Radiation Transport in Z-Pinches

Z-pinches, formed by passing large currents through wires or gas puffs, are the most powerful and energetic laboratory sources of X-rays. As higher current generators become available, Z-pinches incorporate increasingly larger masses of plasma and are nearly always optically thick to some or most of the photons that they produce. Understanding and modeling the transport of this radiation is an important element in attaining an overall picture of the physics of Z-pinches and in optimizing their properties for applications. This paper focuses on the aspects of radiation transport that are most relevant to the Z-pinch environment. The topics covered include: theory of radiation transport and its strengths and limitations, sources of opacity in Z-pinches, requirements for local thermodynamic equilibrium in the presence of opacity, transition to the blackbody limit, and Z-pinch experiments that demonstrate the effects of radiation transport.