X -ray spectral diagnostics of super-strong magnetic fields in ultra-relativistic laser plasma

Under the influence of ultra-intense laser radiation on micro-structured targets a substance may be formed in an extreme state – with the density close to the solid state and with super-strong magnetic fields. Experimental diagnostics of such fields by the optical methods is not possible due to the high density and self -radiation of plasma, therefore, X-ray spectral methods become more preferable. The specific features of the methodology of such diagnostics of super-strong magnetic fields are discussed. The diagnostics is based on the analysis of the spectral line of multi-charged ions profiles. As an example, the targets with the structure formed by regular columns of a micron-size substance irradiated by laser pulses with the parameters of the prospective XCELS facility are considered.