Cascade emission in electron beam ion trap plasma of W${}^{25+}$ ion

Abstract

Spectra of the W${}^{25+}$ ion are studied using the collisional-radiative model (CRM) with an ensuing cascade emission. It is determined that the cascade emission boosts intensities only of a few lines in the $10-3$ nm range. The cascade emission is responsible for the disappearance of structure of lines at about 6 nm in the electron beam ion trap plasma. Emission band at 4.5 to 5.3 nm is also affected by the cascade emission. The strongest lines in the CRM spectrum correspond to $4d^{9}4f^4\to 4f^3$ transitions, while $4f^{2}5d\to 4f^3$ transitions arise after the cascade emission is taken into account.

16 pages including 4 figures and 3 tables