In the presence of a high-intensity optical field, electrons are released from atoms on an attosecond time scale. Moreover,
in the tunnelling regime, this process displays a strong sensitivity to the carrier-envelope phase (CEP) of a few-cycle
light pulse. Tunnelling ionization - a fascinating quantum mechanical phenomenon - leads to a quasi-stepwise increase
of free electron density and, as a consequence, of the refractive index of the medium. These steps of the refractive index,
corresponding to half-cycles of the driving optical field, impose a transient attosecond phase mask. By scattering probe
light off this mask we detect quasi-periodic higher-order harmonics, the spectrum of which, unlike that of the harmonics
originating from intrinsic nonlinearity or driven by electron re-collisions, do not depend on the probe intensity and recollision
dynamics. The implemented noncollinear pump-probe experimental technique allows optical harmonics
generated due to a tunnelling-ionization-induced modulation of the electric current to be spatially separated from the
harmonics originating from atomic and ionic nonlinear susceptibilities, enabling background-free time-resolved detection
of electron-tunnelling-controlled harmonic spectra and offering an attractive solution for attosecond optical metrology of
gases and bulk solids.
Alexander Ignatiev, Viatcheslav Korneev, Viktor Krutov, Sergey Kuzin, Alexander Mitrofanov, Andrey Pertzov, Vladimir Slemzin, Igor Zhitnik, M. Pakhomov, G. Karabadjak, B. Khmelinin, E. Makolkin, Y. Plastinin, Y. Pronin, G. Sipatnhov, G. Sojtchenkov, A. Serebrov, V. Tsibliev
Absorption of solar UV-radiation in the 250 - 280 nm band by ozone layer leads to very low background of radiation scattered by the Earth at altitudes above 80 km. It makes possible to observe from near-Earth orbit with high sensitivity processes in upper atmosphere caused by engines of rockets and spacecrafts during their maneuvering or entering into dense layers of atmosphere. The main characteristics and application of the high sensitive imaging UV-camera specially designed for observations on-board the <<Mir>> manned orbital station (OS) are described. The camera works in the 200 - 350 nm spectral region and includes catadioptric objective, narrow band filters, special UV-sensitive image intensifier, photographic camera or TV-camera. Images are registered with sensitivity of 4 (DOT) 1016 w/cm2 in FOV of 12 degrees with angular resolution of 1,5'. The camera was delivered on-board the <<Mir>> OS in July 1992 and successfully worked during 5 years. Examples of observations of different space objects are given.
The characteristics of different types of thin film XUV filters for the TEREK-C solar telescope and the REC-C spectroheliograph developed in the framework of the CORONAS-I program are presented. We describe the design and properties of Al-Formvar composite filters on rigid mesh supports with a spacing of 0.7 mm and 2 mm, which have been mounted in front of the XUV spectral channels of both instruments. It was proposed to use thin films of SiC as bandpass filters with high transparency in the 13 - 30 nm spectral region and effective cutoff blocking of strong solar Lα (121.7 nm) line radiation. The Al and SiC thin films on fine porous polymer membranes with through pores were placed in close proximity of the entrance plane of the image detectors, designed as a combination of open type microchannel plate and CCD-matrix. The problem of elimination of the influence of diffraction effects on X-ray images in the telescope focal plane is considered. All filters have sustained without damage the launching overloads (the launch took place on March 12, 1994) and successfully worked in the TEREK-C and the RES-C instruments.
Alexander Ignatiev, Nikolai Kolachevsky, Viatcheslav Korneev, Viktor Krutov, Sergey Kuzin, Alexander Mitrofanov, Andrey Pertzov, Eugene Ragozin, Vladimir Slemzin, Igor Tindo, Igor Zhitnik, Nikolai Salashchenko, Roger Thomas
The paper describes the main characteristics of the X-ray optical elements (multilayer spherical and aspherical mirrors and diffraction gratings for the 13-30 nm XUV spectral region, Bragg crystal spherical mirrors for the 0.18 and 0.84 m soft X-ray spectral regions) manufactured for the TEREK-C solar XUV telescope array and the RES-C solar spectroheliograph. The TEREK-C and RES-C instruments were placed aboard the CORONAS-I satellite which was launched on March 2, 1994. The testing procedures and results of laboratory tests in X-ray spectral range are also presented.
Igor Zhitnik, Alexander Ignatiev, Viatcheslav Korneev, Viktor Krutov, Sergey Kuzin, Alexander Mitrofanov, S. Oparin, Andrey Pertzov, Vladimir Slemzin, Igor Tindo, M. Pakhomov, Nikolai Salashchenko, O. Timofeev
The paper describes instruments for solar imaging XUV spectroscopy -- the TEREK-C telescope array and the RES-C spectroheliograph mounted on board the Russian-Ukrainian CORONAS-I satellite (launched on March 2, 1994). The CORONAS project is carried out under scientific guidance of Prof. V.N. Oraevsky, director of the IZMIRAN (Troitsk, Moscow region, Russia) -- leading institute of this project. The instruments were intended to obtain high resolution solar images and spectra from the transition region and the corona of the Sun within the temperature range of 105 - 107 K. The optical design of the TEREK telescope array includes two Herschelian XUV-telescopes with Mo-Si multilayer mirrors: the first one with 3 whole-Sun spectral channels (reflection peaks at (lambda) equals 13.2, 17.5 and 30.4 nm, angular scale 4.7'), the second channel -- with 4 mirrors, each covering 1/4 of the Sun ((lambda) equals 17.5 nm, angular scale 1'). The RES-C spectroheliograph has five measuring channels with a whole-Sun field of view: two XUV channels with orthogonal dispersion planes, equipped with grazing incidence gratings and multilayer mirrors to obtain high resolution spectral images in the 19.2 - 20.1 nm band (spectral resolution 2 (DOT) 10-4 nm/pix, angular scale 4.5'), two MgXII channels having narrow-band imaging systems with orthogonal dispersion planes for the 0.841 - 0.843 nm spectral band, equipped with Bragg crystal spherical mirrors, and one FeXXV imaging system with a ring Bragg crystal mirror for the 0.184 - 0.188 nm spectral band. Two types of image detectors were designed with the use of CCD-matrices (1024 X 1152 elements) and image intensifiers (with an open microchannel plate and a luminescent converter). The paper presents a detailed description of the overall structure, electronic design and the main characteristics of the instruments, preliminary results of flight functioning of the TEREK-C and RES-C instruments and examples of the images and spectra of the Sun obtained in the experiment.
It is proposed to use thin films of silicon carbide as Extreme Ultraviolet bandpass filters transparent within 135-304 A band and with excellent cutoff blocking of the strong L(alpha ) 1216 A line radiation. Mesh or particle track porous membrane supporting 200-800 A thickness SiC filters have been made by RF sputtering techniques. We describe the design and performance of these filters. Such type SiC filter was used in front of the microchannel plate detector of the TEREK X-Ray Telescope mounted on the Solar Observatory CORONAS-I which was successfully launched on March 2, 1994.
Fred Bijkerk, Leonid Shmaenok, Eric Louis, A. van Honk, Marnix van der Wiel, Y. Platonova, Alexander Shevelko, Alexander Mitrofanov, Frank Voss, R. Desor, Helmut Frowein, Bernard Nikolaus
We report results on high power excimer lasers and their application to generating laser plasma soft x-ray sources. A conversion efficiency of laser light to monochromatized soft x- ray radiation of 0.7% has been achieved at 13.5 nm (2% BW). Two methods to mitigate the production of plasma debris have been analyzed: tape targets and the use of Kr as a buffer gas. The optimal coating thickness of tape targets coated with Ta has been determined as 1 micrometers . Ta tape targets and the Kr buffer were used in a debris contamination test of 105 pulses and evaluated by the loss in reflectivity of a normal incidence Mo-Si multilayer mirror.
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