磁場・レーザー融合実験によるマルチスケール
実験室宇宙物理の開拓

境 健太郎
核融合科学研究所
プラズマ量子プロセスユニット
核融合科学研究所 ユニット成果報告会
2024年5月8日

Kentaro Sakai (境 健太郎)
• NIFS since Aug. 2023
• Assistant professor• Ph.D. in Engineering inJuly 2023
• Supervised by Yasuhiro
Kuramitsu• Research interest:
laboratory astrophysics
with high-power lasers

Summary• Multiscale laboratory astrophysics• From electron to MHD scales• Fusion of magnetic device with laser• Large spatiotemporal scales for MHD• Electron-scale resolution and supersonic flow

• One of the target: experimental investigations
on the existence of intermediate shocks• Many other potential applications•••••

JSPS KAKENHI (24K17029)
NIFS Collaboration Research Program (NIFS24KIIQ010)
NINS program of Promoting Research by Networking
among Institutions (01422301, 102050NINS000312)
NINS OPEN MIX LAB Program (OML022405)
Collaborative research program, i-SPES, Kyushu University

Laboratory astrophysics• Reproduce space/astrophysical phenomena• Energetic laser as a driver of supersonic flow
• Shocks and reconnections
Earth’s magnetosphere< 10 km ~ rgi

S. A. Fuselier+, Space Sci. Rev. (2011)

Solar flare< 0.0001 pixel ~ rgiA. O. Benz, Living Rev. Sol. Phys. (2017)• Microscopic electron-scale
governs the onset of magnetic
reconnection• Local observations with MMS
revealed electron dynamics forthe first time
• No global observations

Magnetospheric Multiscale (MMS)

J.L. Burch et al., Science (2016)

NASA/Goddard

Laboratory astrophysics• Reproduce space/astrophysical phenomena• Energetic laser as a driver of supersonic flow
• Shocks and reconnections
Earth’s magnetosphere< 10 km ~ rgi

Solar flarergi ∝ v / B

S. A. Fuselier+, Space Sci. Rev. (2011)< 0.0001 pixel ~ rgi

A. O. Benz, Living Rev. Sol. Phys. (2017)

Laboratory astrophysics• Reproduce space/astrophysical phenomena• Energetic laser as a driver of supersonic flow
• Shocks and reconnections
K. Shibata et al., Astrophys. J. (1995)

High-power
laser

Expanding plasmaControlled v

Solar flare

TargetMagnetControlled B

X point

Plasmoid

A. O. Benz, Living Rev. Sol. Phys. (2017)

Laboratory astrophysics• Reproduce space/astrophysical phenomena• Energetic laser as a driver of supersonic flow
• Shocks and reconnections
Y. Kuramitsu et al., Nat. Commun. (2018)

Less than ion gyroradius

Laboratory experimentControlled manner
Global structure

Solar flare

A. O. Benz, Living Rev. Sol. Phys. (2017)

Laboratory astrophysics• Reproduce space/astrophysical phenomena• Energetic laser as a driver of supersonic flow
• Shocks and reconnections
Y. Kuramitsu et al., Nat. Commun. (2018)

Less than ion gyroradius

Solar flare

Local quantities
A. O. Benz, Living Rev. Sol. Phys. (2017)
K. Sakai et al., Sci. Rep. (2022)

Next step of lab astrophysics• Multiscale lab astrophysics – microphysics
governing macroscopic phenomena• Difficult to observe simultaneously inspace/astrophysical plasmas

S.A. Fuselier and W.S. Lewis,Space Sci. Rev. (2011)

Y. Kuramitsu et al., Nat. Commun. (2018)

Less than ion gyroradius

How can theelectron-scalestructuresconnect to the
MHD structures?
K. Sakai et al., Sci. Rep. (2022)

A. O. Benz, Living Rev. Sol. Phys. (2017)

Next step of lab astrophysics• Multiscale lab astrophysics – microphysics
governing macroscopic phenomena• Connecting multiscale is also challenging in
numerical simulations using the current computerpower

How can theelectron-scalestructures
Electron-scale reconnection simulation (PIC)
connect to the
P. S. Pyakurel+ PoP (2019)
MHD structures?

MHD-scale flare simulation
S. Inoue and Y. Bamba, ApJ (2021)

Limits of laser experiment• Fast plasma flow enlarges gyroradii• Limit of B field strength (technical problem)• Lack of large spatial/temporal scales for MHD• Laser + magnetic device for multiscale experimentElectron scale

Ion kinetic scale

MHD scale

System size
normalized toion gyroradius

Research targets• Multiscale structure of magnetic reconnection• Existence of intermediate shock• Multidimensional structure of slow bow shock• Reforming/rippling collisionless shock• Pickup ions in collisionless shock
Many potential research targets using
magnetic device + laser experimentSummary• Multiscale laboratory astrophysics• From electron to MHD scales• Fusion of magnetic device with laser• Large spatiotemporal scales for MHD• Electron-scale resolution and supersonic flow

• One of the target: experimental investigations
on the existence of intermediate shocks• Many other potential applications•••••JSPS KAKENHI (24K17029)
NIFS Collaboration Research Program (NIFS24KIIQ010)
NINS program of Promoting Research by Networking
among Institutions (01422301, 102050NINS000312)
NINS OPEN MIX LAB Program (OML022405)
Collaborative research program, i-SPES, Kyushu University