ABSTRACT
Highly dense plasma having highly ionized ions is required for the generation of short wavelength X-ray lasers, where plasma is used as a gain medium via a three-step process, i.e. ionization, excitation, and decay. Two principle methods used for excitation are the collision excitation method and the recombination method. The transition of electrons between the ground state and various higher energy levels within the ions leads to the generation of X-ray lasers. In addition to this, this chapter discusses two fundamental processes, i.e. free-electron lasers (FELs) and plasma-based soft X-ray lasers (Plasma SXRL), which are used for the generation of coherent soft X-rays. Chirped pulse amplification (CPA) and Mach-Zehnder techniques also are used to generate X-ray lasers, which are discussed in greater detail.
The ultrashort, ultrafast, and ultrahigh brightness properties of X-ray lasers have carved a niche for themselves in the area of nanoscopy. Other useful applications include coherent diffraction imaging, high-resolution microscopy, phase-resolved X-ray imaging, diagnostic tool for highly dense plasmas, and so forth. These are discussed in the chapter along with the introduction of current achieved parameters of soft and hard X-ray lasers.
