Plasma stability

Abstract: Laser-driven plasma-based accelerators, which are capable of supporting fields in excess of 100 GV/m, are reviewed. This includes the laser wakefield accelerator, the plasma beat wave accelerator, the self-modulated laser wakefield accelerator, plasma waves driven by multiple laser pulses, and highly nonlinear regimes. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse diffraction, electron dephasing, laser pulse energy depletion, and beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Experiments demonstrating key physics, such as the production of high-quality electron bunches at energies of 0.1-1 GeV, are summarized.

Abstract: The paper summarizes the basic information on the equilibrium of a toroidal plasma column in systems of the Tokamak type. It considers the methods of maintaining a plasma in equilibrium with the help of a conducting casing, an external maintaining field and the iron core of a transformer. Attention is paid to the role of the inhomogeneity of the maintaining field. It is shown in particular how the shape of the column cross-section depends on the curvature of the lines of force of the maintaining field. For the case (which has practical importance) weak asymmetry of the field distribution in the transverse cross-section, this paper describes a uniform method of consideration, which takes into account the influence of different factors on the equilibrium position of the column. This method is used for calculating plasma equilibrium in a Tokamak model with a conducting casing. Account is here taken of the effect of gaps in the casing and of finite electrical conductivity. Some cases of plasma equilibrium which are outside the standard Tokamak scheme are also considered, such as equilibrium in a conducting shell having the shape of a racetrack, equilibrium where the whole current is transferred by relativistic runaway electrons and equilibrium at high plasma pressure βI ~R/a.

Abstract: In order for EUV plasma sources to become the next-generation lithographic (NGL) source, significant obstacles still need to be overcome. Improvements in conversion efficiency (CE), plasma stability, and component lifetimes are required. Although the final goal is to produce a suitable 13.5-nm light source, solving the full range of problems will require a more thorough understanding of the plasma than just the EUV optical emission. Because of the complex nature and extreme conditions produced in the EUV plasma sources, many different plasma diagnostics are needed to fully characterize these EUVL sources. Although the development of EUVL light sources is a relatively recent endeavor, similar plasmas have been utilized for many years for other applications. LPPs have been used for applications ranging from laser drilling to x-ray lasers. DPPs have been investigated as potential nuclear fusion sources and also as x-ray sources. Consequently, suitable plasma diagnostics have been developed over many years for the study of these types of plasma sources. This chapter will concentrate on plasma diagnostics not based on optical-emission measurements. Although measurements of the optical emissions from these plasmas provide a great deal of information, many of these techniques have been discussed previously in Chapter 27. Consequently, this chapter will concentrate mainly on diagnostics of emitted plasma debris and other basic plasma properties such as electron density and temperature.

Abstract: A tokamak plasma configuration is reported that simultaneously improves on the maximum stable plasma pressure, the bootstrap current contribution, and kinetic stability to temperature and density gradient driven modes in toroidal geometry. It is characterized by negative magnetic shear in the plasma interior and a peaked pressure profile. Stability to the ideal low-n external kink modes requires a conducting shell at 1.3 times the plasma minor radius. This novel plasma configuration is promising for improved plasma performance in advanced tokamak experiments.