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O3-NaNi

A real underground road tunnel is selected for analyzing the changing law of the supplementary air volume at both ends of tunnel by a multi-scale coupling method. The partial transverse ventilation system has been installed in this tunnel. For a long tunnel, one-dimensional (1D) model or three-dimensional (3D) model has its own limitation in the numerical simulation. A multi-scale model which couples 1D and 3D models has been adopted. The computed results by multi-scale couple model are compared with those by 3D model in which open boundary condition are set at two portals. The results indicated that the air supplement volume at two portals of the tunnel by multi-scale coupling method is less than the recommended value of smoke exhaust by engineering standard. In addition, the multi-scale coupling simulation has obvious advantages in evaluating the functional of partial transverse ventilation systems. A formula has been put forward for the design of smoke exhaust volume. Compared with the recommended value of the smoke production in the engineering specification, this smoke calculation formula is more operable and more convenient to estimate the capacity of the exhaust system in design.

The gyroresonant interaction between electromagnetic ion cyclotron (EMIC) waves and energetic particles was studied in a multi-ion (H+, He+, and O+) plasma. The minimum resonant energy Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα were calculated at the center location of the symmetrical ring current: r ≈ 3.5RE with RE the Earth's radius. Emin is found to decrease rapidly from 10 MeV to a few keV with the increase in Ω in three bands: H+-band, He+-band and O+-band. Moreover, EMIC waves have substantial potential to scatter energetic (~100 keV) ions (mainly H+ and He+) into the loss cone and yield precipitation loss, suggesting that wave-particle interactions contribute to ring current decay.

We study the characteristics of cyclotron wave–particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy -Emin, resonant wave frequency ω, and pitch angle diffusion coefficient Dαα for interactions between R-mode/L-mode and electrons/protons are presented. It is found that -Bmin decreases with ω for R-mode/electron, L-modefproton and L-mode/electron interactions, but increase with ω for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10keV~100keV) electrons and protons and cause precipitation loss at L = 4, indicating that perhaps wave–particle interaction is a serious candidate for the ring current decay.

We construct the bounce-averaged diffusion coefficients and study the bounce-averaged acceleration for energetic electrons in gyroresonance with whistler mode chorus. Numerical calculations have been performed for a band of chorus frequency distributed over a standard Gaussian spectrum specifically in the region near L = 4.5, where peaks of the electron phase space density occur. It is found that whistler mode chorus can efficiently accelerate electrons and can increase the phase space density at energies of about 1 MeV by more than one order of magnitude about one day, in agreement with the satellite observations during the recovery phase of magnetic storms.

We present a study on the gyroresonant interaction between electromagnetic ion cyclotron waves and ring current particles in multi-ion (H+, He+, and O+) plasmas. We provide a first evaluation of the bounce-averaged pitch angle diffusion coefficient (Dαα) for three typical energies of 50, 100 and 150 keV at L ≈ 3.5, the heart of the symmetrical ring current. We show that in the H+-band and He+-band, (Dαα) can approach ~ 10−4 s−1 for ion H+, and ~ 5 × 10−5 s−1 for ion He+; meanwhile, in the O+-band, (Dαα) can reach ~ 10−5 s−1 for ions He+ and O+. The results above show that the EMIC wave can efficiently produce precipitation loss of energetic (~ 100 keV) ions (H+, He+ and even O+), and such a wave tends to be a serious candidate responsible for the ring current decay.