Abstract: In this paper, we explain the diagnostic method of electron temperature and density of a laser-produced plasma using spectral lines of He-like Al ion in detail; the intensity ratios of satellite to resonance line vs the electron temperature and resonance to combination line vs electron density have been given, respectively. Meanwhile, according to the line intensity ratios from experiment, the electron temperature and density for He-like Al ion have been determined.

Key words: diagnostic of the state of plasma, He-like ion, C-R model