Observation of magnetic fields in laser-produced plasma using the Zeeman effect

McLean, E. A.; Stamper, J. A.; Manka, C. K.; Griem, Hans R.; Droemer, D.; Ripin, B. H.

doi:10.1063/1.864747

Cited by 43 publications

(12 citation statements)

References 17 publications

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“…(50). Figures 18, 19 and 20 (example taken from Mc Lean [55,56]) show that the results are quite close to the exact calculation. The main approximation here comes from the fact that g e is replaced by its average value in LS coupling, which is justified in case of very strong magnetic fields (Paschen-Back effect).…”

Section: Approximation Of the Coefficient G Esupporting

confidence: 63%

Characterization of anomalous Zeeman patterns in complex atomic spectra

Pain

Gilleron

2012

Phys. Rev. A

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The modeling of complex atomic spectra is a difficult task, due to the huge number of levels and lines involved. In the presence of a magnetic field, the computation becomes even more difficult. The anomalous Zeeman pattern is a superposition of many absorption or emission profiles with different Zeeman relative strengths, shifts, widths, asymmetries and sharpnesses. We propose a statistical approach to study the effect of a magnetic field on the broadening of spectral lines and transition arrays in atomic spectra. In this model, the σ and π profiles are described using the moments of the Zeeman components, which depend on quantum numbers and Landé factors. A graphical calculation of these moments, together with a statistical modeling of Zeeman profiles as expansions in terms of Hermite polynomials are presented. It is shown that the procedure is more efficient, in terms of convergence and validity range, than the Taylor-series expansion in powers of the magnetic field which was suggested in the past. Finally, a simple approximate method to estimate the contribution of a magnetic field to the width of transition arrays is proposed. It relies on our recently published recursive technique for the numbering of LS-terms of an arbitrary configuration.

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Section: Approximation Of the Coefficient G Esupporting

confidence: 63%

Characterization of anomalous Zeeman patterns in complex atomic spectra

Pain

Gilleron

2012

Phys. Rev. A

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“…An alternative magnetic-field diagnostic, the Zeeman splitting and broadening of spectral lines, was demonstrated by McLean et al 571 and found to give results consistent with Faraday rotation measurements. The diagnostic gives an average magnetic field along the line of sight.…”

Section: F Self-generated Magnetic Fieldssupporting

confidence: 59%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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“…A numerical estimate for the maximum cross section is (12) o Here the wavelength A is an A units and A is the atomic weight of the absorbing atom or ion. Depending on the densities N in the (13) where g is again the Gaunt factor (g ~ 1, 64ana 2 /3 3 / 2 ~ 0.88 x n 0 10-16 cm 2 ). This process is, of course, the inverse of recombination, whereas there is no special term for absorption by inverse bremsstrahlung which is important in laser-matter interactions.…”

Section: Radiative Transportmentioning

confidence: 99%

“…Zeeman splittings in strong and reasonably homogeneous fields have, however, been observed in a plasma focus experiment [15] and in laser-produced plasmas [13]. Since broadening due to thermal Doppler effects and mass motion and also from opacity are competing with Zeeman effects, it is necessary to perform line profile and structure measurements with polarizing optics and to look for small differences in the corresponding spectra.…”

Section: Magnetic Fieldsmentioning

confidence: 99%

Principles of Plasma Spectroscopy

Griem

1986

Fast Electrical and Optical Measurements

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196

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INTRODUCTION 885The diagnosis of plasmas using spectroscopic observations has its origins in various older disciplines, including astronomy and discharge physics. As laboratory plasma physics evolved from low-density, low-temperature discharges to higher energy density plasmas, the need for non-interfering diagnostics arose and spectroscopy was applied to determine the physical state and chemical abundance of the plasmas studied.Such applications of methods originally developed for the quantitative analysis of stellar atmospheres require a quantitative understanding of the interactions between matter in the plasma state and electromagnetic radiation in a large frequency range. Although the principal features of this interaction are well understood in terms of quantum-mechanical perturbation theory, there are nevertheless considerable difficulties in simply transferring experience gained in astronomical research to laboratory plasma physics. These difficulties are connected with the huge factors involved in characteristic densities, and in length and time scales between, e.g., a laser-produced plasma and the atmosphere of a star like the sun. Only if a broader view going beyond diagnostics, e.g., to radiative energy transport is taken, can some similarities be found between line energy transport in stellar interiors and x-ray line spectra from laser compression experiments.In any event, the range of physical conditions and chemical compositions encountered in spectroscopic plasma diagnostics is J. E. Thompson et al. (eds.), Fast Electrical and Optical Measurements

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Observation of magnetic fields in laser-produced plasma using the Zeeman effect

Cited by 43 publications

References 17 publications

Characterization of anomalous Zeeman patterns in complex atomic spectra

Characterization of anomalous Zeeman patterns in complex atomic spectra

Direct-drive inertial confinement fusion: A review

Principles of Plasma Spectroscopy

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