702 research outputs found
Electron acceleration at a low-Mach-number perpendicular collisionless shock
A full particle simulation study is carried out on the electron acceleration
at a collisionless, relatively low Alfven Mach number (M_A=5), perpendicular
shock. Recent self-consistent hybrid shock simulations have demonstrated that
the shock front of perpendicular shocks has a dynamic rippled character along
the shock surface of low-Mach-number perpendicular shocks. In this paper, the
effect of the rippling of perpendicular shocks on the electron acceleration is
examined by means of large-scale (ion-scale) two-dimensional full particle
simulations. It has been shown that a large-amplitude electric field is excited
at the shock front in association with the ion-scale rippling, and that
reflected ions are accelerated upstream at a localized region where the
shock-normal electric field of the rippled structure is polarized upstream. The
current-driven instability caused by the highly-accelerated reflected ions has
a high growth rate to large-amplitude electrostatic waves. Energetic electrons
are then generated by the large-amplitude electrostatic waves via electron
surfing acceleration at the leading edge of the shock transition region. The
present result suggests that the electron surfing acceleration is also a common
feature at low-Mach-number perpendicular collisionless shocks.Comment: 7 pages, 4 figures, ApJ in press. The paper with full resolution
images is http://theo.phys.sci.hiroshima-u.ac.jp/~ryo/papers/shock_lowM.pd
A Simple Expression for the Trajectories under the Effects of Space Charge in a Quadrupole Lens
A simple method for the numerical analysis of the second order non-linear coupled differential equations, which represent the trajectories in a quadrupole lens under the effects of space charge, is shown. The resultant equations of the trajectories are expressed by the usual matrix form. The numerical results are shown for a few typical cases
Truth-table reductions and minimum sizes of forcing conditions : preliminary draft(Proof Theory of Arithmetic)
Advances and technical challenges in development of CMC
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The Effect of Alternating Current Iontophoresis on Rats with the Chronic Constriction Injury to the Infraorbital Nerve
This study aimed to examine the effect of AC iontophoresis on rats with the chronic constriction injury (CCI) to the infraorbital nerve by animal experiments. CCI model rats were divided into four groups, namely, rats that received general anesthesia for 60 min except AC IOP (CCI: n = 5), AC IOP with 0.9% physiological saline for 60 min (CCI + saline AC IOP: n = 5), AC IOP with 4% lidocaine hydrochloride for 60 min (CCI + lidocaine AC IOP: n = 5), and attachment of two electrodes soaked with 4% lidocaine hydrochloride to the facial skin for 60 min (CCI + attach lidocaine: n = 5). In the CCI + lidocaine AC IOP group, an elevated withdrawal threshold was observed after AC IOP, and the duration of efficacy was longer compared with that in the CCI + saline AC IOP and CCI + attached lidocaine groups. A significant decrease in the number of Fos-like immunoreactive (LI) cells was observed in the CCI + lidocaine AC IOP group compared with that in the CCI group. These findings suggest that the effect of CCI + lidocaine AC IOP group may be caused by active permeation of lidocaine into the facial skin and electrical stimulation of the trigeminal nucleus
Two-dimensional full particle simulation of a perpendicular collisionless shock with a shock-rest-frame model
A two-dimensional (2D) shock-rest-frame model for particle simulations is
developed. Then full kinetic dynamics of a perpendicular collisionless shock is
examined by means of a 2D full particle simulation. We found that in the 2D
simulation there are fewer nonthermal electrons due to surfing acceleration
which was seen in the previous 1D simulations of a high Mach number
perpendicular shock in a low-beta and weakly magnetized plasma. This is because
the particle motion along the ambient magnetic field disturbs the formation of
coherent electrostatic solitary structures which is necessary for electron
surfing acceleration.Comment: 4 pages, 4 figures, ApJL in press. The paper with full resolution
images is
http://theo.phys.sci.hiroshima-u.ac.jp/~ryo/papers/shock_rest_2D.pd
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