Antihydrogen formation by autoresonant excitation of antiproton plasmas

In efforts to trap antihydrogen, a key problem is the vast disparity between the neutral trap energy scale ( $\sim\!50\,\upmu\mathrm{eV}$ ), and the energy scales associated with plasma confinement and space charge (~1 eV). In order to merge charged particle species for direct recombination, the larger energy scale must be overcome in a manner that minimizes the initial antihydrogen kinetic energy. This issue motivated the development of a novel injection technique utilizing the inherent nonlinear nature of particle oscillations in our traps. We demonstrated controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm or tenuous plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination. The nature of this injection overcomes some of the difficulties associated with matching the energies of the charged species used to produce antihydrogen.     

The polarization of the plasma cluster in a rail plasma accelerator

In a rail plasma accelerator a polarization of the plasma cluster can occur. The electrons outrun the ions and so a polarization field arises. Some part of energy from the condenser battery corresponds to this field. Simple relations for the maximum polarization length and the polarization energy are derived under conditions of constant cross section area of the plasma cluster and negligible internal magnetic field.     

Correlation in the Al plasma excitation

The density-density correlation function in elementary excitations of the interacting electron gas is calculated from a simple model of the dynamic form factor. For the Al plasma excitation, a correlation length of is found. It is shown that the small correlation length does not contradict the surprisingly large coherence length of almost 10 nm recently found in inelastic interference experiments. The difference of nearly 2 orders of magnitude can be traced back to the long range Coulomb interaction between probe and target electrons.Received: 24 July 2003, Published online: 19 February 2004PACS: 34.80.Pa Coherence and correlation in electron scattering - 71.45.Gm Exchange, correlation, plasmons - 82.80.Pv Electron spectroscopy     

Macroscopic model of plasma accelerator

A simple macroscopic model of plasma accelerator, well describing the process of the plasma cluster acceleration in the accelerator and being directly derived from the physical principles of activity of the accelerator performance, is presented in the present paper.     

Electrode erosion in a pulsed plasma accelerator

There are many papers on cathode phenomena in arcs, but there is no agreed view on the processes near and at the cathode in high-current arcs, in spite of the considerable interest in these phenomena in devices for plasma acceleration [4–7]. Results are presented on cathode damage and cathode spots in plasma accelerators of rail type.     

Three-rails accelerator in one plasma cluster regime

The construction of the three-rails accelerator working in the one plasma cluster regime together with its basic parameters the dependences of the plasma cluster path, velocity, acceleration and mass on time is given in this paper. On the base of the obtained results it is possible to determine the optimum length of the accelerator.     

Determination of the plasma cluster mass in the rail accelerator

Calculations of the plasma cluster mass when changing discharge voltage and capacity of the capacitor battery were performed. The plasma cluster mass is calculated on the basis of experimentally determined dependence of the plasma cluster path on time. Due to these results it is possible to justify the application of the “snow-plough” model to this type of the plasma accelerator.     

Inverse variational problem for the rail plasma accelerator

The Lagrangian function, the Hamiltonian function and the Rayleigh's dissipation function for the electrodynamic model of the rail plasma accelerator and for the phenomenon of polarization of plasma clusters have been found. The generalized momenta and energy, the Hamilton's canonical equations and the equation of energy balance have been derived in both cases.     

Driven spatially autoresonant stimulated Raman scattering in the kinetic regime

The autoresonant behavior of Langmuir waves excited by stimulated Raman scattering (SRS) is clearly identified in particle-in-cell (PIC) simulations in an inhomogeneous plasma. As previously shown via a 3-wave coupling model [T. Chapman et al., Phys. Plasmas 17, 122317 (2010)], weakly kinetic effects such as trapping can be described via an amplitude-dependent frequency shift that compensates the dephasing of the resonance of SRS due to the inhomogeneity. The autoresonance (AR) leads to phase locking and to growth of the Langmuir wave beyond the spatial amplification expected from Rosenbluth's model in an inhomogeneous profile [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)]. Results from PIC simulations and from a 3-wave coupling code show very good agreement, leading to the conclusion that AR arises even beyond the so-called weakly kinetic regime.     

The temperature and pressure in the plasma parallel plate accelerator

This paper presents the results of plasma temperature and pressure calculations in the parallel plate accelerator during the accelerating process. The plasma pressure is calculated by means in Dalton's law.     

激光等离子体加速器的兴起与发展

激光等离子体加速器是近几十年来在世界范围内兴起的一种新型粒子加速器,它在科学研究和日常生活中都有着广泛的应用前景。文章分别从激光电子加速与激光离子加速两方面介绍了它的基本原理与实验发展历程。作为一个新生事物,它取得许多振奋人心的结果,同时也面临着一系列挑战。文章最后对激光等离子体加速器的发展和应用进行了归纳和展望。