Nickel-like Ions Research Articles

Probabilities of Radiative Transitions in the Spectra of Nickel-like Ions Cd XXI, In XXII, and Sn XXIII

Probabilities of electric-dipole 3d94p → 3d10, 3d94s transitions in the spectra of nickel-like ions Cd XXI, In XXII, and Sn XXIII are calculated semiempirically in the intermediate coupling scheme. The radial integrals necessary for obtaining absolute values of the probabilities are calculated in the length form with Hartree–Fock functions.

Вероятности радиационных переходов в спектрах никелеподобных ионов Cd XXI, In XXII, Sn XXIII

AbstractProbabilities of electric-dipole 3 d ^94 p → 3 d ^10, 3 d ^94 s transitions in the spectra of nickel-like ions Cd XXI, In XXII, and Sn XXIII are calculated semiempirically in the intermediate coupling scheme. The radial integrals necessary for obtaining absolute values of the probabilities are calculated in the length form with Hartree–Fock functions.

Semiempirical calculation of radiative constants in the spectra of nickel-like ions Kr IX, Sr XI, Y XII, Ru XVII, Pd XIX, and Ag XX

The probabilities of the electric-dipole transitions 3d 94p, 3d 94f-3d 10, 3d 94s, and 3d 94d in the spectra of nickel-like ions Kr IX, Sr XI, Y XII, Ru XVII, Pd XIX, and Ag XX are calculated semiempirically with the use of published energy levels.

Optimum electron temperature and density for short-wavelength plasma-lasing from nickel-like ions

Soft X-ray lasing across a Ni-like plasma gain-medium requires optimum electron temperature and density for attaining to the Ni-like ion stage and for population inversion in the 3d94d1(J=0)→3d94p1(J=1) laser transition. Various scaling laws, function of operating parameters, were compared with respect to their predictions for optimum temperatures and densities. It is shown that the widely adopted local thermodynamic equilibrium (LTE) model underestimates the optimum plasma-lasing conditions. On the other hand, non-LTE models, especially when complemented with dielectronic recombination, provided accurate prediction of the optimum plasma-lasing conditions. It is further shown that, for targets with Z equal or greater than the rare-earth elements (e.g. Sm), the optimum electron density for plasma-lasing is not accessible for pump-pulses at λ=1ω=1μm. This observation explains a fundamental difficulty in saturating the wavelength of plasma-based X-ray lasers below 6.8nm, unless using 2ω pumping.

Extreme ultraviolet and soft x-ray laser emission from Ni-like Nd ions

We use the energy levels, transition probabilities, and effective collision strengths for the states 1s2 2s2 2p6 3s2 3p6 3d10 and 1s2 2s2 2p6 3s2 3p6 3d9 4 l (l = s, p, d, and f) of a nickel-like Nd ion to determine reduced population for 55 fine-structure levels over a wide range of electron density values (from 1020 to 4 · 1022 cm−3) at various electron plasma temperatures in the range of 1–2 keV. We find the gain coefficients for those transitions with the positive population inversion factor and show their dependences on the electron density.

XUV and Soft X-Ray Laser Radiation from Ni-Like Au

Atomic structure data and effective collision strengths from literature for 1s2 2s2 2p6 3s2 3p63d10 and 34 fine-structure levels contained in the configurations 1s2 2s2 2p6 3s2 3p63d9 4l (l = s, p, d) for the nickel-like Au ion are used in the determination of the reduced population for these levels over a wide range of electron densities and at various electron plasma temperatures. The gain coefficient for those transitions with positive population inversion factor are determined and plotted against the electron density.

Two-electron and one-photon transitions in highly charged nickel-like ions

This paper calculates the transition wavelengths and probabilities of the two-electron and one-photon (TEOP) transition from the (3s1/2-1 4dj) J = 1,2 to (3p3/2-1 4s1/2)J = 1 and the (3p1/2-1 4s1/2) J = 1 to (3dj-1 4dj′)J = 1,2 for highly charged Ni-like ions with atomic number Z in the range 47 ≤ Z ≤ 92. In the calculations, the multi-configuration Dirac–Fock method and corresponding program packages GRASP92 and REOS99 were used, and the relativistic effects, correlation effects and relaxation effects were considered systematically. It is found that the TEOP transitions are very sensitive to the correlation of electrons, and the probabilities will be enhanced sharply in some special Z regions along the isoelectronic sequence. The present TEOP transition wavelengths are compared with the available data from some previous publications, good agreement is obtained.

Observation of Hyperfine Mixing in Measurements of a Magnetic OctupoleDecay in Isotopically Pure Nickel-LikeXe129andXe132Ions

We present measurements of high statistical significance of the rate of the magnetic octupole (M3 ) decay in nickel-like ions of isotopically pure 129Xe and 132Xe. On 132Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06+/-0.24) ms. On 129Xe, an additional fast (2.7+/-0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2 ) radiation.

Multipole (E1, M1, E2, M2, E3, M3) transition wavelengths and rates between 3l−15l′ excited and ground states in nickel-like ions

A relativistic many-body method is used to calculate energy and transition rates for multipole transitions in many-electron ions. This method is based on relativistic many-body perturbation theory (RMBPT), agrees with MCDF calculations in lowest order, includes all second-order correlation corrections and includes corrections from negative energy states. Reduced matrix elements, oscillator strengths and transition rates are calculated for electric-multipole (dipole (E1), quadrupole (E2) and octupole (E3)) and magnetic-multipole (dipole (M1), quadrupole (M2) and octupole (M3)) transitions between 3l−15l′ excited and ground states in Ni-like ions with nuclear charges ranging from Z = 30 to 100. The calculations start from a 1s22s22p63s23p63d10 Dirac–Fock potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the matrix elements. A detailed discussion of the various contributions to the dipole matrix elements and energy levels is given for nickel-like tungsten (Z = 74). The contributions from negative-energy states are included in the second-order E1, M1, E2 M2, E3 and M3 matrix elements. The resulting transition energies and transition rates are compared with experimental values and with results from other recent calculations. These atomic data are important in modelling of M-shell radiation spectra of heavy ions generated in electron beam ion trap experiments and in M-shell diagnostics of plasmas.

Relativistic many-body calculations of multipole (E1, M1, E2, M2, E3, and M3) transition wavelengths and rates between 3l −14l′ excited and ground states in nickel-like ions

Wavelengths, transition rates, and line strengths are calculated for the 76 possible multipole (E1, M1, E2, M2, E3, and M3) transitions between the excited 3s 23p 63d 94l, 3s 23p 53d 104l, and 3s3p 63d 104l and the ground 3s 23p 63d 10 states in Ni-like ions with the nuclear charges ranging from Z = 30 to 100. The relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate energies and transition rates for multipole transitions in hole–particle systems. This method is based on relativistic many-body perturbation theory, agrees with MCDF calculations in lowest-order, includes all second-order correlation corrections, and includes corrections from negative energy states. The calculations start from a 1s 22s 22p 63s 23p 63d 10 Dirac–Fock potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and the second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order E1, M1, E2, M2, E3, and M3 matrix elements. The resulting transition energies and transition rates are compared with experimental values and with results from other recent calculations. As a result, we present wavelengths and transition rates data for the selected transitions that include the 76 possible multipole (E1, M1, E2, M2, E3, and M3) transitions between the excited 3s 23p 63d 94l, 3s 23p 53d 104l, and 3s3p 63d 104l states and the ground 3s 23p 63d 10 state in Ni-like ions. Trends of the line strengths for the 76 multipole transitions and oscillator strengths for the 13 E1 transitions as function of Z are illustrated graphically. The Z-dependence of the energy splitting for all triplet terms of the 3s 23p 63d 94l, 3s 23p 53d 104l, and 3s3p 63d 104l configurations are shown in the range of Z = 30–100.

Theoretical transition probabilities and lifetimes in nickel-like Se $ \mathsf {^{6+}}$ , Y $ \mathsf {^{11+}}$ and Sn $ \mathsf {^{22+}}$ ions

The 17 levels of the 3 d 10 , 3 d 9 4 s and 3 d 9 4 p configurations, and the electric-dipole transitions among these levels are calculated for the three nickel-like ions Se6+, Y11+ and Sn22+ by using large-scale multiconfiguration Dirac-Fock wavefunctions. From these computations, the excitation energies and transition probabilities as well as the lifetimes of 3 d 9 4 p levels are derived, including all dominant effects of relativity, correlation and of the rearrangement of the electron density within the same framework. Comparison is made with the scarce number of experimental data and previous semi-empirical computations.

Generation of highly ionized cadmium plasma columns for a discharge-pumped Nickel-like Cd laser

We report the observation of strong line emission from Ni-like Cd ions in a capillary discharge plasma. Spectroscopically pure Cd vapor was produced in a room temperature environment utilizing a capacitive discharge. The metal vapor was injected into a capillary channel where it was subsequently excited with fast current pulses of up to 200 kA. These results open the possibility of observing laser amplification in the 3d 9 4d-3d 9 4p line of Ni-like Cd at 13.2 nm and in laser lines of other Nickel-like ions in a discharge-created plasma.

Nickellike and neonlike soft X-ray lasing driven by two 200 ps Nd:glass laser pulses

Soft x-ray lasing at 18.9 nm and 20.3 nm in nickel-like molybdenum and niobium ions has been demonstrated using two 200 ps laser pulses with similar to0.2TW laser power at 1.053 mum from XingGuang II laser facility. A comparison has been made of performance of the neon-like chromium soft x-ray lasing at 28.5nm driven by a double 900 ps pulse at 6 TW/cm2, compare to that driven by a double 200 ps pulse at similar irradiance. The 900 ps pulse duration was found to be able to provide stronger emission and narrower divergence of neon-like chromium soft x-ray lasing.

Modeling and demonstration of a saturated Ni-like Mo X-ray laser

The technique of using a nsec pulse to preform and ionize the plasma followed by a psec pulse to heat the plasma has enabled us to achieve saturated laser output for low-Z neon-like and nickel-like ions driven by small lasers with less than ten joules of energy. In this work we present and model recent experiments done using the COMET laser at Lawrence Livermore National Laboratory to illuminate slab targets of Mo up to 1 cm long with a one joule, 600 ps prepulse followed 700 psec later by a five joule, one psec drive pulse. The experiments demonstrate saturated output on the Ni-like Mo 3d{sup 9} 4d {sup 1}S{sub 0} {yields} 3d{sup 9} 4p {sup 1}P{sub 1} laser line at 18.9 nm. The small signal gain and gain length product are estimated by measuring the laser output versus target length. Experiments are done using multilayer mirrors to obtain two-dimensional images of the output aperture of the laser and to measure the total laser energy as a function of various parameters such as the delay between the short and long pulses and the energy of the two pulses. To model the experiments the LASNEX code is used to calculate themore » hydrodynamic evolution of the plasma and provide the temperatures and densities to the XRASER code, which then does the kinetics calculations to determine the gain, The temporal and spatial evolution of the plasma is studied both with and without radiation transport included for the 4f and 4p {yields} 3d Ni-like Mo resonance lines. High gains are predicted for both the 3d{sup 9} 4d {sup 1}S{sub 0} {yields} 3d{sup 9} 4p {sup 1}P{sub 1} laser line at 18.9 nm and the 3d{sup 9} 4f {sup 1}P{sub 1} {yields} 3d{sup 9} 4d {sup 1}P{sub 1} photopumped line which is observed to lase at 22.6 nm.« less

Theoretical Level Structure and Decay Dynamics of Nickel-like Ions: Search for Laser Lines in the Soft X-ray Domain

Multiconfiguration Dirac–Fock wave functions have been applied to study the level structure and transition probabilities of high-Z nickel-like ions in the range 74 ≤ Z ≤ 84. Several level crossings are found which strongly influence the decay dynamics of the excited ions and explain why some of these lines cannot (so easily) be observed for all elements along the isoelectronic sequence. For two selected ions, the role of configuration interactions and relaxation is explored by large-scale expansions.

A review of Ni-like X-ray laser experiments undertaken using the VULCAN laser at the Rutherford Appleton Laboratory

Recent progress using the VULCAN laser at the Rutherford Appleton Laboratory to pump X-ray lasing in nickel-like ions is reviewed. Double pulse pumping with ∼100 ps pulses has been shown to produce significantly greater X-ray laser output than single pulses of duration 0.1–1 ns. With double pulse pumping, the main pumping pulse interacts with a pre-formed plasma created by a pre-pulse. The efficiency of lasing increases as there is a reduced effect of refraction of the X-ray laser beam due to smaller density gradients and larger gain volumes, which enable propagation of the X-ray laser beam along the full length of the target. The record shortest wavelength saturated laser at 5.9 nm has been achieved in Ni-like dysprosium using double pulse pumping of 75 ps duration from the VULCAN laser. A variant of the double pulse pumping using a single ∼100 ps laser pulse and a superimposed short ∼1 ps pulse has been found to further increase the efficiency of lasing by reducing the effects of over-ionisation during the gain period. The record shortest wavelength saturated laser pumped by a short ∼1 ps pulse has been achieved in Ni-like samarium using the VULCAN laser operating in chirped pulse amplified (CPA) mode. Ni-like samarium lases at 7.3 nm.

Review of collisional excitation neon-like and nickel-like soft X-ray lasers pumped by multiple infrared laser pulses at the Institute of Laser Engineering, Osaka University

We report on the soft X-ray laser developments performed at the Institute of Laser Engineering, Osaka University especially for the collisional excitation X-ray lasers at wavelengths between 25 nm and 4 nm. The performance of neon-like and nickel-like ion X-ray lasing pumped by a train of short laser pulses has been investigated. We have also demonstrated double pass amplification using a soft X-ray multi-layer mirror at wavelengths of 19.6 nm and 7.9 nm. Based on these results and experimental technique, two targets were placed in series to double the gain length. Two opposing laser beams irradiated the double targets with a suitable time difference for quasi-traveling wave pumping. The double target amplification was successfully demonstrated with two beam irradiation for Ag, Nd, Yb, Hf and Ta lasing. The estimated absolute photon flux from the saturated amplification Ag X-ray laser was ∼300 μJ. Based on the experimental results, we also discuss the applications of an X-ray laser as a super-high brightness soft X-ray source.

Review of Ni-like ion X-ray laser research at Lawrence Livermore National Laboratory

We have demonstrated saturated output on several nickel-like ion X-ray lasers ranging from niobium to silver by using a psec, high-power, chirped-pulse-amplification, tabletop laser. These results have been achieved at wavelengths from 20.3 to 13.9 nm on the Ni-like 3 d 94 d 1 S 0→3 d 94 p 1 P 1 laser line using a total of 5 to 7 J of energy in a traveling wave excitation scheme. Strong amplification is also observed for Ni-like Sn at 11.9 nm. Gain of 41 cm −1, gain-length product of 18, and output energy of 12 μJ are measured for the Ni-like Pd line at 14.7 nm. For Ni-like Mo, experiments are done using multilayer mirrors to obtain two-dimensional images of the output aperture of the laser and to measure the total laser energy as a function of various parameters such as the delay between the short and long pulses and the energy of the two pulses. For Mo we measure an output energy of 2 μJ and a gain-length product of 16.6. To model the Mo experiments, the LASNEX code is used to calculate the hydrodynamic evolution of the plasma and provide the temperatures and densities to the XRASER code, which then does the kinetics calculations to determine the gain. The temporal and spatial evolution of the plasma is studied both with and without radiation transport included for the 4 f and 4 p→3 d Ni-like Mo resonance lines. High gains are predicted and observed for both the 3 d 94 d 1 S 0→3 d 94 p 1 P 1 laser line at 18.9 nm and the 3 d 94 f 1 P 1→3 d 94 d 1 P 1 photopumped line at 22.6 nm.

Modeling picosecond-laser-driven neonlike titanium x-ray laser experiments

The technique of first using a nanosecond pulse to preform and ionize the plasma and then using a picosecond pulse to heat the plasma enables low-Z neonlike and nickellike ions to lase, driven by small lasers, with only 10 J of energy. Recent experiments at the Compact Multipulse Terawatt laser facility at Lawrence Livermore National Laboratory have demonstrated lasing in neonlike titanium by irradiation of 1-cm-long slab targets of titanium with a 4.8-J, 800-ps prepulse that is followed 1.6 ns later by a 6-J, 1-ps drive pulse. In this study we model the neonlike titanium x-ray laser under those experimental conditions. The LASNEX code is used to calculate the hydrodynamic evolution of the plasma and to provide the temperatures and densities to the XRASER code, which then performs the kinetics calculations to determine the gain. The temporal and spatial evolution of the plasma is studied both with and without radiation transport included for the 3d and the 3s→2p neonlike titanium resonance lines. Large regions with gains greater than 80 cm-1 are predicted for the 3p 1S0→3s 1P1 neonlike titanium laser line at 32.6 nm. The gain is shown to be quasi-steady-state over these time scales with regard to the equilibration of the excited-state populations. The transient nature of the gain is shown to be due to the ionization balance in the plasma. Given the large gain and the large gradients in these plasmas, we calculate x-ray laser propagation, including refraction effects, to understand which regions have the right combination of high gain and low density gradients for an optical contribution to the x-ray laser output. Calculations with different delays between the long and the short pulses and with different durations for the short pulse are presented to provide a better insight into optimization of the laser output. High gain is also predicted and observed for the self-photopumped 3d 1P1→3p 1P1 laser line at 30.1 nm in neonlike titanium, and calculations are presented to help understand this lasing mechanism.

Research on efficient X-ray lasing at XingGuang II Laser Facility

Research on efficient X ray lasing at the XingGuang II Laser Facility has been reviewed, in which lasing at 18.9, 20.3, and 28.5 nm from nickel-like molybdenum, niobium and neon-like chromium ions has been observed by using two 200-ps laser pulses with a total energy of 50 J at 1.053 /spl mu/m. This shows the possibility of extending nickel-like and neon-like X-ray lasing in low-Z elements and paves the may toward small scale X-ray lasers for applications at University laboratories. A comparison has been made of performance of the neon-like chromium soft X-ray lasing at 28.5 nm driven by a double 900-ps pulse at 6 TW/spl middot/cm/sup -2/, with that driven by a double 200-ps pulse at similar irradiance. The double 200-ps pulse has been found to be more efficient to drive the neon-like X ray lasing.