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Current sheets (CSs) are the main region where magnetic reconnections can convert magnetic energy into plasma thermal and kinetic energies. We have studied a CS in the streamer occurred on 3 January 2003 by combining the White-Light (WL) images observed by the Large Angle and Spectrometric Coronagraph (LASCO) and the EUV spectra detected by the Ultraviolet Coronagraph Spectrometer (UVCS). LASCO C2 WL data show that the speed of a blob in the CS increased from 60 km · s − 1 to 340 km · s − 1 with an acceleration of 60 m · s − 2 in its Field-of-View (FOV). By assuming the Light-of-Sight (LOS) depth of 0.3 – 1.5 R ⊙ , the average electron number density of the CS is (1.52 – 7.60) × 10 7 cm − 3 at the height of the UVCS slit. We investigate intensity distributions of the [Fe xviii ] 974 A and Ly α lines along the UVCS slit. It is shown that the intensity of the [Fe xviii ] line at the CS is significantly higher than those of the surroundings, and the deduced electron temperature range of the CS is (2.94 – 4.04) × 10 6 K during the studied period. However, the intensity of the Ly α line at the CS does not change much when compared with those of the surroundings, and within the CS the intensity on both sides are slightly higher than that in the center. It is possible that the plasma move faster in the center resulting in stronger Doppler dimming effect. Using the observed intensity ratio of the Ly α and [Fe xviii ] lines provided by the UVCS and the calculated electron temperature as constraints, we find that the theoretically calculated emissivity ratio of the Ly α and [Fe xviii ] lines is close to their observed intensity ratio when the plasma speed range is 237 – 254 km · s − 1 at the position of the CS. The collisional component of the Ly α line is about 42 % − 57 % of the radiative component in the CS within the speed range above. The streamer CS we studied has a higher plasma temperature and a faster blob speed than typical values in normal situations. The possible reason is that these two CMEs at the southern side enhanced the magnetic reconnection process in the CS, and more magnetic energy is released to heat and accelerate plasma. Our results on the CS can be regarded as pre-studies of the data analyses for the future mission of the Advanced Space-based Solar Observatory (ASO-S).

The absorption coefficient of dusty plasma is deduced on the basis of considering the influence of dust particles electric potential, and its absorption characteristic in the near infrared region is discussed. The involved results manifest that the absorption coefficient of dusty plasma with the dust particles potential is considered is obviously bigger than that of not considered in the given temperature, pressure and frequency ranges, which proves the influence of dust particles potential can not be omitted. Besides, the results also indicate that the maximal absorption ability of the dusty plasma does not occur where the maximal electron number density (plasma resonance frequency) appears. Consequently, two conditions, which determine where the maximal absorption appears, are presented by a series of theoretical deduction.

By using the coupled cluster method and the numerical density matrix renormalization group method, we investigate the properties of the quantum plateau state in an alternating Heisenberg spin chain. In the absence of a magnetic field, the results obtained from the coupled cluster method and density matrix renormalization group method both show that the ground state of the alternating chain is a gapped dimerized state when the parameter α exceeds a critical point αc. The value of the critical points can be determined precisely by a detailed investigation of the behavior of the spin gap. The system therefore possesses an m = 0 plateau state in the presence of a magnetic field when α > αc. In addition to the m = 0 plateau state, the results of density matrix renormalization group indicate that there is an m = 1/4 plateau state that occurs between two critical fields in the alternating chain if α > 1. The mechanism for the m = 1/4 plateau state and the critical behavior of the magnetization as one approaches this plateau state are also discussed.

By using the method of exact diagonalization, the properties of the spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain are investigated. The spin-spin correlation, the sublattice magnetizations, the spin excitation spectrum and the magnetization curve of the model are calculated and compared with the corresponding properties of the mixed spin chain. The results show that the behaviors of the alternating Heisenberg chain are equivalent to those of the mixed spin chain when the ratio of antiferromagnetic to ferromagnetic coupling strength is very small. So, the properties of the mixed spin chain can be analyzed by using the spin-1/2 ferromagnetic-antiferromagnetic-antiferromagnetic alternating Heisenberg chain.

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