4,687 research outputs found
Microscopic laser-driven high-energy colliders
The concept of a laser-guided collider in the high-energy regime is
presented and its feasibility discussed. Ultra-intense laser pulses and strong
static magnetic fields are employed to unite in one stage the electron and
positron acceleration and their head-on-head collision. We show that the
resulting coherent collisions in the GeV regime yield an enormous enhancement
of the luminosity with regard to conventional incoherent colliders
Satellite power system: Concept development and evaluation program. Volume 3: Power transmission and reception. Technical summary and assessment
Efforts in the DOE/NASA concept development and evaluation program are discussed for the solar power satellite power transmission and reception system. A technical summary is provided together with a summary of system assessment activities. System options and system definition drivers are described. Major system assessment activities were in support of the reference system definition, solid state system studies, critical technology supporting investigations, and various system and subsystem tradeoffs. These activities are described together with reference system updates and alternative concepts for each of the subsystem areas. Conclusions reached as a result of the numerous analytical and experimental evaluations are presented. Remaining issues for a possible follow-on program are identified
Observation of the diocotron instability in a diode with split cathode
Diocotron instability has been observed in the pure electron plasma formed in
a split cathode coaxial diode. This plasma consists of electrons, trapped in
the longitudinal potential well between the two parts of the cathode. The
mathematical model of the electron squeezed state, which allows calculation of
the equilibrium plasma density, is presented. The model is applied in a
comprehensive analysis of experimental data and the presence of the diocotron
instability is unambiguously confirmed.Comment: Accepted for publication in Physics of Plasma
Excitation of Small Quantum Systems by High-Frequency Fields
The excitation by a high frequency field of multi--level quantum systems with
a slowly varying density of states is investigated. A general approach to study
such systems is presented. The Floquet eigenstates are characterized on several
energy scales. On a small scale, sharp universal quasi--resonances are found,
whose shape is independent of the field parameters and the details of the
system. On a larger scale an effective tight--binding equation is constructed
for the amplitudes of these quasi--resonances. This equation is non--universal;
two classes of examples are discussed in detail.Comment: 4 pages, revtex, no figure
Reducing multiphoton ionization in a linearly polarized microwave field by local control
We present a control procedure to reduce the stochastic ionization of
hydrogen atom in a strong microwave field by adding to the original Hamiltonian
a comparatively small control term which might consist of an additional set of
microwave fields. This modification restores select invariant tori in the
dynamics and prevents ionization. We demonstrate the procedure on the
one-dimensional model of microwave ionization.Comment: 8 page
Coherent states for the hydrogen atom
We construct wave packets for the hydrogen atom labelled by the classical
action-angle variables with the following properties. i) The time evolution is
exactly given by classical evolution of the angle variables. (The angle
variable corresponding to the position on the orbit is now non-compact and we
do not get exactly the same state after one period. However the gross features
do not change. In particular the wave packet remains peaked around the labels.)
ii) Resolution of identity using this overcomplete set involves exactly the
classical phase space measure. iii) Semi-classical limit is related to
Bohr-Sommerfield quantization. iv) They are almost minimum uncertainty wave
packets in position and momentum.Comment: 9 pages, 2 figures, minor change in language and journal reference
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Diffusive Ionization of Relativistic Hydrogen-Like Atom
Stochastic ionization of highly excited relativistic hydrogenlike atom in the
monochromatic field is investigated. A theoretical analisis of chaotic dynamics
of the relativistic electron based on Chirikov criterion is given for the cases
of one- and three-dimensional atoms. Critical value of the external field is
evaluated analitically. The diffusion coefficient and ionization time are
calculated.Comment: 13 pages, latex, no figures, submitted to PR
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