Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere

Stanislav Boldyrev; Daniel Humphrey; Vadim Roytershteyn

Home/Archive/arXiv

arXiv · 2610.40925

Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere

Stanislav Boldyrev·Daniel Humphrey·Vadim Roytershteyn

View original source ↗Read source document ↗Export metadata ↓

Abstract

Suprathermal ion tails throughout the heliosphere follow a ``common spectrum,'' $f(v)\propto v^{-5}$. We show that scale-by-scale equipartition between strong Alfvénic turbulence and the ions it accelerates predicts both this exponent and the absolute amplitude, $F(v)=B^2/(16π^3 m_i v^5)$, with no free parameters. The prediction agrees within a factor of a few with ACE and Voyager 1 spectra across three decades in magnetic energy. We argue that this saturated level is reached where strong turbulence accelerates particles locally; quiet-time tails lie well below it, consistent with nonlocal acceleration.

Explore related subjects

physics.plasm-ph astro-ph.GA physics.space-ph

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Stanislav Boldyrev, Daniel Humphrey, Vadim Roytershteyn. 2026-10-29. Equipartition between Alfvénic turbulence and energetic ions as the origin of the -5 common spectrum in the heliosphere. https://arxiv.org/abs/2610.40925

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

On the stability and emittance growth of different particle phase-space distributions in a long magnetic quadrupole channel

The behavior of K-V, waterbag, parabolic, conical and Gaussian distributions in periodic quadrupole channels is studied by particle simulations. In the parameter range studied, the response associated with the K-V instabilities becomes progressively less pronounced toward the Gaussian distribution. For the third-order instability studied here, the emittance growth factor of an initially Gaussian beam after a large number of periods is considerably lower than that of an equivalent K-V distribution.\newline\indent In addition, the non-K-V distributions exhibit a rapid initial emittance growth within approximately one period of the channel, which becomes very significant at high beam intensities. This growth is attributed to the homogenization of the space-charge density, resulting in a conversion of electric-field energy into transverse kinetic and potential energy. Two simple analytical formulae based on different energy-partition assumptions are derived as estimates for this effect and are compared with the results obtained from particle simulations. They are not rigorous lower and upper bounds for arbitrary beam evolution. \\[6pt] Revised version of: Particle Accelerators {\bf 15}, 47--65 (1984)}

physics.plasm-ph↗

arXiv2026

Plasma waveguides for high-intensity laser pulses

Fundamental to many applications of laser pulses in science and technology is an extended interaction length with matter that significantly exceeds the distance over which the pulse would normally diffract and transversely spread. At low intensity, the interaction could simply be the linear refraction provided by a glass optical fiber to keep the pulse from spreading. At higher pulse intensities, however, the goal extends beyond diffraction-free pulse transport: an extended interaction length of high intensity light can give rise to bright secondary sources of photons and, at relativistic intensities, beams of high energy charged particles. Since these applications require laser intensities well above the threshold for ionization of atoms, new methods for overcoming pulse diffraction in a plasma have been developed. Chief among them are plasma waveguides -- optical fibers composed of plasma, with characteristic mode structure. This article reviews the methods and theory of plasma waveguides, highlighting the recent development of meter-scale plasma waveguides that have been instrumental to the laser acceleration of high-charge electron beams to energies ~10 GeV

physics.plasm-ph↗

arXiv2026

Polarized quantum effects in countable signals from intense laser - electron beam interactions

We investigate the feasibility of precision counting experiments in laser-electron-beam collisions for testing strong-field quantum electrodynamics (QED), with particular emphasis on spin-dependent effects. To resolve such rare signals, we develop a high-precision Monte Carlo model combining spin- and polarization-resolved QED rates with weighted photon packets, hierarchical-mesh sampling, and adaptive time stepping. The model is quantitatively benchmarked against the high-energy edge of the photon spectrum and the positron yield in the SLAC E-144 experiment. The high-energy photon spectrum and total positron yield are only weakly affected by spin-dependent corrections, even at higher laser intensities. In contrast, we find that spin asymmetry in photon emission significantly affects the polarization of photons in the high-energy tail, while spin asymmetry in pair production manifests itself as a spin-dependent imbalance in the large-angle positron population. These microscopic spin asymmetries give rise to experimentally countable signals through their correlations with the oscillating laser field. Our predictions could be tested using moderate-energy electron beams and optical lasers with intensities of approximately 10^22 W/cm2, as envisaged in future ELI-NP experiments.

physics.plasm-ph↗