Abstract
Heat transport in reduced-mass targets irradiated with a high intensity laser pulse was studied. K alpha lines from partially ionized chlorine embedded in the middle of a triple-layered plastic target were measured to evaluate bulk electron temperature in the tracer region inside the target. Two groups of K alpha lines, one from Cl+-Cl6+ (hereby called "cold K alpha"), and the other from Cl9+ and Cl10+ ("shifted K alpha") are observed from different regions within the target. Two-dimensional collisional particle-in-cell simulations show two distinct heating mechanisms occurring concurrently: uniform heating by refluxing electrons and local heating by diffusive electrons in the central region. These two heating processes, which made the target temperature distribution nonuniform, are responsible for producing the two groups of K alpha lines in the experiment. The blue-shift of cold K alpha lines in the experiment is the signature of higher temperatures achieved by the refluxing heating in smaller-mass targets. (C) 2011 American Institute of Physics. [doi:10.1063/1.3551591]