scholarly journals Monochromatic X-Ray Imagers of the Sun Based on the Bragg Crystal Optics

2021 ◽  
Vol 8 ◽  
Author(s):  
Anton A. Reva ◽  
Sergey V. Kuzin ◽  
Alexey S. Kirichenko ◽  
Artem S. Ulyanov ◽  
Ivan P. Loboda ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Corona ◽  
Spectral Lines ◽  
Coronal Plasma ◽  
The Sun ◽  
Spectral Filter ◽  
Crystal Optics ◽  
X Ray ◽  
Hot Plasma ◽  
Wide Range

Investigations of solar activity require information about plasma in a wide range of temperatures. Generally, researchers require observations from telescopes producing monochromatic images of coronal plasma with cool, warm, and hot temperatures. Until now, monochromatic telescopic imaging has been made only in the Mg XII 8.42 Å line with the Mg XII spectroheliograph on board CORONAS-I, CORONAS-F, and CORONAS-PHOTON satellites. The Mg XII spectroheliograph used Bragg crystal optics. Its design is based on two main principles: (1) to select the working wavelength and the crystal in such a way that reflection occurs at small incident angles; (2) to use the aperture of the mirror as a spectral filter. We believe that these design principles can be applied to other spectral lines. In this article, we will review the design of the Mg XII spectroheliograph and present our thoughts on how to apply these principles to the Si XIV 6.18 Å and Si XIII 6.65 Å lines. A combination of the monochromatic Mg XII 8.42 Å, Si XIV 6.18 Å, and Si XIII 6.65 Å images will help us to study the dynamics of the hot plasma in the solar corona.

scholarly journals Solar activity and solar oscillations

1997 ◽  
Vol 181 ◽  
pp. 277-285
Author(s):  
Y. Elsworth
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Radio Emission ◽  
Surface Temperature ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermal Component ◽  
X Ray ◽  
Convective Flows ◽  
Wide Range

Helioseismology provides us with the tools to probe solar activity. So that we can consider how the solar oscillations are influenced by that activity, we first consider the phenomena that we associate with the active Sun. The surface of the Sun is not quiet but shows evidence of convection on a wide range of scales from a few hundred kilometres through to several tens-of-thousands of kilometres. The surface temperature shows signs of the convection structures with the temperature in the bright granules being some 100 K to 200 K hotter than the surrounding dark lanes. Sunspots, which are regions of high magnetic field that suppress convective flows, are clearly visible to even quite crude observations. They are several tens-of-thousands of kilometres in diameter and about 2000 K cooler than their surroundings. Ultraviolet and X-ray pictures from satellites show that the higher layers of the solar atmosphere are very non-uniform with bright regions of high activity. Contemporaneous magnetograms show that these regions are associated with sunspots. Flares - regions of magnetic reconnections - are seen at all wavelengths from X-ray through the visible to radio. They are the non-thermal component of the radio emission of the Sun. There are many other indicators of activity on the Sun.

scholarly journals Closing up onto our sun: solar imaging

2020 ◽  
Vol 240 ◽  
pp. 07011
Author(s):  
Kushagra Shrivastava ◽  
Keith Wen Kai Chia ◽  
Kang Jun Wong ◽  
Alfred Yong Liang Tan ◽  
Hwee Tiang Ning
Keyword(s):  
Solar Activity ◽  
The Sun ◽  
Research Needs ◽  
Large Numbers ◽  
Wide Range ◽  
Future Science ◽  
Insight Into ◽  
Term Data ◽  
Made In

Solar activity research provides insight into the Sun’s past, future (Science Daily, 2018). The solar activity includes observations of large numbers of intense sunspots, flares, and other phenomena; and demands a wide range of techniques and measurements on the observations. This research needs long term data collection before critical analyses can occur, to generate meaningful learning and knowledge. In this project, we will use solar imaging to make observations of solar activity, and take our baby steps to make contributions in citizen science. Observations will be made in 3 wavelengths to gain a more thorough analysis by looking at different perspectives of the Sun, namely H-Alpha, Calcium-K, and white light.

scholarly journals A Rocket-Borne X-Ray Spectrometer/Monochromator System for Mapping the Solar Corona

1971 ◽  
Vol 41 ◽  
pp. 181-181
Author(s):  
L. W. Acton ◽  
R. C. Catura ◽  
J. L. Culhane ◽  
A. J. Meyerott
Keyword(s):  
Spatial Distribution ◽  
Solar Corona ◽  
Proportional Counter ◽  
Line Emission ◽  
Field Of View ◽  
The Sun ◽  
X Ray ◽  
Rocket Flight

A rocket payload is being prepared for the purpose of examining the spatial distribution of line emission from two important ions, Ovii and Neix, in the solar corona. The payload will contain the following integrated set of instruments.(1) A pair of X-ray spectrometers utilizing KAP crystals of approximately 100 cm2 area.(2) An optical aspect camera with a 1 Å bandpass H-α filter to measure the location of the field of view of the X-ray systems on the sun through out the rocket flight.(3) A collimated proportional counter spectrometer operating in the 3 to 15 keV range.

Solar X-ray Emission and Metre-Wave Radio Bursts

1977 ◽  
Vol 3 (2) ◽  
pp. 154-157 ◽  
Author(s):  
R. A. Duncan
Keyword(s):  
Solar Corona ◽  
Coronal Holes ◽  
The Sun ◽  
Radio Bursts ◽  
X Ray ◽  
Wave Radio

Soft X-ray photographs of the Sun taken from the manned Skylab satellite (Vaiana et al. 1973) gave, not the earliest, but perhaps the most graphic evidence that the solar corona is patchy. During the Skylab mission (May 1973 to February 1974), the solar corona as usually envisaged covered only 80% of the Sun (Bohlin 1977). The areas lacking a ‘dense’ corona are called coronal holes (Withbroe al. 1971; Waldmeier 1975).

Planetary Modulation of Solar Activity

1967 ◽  
Vol 1 (2) ◽  
pp. 53-54 ◽  
Author(s):  
E. K. Bigg ◽  
P. S. Mulhall
Keyword(s):  
Solar Activity ◽  
Solar Surface ◽  
Relative Equilibrium ◽  
High Tide ◽  
The Other ◽  
The Sun ◽  
Sunspot Numbers ◽  
Tidal Forces ◽  
Wide Range ◽  
Degree Of Control

It has recently been shown that the planet Mercury exerts a small control on relative sunspot numbers, the degree of control depending on the positions of the other planets.This paper describes the results of extending the work to include all the planets.As a working hypothesis we have assumed that gravitational tidal forces induced on the Sun by the planets may modulate solar activity and have accordingly calculated relative equilibrium ‘high tide’ displacements of the solar surface for each day from the positions, masses and distances of the first six planets. Although the tides are very slight, the mass of displaced material is appreciable and varies over the very wide range of nearly 5 to 1.

Detailed Calibration of the Off-Axis Optical Characteristics for the X-Ray Telescope onboard Hinode

2020 ◽  
Author(s):  
Junho Shin ◽  
Takashi Sakurai ◽  
Ryouhei Kano ◽  
Yong-Jae Moon ◽  
Yeon-Han Kim
Keyword(s):  
Solar Corona ◽  
Energy Dependence ◽  
Scattered Light ◽  
Field Of View ◽  
Coronal Plasma ◽  
Optical Characteristics ◽  
Optical Center ◽  
Wide Field ◽  
Plasma Properties ◽  
X Ray

<p>The X-Ray Telescope (XRT) onboard the Hinode satellite has a specially designed Wolter type grazing-incidence (GI) optics with a paraboloid-hyperboloid mirror assembly to measure the solar coronal plasma of temperatures up to 10 MK with a resolution of about one arcsec. One of the main purposes of this scientific mission is to investigate the detailed mechanism of energy transfer processes from the photosphere to the upper coronal region leading to its heating and the solar wind acceleration. To theoretically model the three-dimensional coronal structures is sensitive to the values of plasma properties at the base of solar corona and thus requires beforehand accurate empirical description of those properties. Though the telescope has provided unprecedented observations of solar corona for more than a decade, due to a wide field of view of 34 x 34 arcmin covering the full Sun, the optical performance of the instrument gradually deteriorates as it goes away from the optical center. For this reason, the off-axis characteristics of Hinode/XRT should be examined with care in order to precisely interpret the coronal plasma properties near the solar limb area.</p><p>This presentation will explain the importance of accurate calibration of the optical characteristics, especially for the data taken in the off-axis region. Our previous study has shown that the scattered light caused by the XRT mirror surface roughness has a power-law distribution and also shows an energy dependence, with which the PSF profile from the core to the scattering wing has been completed. We will introduce in this study how the level of scattering wing can be determined quantitatively for each focal plane filter from in-flight data analysis. We have also evaluated the vignetting effect in Hinode/XRT by analyzing the 2D distribution of effective area in the field of view taken from MSFC/XRCF pre-launch experiment. It is revealed that, unlike the case of Yohkoh/SXT, the degree of offset of an optical center is not serious and thus shows little deviation from rotational symmetry. Also important is that the vignetting pattern in XRT shows an energy dependence, which has never been considered before for the analyses of XRT data. More interesting results on the calibration of Hinode/XRT scattered light and the correction of vignetting effect will be introduced and discussed thoroughly. </p>

scholarly journals High-efficiency coherence-preserving harmonic rejection with crystal optics

2018 ◽  
Vol 25 (5) ◽  
pp. 1354-1361 ◽  
Author(s):  
Fan Zhang ◽  
Andrew J. Allen ◽  
Lyle E. Levine ◽  
Gabrielle G. Long ◽  
Ivan Kuzmenko ◽  
...  
Keyword(s):  
High Efficiency ◽  
Flux Ratio ◽  
Storage Rings ◽  
X Rays ◽  
Crystal Optics ◽  
X Ray ◽  
Harmonic Radiation ◽  
Harmonic Rejection ◽  
Wide Range ◽  
Fundamental Radiation

This work reports a harmonic-rejection scheme based on the combination of Si(111) monochromator and Si(220) harmonic-rejection crystal optics. This approach is of importance to a wide range of X-ray applications in all three major branches of modern X-ray science (scattering, spectroscopy, imaging) based at major facilities, and especially relevant to the capabilities offered by the new diffraction-limited storage rings. It was demonstrated both theoretically and experimentally that, when used with a synchrotron undulator source over a broad range of X-ray energies of interest, the harmonic-rejection crystals transmit the incident harmonic X-rays on the order of 10−6. Considering the flux ratio of fundamental and harmonic X-rays in the incident beam, this scheme achieves a total flux ratio of harmonic radiation to fundamental radiation on the order of 10−10. The spatial coherence of the undulator beam is preserved in the transmitted fundamental radiation while the harmonic radiation is suppressed, making this scheme suitable not only for current third-generation synchrotron sources but also for the new diffraction-limited storage rings where coherence preservation is an even higher priority. Compared with conventional harmonic-rejection mirrors, where coherence is poorly preserved and harmonic rejection is less effective, this scheme has the added advantage of lower cost and footprint. This approach has been successfully utilized at the ultra-small-angle X-ray scattering instrument at the Advanced Photon Source for scattering, imaging and coherent X-ray photon correlation spectroscopy experiments. With minor modification, the harmonic rejection can be improved by a further five orders of magnitude, enabling even more performance capabilities.

Opacity effects in soft X-ray spectral lines of the solar corona

1997 ◽  
Vol 20 (12) ◽  
pp. 2259-2262
Author(s):  
J.T. Schmelz ◽  
J.C. Chauvin ◽  
J.L.R. Saba
Keyword(s):  
Solar Corona ◽  
Spectral Lines ◽  
X Ray
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