(2006) have conducted a fully relativistic R-matrix calculation of Ne IX, including resonances and radiation damping. Again, proper treatment of resonances, relativistic effects, and radiation damping is important. Line spectra from He-like ions are arguably the most important X-ray astrophysical diagnostics for temperature, density, absorption, and tests of ionization equilibrium. Brickhouse, in Advances In Atomic, Molecular, and Optical Physics, 2014 3.2.2 He-Like Ions
Moreover, since the arc GP is equal to the arc SC it follows that the ray reflected at R again passes through P. Hence, since C is the centre of curvature of the grating, the angle of incidence SRC and consequently also the angle of reflection are again equal to α. If the diameter of the circle is sufficiently large (in practice it is usually several feet), then no appreciable error is introduced by assuming R to lie on the circle K. Consider now another ray from S incident upon the grating at a different point R. If α = SQC is the angle of incidence, the angle CQP of reflection is also equal to α and, moreover, the arc SC is equal to the arc CP. To show this, construct the reflected ray QP corresponding to the incident ray SQ. We shall prove that light from any point P of the circle K will be approximately reflected to a point P and diffracted to points P″, P″, … on the circle, each of these points being a focus for diffracted rays of a particular order. Let Q be the midpoint of the surface of the grating and C its centre of curvature, and describe a circle K with centre at the midpoint O of QC and with radius r = OQ = OC ( Fig.
0 kommentar(er)
