A sensitive method to study a dilute ultracold plasma based on the autoionization resonances of Rydberg atoms is demonstrated. Ultracold ⁴⁰Ca Rydberg atoms are prepared in a continuously operating magneto-optical trap. A method that allows the detection of the plasma with ion and electron densities below 10⁹ m^–3 is shown. Experimental studies of resonances at the two-photon \(4s3d{{\,}^{1}}{{D}_{2}}{-} 90{{\,}^{1}}{{D}_{2}}\) Rydberg transition have been carried out using 672 and 798 nm resonant laser beams. The autoionization resonance is observed during fluorescence of single-charged ⁴⁰Ca ions at a wavelength of 397 nm. The dependence of the amplitude of autoionization resonance on the density of ions in the continuously generated ultracold plasma is obtained.

展示了一种基于Rydberg原子自电离共振研究稀冷超冷等离子体的灵敏方法。在一个连续运行的磁光阱中制备⁴⁰ c Ca Rydberg超冷原子。显示了一种方法，该方法可以检测离子密度和电子密度低于10 ⁹ m ^–3的等离子体。双光子\（4s3d {{\，} ^ {1}} {{D} _ {2}} {-} 90 {{\，} ^ {1}} {{D} _ {2}} \）使用672和798 nm共振激光束进行了Rydberg跃迁。在单电荷^40的荧光过程中观察到自电离共振钙离子的波长为397 nm。获得了自电离共振的幅度对连续产生的超冷等离子体中离子密度的依赖性。