FeXVII X-ray lines in solar coronal and laboratory plasmas.
Abstract
Theoretical intensities of the Fe XVII X-ray lines due to transitions 2p^6^-2p^5^3d (near 15Å) and 2p^6^-2p^5^3s (near 17Å) are presented, and compared with solar flare and active region spectra. The ratio of the 15Å lines to the 17Å lines is a function of temperature T_e_, but for solar spectra this is not of practical use because of the resonance scattering of the intense 15.015Å line. Instead we use the ratio of a nearby Fe XVIII line to obtain T_e_. We find very satisfactory correspondence between solar spectra and synthetic spectra based on calculated line intensities with appropriately chosen T_e_ apart from the 15.015Å line, which is sometimes less intense than its theoretical value, apparently owing to resonance scattering. Spectra emitted by DITE and JET tokamak plasmas with measured T_e_ and N_e_ are also considered. A predicted density variation of the ratio of the Fe XVII lines at 17.051Å and 17.096 Å is confirmed, and using Abel inversion techniques applied to a sequence of DITE spectra with different radial distances good agreement is found between the theoretical temperature variation of the I(15.015Å)/I(16.776Å) line ratio and that derived from these spectra. We conclude that our calculated Fe XVII line intensities are very reliable and may therefore be used in future analysis.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 1997
- Bibcode:
- 1997A&A...324..381P
- Keywords:
-
- ATOMIC DATA;
- ATOMIC PROCESSES;
- SUN: ACTIVITY;
- SUN: FLARES;
- SUN: X-RAYS;
- GAMMA RAYS