Plasma temperatures density profiles

Theoretical estimates of the erosion of the first wall and plasma contamination due to sputtering requires a knowledge of particle and photon fluxes to the wall, as well as data on the erosion yields. Sputtering will be discussed in a later part of this chapter. Here we shall briefly summarize some of the calculations done on primary fluxes in future fusion reactors. The calculations are rather uncertain because of the poor understanding of various parameters such as divertor efficiency, refueling, neutral beam heating, plasma temperature and density profiles, including the scrape-off layer in the case of divertor operated Tokamaks. 

Determination of Flame and Plasma Temperatures and Density Profiles by Means of Laser-Excited Fluorescence... 

The MPRES simulator has been validated by comparing predictions to experimental data taken in a Gaseous Electronics Conference (GEC) reference cell [155]. Predicted [101] (lines) and measured [156] (points) radial profiles of electron density, electron temperature, and plasma potential for a chlorine plasma are shown in... 

Fig. 26. Comparison of MPRES simulator predictions [101, 152] (solid lines) to experimental data [156] (points). Spatial profiles of electron density (top), electron temperature (middle), and plasma potential (bottom). Pressure 20 mtorr, power 180 W.

Fig. 27. SIMS profiles of the total deuterium density produced by exposing near-intrinsic silicon (pa 100 flcm) to plasma products at various temperatures (Johnson, 1987, 1988 Corbett et al., 1988 a,b).

Fig. 1. Deuterium concentration profiles in bulk n-type GaAs Si after exposure to a rf deuterium plasma for 90 min. at various temperatures (rf power density = 0.2 W/cm2). 

Fig. 6. Deuterium concentration profiles in LPE grown p-type GaAs Si (p 7x 1018 cm-3) exposed to a rf deuterium plasma for 90 min. at different temperatures (rf power density = 0.2 W/cm2). For these diffusion temperatures, the plateau region is well defined with a deuterium solubility slightly above the silicon acceptor concentration. J. Chevallier era/., Mat. Res. Soc. Symp. Proc. 104, 337 (1988). Materials Research Society. 

Fig. 7. Deuterium concentration profiles in a GaInAs/InP Zn OMVPE structure after exposure to a rf deuterium plasma for 20 min. at different temperatures (rf power density = 0.08 W/cm2). The dashed line represents the active zinc concentration profile as deduced from a POLARON semiconductor profiler. Note that the deuterium concentration matches the zinc concentration at all investigated temperatures. J. Chevallier et al., Materials Science Forum, 38-41, 991 (1989). Trans. Tech. Publications Semicond. Sci. Technol. 4, 87 (1989). IOP Publishing Ltd.

The experimental results were analyzed using an integrated approach. To obtain the temporal evolution of the temperature and the density profiles of the bulk plasma, the experimental hot-electron temperature was used as an initial condition for the 1D-FP code [26]. The number of hot electrons in the distribution function were adjusted according to the assumed laser absorption. The FP code is coupled to the 1-D radiation hydrodynamic simulation ILESTA [27]. The electron (or ion) heating rate from hot electrons is first calculated by the Fokker-Planck transport model and is then added to the energy equation for the electrons (or ions) in ILESTA-1D. Results were then used to drive an atomic kinetics package [28] to obtain the temporal evolution of the Ka lines from partially ionized Cl ions. 

Although there is significant local recycling near the limiter blade, it is still too weak to cause substantial poloidal variations in the plasma density and temperature profiles. The plasma flow is in a simple isothermal regime, with weak influence of atomic processes, and with the power flow to the limiter being determined by the electrostatic sheath in front of the limiter [1] (and not by atomic and molecular processes). 

Fig. 5.8. Profiles of (a) electron temperature, (b) density, and (c) ion flux measured with Langmuir probes at the divertor plates in an attached and a detached divertor plasma. The distance from the strike point (dl) is measured along the outer divertor plates as shown in the right-hand figure...

Upon publication of the first book on plasma polymerization, the author had a well established concept that plasma polymerization is not an ionization driven chemical process, but a chemical process driven by the dissociation of molecules caused by the impact of low energy electrons—but could not find the decisive phenomenon to support the concept. After beginning to write the follow up of the first book on plasma polymerization, on the basis of the hypothesis, the author decided to present a picture of a DC glow discharge, of which the distribution profile of electron temperature and electron density were available. 

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