Beam heating

Fig. 1. Vacuum evaporation process with use of electron beam heating where A represents the material to be deposited. The flux profile ( ) is at a...

Materials having a higher vapor pressure at low temperatures ate typically vaporized from resistively heated sources such as those shown in Figure 5a. Refractory materials requite a high temperature to be vaporized. A focused high energy electron-beam heating is necessary for vaporization (Fig. 5b). 

Changes in the composition of a specimen over the analyzed depth can be caused by beam heating or by beam charging of the specimen. Beam heating can lead to selective vaporization of some elements or diffrisional redistribution of the elements. If the surflice charges up to some potential, then electric-field enhanced diffusion can selectively redistribute certain elements. Beam-heating effects usually... 

The co-condensation at low temperature of a metal vapor (commonly produced by resistance or electron-beam heating of metals) with a vapor of weakly stabilizing organic ligands (such as -pentane, toluene, tetrahydrofu-ran, acetone, or acetonitrile), using commercially available reactors, affords solid matrices, where reactions between the ligand molecules and metal atoms can take place (Scheme 1(A) Figure 1) [5]. 

The diode laser is scanned up and down in frequency by a triangle wave, so that the scan should be linear in time and have the same rate in both directions. In the thermal accommodation coefficient experiments, the external beam heats the microsphere to a few K above room temperature and is then turned off. The diode laser is kept at fairly low power ( 7 pW) so that it does not appreciably heat the microsphere. Displacement of a WGM s throughput dip from one scan trace to the next is analyzed to find the relaxation time constant as the microsphere returns to room temperature. Results from the two scan directions are averaged to reduce error due to residual scan nonlinearity. This is done over a wide range of pressures (about four orders of magnitude). The time constant provides the measured thermal conductivity of the surrounding air, and fitting the thermal conductivity vs. pressure curve determines the thermal accommodation coefficient, as described in Sect. 5.5.2. 

Kriminski, S., Kazmierczak, M. and Thorne, R. E. (2003). Heat transfer from protein crystals impUcations for flash-cooling and X-ray beam heating. Acta Crystallogr. D 59,697-708. 

Extensive research on crystallographic shear (CS) planes has been reported in the literature as described earlier. Based on this research, including beam-heating studies in electron microscopy, it has been concluded that slight reduction of certain transition-metal oxides (e.g. simple model oxides, WO3, M0O3, V2O5,... 

The results indicate that a supersaturation of vacancies, c/co — 10, at the catalyst s surface is required to nucleate CS planes in M0O3 catalysts. CS planes are formed by the elimination of anion vacancies in supersaturation (where the supersaturation is defined relative to the background concentration of anion vacancies in equilibrium with CS planes, as described earlier) (Gai 1981, Gai et al 1982). The driving force for the nucleation of the CS fault is the difference between the chemical stress due to the supersaturation of anion vacancies of the faulted (defective) structure and the force required to create the fault. The estimate of Co is consistent with the equilibrium concentration of anion vacancies found in electron beam heating studies of M0O3 in vacuum (Bursill 1969). 

Fig. 8.1.4 Schematic illustration of the evaporation apparatus with electron beam heating, DP and MBP mean diffusion pump and mechanical booster pump, respectively. (Reprinted from J Cryst Growth, 56 S Iwama et a].. Ultrafine powders of TiN and AIN produced by a reactive gas evaporation technique with electron beam heating, pp 265-269. Copyright 1982, with permission from Elsevier Science )...

Electron-beam heating, in metal vapor synthesis, 1, 232 Electron-beam vaporization, in metal vapor synthesis, 1, 224 Electron correlation, and computational chemistry, 1, 642 Electron counting, in transition metal complexes bridging ligands, 1, 14 examples, 1, 9 ligand electrons, 1, 5/... 

Lanthanide triflates, for allylic tin reactions, 9, 354 Laser beam heating, in metal vapor synthesis, 1, 224 Laser methods, in mechanistic studies, 1, 248 Laser photochemical vapor deposition, with organometallic complexes, 1, 259... 

L. D. Stodiek, W. R. Stooksberry, R. Strachan, J.D. Suckewer, S. Takahasi, H. Tait, G.D., Ulrickson, M. von Goeler, S. Yamada, M. "PLT Neutral Beam Heating Results" in Proc. of the 7th Intern. Conf. on Plasma Physics and Controlled Nuclear Fusion Research, Innsbruck, Austria, 1979, (IAEA, Vienna, 1979) Vol. 1, p. 167. 

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. 

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