Confirmation on origin of primary electron in solid state cathodoluminescence

This paper utilizes the brightness-voltage waveform curve to investigate the primary electron in solid state cathodoluminescence. The results indicate that the primary electron is from the interface state of SiO2/MEH-PPV （Poly[2- methoxy-5-（2-ethylhexyloxy）-1,4-phenylenevinylene]） under the lower electric field which contributes to the 580-nm emission. With increasing the electric field, the 405-nm emission is obtained, and under this condition, the origin of the primary electron is mainly from tunneling.

Confinement characteristic of primary electrons with the variation of channel width in the discharge chamber of annular ion thruster

In this paper,the confinement characteristic of primary electrons in the non-axisymmetric discharge chamber of annular ion thruster is investigated by a three-dimensional(3 D)non-self-consistent particle tracking model with Monte Carlo Collision(MCC)method.The results show that:The density of primary electrons upstream of ion optics on cathode axis is about 5–50 times higher than that of the other side,which means that the density of primary electrons is obviously non-axisymmetric.The channel width has a significant effect on the average density and uniformity of primary electrons.The average density can be increased by nearly 1.5 times under the appropriate channel width,meanwhile,the variance of density distribution can be reduced by more than 2 times.This is because that increasing the channel width can improve the average confinement length of primary electrons greatly.Furthermore,there is an infection point in the increase of primary electron average confinement length with the channel width,which caused by the significant change of magnetic field structure.Under the case after the inflection point,primary electron mainly(more than 50%)moves to the channel center,which makes the average confinement length of primary electrons and their number in the discharge chamber increase largely.

Spatial dependent diffusion of cosmic rays and the excess of primary electrons derived from high precision measurements by AMS-02

The precise spectra of Cosmic Ray （CR） electrons and positrons have been published by the measurement of AMS-02. It is reasonable to regard the difference between the electron and positron spectra （△Ф=Фe- -Фe＋） as being dominated by primary electrons. The resulting electron spectrum shows no sign of spectral softening above 20 GeV, which is in contrast with the prediction of the standard model of CR propagation. In this work, we generalize the analytic one-dimensional two-halo model of diffusion to a three-dimensional realistic calculation by implementing spatial variant diffusion coefficients in the DRAGON package. As a result, we can reproduce the spectral hardening of protons observed by several experiments, and predict an excess of high energy primary electrons which agrees with the measurement reasonably well. Unlike the break spectrum obtained for protons, the model calculation predicts a smooth electron excess and thus slightly over-predicts the flux from tens of GeV to 100 GeV. To understand this issue, further experimental and theoretical studies are necessary.

Evaluation of Particle Properties of MgO/TiO2 Material by Monte Carlo Simulation Method

The simulation by the Monte Carlo method executed by the software PyPENELOPE proved effective to specify the particle propagation characteristics by calculating the absorption fractions, backscattering and transmission of electrons and secondary photons under the incidence of 0.5 to 20 KeV range of primary electrons. More than 99.9% of the primary electrons were transmitted in the 125 nm thick MgO/TiO2 material at 20 KeV. This occurred because several interactions took place in the transmitted primary irradiation such as characteristic, fluorescence, and bremsstrahlung produced when of the occupation of the KL3, KL2, KM3, and KM2 shell and sub-shell of titanium and magnesium which are the elements with a high atomic number in the material. The transmission particle characteristic of this material is therefore an indicator capable of improving the electrical performance and properties of the sensor.

THE ELECTRON SPIN RESONANCE STUDY ON PRIMARY PHOTOCHEMICAL REACTION OF HEMATOPORPHYRIN DERIVATIVE

The rate of oxygen consumption and the yield of free radical anion of hematoporphyrin derivative (HPD) in aqueous solutions of HPD and pyrocatechol were measured by the probe 2,2,6,6-tetramethyl4-piperidone-1-oxyl.It has been found that both singlet oxygen and free radical mechanisms exist simultaneously in primary photochemical reactions, and there is a competition between both mechanisms. When the oxygen concentration in solutions comes down to 12-14% of the stanting level, the predominant mechanism can be changed from the singlet oxygen to the free radical.Whether HPD exists in aggregation state is very important to photosensitization mechanisms.In the presence of the aggregation state of HPD, the predominant mechanism is the free radical,and photosensitization effects of HPD are all the better.