Dynamics of heat fluxes in a channel area heated by a pulsed high-current discharge

The dynamics of thermal fields of dielectric surfaces heated as a result of initiation of a pulsed high-current surface discharge (plasma sheet) was studied. A pulsed surface discharge sliding along the surface of a dielectric was generated on the upper (flat) and lower (stepped) walls of the discharge chamber with quartz windows. Sequential images of optical (nanosecond range) and infrared (millisecond range) radiation were obtained near a dielectric ledge in the shape of a rectangular parallelepiped measuring $6 \times 2 \times 48$ mm$^3$. The time evolution of thermal radiation from surfaces was recorded with time-lapse photography in the infrared range at pressures from $65$ to $290$ Torr. It is shown that the cooling time of a plasma-heated region localized near the dielectric ledge can last up to $30$ ms and significantly exceeds the cooling time of a flat upper wall heated by a discharge fairly uniformly distributed over the surface of the dielectric.