![]() ![]() The plot was used to verify if the given photon energy transmission and a given film thickness were accurate. All six anodes are shown with their respective step wedge transmission, all normalized to the unfiltered region. for each of the 12 regions of the step wedge normalized to 1 of the region with no filter. Figure 4 has the modeled CXRO 16 transmission for given photon energy plotted alongside the calculated O.D. The aluminum step wedge filter was selected for the higher energy photons for the Mg (K α 1245 eV), Al (K α 1487 eV), Mo (L α 2345 eV), and Ti (K α 4620 eV). The Mylar step wedge filter is paired with the lower photon energy anodes, Fe (L α 705 eV) and Cu (L α 930 eV). The photodiode detector produces a current proportional to the x-ray beam intensity, which is then converted to a fluence using the exposure time. The x-ray beam overfills the area of the photodiode detector. 11 for IP characterization using a Manson source. This is using a similar technique described by Rosenberg et al. The dominant line feature FWHM is typically in the range of less than a few hundred eV and makes up the majority of the photons. The spread of photon energies incident on the film was >1 keV. Figure 3 shows the spectrum resulting from each of the six anodes/filter pairs used for these calibration efforts. The filters in the source chamber are used to isolate a narrow wavelength band of x rays. The typical spectrum of the selected anode will emit a broadband spectrum, including bremsstrahlung and the anode material’s spectral lines. They are mounted on pneumatic actuators so that they can be moved into or out of the beam. ![]() Test chambers have a photodiode and an energy dispersive detector for measuring x-ray flux and the x-ray spectrum. Figure 2 details the setup for exposure of the film cassette on one of the diagnostic arms, with the step-wedge filter placed directly in front of the film cassette on arm No. The film is mounted to the end of the chamber with enough distance to ensure the film is covered uniformly by the source. The two test chambers are connected to the main chamber by stainless steel vacuum components that include an isolation gate valve and a mechanical shutter. The electron beam impact forms a small spot, ∼1 mm diameter, on the anode, providing a flat spot at the target. The anode array rotates to adjust between the six anode materials in front of the filament. The source chamber contains the anode array, the filament, and the filters. 10 The Manson source comprises three independent vacuum compartments: the source chamber and two test chambers (diagnostic arms). The Manson source holds multiple anodes for ease in selecting various spectral lines in the spectral energy range from 400 to 9000 eV. ![]() The measurements were conducted at NNSS Livermore Operations (NNSS-LO) using the medium resolution x-ray source (MRXS), 10 also known as a Manson source, which is a diode type x-ray source used to test and calibrate various devices. The measurements were taken using selected anodes, filters, and applied voltages to produce well-defined energy lines. A broader range of energies was selected to compare results with previously published data. ![]() The absolute response of Agfa D4 x-ray film from 705 to 4620 eV has been measured using the Nevada National Security Site Manson x-ray source. These calibration efforts are vital to the accuracy of the NIF opacity measurements and are conducted in a previously un-studied x-ray energy range under a new film development protocol required by NIF. The calibration of Agfa D4 x-ray film for use in the OpSpec is communicated here. However, Agfa D4 and D3sc x-ray films’ higher spatial resolution provides increased spectral resolution to the data over the IP-TR image plates, driving the desire for regular use of x-ray film as a detecting medium. The soft x-ray Opacity Spectrometer (OpSpec) fielded at the NIF has an elliptically shaped crystal design that measures x rays in the 900–2100 eV range and currently uses an image plate as the detecting medium. X-ray films remain a key asset for high-resolution x-ray spectral imaging in high-energy-density experiments conducted at the National Ignition Facility (NIF). ![]()
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