Experimental study of ultracold Ca (40) plasma

Experimental study of ultracold ⁴⁰Ca plasma

This work describes the approach that makes possible creation of the steady-state ultracold plasma having various densities and temperatures by means of continuous two-step optical excitation of ⁴⁰Ca atoms in the MOT. A strongly coupled ultracold plasma can be used as an excellent test platform for studying many-body interactions associated with various plasma phenomena. The parameters of the plasma are studied using laser-induced fluorescence of calcium ions. The strongly coupled plasma with the peak ion density of 2.7X10⁶  cm^-3 and the minimum electron temperature near 2K has been prepared. The experimental setup for laser cooling of ⁴⁰Ca atoms enables the capture of approximately 3X10⁷  atoms in the trap. Spectra of Rydberg transitions in n¹S₀ states were recorded for n ranging from 40 to 120. The energies of these transitions allowed for the determination of the most precise value of the ionization potential, which is 49305.91966(4) cm^-1 compared to known data. A sensitive diagnostic method for sparse ultracold plasma, based on the autoionization effect of Rydberg states of ⁴⁰Ca atoms, has been developed. This method enables the detection of plasma with ion concentrations of up to 10³  cm^-3, roughly equivalent to an electric field intensity of  10^-2  V/m.