Potassium channels play an important role in repolarizing the nerve cell action potentials. There are many types of potassium channel proteins, and potassium channels allow potassium ions to specifically pass through the cell membrane, thereby maintaining the resting potential of nerve cells. In this paper, molecular dynamics simulation method is used to simulate the effects of 53.7 THz terahertz wave with different amplitudes on the secondary structure of KcsA potassium channel protein and the potassium ions rate. It is found in this study that under the action of the 53.7 THz terahertz wave, the number of alpha helices in KcsA potassium channel protein decreases, and the number of beta sheets and the number of coils increase. In addition, the 53.7 THz terahertz wave can accelerate potassium ions through the KcsA potassium channel. In this article, the effects of terahertz waves on potassium channel proteins are analyzed through the secondary structure of proteins, and a new perspective for the interaction between terahertz waves and biological functional molecules is presented as well.

The size of nerve cell is comparable to the wavelength of terahertz (THz) wave. In this work, a new concept of weak resonance effect of nerve cells is proposed. The permittivity of intracellular fluid is measured experimentally by using a THz-TDS system, and the relationship between the permittivity of nerve cells and the frequency is obtained by fitting the double Debye model. The propagation characteristics of THz waves in nerve cells are studied by finite difference time domain. The results show that when the dielectric constant of nerve cell is higher than that of the external medium, THz wave can be enhanced in the nerve cell. Meanwhile, as the dielectric constant of the external medium increases, the resonance will be close to the cell membrane. And it shows the focusing property of THz waves, as a convex lens does. The weak resonance effect is related to the dielectric constant of the background medium, and increases with the cell size and frequency increasing. These results provide a new model to explain the interaction between THz wave and nerve cells, contributing to the study of the transmission mechanism of THz wave in biological nervous system.

The physical properties and dynamics of molecules can be studied by the interaction between electromagnetic field and molecular system. The continuous development of terahertz technology provides a terahertz source capable of generating a sub-picosecond directional intense electric field. The generated intense-field terahertz wave has the same electric field intensity as the molecular local electric field environment, and on a sub-picosecond time scale of the directional electric field there can happen many ultrafast physical and chemical reactions. At present, the interaction between terahertz waves and molecules is limited mainly to the resonance interaction, that is, the molecules transition at different vibrational levels, caused through dipole interaction. In this work, based on the density functional theory calculation and the finite difference time domain solution method of Schrödinger equation, the intense non-resonance effect of intense terahertz wave electric field on hydrogen molecules is studied. The results show that under the action of intense terahertz wave sub-picosecond directional intense electric field, hydrogen molecule will produce an induced dipole moment. This dipole interacts with the external terahertz field, resulting in the fluctuation of proton probability density distribution and the change of vibration energy level population. Based on the non-resonant interaction between non-polar diatomic molecule hydrogen and intense terahertz wave, a unique way of producing the interaction between electromagnetic waves and molecules is displayed in this work, which is a method of studying the dynamics of non-polar molecules and molecules with weak polarity in intense terahertz field.

The plasma current (<i>I</i>_p<italic/>), magnetic field (<i>B</i>), and safety factor distribution (<i>q</i> profile) of the HL-2A tokamak device are crucial to monitoring the steady-state operational scenarios (in high confinement mode, H mode). Based on real experimental data and integrated modeling simulation method (OMFIT), the plasma parameters’ profiles such as magnetic field configuration and current density profiles in H mode were reconstructed. By building up an integrated simulation platform for dynamic equilibrium configuration, and combining the rapid workflow processing method and experimental data with integrated simulation models, the ion and electron temperature, density, and current density profiles were obtained. The integration simulation platform was established to reconstruct the internal magnetic surface configuration, the plasma boundary parameter distribution, the ion/electron temperature, current density, and the <i>q</i> profile. The Ohmic current, bootstrap current, and radio-frequency current profiles with its fractions were calculated. The width of the pedestal region was about 7.52 cm according to our simulation results. It was found that the pressure gradient changes its direction at radial coordinate <i>ρ</i>(<i>r/a</i>) = 0.1 and reaches its maximum value near <i>ρ</i> = 0.7, which may be the internal transport barrier (ITB) configuration caused by negative shear. The profile reconstruction and real-time monitoring of the physical parameters are conducive to evaluating the quality of H mode discharge experiment and can assist in the steady-state operation of advanced operating modes such as HL-2M high normalized beta (<i>β_n</i>) discharge.