摘要:

A free standing x‐ray transmission grating has been coupled with a soft x‐ray streak amera to produce a time resolved x‐ray spectrometer. The instrument has a temporal resolution of ∼20 psec, is capable of covering a broad spectral range, 2−120 A˚, has high sensitivity, and is simple to use requiring no complex alignment procedure. In recent laser fusion experiments the spectrometer successfully recorded time resolved spectra over the range 10−120A˚ with a spectral resolving power, &lgr;/&Dgr;&lgr; of 4−50, limited primarily by source size and collimation effects.

ISSN:0094-243X    

DOI:10.1063/1.33125

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Transport of energy in laser‐produced plasmas is scrutinized by devising spectrally and temporally identifiable characteristics in the x‐ray emission history which identify the heat‐front position at various times in the heating process. Measurements of the relative turn‐on times of these characteristics show the rate of energy transport between various points. These measurements can in turn constrain models of energy transport phenomena. We are time‐resolving spectrally distinguishable subkilovolt x‐ray emissions from different layers of a disk target to examine the transport rate of energy into the target. A similar technique is used to measure the lateral expansion rate of the plasma spot. A soft x‐ray streak camera with 15‐psec temporal resolution is used to make the temporal measurements. Spectral discrimination of the incident signal is provided by multilayer x‐ray interference mirrors. These synthetic x‐ray crystals have been characterized for reflectivity and bandwidth and exhibit resolutionsE/&Dgr;Eof 10 to 90.

ISSN:0094-243X    

DOI:10.1063/1.33126

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

This paper describes an experimental arrangement utilized at SSRL for obtaining high‐quality Fraunhofer diffraction spectra from a group of specially‐fabricated gold transmission gratings prepared at IBM. The data taken will ultimately be utilized to estimate the optical constants of gold in the 120 eV‐640 eV range, but in the present paper our focus is on the new advances achieved in the attained spectral quality of our measurements in this range and on the improvements that are plausible in future utilizations of the same experimental scheme.

ISSN:0094-243X    

DOI:10.1063/1.33127

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In this paper we present a blazing scheme they may be generated on any rectangular grating and that is sufficiently general to cover all conceivable cases of linear blazing imposed on rectangular transmission gratings. Characterizing the blazed grating completly by a group of parameters, we develop the analytical formula for the intensity spetrum of a blazed grating set perpendicularly to the irradiating light in terms of these parameters. The analysis given is valid for the regions of material properties and light energies where refraction may be ignored. Practical implications of the modelled equations are discussed and are shown to have great potential in the development of new instrumentation in the soft x‐ray range.

ISSN:0094-243X    

DOI:10.1063/1.33128

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Synchrotron radiation facilities (such as SSRL) could be used to manufacture superfine, i.e. high line density gratings with ∼5.104lines per mm.

ISSN:0094-243X    

DOI:10.1063/1.33129

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The general requirements of obtaining high resolution molecular X‐ray emission spectroscopy (0.01 to 0.1 eV) are inspected. Various X‐ray optics, sources, and detectors are reviewed in terms of intensity and resolution. An approximate theoretical formulation is offered to compare the speed of photograplhic detection with that obtained by scanning and position sensing photoelectric detection. The main features of the recently developed, automated scanning photoelectric attachment for a 5 M grating spectrometer are described. Experimentally obtained photographic and scanning photoelectric data for first order 0 K emission are compared.

ISSN:0094-243X    

DOI:10.1063/1.33130

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A subkilovolt spectrometer has been produced to permit high‐energy‐resolution, time‐dependent x‐ray intensity measurements. The diffracting element is a curved mica (d=9.95A˚) crystal. To preclude higher order (n≳1) diffractions, a carbon x‐ray mirror that reflects only photons with energies less than ∼1.1 keV is utilized ahead of the diffracting element. The nominal energy range of interest is 800 to 900 eV. The diffracted photons are detected by a gold‐surfaced photoelectric diode designed to have a very good frequency response, and whose current is recorded on an oscilloscope. A thin, aluminum light barrier is placed between the diffracting crystal and the photoelectric diode detector to keep any UV generated on or scattered by the crystal from illuminating the detector. High spectral enegy resolution is provided by many photocathodes between 8‐ and 50‐eV wide placed serially along the diffracted x‐ray beam at the detector position. The spectrometer was calibrated for energy and energy dispersion using the Ni L&agr;1,2lines produced in the LLNL IONAC accelerator and in third order using a molybdenum target x‐ray tube. For the latter calibration the carbon mirror was replaced by one surfaced with rhodium to raise the cut‐off energy to about 3 keV. The carbon mirror reflection dependence on energy was measured using one of our Henke x‐ray sources. The curved mica crystal diffraction efficiency was measured on our Low‐Energy X‐ray (LEX) machine. The spectrometer performs well although some changes in the way the x‐ray mirror is held are desirable.

ISSN:0094-243X    

DOI:10.1063/1.33131

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Seven x‐ray spectrometers have been built to the same specifications (1). The data show the degree of reproducibility of the components: 1) amorphous carbon mirrors, 2) mica crystals bent to a 5 cm radius of curvature for Bragg type refletions, and 3) photo diodes (XRDs) to measure the x‐rays. The effiiences agree to about 10%. Calibration numbers are presented. Mirror reflectivities were measured from 0.75 keV to 2 keV. The mica spectrometers were measured at L&agr;x‐ray lines from Co, Ni, and Cu at energies of 775, 851, and 930 eV, respectively. The photo diodes were measured at a similar set of energies.

ISSN:0094-243X    

DOI:10.1063/1.33132

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In this paper we present an analytical study of a rectangular and translucent diffraction grating composed of a material with known optical constants covered with a vacuum (in situ) deposit of a thin film of a material with unknown optical constants. We show that by choosing gratings of the proper material and dimensions and by measuring the intensity spectra of the coated gratings, we can use the ratios of the observed orders to calculate the optical constants of the thin‐film material. The method’s great advantage is its independence from the absolute intensities of the incoming and transmitted light, i.e., no measurements need be made of the absolute intensities.

ISSN:0094-243X    

DOI:10.1063/1.33133

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Previous work has shown that careful measurement of the intensity spectra of two or more rectangular transmission grating splaced perpendicularly to the irradiating light can yield enough information to alculate the optical constants of the grating material. In this paper we examine the possibility of estimating the optical constants by rotating a single rectangular grating and observing the angle at which certain of the diffracted orders peak. Assuming this method, we examine the criteria under which it remains feasible and investigate the advantages that can possibly accrue from its use in subsequent experiments designed to measure optical constants in the soft x‐ray range.

ISSN:0094-243X    

DOI:10.1063/1.33134

出版商:AIP    

年代:1981

数据来源: AIP