The acceleration of energetic particle fluxes in shock fronts in interplanetary space

1968 ◽  
Vol 46 (10) ◽  
pp. S844-S848 ◽  
Author(s):  
U. R. Rao ◽  
K. G. McCracken ◽  
R. P. Bukata
Keyword(s):  
Particle Acceleration ◽  
Interplanetary Space ◽  
Forbush Decrease ◽  
Wave Model ◽  
Interplanetary Shocks ◽  
Forbush Decreases ◽  
Anisotropic Character ◽  
Particle Fluxes ◽  
Shock Wave Model ◽  
Shock Fronts

On six occasions during 1966, enhanced fluxes of > 7.5-MeV energetic particles have been observed coincident with the onset of a Forbush decrease which was initiated by a solar flare. The anisotropic character of the particle fluxes indicates that the particles were not trapped and that particle acceleration was occurring in the region associated with the onset of the Forbush decreases. Subsequent to the onset of the Forbush decreases, bidirectional anisotropies of 7.5–45 MeV-protons were observed. It will be shown that these observations provide strong evidence for the shock-wave model for the Forbush decrease. It is suggested that particle acceleration in interplanetary shocks is a commonly occurring phenomenon, and, in particular, it is suggested that recurrent ≈1-MeV proton events are due to particle acceleration in corotating shock fronts.

A new model describing Forbush Decreases at Mars: combining the heliospheric modulation and the atmospheric influence

2020 ◽  
Author(s):  
Jingnan Guo ◽  
Robert Wimmer-Schweingruber ◽  
Mateja Dumbovic ◽  
Bernd Heber ◽  
Yuming Wang
Keyword(s):  
Interplanetary Space ◽  
Atmospheric Transport ◽  
Forbush Decrease ◽  
Martian Atmosphere ◽  
Galactic Cosmic Rays ◽  
Interplanetary Coronal Mass Ejections ◽  
Forbush Decreases ◽  
Mars Atmosphere ◽  
Interaction Regions ◽  
Energy Dependent

<p>Forbush decreases are depressions in the galactic cosmic rays (GCRs) which are mostly caused by the modulations of interplanetary coronal mass ejections (ICMEs) and also sometimes by stream/corotating interaction regions (SIRs/CIRs). Forbush decreases have been studied extensively using neutron monitors at Earth and have been recently, for the first time, measured on the surface of another planet - Mars by the Radiation Assessment Detector (RAD), on board Mars Science Laboratory’s (MSL) rover Curiosity. The modulation of the GCR particles by heliospheric transients in space is energy-dependent and afterwards these particles are also interacting with the Martian atmosphere with the interaction process depending on the particle type and energy. In order to study the space weather environment near Mars using the ground-measured Forbush decreases, it is important to understand and quantify the energy-dependent modulation of the GCR particles by not only the pass-by heliospheric disturbances but also the Martian atmosphere. In this study, we develop a model which combines the heliospheric modulation of GCRs and the atmospheric modification of such modulated GCR spectra to quantify the amplitudes of the Forbush decreases at Mars: both on ground and in the interplanetary space near Mars during the pass-by of an ICME/SIR. The modeled results are in good agreement when compared to studies of Forbush decreases caused by ICMEs/SIRs measured by MSL on the surface of Mars and by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft in orbit.  This supports the validity of both the Forbush decrease description and the Martian atmospheric transport models.  Our model can be potentially used to understand the property of ICMEs and SIRs passing Mars.</p>

A comparison of the characteristics of corotating and flare-initiated Forbush decreases

1968 ◽  
Vol 46 (10) ◽  
pp. S994-S998 ◽  
Author(s):  
R. P. Bukata ◽  
K. G. McCracken ◽  
U. R. Rao
Keyword(s):  
Blast Wave ◽  
Time Scale ◽  
Forbush Decrease ◽  
Time Profile ◽  
Blast Waves ◽  
Time Structure ◽  
Deep Space ◽  
Forbush Decreases ◽  
Similarities And Differences ◽  
Shock Fronts

Data acquired by the deep space probes Pioneer VI and Pioneer VII which differ by [Formula: see text] in heliographic longitude are presented to illustrate the basic similarities and differences between the classes of Forbush decrease resulting from corotating shock fronts and radially propagating blast waves. An example is presented to establish directly the existence of the corotating Forbush decrease, and from the intensity–time profile of the event it is concluded that the detailed time structure of the Forbush decrease is invariant over a time scale of about 4 days. An example of the Forbush decrease resulting from a solar-induced blast wave is also presented wherein an azimuthal gradient of about a factor of 4 per 60° of azimuth is observed.

Corotating Forbush Decreases

1968 ◽  
Vol 1 (4) ◽  
pp. 145-146 ◽  
Author(s):  
K. G. McCracken ◽  
I. Palmer
Keyword(s):  
Interplanetary Space ◽  
Forbush Decrease ◽  
Forbush Decreases ◽  
Particle Event

A natural introduction to this topic is a brief discussion of two phenomena observable in interplanetary space near Earth—the energetic storm particle event (ESPE), and the recurrent Forbush decrease.

scholarly journals Shock Propagation and Associated Particle Acceleration in the Presence of Ambient Solar-Wind Turbulence

2021 ◽  
Vol 8 ◽  
Author(s):  
Fan Guo ◽  
Joe Giacalone ◽  
Lulu Zhao
Keyword(s):  
Solar Wind ◽  
Particle Acceleration ◽  
Energetic Particles ◽  
Low Energy ◽  
Shock Propagation ◽  
Interplanetary Shocks ◽  
Solar Wind Turbulence ◽  
Wind Turbulence ◽  
Shock Fronts ◽  
Ambient Solar Wind

The topic of this review paper is on the influence of solar wind turbulence on shock propagation and its consequence on the acceleration and transport of energetic particles at shocks. As the interplanetary shocks sweep through the turbulent solar wind, the shock surfaces fluctuate and ripple in a range of different scales. We discuss particle acceleration at rippled shocks in the presence of ambient solar-wind turbulence. This strongly affects particle acceleration and transport of energetic particles (both ions and electrons) at shock fronts. In particular, we point out that the effects of upstream turbulence is critical for understanding the variability of energetic particles at shocks. Moreover, the presence of pre-existing upstream turbulence significantly enhances the trapping near the shock of low-energy charged particles, including those near the thermal energy of the incident plasma, even when the shock propagates normal to the average magnetic field. Pre-existing turbulence, always present in space plasmas, provides a means for the efficient acceleration of low-energy particles and overcoming the well known injection problem at shocks.

Utilizing galactic cosmic rays as signatures of coronal mass ejections

2021 ◽  
Author(s):  
Mateja Dumbovic
Keyword(s):  
Coronal Mass Ejections ◽  
Interplanetary Space ◽  
Flux Rope ◽  
Forbush Decrease ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Forbush Decreases ◽  
Magnetic Structures ◽  
Different Types ◽  
Galactic Cosmic Ray

<p>Coronal mass ejections (CMEs) are the most violent eruptions in the solar system. They are one of the main drivers of the heliospheric variability and cause various interplanetary as well as planetary disturbances. One of their very common in-situ signatures are short-term reductions in the galactic cosmic ray (GCR) flux (i.e. Forbush decreases), which are measured by ground-based instruments at Earth and Mars, as well as various spacecraft throughout the heliosphere (most recently by Solar Orbiter). In general, interplanetary magnetic structures interact with GCRs producing depressions in the GCR flux. Therefore, different types of interplanetary magnetic structures cause different types of GCR depressions, allowing us to distinguish between them. In the interplanetary space the CME typically consists of two structures: the presumably closed flux rope and the shock/sheath which is formed ahead of the flux rope as it propagates and expands in the interplanetary space. Interaction of GCRs with these two structures is modelled separately, where the flux-rope related Forbush decrease can be modelled assuming that the GCRs diffuse slowly into the expanding flux rope, which is initially empty at its center (ForbMod model). The resulting Forbush decrease at a given time, i.e. heliospheric distance, reflects the evolutionary properties of CMEs. However, ForbMod is not yet able to take into account complex, non-self-similar evolution of the flux rope. Nevertheless, Forbush decreases can undoubtedly give us information on the CMEs in the heliosphere, especially where other measurements are lacking, and with further development, Forbush decrease reverse modelling could provide insight into the CME evolution.</p>

A shock wave model of unstable rocket combustors

AIAA Journal ◽  
1964 ◽  
Vol 2 (7) ◽  
pp. 1285-1296 ◽  
Author(s):  
L. CROCCO ◽  
W. A. SIRIGNANO
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Shock Wave Model

Acoustic energy radiated by nonlinear spherical oscillations of strongly driven bubbles

2010 ◽  
Vol 466 (2118) ◽  
pp. 1829-1847 ◽  
Author(s):  
Joachim Holzfuss
Keyword(s):  
Wave Model ◽  
High Amplitude ◽  
Compressible Liquid ◽  
Acoustic Energy ◽  
Compressible Medium ◽  
Relevant Parameter ◽  
Wafer Cleaning ◽  
Viscous Compressible Liquid ◽  
Shock Wave Model ◽  
Polytropic Exponent

Based on the theory of F. Gilmore ( Gilmore 1952 The growth or collapse of a spherical bubble in a viscous compressible liquid ) for radial oscillations of a bubble in a compressible medium, the sound emission of bubbles in water driven by high-amplitude ultrasound is calculated. The model is augmented to include expressions for a variable polytropic exponent, hardcore and water vapour. Radiated acoustic energies are calculated within a quasi-acoustic approximation and also a shock wave model. Isoenergy lines are shown for driving frequencies of 23.5 kHz and 1 MHz. Together with calculations of stability against surface wave oscillations leading to fragmentation, the physically relevant parameter space for the bubble radii is found. Its upper limit is around 6 μm for the lower frequency driving and 1–3 μm for the higher. The radiated acoustic energy of a single bubble driven in the kilohertz range is calculated to be of the order of 100 nJ per driving period; a bubble driven in the megahertz range reaches two orders of magnitude less. The results for the first have applications in sonoluminescence research. Megahertz frequencies are widely used in wafer cleaning, where radiated sound may be implicated as responsible for the damage of nanometre-sized structures.

scholarly journals Shock-wave model of the earthquake and Poincaré quantum theorem give an insight into the aftershock physics.

2018 ◽  
Vol 62 ◽  
pp. 03006
Author(s):  
Vladimir Kuznetsov
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Particle Systems ◽  
Many Body ◽  
Initial State ◽  
Recurrence Theorem ◽  
Shock Wave Model ◽  
Quantum Phenomena ◽  
First Time ◽  
Insight Into

A fundamentally new model of aftershocks evident from the shock-wave model of the earthquake and Poincaré Recurrence Theorem [H. Poincare, Acta Mathematica 13, 1 (1890)] is proposed here. The authors (Recurrences in an isolated quantum many-body system, Science 2018) argue that the theorem should be formulated as “Complex systems return almost exactly into their initial state”. For the first time, this recurrence theorem has been demonstrated with complex quantum multi-particle systems. Our shock-wave model of an earthquake proceeds from the quantum entanglement of protons in hydrogen bonds of lithosphere material. Clearly aftershocks are quantum phenomena which mechanism follows the recurrence theorem.

A periodic shock wave model for Mira variable atmospheres

1985 ◽  
Vol 299 ◽  
pp. 167 ◽  
Author(s):  
E. Bertschinger ◽  
R. A. Chevalier
Keyword(s):  
Shock Wave ◽  
Wave Model ◽  
Mira Variable ◽  
Periodic Shock ◽  
Shock Wave Model ◽  
Periodic Shock Wave
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