Effects of ultraintense magnetic fields due to relativistic laser-plasma interactions on Langmuir-wave-caused dips in x-ray spectral line profiles

Abstract GigaGauss (GG) or even multi-GG magnetic fields are expected to develop during relativistic laser-plasma interactions. In our previous paper we proposed a method for measuring GG magnetic fields based on the phenomenon of Langmuir-wave-cased dips (L-dips) in x-ray line profiles. The L-dips were observed in several experimental spectroscopic studies of relativistic laser-plasma interactions. Ultra-strong magnetic fields affect the separation of the L-dips from one another, so that this separation can be used to measure such fields. In the present paper we provide some new results concerning the effect of the ultra-strong magnetic fields on the separation between the L-dips. But the primary focus of the present paper is at another effect of the GG magnetic fields on the L-dips: we study how these ultra-intense magnetic fields affect the halfwidth of the L-dips. One of the results turns out to be counterintuitive : for the case of the two-quantum resonance, the halfwidth of the L-dips is a non-monotonic function of the magnetic field. By advancing the results of the previous work, the present paper expands the possibilities for measuring super-strong magnetic fields up to ~ 10 GG expected to arise during relativistic laser-plasma interactions.