Criteria for ion acceleration in laboratory magnetized quasi-perpendicular collisionless shocks: when are 2D simulations enough?

Abstract

The study of collisionless shocks and their role in cosmic ray acceleration has gained importance through observations and simulations, driving interest in reproducing these conditions in laboratory experiments using high-power lasers. In this work, we examine the role of three-dimensional (3D) effects in ion acceleration in quasi-perpendicular shocks under laboratory-relevant conditions. Using hybrid particle-in-cell simulations (kinetic ions and fluid electrons), we explore how the Alfvénic and sonic Mach numbers, along with plasma beta, influence ion energization, unlocked only in 3D, and establish scaling criteria for when conducting 3D simulations is necessary. Our results show that efficient ion acceleration requires Alfvénic Mach numbers $\ge 25$ and sonic Mach numbers $\ge 13$, with plasma-$\beta \le 5$. We theoretically found that, while 2D simulations suffice for current laboratory-accessible shock conditions, 3D effects become crucial for shock velocities exceeding 1000 km/s and experiments sustaining the shock for at least 10 ns. We surveyed previous laboratory experiments on collisionless shocks and found that 3D effects are unimportant under those conditions, implying that 1D and 2D simulations should be enough to model the accelerated ion spectra. However, we do find that the same experiments are realistically close to accessing the regime relevant to 3D effects, an exciting prospect for future laboratory efforts. We propose modifications to past experimental configurations to optimize and control 3D effects on ion acceleration. These proposed experiments could be used to benchmark plasma astrophysics kinetic codes and/or employed as controllable sources of energetic particles.

15 pages, 6 figures. Few comments and clarifications added, results unchanged. Matches version published by PoP

References in corpus (24)

• Particle Acceleration on Megaparsec Scales in a Merging Galaxy Cluster
• Circumstellar Emission from Type Ib and Ic Supernovae
• First detection of VHE gamma-rays from SN 1006 by H.E.S.S
• Simulations and Theory of Ion Injection at Non-relativistic Collisionless Shocks
• Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. I. Particle Energy Spectra and Acceleration Mechanism
• Simulations of Ion Acceleration at Non-relativistic Shocks. III. Particle Diffusion
• Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. II. Firehose-Mediated Fermi Acceleration and its Dependence on Pre-Shock Conditions
• Electron Shock Surfing Acceleration in Multidimensions: Two-dimensional Particle-In-Cell Simulation of Collisionless Perpendicular Shock
• Electron Surfing and Drift Accelerations in a Weibel-dominated High-Mach-number Shock
• Relativistic electrons produced by foreshock disturbances
• Nonrelativistic collisionless shocks in weakly magnetized electron--ion plasmas: two-dimensional particle-in-cell simulation of perpendicular shock
• A database of MMS bow shock crossings compiled using machine learning
• Electron Preacceleration in Weak Quasi-perpendicular Shocks in High-beta Intracluster Medium
• Magnetic field amplification by the Weibel instability at planetary and astrophysical high-Mach-number shocks
• dHybridR: a Hybrid--Particle-in-Cell Code Including Relativistic Ion Dynamics
• Kinetic simulations of nonrelativistic perpendicular shocks of young supernova remnants. I. Electron shock-surfing acceleration
• The supernova remnant SN 1006 as a Galactic particle accelerator
• Non-thermal particle acceleration at highly oblique non-relativistic shocks
• High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest
• Cosmic Ray Acceleration and Nonthermal Radiation at Accretion Shocks in the Outer Regions of Galaxy Clusters
• Electron Preacceleration at Weak Quasi-perpendicular Intracluster Shocks: Effects of Preexisting Nonthermal Electrons
• Pre-acceleration in the Electron Foreshock II: Oblique Whistler Waves
• Enhanced Magnetic Field Amplification by Ion-Beam Weibel Instability in Weakly Magnetized Astrophysical Shocks
• Mach Number Dependence of Ion-scale Kinetic Instability at Collisionless Perpendicular Shock: Condition for Weibel-dominated Shock

Cited by in corpus (2)

• Acceleration of Heavy Ions at Non-Relativistic Collisionless Shocks
• Ion Weibel Instability in the hybrid framework: the optimal resolution