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17Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2019
ON OBSERVATION OF X-RAY LINE POLARIZATION IN EMISSION FROM
HOT LASER-PRODUCED PLASMA
A.I. Magunov1,2
1Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia,
e-mail: magunov@ fpl.gpi.ru
State Scientific Centre of the Russian Federation VNIIFTRI, Mendeleevo, Moscow region, Russia
The effects of fast electron beam generated in ultrahigh intensity laser pulse interaction with matter are of fundamental importance for understanding mechanisms of plasma heating (see, e.g., [1] and references therein). These effects can be detected in line emission of multicharged ions in plasma using high-resolution spherically bent crystal Bragg spectrometers [2]. Usually, the relative intensities of resonance lines of H- and He-like multicharged ions and there dielectronic satellites are used for plasma diagnostics. An additional tool is the line polarization induced by excitation of ions in collisions with fast electrons having an anisotropic velocity distribution function. The line polarization can be also detected by a pair of specially aligned Bragg spectrometers [3, 4].
In this report theoretical evaluations are presented of line intensities of the He-like and Li-like ions of chlorine doped in a plastic target for ultrahigh intensity laser pulses as a source of high temperature plasma. The intensities of resonance lines and there dielectronic satellites as well as their linear polarization degree are studied as a function of the bulk electron density and temperature and the fraction and average energy of fast electrons. Particular attention is paid to the effect of optical thickness of plasma.
1
2
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R —Thiri — L=30 — L=60
il 1 d,a q.b.r c,k J
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4.44 4.45 4.46 4.47 4.48 4.49 Wavelength (A)
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Fig. 1. (1) Synthetic spectrum of the resonance (R) and intercombination (I) lines of He-like chlorine and there dielectronic satellites for x-ray emission polarized along the symmetry axis of the electron velocity
distribution function. (2) The same for the x-ray emission polarized in a perpendicular direction.
Figure 1, 1-2 shows the model calculations of the x-ray emission spectra from a uniform laser-produced plasma slab of the C8H7Cl target with the following plasma parameters (Te = 300 eV, Ne = 1013cm-3, f = 0.4%, Efast = 50 keV). The curves correspond to different values of the slab depth L (in ^m). The polarization degree for the resonance line R reduces from P = -46.5% in optically thin case to the values P = -9.2% at L = 30 |m (optical thickness at the line center t= 2.5) and P = -2.6% at L = 60 |m (t= 5.1).
References
[1] A. Morace et al. 2009 Phys. Plasmas 16 (12) 122701.
[2] F. Blasco, C. Stenz, F. Salin, A.Ya. Faenov, et al. 2001 Rev. Sci. Instrum. 72 (4) 1956.
[3] Y. Inubushi et al. 2004 Rev. Sci. Instrum. 75 (10) 3699.
[4] D.L. Robbins, P. Beiersdorfer, A.Ya. Faenov, et al. 2006 Phys. Rev. A 74 (2) 022713.
