Negative charge transfer from the ionosphere to the ground on the background of a magnetic storm

Во время магнитосферной бури 22.06.2015, сопровождаемой Форбуш – понижением, отдельные установки, регистрирующие космические лучи на уровне земли, зафиксировали положительное возмущение интенсивности частиц в период 19:00 –22:00 UT. В работе приводится регистрация указанного всплеска на территории Кавказских гор установкой «Ковёр» БНО ИЯИ РАН. Приводится экспериментальное свидетельство медленного спуска в этот период большого отрицательного заряда с ионосферы на землю. During a magnetic storm on June 22, 2015, was accompanied by a Forbush decrease, some detectors of cosmic rays on the ground level recorded a positive disturbance of the particle intensity in the period 19:00 – 22:00 UT. This paper presents the data of detecting this burst in the North Caucasus region by the Carpet air shower array of the Baksan Neutrino Observatory. Experimental evidence in favor of a slow transfer in this period of a large negative charge from the ionosphere to the ground is presented.

Dependence of fishbone cycle on energetic particle intensity in EAST low-magnetic-shear plasmas

The dependence of fishbone cycle on energetic particle intensity has been investigated in EAST low-magnetic-shear plasmas. It is observed that the fishbone mode growth rate, saturation amplitude as well as fishbone cycle frequency clearly increase with increasing neutral beam injection (NBI) power. Moreover, enhanced electron density and temperature perturbations as well as energetic particle loss were observed with greater injected NBI power. Simulation results using M3D-K code show that as the NBI power increases, the resonant frequency and the energy of the resonant particles become higher, and the saturation amplitude of the mode also changes, due to the non-perturbative energetic particle contribution. The relationship between the calculated energetic particle pressure ratio and fishbone cycle frequency is obtained as ${f_{\textrm{FC}}} = 2.2{(1000{\beta _{\textrm{ep,calc}}} - 0.1)^{5.9 \pm 0.5}}$ . Results consistent with the experimental observations have been achieved based on a predator–prey model.

General Spectrum Fitting for Energetic Particles

<p>We propose a general fitting formula of energy spectrum of suprathermal particles, J=AE<sup>-β1</sup>[1+(E/E<sub>0</sub>)<sup>α</sup>]<sup>(β1-β2)/α</sup>, where J is the particle flux (or intensity), E is the particle energy, A is the amplitude coefficient, E<sub>0</sub> represents the spectral break energy, α (>0) describes the sharpness of energy spectral break around E<sub>0</sub>, and the power-law index β<sub>1</sub> (β<sub>2</sub>) gives the spectral shape before (after) the break.  When α tends to infinity (zero), this spectral formula becomes a classical double-power-law (logarithmic-parabola) spectrum. When both β<sub>2</sub> and E<sub>0</sub> tend to infinity, this formula can be simplified to an Ellison-Ramaty-like equation. Under some other specific parameter conditions, this formula can be transformed to a Kappa or Maxwellian function. Considering  the uncertainties both in particle intensity and energy, we fit this general formula well to the representative energy spectra of various suprathermal particle phenomena including solar energetic particles (electrons, protons,  <sup>3</sup>He and heavier ions), shocked particles, anomalous cosmic rays, hard X-rays, solar wind suprathermal particles, etc. Therefore, this general spectrum fitting formula would help us to comparatively examine the energy spectrum of different suprathermal particle phenomena and understand their origin, acceleration and transportation.</p>

Interplanetary spread of solar energetic protons near a high-speed solar wind stream

Aims. We study how a fast solar wind stream embedded in a slow solar wind influences the spread of solar energetic protons in interplanetary space. In particular, we aim at understanding how the particle intensity and anisotropy vary along interplanetary magnetic field (IMF) lines that encounter changing solar wind conditions such as the shock waves bounding a corotating interaction region (CIR). Moreover, we study how the intensities and anisotropies vary as a function of the longitudinal and latitudinal coordinate, and how the width of the particle intensities evolves with the heliographic radial distance. Furthermore, we study how cross-field diffusion may alter these spatial profiles. Methods. To model the energetic protons, we used a recently developed particle transport code that computes particle distributions in the heliosphere by solving the focused transport equation (FTE) in a stochastic manner. The particles are propagated in a solar wind containing a CIR, which was generated by the heliospheric model, EUHFORIA. We study four cases in which we assume a delta injection of 4 MeV protons spread uniformly over different regions at the inner boundary of the model. These source regions have the same size and shape, yet are shifted in longitude from each other, and are therefore magnetically connected to different solar wind conditions. Results. The intensity and anisotropy profiles along selected IMF lines vary strongly according to the different solar wind conditions encountered along the field line. The IMF lines crossing the shocks bounding the CIR show the formation of accelerated particle populations, with the reverse shock wave being a more efficient accelerator than the forward shock wave. The longitudinal intensity profiles near the CIR are highly asymmetric in contrast to the profiles obtained in a nominal solar wind. For the injection regions that do not cross the transition zone between the fast and slow solar wind, we observe a steep intensity drop of several orders of magnitude near the stream interface (SI) inside the CIR. Moreover, we demonstrate that the longitudinal width of the particle intensity distribution can increase, decrease, or remain constant with heliographic radial distance, reflecting the underlying IMF structure. Finally, we show how the deflection of the IMF at the shock waves and the compression of the IMF in the CIR deforms the three-dimensional shape of the particle distribution in such a way that the original shape of the injection profile is lost.