| Institution: | a Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, U.K. b Department of Physics, Queen's University, Belfast BT7 1NN, N. Ireland, U.K. c Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, U.S.A. d JET Joint Undertaking, Abingdon, Oxfordshire OX14 3EA, U.K. |
| Abstract: | Calculated intensities of the Fe 
X-ray lines due to transitions 2p6 − 2p53d lines (near 15 Å) and 2p6 − 2p53s lines (near 17 Å) are compared with measured line intensities in solar and tokamak spectra. For the solar spectra, temperature Te is obtained from the ratio of the Fe
16.776 Å line to a nearby Fe 
line. We find excellent agreement for all the major Fe
line features in the 15–17 Å region except the Fe
15.015 Å line, the observed flux of which is less than the theoretical by a factor f. We find that f strongly depends on the heliocentric angle θ of the emitting region, being smallest (0.2) when the region is nearest Sun centre, but nearly 1 near the limb. Attributing this to resonance scattering, we are able to deduce the path length and electron density from the observations. Possible application to stellar active regions is given. |
