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The results are given of the observations, in the 2–19-A wavelength range, of spectral lines emitted from laser plasmas of hydrogen- and helium-like ions of Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, and V (Z = 11–23, ionization potentials up to 6.86 keV). Transitions of the n l n' l' – 1s n' l' and 1s 2p n l – 1s2 n l type in helium- and lithium-like ions, respectively, are identified. A total of 180 lines are described and identified. The precision of the wavelength measurements is 0.002 A at λ ≈ 10 A and 0.0005 A at λ ≈ 2.5 A. The results obtained are combined with the results of published laboratory and astrophysical investigations in a review table.

We define the conditions for which a population inversion with respect to the ground state, due to recombination at high electron densities, can appear in cold laser plasmas. We point out the interest of giant and short laser pulses for producing such plasmas.

The typical noble gas ion laser plasma consists of a high-current-density glow discharge in a noble gas, in the presence of a magnetic field. Typical CW plasma conditions are current densities of 100 to 2000 A/cm^2, tube diameters of 1 to 10 mm, filling pressures of 0.1 to 1.0 torr, and an axial magnetic field of the order of 1000 G. Under these conditions the typical fractional ionization is about 2 percent and the electron temperature between 2 and 4 eV. Pulsed ion lasers typically use higher current densities and lower operating pressures. This paper discusses the properties of ion laser plasmas, in terms of both their external discharge parameters and their internal ion and excited state densities. The effect these properties have on laser operation is explained. Many interesting plasma effects, which are important in ion lasers, are given attention. Among these are discharge nonuniformity near tube constrictions, extremely high ion radial drift velocities, wall losses intermediate between ambipolar diffusion and free fall, gas pumping effects, and radiation trapping. The current status of ion laser technology is briefly reviewed.

The production of uniform large-volume laser plasmas with electron-ion densities on the order of 1012/cm3or larger by means of photoionization is investigated. An externally applied electric field heats the electron gas to the optimal temperature for excitation of laser levels. Photoionization by intense UV light may take place in a low partial pressure gas of low ionization potential species dispersed throughout the host laser medium, or the laser medium itself may serve as the photoionized species. Both single-photon ionization and two-photon two-step ionization are shown to be applicable.

A number of photoionization mechanisms and how they can be used to generate large-volume laser plasmas are discussed. Reaction rates for two-step photoionization of the cesium atoms as well as formation of molecular ions (Cs 2 +) are estimated. The necessary cross-section data were obtained from related research in thermionic energy converters.

An investigation was made of the spectra of Mg XI, Mg XII, Al XII, and Al XIII ions generated by laser radiation focused on solid targets. The relative intensities of the allowed and forbidden lines and of the lines beginning from self-ionized levels yielded the electron density (Ne ≈ 1020 cm–3) and temperature (kTe ≈ 300 eV) of the radiating region. The method employed was suitable for the diagnostics of plasmas with Ne ≈ 1023 cm–3 provided the spectra of strongly ionized hydrogen-like and helium-like ions were observed.

Measurements of the back reflection from laser-produced plasmas have been carried out for laser intensities of up to 1.5\ifmmode\times\else\texttimes\fi{}${10}^{16}$ W/${\mathrm{cm}}^{2}$ with pulse durations of 120 psec using spherical low-$Z$ targets. The reflectivity of the plasma increases with incident intensity but saturates at a value of 10%. The intensity-dependent reflectivity is attributed to stimulated Brillouin scattering.

The time history of conversion of input laser radiation to output soft X-rays from an oxygen-doped, spherical, laser-produced plasma is calculated. Experimental measurements of total X-ray conversion efficiency are found to be in good agreement with the theoretical model. The predicted fast risetime (

The summary of two methods of producing laser plasmas with electron densities of the order of 10 12 /cm 3 and greater via photoionization is presented.

The electron energy distribution function has been calculated for CO2 laser plasmas in gas mixtures of CO2, N2, and He using available cross‐section data. Electron‐molecule energy exchange rates were then calculated and used to evaluate the role of dissociation products in electron energy exchange processes. Under circumstances typical of CO2 lasers, the calculation shows that more than 15% of the electron energy can be transferred to CO vibrational levels. The sensitivity of electron kinetic processes to vibrational temperature variations was also evaluated for plasma systems dominated by N2. Changes in vibrational temperature were found to have a relatively small effect on electron power transfer.

Measurements are reported showing the influence of xenon on the discharge properties of CO2 lasers. Small admixtures of xenon lower the electron temperature considerably and it is possible to operate the CO2 laser without nitrogen and with little decrease in output power for low flow rates or sealed‐off operation. The influence of added CO is reported briefly. It is proposed that direct electronic excitation to the vibrational levels of CO and consequent vibrational energy transfer from the CO (v = 1) to the CO2 upper laser level is the most important mechanism when N2 is absent.

Reports of spontaneously generated magnetic fields in laser-created plasmas are briefly reviewed and theoretical explanations mentioned. Observations which indicate that a dynamo effect might be operative are pointed out. Standard plasma equations are proved to imply an Einstein-de Haas effect, i.e. magnetically induced mass rotation, and a Barnett effect, i.e. a dynamo mechanism. The experimental support for these two effects is discussed. A theorem concerning rotation of theta-pinches and denying the effects is shown to be based on a too simplified continuum plasma description. Indications are presented that the dynamo magnetic field may have plasma confining properties.

A nonthermal beam‐target model is proposed to explain the anomalous generation of neutrons from laser plasmas. The model requires the presence of a multimicrosecond prepulse that generates an extended low‐density gas cloud, and it predicts the effects of the addition of a background gas to the experiments.