6,433 research outputs found
Electrodynamic effects of Jupiter's satellite Io
Electrodynamic effects of Jupiters satellite I
SETI science working group report
This report covers the initial activities and deliberations of a continuing working group asked to assist the SETI Program Office at NASA. Seven chapters present the group's consensus on objectives, strategies, and plans for instrumental R&D and for a microwave search for extraterrestrial in intelligence (SETI) projected for the end of this decade. Thirteen appendixes reflect the views of their individual authors. Included are discussions of the 8-million-channel spectrum analyzer architecture and the proof-of-concept device under development; signal detection, recognition, and identification on-line in the presence of noise and radio interference; the 1-10 GHz sky survey and the 1-3 GHz targeted search envisaged; and the mutual interests of SETI and radio astronomy. The report ends with a selective, annotated SETI reading list of pro and contra SETI publications
Electron Holes and Heating in the Reconnection Dissipation Region
Using particle-in-cell simulations and kinetic theory, we explore the
current-driven turbulence and associated electron heating in the dissipation
region during 3D magnetic reconnection with a guide field. At late time the
turbulence is dominated by the Buneman and lower hybrid instabilities. Both
produce electron holes that co-exist but have very different propagation
speeds. The associated scattering of electrons by the holes enhances electron
heating in the dissipation region.Comment: 14 pages, 5 figures, submitted to GR
Nonlinear Development of Streaming Instabilities In Strongly Magnetized Plasmas
The nonlinear development of streaming instabilities in the current layers
formed during magnetic reconnection with a guide field is explored. Theory and
3-D particle-in-cell simulations reveal two distinct phases. First, the
parallel Buneman instability grows and traps low velocity electrons. The
remaining electrons then drive two forms of turbulence: the parallel
electron-electron two-stream instability and the nearly-perpendicular lower
hybrid instability. The high velocity electrons resonate with the turbulence
and transfer momentum to the ions and low velocity electrons.Comment: Accepted by PR
Long-range interactions between a He() atom and a He() atom for like isotopes
For the interactions between a He() atom and a He() atom for
like isotopes, we report perturbation theoretic calculations using accurate
variational wave functions in Hylleraas coordinates of the coefficients
determining the potential energies at large internuclear separations. We
evaluate the coefficient of the first order resonant dipole-dipole
energy and the van der Waals coefficients , , and for
the second order energies arising from the mutual perturbations of
instantaneous electric dipole, quadrupole, and octupole interactions. We also
evaluate the coefficient of the leading contribution to the third order
energy. We establish definitive values including treatment of the finite
nuclear mass for the He()--He() and He()--He() interactions.Comment: This article has been accepted by Physical Review
Long-range interactions for He()--He and He()--He
The energetically lowest five states of a helium atom are: He(),
He(), He(), He(), and He(). Long-range interaction
coefficients , , , , and for all and
pairs of these states are calculated precisely using correlated wave functions
in Hylleraas coordinates. Finite nuclear isotope mass effects are included
Eigenvalues of the 2p3pP3 and 2p3dD1,3 bound states of the helium isoelectronic sequence
The 1Z expansion method is used to calculate the eigenvalues of the 2p3pP3 and 2p3dD1,3 states of the helium isoelectronic sequence. The results are compared to variational calculations for neutral helium. Wavelengths are predicted for a number of transitions originating in doubly excited states of the heliumlike ions up to Fe xxv. The results for neutral helium are compared to recent beam-foil experiments and alternative line identifications are made. The predicted wavelength for the 2p3dD3-2p2P3 transition is 3014, in close agreement with the line observed by Berry et al. at 3012 ± 2. © 1972 The American Physical Society
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