Formation of a shielding layer near a solid target under the action of a high-power plasma flow

The dynamics of the target plasma produced in the interaction of a powerful (W similar to 10 MW/cm(2)) flow of a high-temperature (T-i + T-e less than or equal to 1 keV) hydrogen plasma with a solid target is studied experime ntally. The plasma-target interaction proceeds in the magnetic field B = 2 T oriented perpendicular to the target surface. The target materials are gr aphite, Plexiglass, quartz, boron nitride, aluminum, stainless steel, coppe r, molybdenum, and tungsten. It is shown that, within 1-2 mu s, a dense (n > 10(17) cm(-3)) target-plasma layer is formed, which protects the target s urface against the direct action of the plasma how. The magnetic field supp resses the expansion of the target plasma across the magnetic field lines; as a result, quasi-one- dimensional hydrodynamic plasma motion is establish ed. The dynamics and parameters of the plasma in the shielding layer are sh own to depend strongly on the target material.