14,879 research outputs found
Expansions of the solutions of the biconfluent Heun equation in terms of incomplete Beta and Gamma functions
Starting from equations obeyed by functions involving the first or the second
derivatives of the biconfluent Heun function, we construct two expansions of
the solutions of the biconfluent Heun equation in terms of incomplete Beta
functions. The first series applies single Beta functions as expansion
functions, while the second one involves a combination of two Beta functions.
The coefficients of expansions obey four- and five-term recurrence relations,
respectively. It is shown that the proposed technique is potent to produce
series solutions in terms of other special functions. Two examples of such
expansions in terms of the incomplete Gamma functions are presente
In-Space technology experiments program. A high efficiency thermal interface (using condensation heat transfer) between a 2-phase fluid loop and heatpipe radiator: Experiment definition phase
Space Station elements and advanced military spacecraft will require rejection of tens of kilowatts of waste heat. Large space radiators and two-phase heat transport loops will be required. To minimize radiator size and weight, it is critical to minimize the temperature drop between the heat source and sink. Under an Air Force contract, a unique, high-performance heat exchanger is developed for coupling the radiator to the transport loop. Since fluid flow through the heat exchanger is driven by capillary forces which are easily dominated by gravity forces in ground testing, it is necessary to perform microgravity thermal testing to verify the design. This contract consists of an experiment definition phase leading to a preliminary design and cost estimate for a shuttle-based flight experiment of this heat exchanger design. This program will utilize modified hardware from a ground test program for the heat exchanger
Adiabatic tracking for photo- and magneto-association of Bose-Einstein condensates with Kerr nonlinearities
We develop the method of adiabatic tracking for photo- and
magneto-association of Bose-Einstein atomic condensates with models that
include Kerr type nonlinearities. We show that the inclusion of these terms can
produce qualitatively important modifications in the adiabatic dynamics, like
the appearance of bifurcations, in which the trajectory that is being tracked
loses its stability. As a consequence the adiabatic theorem does not apply and
the adiabatic transfer can be strongly degraded. This degradation can be
compensated by using fields that are strong enough compared with the values of
the Kerr terms. The main result is that, despite these potentially detrimental
features, there is always a choice of the detuning that leads to an efficient
adiabatic tracking, even for relatively weak fields
Photoassociation of a cold atom-molecule pair: long-range quadrupole-quadrupole interactions
The general formalism of the multipolar expansion of electrostatic
interactions is applied to the calculation the potential energy between an
excited atom (without fine structure) and a ground state diatomic molecule at
large separations. Both partners exhibit a permanent quadrupole moment, so that
their mutual quadrupole-quadrupole long-range interaction is attractive enough
to bind trimers. Numerical results are given for an excited Cs(6P) atom and a
ground state Cs2 molecule. The prospects for achieving photoassociation of a
cold atom/dimer pair is thus discussed and found promising. The formalism can
be easily generalized to the long-range interaction between molecules to
investigate the formation of cold tetramers.Comment: 5 figure
- …