Investigation of shock-shock interaction and Mach reflection in laterally colliding laser-blow-off plasmas

Abstract

Interactions of two Li plasma plumes and shock waves are investigated at various pressures (∼10−5 to 3 mbar) in the argon gas ambient. Fast imaging and optical emission spectroscopy are used to study the plume dynamics and characteristic emission of plasmas. The plasma plumes are created in laser-blow-off geometry. The expansion of plasma plumes in the ambient gas leads to the formation of an interaction zone. The formation of interaction zone is dependent on the ambient pressure and below a certain pressure, no significant change is observed in the shape and size of the interaction plasma. In the higher pressure, formation of interaction zone and its shape are dependent on ambient pressure. Dynamics of seed plasmas and interaction zone are also affected by the shock-shock interactions. The shock-shock interaction depends on the angle of incidence (α) between two shock waves at the initial time of interaction but as the plumes expand, the shock-shock interaction does not follow α dependence.

Numerical study of the effect of atomic mass of the ambient gas on the expansion and the lateral interactions of LBO plumes

“…Further colliding plasmas are used to understand the stagnation on hohlraum axis and capsule implosions in ICF [10,11]. In addition to the widely explored collision between the conventional laser produced plasmas, recently several experiments have been conducted to understand the interaction between the laser-blowoff (LBO) of the thin film [24,25]. Due to the difference in ablation mechanism, the thermal history, composition and evolution of LBO plume is significantly different from the plasma plume produced by a bulk solid target [26].…”

“…Also, the interaction between the plasma plumes in the presence of ambient gas is more complex in comparison to the case of vacuum because of the presence of shock front ahead of the plasma plume [29][30][31]. In the presence of shock front, the interaction between the plumes is governed by shock-shock collision and its reflection [24]. The understanding of colliding shock is important, especially in probing astronomical objects in a laboratory scale [12,13].…”

Effect of magnetic field on the laterally colliding plasma plumes

“…[1,[7][8][9][10] Colliding plasma with different targets, laser parameters, ambient and ablation geometries have been reported by several authors. [11][12][13][14][15][16][17][18][19][20][21][22][23][24] In our earlier work in aluminium colliding plasma we had found a clear distinct interaction zone and neutral emission is significantly enhanced at later times due to increase in three body recombination. [25] Plasma-plasma interaction in the presence of external magnetic field is an interesting phenomenon to study because of its implications from the understanding fundamental physics as well as applications.…”

Molecular formation in the stagnation region of colliding laser-produced plasmas

“…Laser-produced colliding plasmas and the stagnation region formed at the plasmas' intersection zone have found attractive applications in the fields of x-ray lasers, pulsed-laser deposition, fusion science, laser ion sources, plasma light sources and in the generation of astrophysical objects in the laboratory frame [1][2][3][4][5][6][7][8][9][10][11]. Several target and laser-plasma configurations were used for generating colliding plasmas in a laboratory frame; some of the plasma collision schemes were head-on, lateral and orthogonal [10,[12][13][14][15][16][17][18][19]. Previous studies showed that charge-exchange collisions among the species in the plume happening during interpenetration of the plasmas at early time followed by formation of a stagnation layer at later times [4,20,21].…”