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1.
Rev Sci Instrum ; 89(10): 10G107, 2018 Oct.
Article in English | MEDLINE | ID: mdl-30399661

ABSTRACT

A high speed solid-state framing camera has been developed which can operate in interferometric mode. This camera measures the change in the index of refraction of a semiconductor when x-rays are incident upon it. This instrument uses an x-ray transmission grating/mask in front of the semiconductor to induce a corresponding phase grating in the semiconductor which can then be measured by an infrared probe beam. The probe beam scatters off of this grating, enabling a measure of the x-ray signal incident on the semiconductor. In this particular instrument, the zero-order reflected probe beam is attenuated and interfered with the diffracted orders to produce an interferometric image on a charge coupled device camera of the phase change induced inside the semiconductor by the incident x-rays.

2.
Rev Sci Instrum ; 83(10): 10D307, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23126834

ABSTRACT

We report recent progress in the development of RadOptic detectors, radiation to optical converters, that rely upon x-ray absorption induced modulation of the optical refractive index of a semiconductor sensor medium to amplitude modulate an optical probe beam. The sensor temporal response is determined by the dynamics of the electron-hole pair creation and subsequent relaxation in the sensor medium. Response times of a few ps have been demonstrated in a series of experiments conducted at the LLNL Jupiter Laser Facility (JLF). This technology will enable x-ray bang-time and fusion burn-history measurements with ∼ ps resolution.

3.
Rev Sci Instrum ; 83(10): 10E525, 2012 Oct.
Article in English | MEDLINE | ID: mdl-23127032

ABSTRACT

Hohlraums are employed at the national ignition facility to convert laser energy into a thermal x-radiation drive, which implodes a fusion capsule, thus compressing the fuel. The x-radiation drive is measured with a low spectral resolution, time-resolved x-ray spectrometer, which views the region around the hohlraum's laser entrance hole. This measurement has no spatial resolution. To convert this to the drive inside the hohlraum, the size of the hohlraum's opening ("clear aperture") and fraction of the measured x-radiation, which comes from this opening, must be known. The size of the clear aperture is measured with the time integrated static x-ray imager (SXI). A soft x-ray imaging channel has been added to the SXI to measure the fraction of x-radiation emitted from inside the clear aperture. A multilayer mirror plus filter selects an x-ray band centered at 870 eV, near the peak of the x-ray spectrum of a 300 eV blackbody. Results from this channel and corrections to the x-radiation drive are discussed.

4.
Rev Sci Instrum ; 81(10): 10E538, 2010 Oct.
Article in English | MEDLINE | ID: mdl-21034065

ABSTRACT

The static x-ray imager at the National Ignition Facility is a pinhole camera using a CCD detector to obtain images of Hohlraum wall x-ray drive illumination patterns seen through the laser entrance hole (LEH). Carefully chosen filters, combined with the CCD response, allow recording images in the x-ray range of 3-5 keV with 60 µm spatial resolution. The routines used to obtain the apparent size of the backlit LEH and the location and intensity of beam spots are discussed and compared to predictions. A new soft x-ray channel centered at 870 eV (near the x-ray peak of a 300 eV temperature ignition Hohlraum) is discussed.

5.
Opt Lett ; 18(9): 672-4, 1993 May 01.
Article in English | MEDLINE | ID: mdl-19802235

ABSTRACT

Chirped Mo-Si multilayer coatings, where the multilayer period is systematically varied throughout the deposition process, exhibit an increased x-ray bandwidth at normal incidence with a corresponding increase in the integrated reflectance of as much as 20% at lambda ~ 13 nm. The increased bandwidth is accompanied by a slight reduction in peak reflectance. The relation between the integrated and peak reflectance is used to determine the chirp required to optimize the x-ray throughput of a multiple-element optical system.

6.
Appl Opt ; 32(34): 6952-60, 1993 Dec 01.
Article in English | MEDLINE | ID: mdl-20856551

ABSTRACT

Recent advances in multilayer mirror technology meet many of the stringent demands of soft-x-ray projection lithography (SXPL). The maximum normal-incidence reflectivity achieved to date is 66% for Mo/Si multilayers at a soft-x-ray wavelength of 13.4 am, which is sufficient to satisfy the x-ray throughput requirements of SXPL. These high-performance coatings can be deposited on figured optics with layer thickness control of ˜ 0.5%. Uniform multilayer coatings are required for SXPL imaging optics, for which maintaining the surface figure is critical to achieving diffraction-limited performance.

In contrast the coatings on the condenser optics will be graded to accommodate a large range of angles of incidence. Graded multilayer coatings can also be used to modify the figure of optical substrates without increasing the surface roughness. This offers a potential method for precise fabrication of aspheric imaging optics.

7.
Appl Opt ; 32(34): 6969-74, 1993 Dec 01.
Article in English | MEDLINE | ID: mdl-20856553

ABSTRACT

X-ray multilayer (ML) structures that are fabricated by the use of magnetron-sputter deposition exhibit a degradation in structural quality as the deposition pressure is increased. The observed change in morphology is attributed to a reduced mobility of surface adsorbed atoms, which inhibits the formation of smooth, continuous layers. The application of a negative substrate bias produces ion bombardment of the growing film surface by sputtering gas ions extracted from the plasma and permits direct control of the energy density supplied to the film surface during thin-film growth. The technique supplements the energy lost to thermalization in high-pressure deposition and permits the fabrication of high-quality ML structures at elevated processing pressures. A threefold improvement in the soft-x-ray normal-incidence reflectance at 130 A results for substrate bias voltages of the order of ˜ - 150 V for Mo-Si ML's deposited at 10-mTorr Ar.

8.
Opt Lett ; 16(16): 1283-5, 1991 Aug 15.
Article in English | MEDLINE | ID: mdl-19776946

ABSTRACT

Multilayer (ML) structures composed of alternating, ultrathin layers of Ru and B(4)C have been grown by dc magnetron sputtering. The ML microstructure has been characterized using x-ray diffraction and highresolution transmission electron microscopy, and the normal-incidence reflectivity has been measured using synchrotron radiation. It is found that, under optimum deposition conditions, the ML structures exhibit smooth and compositionally abrupt interfaces, with a normal-incidence reflectivity as high as 20% at 7.2 nm. The reflectivity decreases when the ML structures are annealed at 500 degrees C owing to interdiffusion and com-pound formation at the interfaces.

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