Dense matter characterization by X-ray Thomson scattering

Abstract

We discuss the extension of the powerful technique of Thomson scattering to the x-ray regime for providing an independent measure of plasma parameters for dense plasmas. By spectrallyresolving the scattering, the coherent (Rayleigh) unshifted scattering component can be separated from the incoherent Thomson component, which is both Compton and Doppler shifted. The free electron density and temperature can then be inferred from the spectral shape of the high frequency Thomson scattering component. In addition, as the plasma temperature is dcreased, the electron velocity distribution as measured by incoherent Thomson scattering will make a transition from the traditional Gaussian Boltzmann distribution to a density-dependent parabolic Fermi distribution to. We also present a discussion for a proof-of-principle experiment appropriate for a high energy laser facility.

Observations of Plasmons in Warm Dense Matter

“…Therefore, new and precise techniques [3][4][5][6][7] that make use of x rays to penetrate dense or compressed materials are broadly applicable in the dense matter community, e.g., [8,[10][11][12][13][14][15][16][17]. Recently, spectrally-resolved xray scattering has been demonstrated in dense plasmas [18] allowing accurate measurements of the electron velocity distribution function, temperature, and ionization state.…”

An apparatus for the characterization of warm, dense deuterium with inelastic x-ray scattering

“…This is sufficiently high to allow precise measurements of plasmon positions at even low ionization fractions of 0.1 in weakly compressed hydrogen. In Figure 7, we illustrate this with synthetic scattering spectra for ionization states of Z = 0.1, 0.2 and 0.5 assuming a mass density of ρ = 0.5 g/cm 3 and a temperature of T e =0.35 eV. The redshifted inelastic feature from emerging plasmons is already clearly visible as a shoulder on the elastic feature at an ionization of Z = 0.1; as ionization increases, the growing electron density causes the plasmon to shift away from the elastic feature to lower energies.…”

The Matter in Extreme Conditions instrument at the Linac Coherent Light Source

“…The spectral analysis of the elastically and inelastically scattered X-rays has provided valuable information about electron density, temperature, ionization state and collective behavior Landen et al, 2001;Gregori et al, 2003;Lee et al, 2009;Kritcher et al, 2008;Ma et al, 2014). However, experimental constraints due to the broadband uncollimated laser-produced X-ray sources (i.e.…”