mechanisms are influenced by the relative voltage and also the relative phase of the two frequencies.

Plasma Ionization in Low-Pressure Radio-Frequency Discharges. Part I: Optical Measurements

The electron dynamics in the low-pressure operation regime ($«$ 5 Pa) of a neon capacitively coupled plasma is investigated using phase-resolved optical emission spectroscopy. Plasma ionization and sustainment mechanisms are governed by the expanding and contracting sheath and complex wave–particle interactions. Electrons are energized through the advancing and retreating electric field of the RF sheath. The associated interaction of energetic sheath electrons with thermal bulk plasma electrons drives a two-stream instability also dissipating power in the plasma.