Large-Scale Solar Magnetic Fields Observed with the Infrared Spectro-Polarimeter IRmag at the National Astronomical Observatory of Japan: Comparison of Measurements Made in Different Spectral Lines and Observatories

Demidov, M. L.; Hanaoka, Yoichiro; Sakurai, Takashi; Wang, Xiaofeng

doi:10.1007/s11207-020-01620-4

Cited by 5 publications

(3 citation statements)

References 14 publications

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“…Its wavelength is not much longer than those of the visible lines, but it has advantages of transmittance to fused silica and being less susceptible to the effect of blackbody radiation from plasma-facing components and spectroscopic instruments. The line has also been widely employed for Stokes spectropolarimetry of astrophysical plasmas 35 – 37 .…”

Section: Methodsmentioning

confidence: 99%

Spatially resolved measurement of helium atom emission line spectrum in scrape-off layer of Heliotron J by near-infrared Stokes spectropolarimetry

Chatani

Shikama

Ueno

et al. 2022

Sci Rep

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For plasma spectroscopy, Stokes spectropolarimetry is used as a method to spatially invert the viewing-chord-integrated spectrum on the basis of the correspondence between the given magnetic field profile along the viewing chord and the Zeeman effect appearing on the spectrum. Its application to fusion-related toroidal plasmas is, however, limited owing to the low spatial resolution as a result of the difficulty in distinguishing between the Zeeman and Doppler effects. To resolve this issue, we increased the relative magnitude of the Zeeman effect by observing a near-infrared emission line on the basis of the greater wavelength dependence of the Zeeman effect than of the Doppler effect. By utilizing the increased Zeeman effect, we are able to invert the measured spectrum with a high spatial resolution by Monte Carlo particle transport simulation and by reproducing the measured spectra with the semiempirical adjustment of the recycling condition at the first walls. The inversion result revealed that when the momentum exchange collisions of atoms are negligible, the velocity distribution of core-fueling atoms is mainly determined by the initial distribution at the time of recycling. The inversion result was compared with that obtained using a two-point emission model used in previous studies. The latter approximately reflects the parameters of atoms near the emissivity peak.

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Section: Methodsmentioning

confidence: 99%

Spatially resolved measurement of helium atom emission line spectrum in scrape-off layer of Heliotron J by near-infrared Stokes spectropolarimetry

Chatani

Shikama

Ueno

et al. 2022

Sci Rep

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“…Also, numerous technical applications have used these materials that have some degree of ordering in the arrangement of its molecules, as solid crystals, but they flow like a liquid [1][2][3] . Solar physics [4][5][6] , astronomy 7 , biomedicine 8,9 , atomic clocks [10][11][12] , LiDAR (Light Detection And Ranging) 13 and LADAR (LAser Detection And Ranging) 14,15 teledetection are some of the many fields where they are utilized. In particular, Liquid Crystal Variable Retarders (LCVRs) are used to modulate the polarization state of the light in many instruments.…”

Section: Introductionmentioning

confidence: 99%

Liquid crystal devices for compact optical space instruments

Álvarez-Herrero,

García Parejo,

Campos-Jara

et al. 2024

Polarization: Measurement, Analysis, and Remote Sensing XVI

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Our group in the Space Optics Department at INTA has been working during more than 20 years in the development of devices based on liquid crystals for optical payloads onboard space missions. Currently, there are three of our devices successfully in operation in the PHI and METIS instruments of the Solar Orbiter ESA/NASA mission. Therefore, they have the highest technology maturity level, TRL9 (Technology Readiness Level). To the best of our knowledge, we are pioneers of the use of polarization modulators based on liquid crystals in a telescope or a camera in a space platform.Liquid crystal devices avoid using standard solutions that involve mechanisms with rotatory polarization optical parts. Instead, we use this technology that minimizes the size, mass and power consumption of the device while maximizing its useful aperture and performance. These new capabilities open up new possibilities for small satellites that were previously only attainable by larger satellites. Liquid crystal-based polarization modulator technology is highly versatile and can be configured in multiple ways to suit diverse applications. It is based on the ability of liquid crystal variable retarders to control, modify and measure the polarization state of light, be it in an image or in a spot beam.The application fields are numerous, from Astrophysics to Earth Observation. This work will introduce some of the main instruments that we are working on: from the Vigil ESA mission for Space Weather to Quantum Communication Space Systems, and including the Miniature Absolute Magnetometer for the NanoMagSat mission of ESA's SCOUT Program. Also, we will show the development status of other liquid-crystal devices for compact space instrumentation that we are developing as Liquid Crystal Tunable Filters (LCTFs) and Spatial Light Modulators (SLMs).In October 2023, the INTA spinoff Eye4Sky was established to the exploitation and commercialization of this optical technology of liquid crystal devices for space applications. This deep-tech startup has been selected for the prestigious European Space Agency Business Incubation Centre (ESA BIC) program.

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“…As is known from numerous previous studies, the full-disk solar magnetograms [1][2][3], synoptic maps [4], the size and location of the calculated coronal holes and heliospheric current sheet [5], as well as interplanetary field strength [6] can sometimes differ very significantly when observations from different instruments are used. So it is very interesting to explore the possible differences in the calculations of the solar wind speed (one of the important space weather parameters) when different synoptic maps (low boundary conditions) from different observatories are used.…”

Section: Introductionmentioning

confidence: 99%

On the role of empirical boundary conditions in space weather prediction results

Demidov¹

2022

Proceedings of the Multifaceted Universe: Theory and Observations - 2022 — PoS(MUTO2022)

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Prediction of the conditions in the near-Earth space environment (space weather) is an urgent scientific and practical task, and there are several scientific teams in the world which have been deeply involved in this research using various model assumptions. One of the most important problems in such calculations is the reliability of the initial data -synoptic maps of the solar magnetic fields. The most famous Space Weather Prediction Center (SWPC) uses observations of the Global Oscillations Network Group (GONG). However, there are other sources of measurements of the full-disk solar magnetic fields (WSO, SDO/HMI and SOLIS in the USA, IRmag at Mitaka in Japan, SMAT in China, STOPs in Russia), and it is of interest to use them to calculate the parameters of the solar wind. In this paper this is done on the example of Carrington Rotation (CR) 2164 using observations from Wilcox Solar Observatory (WSO), GONG, Solar Telescope for Operative Prediction (STOP) at the Sayan Solar Observatory (SSO). The calculations are based on the Wang-Sheeley-Arge (WSA) model and include the determination of the parameters of the coronal magnetic field in the Potential Field Source Surface (PFSS) approximation. The propagation of the solar wind to Earth's orbit is calculated using the HUX (Heliospheric Upwind eXtrapolation) model. It is shown that the differences in solar wind speeds for different data sets can reach 200 km/s or even more. The results of model simulations are compared with the experimental ACE satellite data.

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Large-Scale Solar Magnetic Fields Observed with the Infrared Spectro-Polarimeter IRmag at the National Astronomical Observatory of Japan: Comparison of Measurements Made in Different Spectral Lines and Observatories

Cited by 5 publications

References 14 publications

Spatially resolved measurement of helium atom emission line spectrum in scrape-off layer of Heliotron J by near-infrared Stokes spectropolarimetry

Spatially resolved measurement of helium atom emission line spectrum in scrape-off layer of Heliotron J by near-infrared Stokes spectropolarimetry

Liquid crystal devices for compact optical space instruments

On the role of empirical boundary conditions in space weather prediction results

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