The Thomson-scattering spectrum as a function of the scattering parameter . The charge state and the electron and ion temperatures are held constant while the density is varied to change the scattering parameter.
The experimental setup is shown. The primary beam is normal to the direction of scattered light collection. The probe beam is normal to the plane defined by and . The beam timing configurations, a sample gas jet interferogram, and the Thomson-scattering k-vector diagram are shown.
The 1/3 m spectrometer coupled to a streak camera is calibrated for wavelength sensitivity using a tungsten lamp. The measured spectrum for an S-20 streak tube is shown (dotted-dashed line). The ratio of the known spectrum (black line) to the measured spectrum (dotted line) results in the correction factor. Two correction factors are shown, one for the S-1 (dashed line) streak tube and one for the S-20 (blue line) streak tube.
A measured high-frequency scattering spectrum (red line) is compared to the Thomson-scattering form factor using a relativistic (black line) and a “nonrelativistic” (blue line) treatment. Both calculations use an electron density of and an electron temperature of 410 eV. The scattering parameter for these conditions is and from Eq. (5).
Three streak camera records of the Thomson-scattering spectrum from the electron feature are shown for different plasma conditions. The scattering parameter decreases as the density decreases: (a) , (b) , and (c) . The spectra at 0.5 ns in each streak record (black lines) are shown. The calculated Thomson-scattering spectrum (dashed white line) using the temperature and density is plotted for each spectrum. The attenuated region at is due to the notch filter.
By varying the electron temperature and density the error in the measurement can be assessed. The experimental data are shown in red and the best fit for each spectra is shown in black: , for (a) and (c), and , for (b) and (d). In plot (a) is increased by 15% for the blue curve and decreased by 15% for the green curve, is held constant. In plot (b) is increased by 15% for the blue curve and decreased by 15% for the green curve, is held constant. In plot (c) is held constant and is increased by 10% for the blue curve and decreased by 10% for the green curve. In plot (d) is held constant and is increased by 25% for the blue curve and decreased by 25% for the green curve. The actual error in the measurement of and is clearly less than the ranges shown here.
(a) A streak camera record of the Thomson-scattering from the ion feature is shown. The spectra at 2.5 ns are plotted in (b) where the best fit is shown using the electron temperature and density from the simultaneously measured electron feature (, ). The ion temperature is then varied to fit the ion feature spectra. The best fit is calculated for . To assess the error in the ion temperature the spectra are calculated for plus (blue line) and minus (green line) 60 eV.
The electron temperature (a) and density (b) were measured as a function of time for configuration A. The electron density (c) and temperature (d) are shown as circles measured using the electron feature for configuration B. The ion temperature (d) is shown as squares measured using the ion feature.
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