同轴空心阴极氦等离子体的电子激发温度研究

利用同轴空心阴极放电装置,产生氦低温等离子体。通过对等离子体的发射光谱进行测量和计算,研究放电功率以及氦气压强对等离子体的电子激发温度的影响。结果表明:氦低温等离子体的发射光谱主要由连续谱和原子谱线构成,放电功率和压强对谱线的强度具有明显影响。压强的变化不仅影响电子从电场中获得的能量,还会影响电子与原子的碰撞频率,从而导致电子激发温度随着氦气压强的增大,出现先上升后下降的变化趋势。     

Differential and Integral Cross Sections for Electron Impact Excitation of Lithium

The differential and integral cross sections for electron impact excitation of lithium from the ground state 1s22s to excited states 1s22p, 1s23l （l=s, p, d） and 1s24l （l=s, p, d, f）at incident energies ranging from 5 eV to 25 eV are calculated by using a full relativistic distorted wave method. The target state wavefunctions are calculated by using the Grasp92 code. The continuum orbitals are computed in the distorted-wave approximation, in which the direct and exchange potentials among all the electrons are included. A part of the cross sections are compared with the available experimental data and with the previous theoretical values. It is found that, for the integral cross sections, the present calculations are in good agreement with the time-independent distorted wave method calculation, for differential cross sections, our results agree with the experimental data very well.     

Coupled-Channels Optical Calculation for Electron Scattering from Metastable Helium

Coupled-channels optical calculations for total and resonance excitation integral cross sections for electron scattering on the metastable level 2^1,3S of helium are presented. The results are in agreement with other theoretical and experimental data.     

α粒子激励下氦,氪的光谱

利用自制的单光子计数装置，测定了氦，氪在α粒子激励下的发射光谱，在３７０．０～７２０．０ｎｍ波长范围内，辨认出５条ＨｅＩ，１条ＫｒＩ和６条ＫｒⅡ的光谱线，并在α粒子激励下观察到氦的分子谱带，实验研究了谱线强度随气体压强的变化规律，对α粒子激励下氦，氪可能的激发机理进行了探讨。     

Quantum Gravity from the Point of View of Locally Covariant Quantum Field Theory

We construct perturbative quantum gravity in a generally covariant way. In particular our construction is background independent. It is based on the locally covariant approach to quantum field theory and the renormalized Batalin–Vilkovisky formalism. We do not touch the problem of nonrenormalizability and interpret the theory as an effective theory at large length scales.     

The Casimir Effect from the Point of View of Algebraic Quantum Field Theory

We consider a region of Minkowski spacetime bounded either by one or by two parallel, infinitely extended plates orthogonal to a spatial direction and a real Klein-Gordon field satisfying Dirichlet boundary conditions. We quantize these two systems within the algebraic approach to quantum field theory using the so-called functional formalism. As a first step we construct a suitable unital ?-algebra of observables whose generating functionals are characterized by a labelling space which is at the same time optimal and separating and fulfils the F-locality property. Subsequently we give a definition for these systems of Hadamard states and we investigate explicit examples. In the case of a single plate, it turns out that one can build algebraic states via a pull-back of those on the whole Minkowski spacetime, moreover inheriting from them the Hadamard property. When we consider instead two plates, algebraic states can be put in correspondence with those on flat spacetime via the so-called method of images, which we translate to the algebraic setting. For a massless scalar field we show that this procedure works perfectly for a large class of quasi-free states including the Poincaré vacuum and KMS states. Eventually Wick polynomials are introduced. Contrary to the Minkowski case, the extended algebras, built in globally hyperbolic subregions can be collected in a global counterpart only after a suitable deformation which is expressed locally in terms of a *-isomorphism. As a last step, we construct explicitly the two-point function and the regularized energy density, showing, moreover, that the outcome is consistent with the standard results of the Casimir effect.     

Spectroscopic Mapping of the Nonequilibrium between Electron and Excitation Temperatures in a 1 ATM Helium ARC

The thermostatic states of a 100 amp, 1.016 bar, free-burning helium short arc with a 10 mm electrode gap are mapped from spectroscopic measurements at eight cross sections. The theoretical model used is a multifluids model extended to consider nonequilibrium between electron and excitation temperatures, as well as simple nonequilibrium among excited electronic levels. Seven helium lines are used to determine population densities and upper level excitation temperatures. The electron density is calculated from continuum intensity measurements at C4690. Electron temperatures are found from an astrophysical method suggested by Athay and Menzel. The effective total excitation temperature is obtained by iteration using the multifluids model. The results indicate total excitation temperature values close to the usually calculated "LTE" temperatures, but electron temperatures up to three times larger than the total excitation temperature on the arc centerline near the electrodes. The ratio is approximately 1.5 in the middle of the arc. The heavy particle kinetic temperatures appear to follow the electron temperature, except near the anode, where they drop to values smaller than the total excitation temperatures.     

He原子价壳层跃迁的电子碰撞研究

在入射电子能量 2 5 0 0eV下测量了He的 11S→ 2 1S ,2 1P ,31S和 31P的微分散射截面和广义振子强度 ,并与前人的实验和理论结果进行了比较 ,认为在此入射电子能量下一阶Born近似对此 4个跃迁成立. With electron impact energy of 2 500 eV and energy resolution of 85 meV, the differential cross sections and the generalized oscillator strengths of the excitations of 1 1S→2 1S, 2 1P, 3 1S and 3 1P of helium has been measured by electron energy loss spectroscopy . Comparing with previous experimental and theoretical results, it seems that the first Born approximation is valid for these excitations under such an electron impact energy.     

The Evolution of a Gas in a Radiation Field from a Kinetic Point of View

An existence theorem is derived for a system of kinetic equations describing the evolution of a gas in a radiation field from a kinetic point of view. The geometrical setting is the slab and given indata. The photons ingoing distribution functions are Dirac measures.     

Nuclear Excitation by Electron Transition and Gamma-Ray Laser

This paper studies nuclear excitation by electron transition (NEET) and is potential application in developing gamma-ray laser.A quantum mechanics formula to calculate NEET probabilities was presented with emphasis on the calculations of the transition matrix elements and discussions of the transition selection rules.The NEET probabilities for a number of nuclides were calculated.The upper limit of NEET probability is evaluated to be about 10^－5.The possibility for applying the technique of NEET in the development of gamma laser was investigated.     

Electron Correlation in Nonsequential Double Ionization of Helium by Two-Color Pulses

We investigate the momentum and energy correlations between the two electrons from nonsequential double ionization （NSDI） of helium by strong two-color pulses with the classical three-dimensional ensemble model. The correlated momentum distribution in the direction parallel to the laser field exhibits an arc-like structure and the sum-energy spectrum shows a sharp peak for the NSDI of helium in the two-color fields. Back analysis reveals that the narrow time interval during which recollisions occur, the low returning energy and the short time delay between recollision and double ionization lead to the novel momentum and energy correlations.     

碱金属价电子的多光子散射截面

按照辐射场的量子理论，给出了三光子过程的微分散射截面，在碱金属的实验中，对高激发态的研究提供了方便。     

Electron Energy Distribution in a Helium Plasma Created by Nuclear Radiations

An integral balance technique for calculation of the electron energy distribution in a radiation-induced plasma is described. Results predict W-values reasonably well and compare favorably with more complicated Monte-Carlo calculations. The distribution found differs from that in a normal electrical discharge and is of interest in radiation-pumped laser research.     

Excitation of Electroluminescence by a Rotating Electric Field

The principle of operation of an electroluminescence capacitor (ELC) in which a powder zinc sulfide electroluminophor is excited by threephase voltage is described. Rotation of the electric field intensity vector in a luminophordielectric layer allows a substantially greater number of energy barriers to be involved in the collision processes in the luminophor grains than in a conventional ELC. This provides the possibility of retarding the ELC degradation: at the same initial brightness the time of its halfdecay increases several times.     

Nuclear Astrophysics from View Point of Few-Body Problems

Few-body systems provide very useful tools to solve different problems for nuclear astrophysics. This is the case of indirect techniques, developed to overcome some of the limits of direct measurements at astrophysical energies. Here the Coulomb dissociation, the asymptotic normalization coefficient and the Trojan Horse method are discussed.     

Fully RDWB for Electron Impact Excitation of Be-Like Neon

The collision strengths of Be-like neon ion for excitation from ground state 2s²(¹S₀) to nine excited states (principal quantum number n=2) by electron impact are presented.filly relativistic distorted-wave Born (RDWB) program [CHEN Guoxin, Phys. Rev. A53 (1996) 3227] is used for the calculations. Two transitions are compared with other's work. The rest seven transitions are predicted without other ROWB calculations. There are several detailed considerations in our procedures, so the present results should be reliable and accurate.