Development of an electron density probe Final report, 22 Jun. 1964 - 22 Mar. 1965

Electron density probes to perform measurements in flow fields at high altitude

Development of an electron density probe Final report, 28 May 1965 - 28 Feb. 1966

Electron density probe and its application in separated flow region of reentry Apollo spacecraft for typical trajector

Pulsed calibration of the soft x-ray streak camera

In order to better understand laser plasma interactions an effort is being made to obtain quantitative temporally and spectrally resolved measurements in the low energy x-ray region using a soft x-ray streak camera. X-ray mirrors and absorption filters are employed to perform broad band spectroscopy measurements. The components of these systems have now been calibrated and the results of these measurements will be reported. The calibration of the x-ray streak camera, needed to make absolute flux measurements, cannot be measured using the usual x-ray sources because backgrounds interfere with the operation in the D.C. mode. Repetition rates and duty cycles are too low to complete calibration on a D.C. source in a reasonable time using the camera in a pulsed mode. As an alternative the calibrations are being done using a Nd(YAG) laser producing pulses of approx. 1 joule having pulse widths of approx. 150 ps. The x-ray flux is being monitored by three x-ray diodes having Al photocathodes. Absorption filters having the same thicknesses as those used with the streak camera provide x-ray energy responses of the diodes which approximate the channel responses of the streak camera. By comparing the charge from the diode with the integral response of the streak camera, the camera response can be measured. Preliminary results will be discussed

Quantitative measurements using soft-x-ray streak cameras

A Soft X-Ray Streak Camera (SXRSC) is a fast timing instrument sensitive to x rays from 100 eV to 300 keV. The instrument has excellent time resolution (approx. 15 ps) and large dynamic range (approx. 10/sup 3/) which are well suited for measuring x-ray pulses produced by laser-fusion targets. The SXRSC uses a thin transmission photocathode to convert x-rays to a secondary electron signal which is accelerated, focused, and deflected onto a phosphor producing an image of the x-ray pulse time history. In the past, such instruments have been used only to make relative measurements of the time history. At LLNL we have calibrated the SXRSC in order to make absolute intensity measurements of the soft x-ray flux from laser fusion targets. Such measurements will assist in understanding the laser plasma processes and conditions needed to attain laser-produced fusion. Because of the nature of the instrument, we have calibrated it in the dynamic mode using a small laser-produced pulsed x-ray source

At-wavelength characterization of the extreme ultraviolet Engineering Test Stand Set-2 optic

At-wavelength interferometric characterization of a new 4x-reduction lithographic-quality extreme ultraviolet (EUV) optical system is described. This state-of-the-art projection optic was fabricated for installation in the EUV lithography Engineering Test Stand (ETS) and is referred to as the ETS Set-2 optic. EUV characterization of the Set-2 optic is performed using the EUV phase-shifting point diffraction interferometer (PS/PDI) installed on an undulator beamline at Lawrence Berkeley National Laboratory's Advanced Light Source. This is the same interferometer previously used for the at-wavelength characterization and alignment of the ETS Set-1 optic. In addition to the PS/PDI-based full-field wavefront characterization, we also present wavefront measurements performed with lateral shearing interferometry, the chromatic dependence of the wavefront error, and the system-level pupil-dependent spectral-bandpass characteristics of the optic; the latter two properties are only measurable using at-wavelength interferometry

Streak cameras for soft x-ray and optical radiation

The principal component of a streak camera is the image converter tube. A slit-shaped photocathode transforms the radiation into a proportional emission of electrons. An electron - optics arrangement accelerates the electrons and projects them into a phosphor screen creating the image of the slit. A pair of deflection plates deflects the electronic beam along a direction perpendicular to the main dimension of the slit. Different portions of the phosphor screen show the instantaneous image of the slit with brightness proportional to the number of emitted electrons and, consequently, to the intensity of the radiation. For our x-ray streak cameras, we use the RCA C73435A image conventer tube intended for the measurement of the radiation of light and modified to have an x-ray sensitive photocathode. Practical considerations lead to the use of transparent rather than reflecting photocathodes. Several of these camera tubes are briefly described

Time-resolved spectral measurements above 80 A

We have made time-resolved spectral measurements above 80 A from laser-produced plasmas. These are made using a transmission grating spectrograph whose primary components are a cylindrically-curved x-ray mirror for light collection, a transmission grating for spectral dispersions, and an x-ray streak camera for temporal resolution. A description of the instrument and an example of the data are given

X-ray streak crystal spectography

We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11/sup 0/ to 38/sup 0/ and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/..delta..E > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given

Absolutely calibrated soft-x-ray streak camera for laser-fusion applications

The intensity output of a soft-x-ray streak camera was calibrated (SXRSC) in order to make absolute flux measurements of x rays emitted from laser-produced plasmas. The SXRSC developed at LLNL is used to time-resolve x-ray pulses to better than 20 ps. The SXRSC uses a Au photocathode on a thin carbon substrate which is sensitive to x rays from 100 eV to greater than 10 keV. Calibrations are done in the dynamic mode using a small laser-produced x-ray source. The SXRSC is calibrated by comparing its integrated signal to the output of calibrated x-ray diodes monitoring the source strength. The measured SXRSC response is linear over greater than two orders of magnitude. Using these calibrations, absolute intensities can be measured to an accuracy of +-30%

Development of soft x-ray streak cameras at Lawrence Livermore National Laboratory

Soft x-ray streak cameras are used in conjunction with several instruments for the diagnostic of laser irradiated targets. A program was undertaken to develop cameras satisfying the requirements of the laser facility, to improve the reliability and performance of the camera and to reduce the level of effort required to set and operate each diagnostic. The implemented soft x-ray streak cameras can be operated either manually or automatically