Ray-tracing simulations for the ultra-lightweight X-ray optics toward a future jupiter exploration mission

Mitsuishi, Ikuyuki; Ezoe, Yuichiro; Ogawa, Tomohiro; Sato, M.; Nakamura, Kiyotaka; Numazawa, Masaki; Takeuchi, Kazuma; Ohashi, T.; Ishikawa, Kumi; Mitsuda, Kazuhisa

doi:10.1016/j.asr.2015.08.022

Cited by 12 publications

(6 citation statements)

References 18 publications

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“…Nickel-and Iridium-coated silicon optics achieve greater effective areas than purely silicon optics at all energies except the at the L-shell absorption edge of Nickel around 1 keV. Nickel provides the greatest The grasp at 600 eV as a function of the mirror surface roughness in rms (Mitsuishi et al 2016) effective areas for the energies below 1 keV which are of greatest interest. From recent experiments, a mirror surface roughness of 1 nm or less is achievable.…”

Section: Optical Elementsmentioning

confidence: 99%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

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Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in con- text by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the KelvinHelmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time-and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (∼ 1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers.Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significanc...

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Section: Optical Elementsmentioning

confidence: 99%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

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“…To evaluate the performance of the MuLE optics, including the surface roughness of the mirrors, misalignment of the LE mirror cells, and a realistic detector configuration, we performed a ray tracing simulation by modifying a previously built simulator. 19 The values of the surface roughness and the mirror cell misalignment were taken from our past mirror fabrication. 20 In this study, we treated only one parameter set because we aimed to evaluate the working principle of the MuLE optics.…”

Section: Ray Tracing Simulationmentioning

confidence: 99%

Multiplexing lobster-eye optics: a concept for wide-field x-ray monitoring

Tamagawa

Uchiyama

Otsubo

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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We propose a concept of multiplexing lobster-eye (MuLE) optics to achieve significant reductions in the number of focal plane imagers in lobster-eye (LE) wide-field X-ray monitors. In the MuLE configuration, an LE mirror is divided into several segments and the X-rays reflected on each of these segments are focused on a single image sensor in a multiplexed configuration. If each LE segment assumes a different rotation angle, the azimuthal rotation angle of a cross-like image reconstructed from a point source by the LE optics identifies the specific segment that focuses the X-rays on the imager. With a focal length of 30 cm and LE segments with areas of 10 × 10 cm 2 , ∼1 sr of the sky can be covered with 36 LE segments and only four imagers (with total areas of 10 × 10 cm 2). A ray tracing simulation was performed to evaluate the nine-segment MuLE configuration. The simulation showed that the flux (0.5 to 2 keV) associated with the 5σ detection limit was ∼2 × 10 −10 erg cm −2 s −1 (10 mCrab) for a transient with a duration of 100 s. The simulation also showed that the direction of the transient for flux in the range of 14 to 17 mCrab at 0.6 keV was determined correctly with 99.7% confidence limit. We conclude that the MuLE configuration can become an effective on-board device for small satellites for future X-ray wide-field transient monitoring.

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“…Design parameters are to meet requirements of an X-ray imager proposed for the future Jupiter exploration mission (Table 1) as demonstrated by ray-tracing simulations (Mitsuishi et al 2016). Table 2 summarizes the parameters of the optic.…”

Section: Introductionmentioning

confidence: 99%

First X-ray imaging with a micromachined Wolter type-I telescope

et al. 2016

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be a new probe to investigate chemical compositions of planetary atmospheres, surfaces of planets, moons or asteroids and high energy particles in planetary magnetospheres. A potential future Japanese exploration to Jupiter needs a light-weight (<10 kg) X-ray imager in order to capture X-ray auroras from Jupiter . However, limited resources, i.e., mass, power, size, have hindered exploration satellites from carrying a good angular resolution and large effective area X-ray telescope.Wolter type-I telescopes have been widely used in X-ray astronomy. X-rays are doubly reflected upon paraboloid and hyperboloid mirrors, to minimize aberrations (Wolter 1952). A few to hundreds of mirrors are conically nested to increase the effective area. Each mirror is fabricated individually with either polishing of thick mirror substrates, replication of precisely fabricated mandrels, or thermal forming of thin aluminum foils. However, these mirrors have to be heavy when a high angular resolution is sought for Bavdaz et al. (2004). Furthermore, the lightest aluminum foil mirror approximates ideal mirror surfaces with cones, which degrades the angular resolution to 10 arcmin under a short focal length less than 1 m. Therefore, a new mirror fabrication technology is needed for future X-ray astronomy missions as well as planetary explorations.A possible solution is micropore optics (Frazer 1997). Sidewalls of micro pores whose width is typically of the order of 10 to 100 µm are used for X-ray mirrors. The mirror thickness can be extremely thin, of the order of 100 µm to 10 mm. The micropore optics can thus be ultralight weight. Three types of micropore optics are proposed and being developed.The first type is silicon pore optics (SPO) (Bavdaz et al. 2004(Bavdaz et al. , 2010 which is composed of flat silicon wafers with groove structures as mirrors. The wafers are stacked and elastically bent into a conical shape. This type is being developed aiming at an angular resolution of ∼10 arcsec for the future gigantic X-ray astronomy satellite Athena. 1 1 http://www.the-athena-x-ray-observatory.eu.Abstract A light-weight Wolter type-I telescope for future space X-ray observations is prototyped by using micromachining technologies. Curvilinear micro pores with a width of 20 µ m are fabricated with deep reactive ion etching. Sidewalls of the pores are smoothed with high temperature annealing. Then, two wafers are deformed to different curvature radii, 1000 and 333 mm. The two wafers are aligned using parallel X-ray beams which are dominated by Al-K α line at 1.49 keV. High angular and positional accuracies of the order of arcsec and µm are achieved using movable stages. The first clear X-ray focusing is confirmed. Its angular resolution is 4.1 arcmin in full width half maximum while it is at least 92 arcmin in half power width. The effective area is 19.0 mm 2 which is ∼5 times smaller than a model calculation. We discuss causes of the degraded angular resolution and effective area and also future improvements.

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Ray-tracing simulations for the ultra-lightweight X-ray optics toward a future jupiter exploration mission

Cited by 12 publications

References 18 publications

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Multiplexing lobster-eye optics: a concept for wide-field x-ray monitoring

First X-ray imaging with a micromachined Wolter type-I telescope

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