X-Ray Spectroheliograph Research Articles

Calibration of the X-Ray spectroheliograph Mg XII for the 0.84 nm spectral line for the TESIS experiment

The spectroheliograph for monochromatic imaging of the solar corona at the 0.84 nm resonance line of a Mg XII ion is a part of the TESIS instrumentation onboard the CORONAS-PHOTON satellite. The main optical elements of the spectroheliograph are the focusing crystalline mirror and imaging detector based on a CCD array. The optical scheme of the spectroheliograph, procedure, and results of calibrations of the optical elements within the working spectral range are presented. Diffraction efficiency and the rocking curve of the crystalline mirror, sensitivity, and radiation hardness of the detector were measured. It was found that the diffraction efficiency is 10%, the width of the rocking curve is ∼3′, the detector sensitivity is 31 ADC units per photon, and the radiation hardness is better than 107 rad within the working spectral range.

Using x-ray spectroheliograph technique for investigations of laser-produced plasma under interaction with strong magnetic field

A dense jet of a plasma consisting of multiply charged ions was generated in the interaction of a laser plasma with a strong external axial magnetic field. It is shown that using the high-luminosity x-ray spectroheliograph technique allows to measure plasma emission spectra with 2-dimensional spatial resolution even in the cases when these spectra have small intensities. The x-ray spectroscopy and interferometry methods are used to measure plasma parameter distributions. The dependencies of Ne(z) and Te(z) measured in this paper can be used to calculate the evolution of plasma ionization state during plasma expansion. The quasihomogeneous laser jet, which appears when a laser plasma interacts with an external magnetic field can be used not only to form an active medium of a short wavelength laser, but probably also to tackle the urgent problem of transport in a laser ion injector.

Multi-Spectral Solar Telescope Array

The development of multilayer optics has profound implications for soft x-ray/extreme ultraviolet (XUV) astronomy. During the October 1987 flight of the Stanford/Marshall Space Flight Center Rocket X-Ray Spectroheliograph, narrow wavelength band, low scatter soft x-ray/extreme ultraviolet spectroheliograms were obtained with -1 arcsec spatial resolution at X - 173 A (Fe IX, Fe X) and at is. - 256 A (He II Ly-3). Although the Cassegrain telescopes used in this experiment were small (63.5 mm diameter) and utilized spherical rather than paraboloidal/hyperboloidal mirrors, the images produced exceed in quality any XUV spectroheliograms previously obtained with either normal or grazing incidence techniques. We describe a new rocket spectroheliograph instrument, the Multi- Spectral Solar Telescope Array (MSSTA), that is currently being prepared for launch in August 1990. This instrumentwill utilizetrue Ritchey-Chrétien optics of 127 mm diameter and parabolic Herschelian optics of 40 mm diameter, which will allow spectroheliograms to be obtained over the soft x-ray/extreme ultraviolet/far ultraviolet spectral range (40 to 1550 A). The performance of this new instrument should definitely demonstrate the unique combination of ultrahigh spatial resolution and spectral differentiation that multilayer optics afford for astronomical observations. The MSSTA will also represent the first astronomical use of an important new optical device, the multilayer grating. The MSSTA should obtain unprecedented information regarding the structure and dynamics of the solar atmosphere in the temperature range i04 to i07 K.

Design of a normal incidence multilayer imaging X-ray microscope

Normal incidence multilayer Cassegrain x-ray telescopes were flown on the Stanford/ MSFC Rocket X-Ray Spectroheliograph. These instruments produced high spatial resolution images of the Sun and conclusively demonstrated that doubly reflecting multilayer x-ray optical systems are feasible. The images indicated that aplanatic imaging soft x-ray/EUV microscopes should be achievable using multilayer optics technology. We have designed a doubly reflecting normal incidence multilayer imaging x-ray microscope based on the Schwarzschild configuration. The Schwarzschild microscope utilizes two spherical mirrors with concentric radii of curvature which are chosen such that the third-order spherical aberration and coma are minimized. We discuss the design of the microscope and the results of the optical system ray trace analysis which indicates that diffraction-limited performance with 600 Å spatial resolution should be obtainable over a 1 mm field of view at a wavelength of 100 Å. Fabrication of several imaging soft x-ray microscopes based upon these designs, for use in conjunction with x-ray telescopes and laser fusion research, is now in progress. High resolution aplanatic imaging x-ray microscopes using normal incidence multilayer x-ray mirrors should have many important applications in advanced x-ray astronomical instrumentation, x-ray lithography, biological, biomedical, metallurgical, and laser fusion research.

Design of a Normal Incidence Multilayer Imaging X-Ray Microscope

Normal incidence multilayer Cassegrain x-ray telescopes were flown on the Stanford/MSFC Rocket X-Ray Spectroheliograph. These instruments produced high spatial resolution images of the Sun and conclusively demonstrated that doubly reflecting multilayer x-ray optical systems are feasible. The images indicated that aplanatic imaging soft x-ray /EUV microscopes should be achievable using multilayer optics technology. We have designed a doubly reflecting normal incidence multilayer imaging x-ray microscope based on the Schwarzschild configuration. The Schwarzschild microscope utilizes two spherical mirrors with concentric radii of curvature which are chosen such that the third-order spherical aberration and coma are minimized. We discuss the design of the microscope and the results of the optical system ray trace analysis which indicates that diffraction-limited performance with 600 Å spatial resolution should be obtainable over a 1 mm field of view at a wavelength of 100 Å. Fabrication of several imaging soft x-ray microscopes based upon these designs, for use in conjunction with x-ray telescopes and laser fusion research, is now in progress. High resolution aplanatic imaging x-ray microscopes using normal incidence multilayer x-ray mirrors should have many important applications in advanced x-ray astronomical instrumentation, x-ray lithography, biological, biomedical, metallurgical, and laser fusion research.

The GSFC EUV and X-ray spectroheliograph on OSO-7

The Goddard Space Flight Center instrument carried on the pointed section of the OSO-7 satellite is described. This instrument contains: An extreme ultraviolet spectroheliograph using glancing incidence optics of Wolter's Type II to focus the Sun's light on the entrance slit of a concave grating spectrometer; an auxiliary Hα system; two X-ray spectroheliographs using mechanical collimators for spatial resolution and Ross filters to isolate spectral bands of interest, and a flare polarimeter operating in the 15–40 keV X-ray region. These subsystems may be operated in a number of modes which, when combined with the spacecraft modes, give the instrument great flexibility for making solar observations. Representative results from each of the subsystems are presented.

The Skylab X-Ray Spectroheliograph

On May 14, 1973, Skylab was placed in earth orbit by the National Aeronautics and Space Administration. The major scientific payload of this experimental space station is the Apollo Telescope Mount (ATM) which houses six major telescope instruments. As a group, these instruments are capable of observing the sun's radiation from X-rays to visible light. The Skylab program consists of three manned observing periods; the first period having a twenty-eight day duration, the second and third each having fifty-six days duration. These three observing periods are separated by unmanned periods of approximately forty days duration. From the data collected in these three observing periods, solar physicists will try to answer some of the basic questions concerning solar flares, solar activity, the heating of the solar corona and the solar cycle. The purpose of this paper is to give a brief description of the hardware and performance of one of these instruments, the X-ray spectroheliograph. The conceptual design of this instrument and scientific details of the subsystems have been discussed in Reference 2 as part of a general discussion on "Imaging in X-Ray Astronomy". A more extensive presentation of the instrument as a whole in the context of the goals in the solar physics area is in preparation (Reference 3).

A satellite-borne X-ray spectroheliograph

A grazing incidence X-ray telescope for the study of the spatial and temporal variation of solar X-radiation in the region 0.8 to 1.6 nm, with proportional counters and pulse height wavelength discrimination, is described in some detail. An accompanying slit system covering the 0.3 to 0.9 nm region provides a more rapid coverage of flares than the spacecraft raster period would otherwise allow. Results are given illustrating the types of data being received from this instrument, which has been operating correctly for 18 months.

A scanning X-ray spectroheliograph

A grazing incidence reflector which focuses radiation on to a proportional counter has been used to obtain X -ray pictures of the Sun in a number of relatively narrow wavelength bands below 2 nm. The design and development of the instrument is discussed together with the preliminary results from two rocket flights.