Carlos A. Ordonez

CRYOGENIC HEAT ENGINE EXPERIMENT

Experimental results on the operation of a cryogenic heat engine are presented. A cryogenic heat engine employs a cryogenic medium as a heat sink and the atmoxad sphere as a heat source. Cold thermal storage by refrigeration to produce the cryogenic medium is thus equivalent to energy storage. Using liquid nitrogen as the cryogenic medium, a small cryogenic heat engine which utilizes a simple gas expansion process has been evaluated to experimentally provide 19 kj of mechanical energy per kilogram of nitrogen exhausted. Theoretical modeling indicates that larger specific energy values are readily possible using more advanced cryogenic heat engine processes. Cryogenic heat engines are potentially suitable as power systems for zero emission vehicles. In order to prove that this is possible, an automobile has been converted for operation using liquid nitrogen as its fuel. In addition, a study has been conducted to assess the feasibility of using a cryogenic heat engine as a zero emission vehicle power system.

Simulation of an aperture-based antihydrogen gravity experiment

A Monte Carlo simulation is presented of an experiment that could potentially determine whether antihydrogen accelerates vertically up or down as a result of earths gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations and would employ a Penning trap for the production of antihydrogen within a uniform magnetic field. The axis of symmetry of the cylindrical trap wall would be oriented horizontally, and an axisymmetric aperture (with an inner radius that is smaller than the cylindrical trap wall radius) would be present a short distance away from the antihydrogen production region. Antihydrogen annihilations that occur along the cylindrical trap wall would be detected by the experiment. The distribution of annihilations along the wall would vary near the aperture, because some antihydrogen that would otherwise annihilate at the wall would instead annihilate on the aperture. That is, a shadow region forms behind the aperture, and the distribution of annihil...

Aperture-based antihydrogen gravity experiment: Parallel plate geometry

An analytical model and a Monte Carlo simulation are presented of an experiment that could be used to determine the direction of the acceleration of antihydrogen due to gravity. The experiment would rely on methods developed by existing antihydrogen research collaborations. The configuration consists of two circular, parallel plates that have an axis of symmetry directed away from the center of the earth. The plates are separated by a small vertical distance, and include one or more pairs of circular barriers that protrude from the upper and lower plates, thereby forming an aperture between the plates. Antihydrogen annihilations that occur just beyond each barrier, within a “shadow” region, are asymmetric on the upper plate relative to the lower plate. The probability for such annihilations is determined for a point, line and spheroidal source of antihydrogen. The production of 100,000 antiatoms is predicted to be necessary for the aperture-based experiment to indicate the direction of free fall acceleration of antimatter, provided that antihydrogen is produced within a sufficiently small antiproton plasma at a temperature of 4 K.

Drifting Plasma Confinement With a Spatially Periodic Field

Some possible plasma confinement configurations are identified in which a spatially periodic electrostatic or magnetostatic field may provide or enhance ion confinement. The plasma drifts at a speed much faster than the ion thermal speed. The periodic field has a spatial period that is much smaller than the plasma size, and the field has a nonnegligible strength only at the plasma edge. The periodic field could be produced, for example, by a sequence of electrodes with alternating applied voltages or a sequence of wires with alternating current directions. Classical trajectory Monte Carlo simulation results are used to develop expressions for predicting the conditions under which ions are reflected away from an artificially structured boundary that produces a spatially periodic field, without the ions reaching the artificially structured boundary.

Spatially Periodic Electromagnetic Force Field For Plasma Confinement and Control

A scientific concept referred to as a force field is defined as a short-range, static electromagnetic field that can reflect a charged particle of either sign of charge that approaches at any angle of incidence. A force field is envisioned as consisting of a spatially periodic sequence of magnetic cusps that are electrostatically plugged using applied electrostatic voltage variations similar to those found in nested Penning traps. The effective range of the force field would be small compared to the dimensions of a nearby source of charged particles, such as a plasma confined by the force field. A theoretical understanding is developed of the single-particle reflection properties of a force field, considering the incident charged particles to have a non-drifting, isotropic velocity distribution. Classical trajectory Monte Carlo simulations and analytical modeling are employed. The initiation of an experimental effort to study force fields is described.

Plasma Interaction With a Static Spatially Periodic Electromagnetic Field

Initial research on a static electromagnetic “force field” is presented. The force field consists of a planar sequence of magnetic cusps that are electrostatically plugged. Electrostatic plugging with applied potential variations that are similar to those applied to one side of a nested Penning trap allows a force field to reflect incident charged particles of either signs of charge. Experimental and computational results are reported.

Classical trajectory Monte Carlo simulations of particle confinement using dual levitated coils

The particle confinement properties of plasma confinement systems that employ dual levitated magnetic coils are investigated using classical trajectory Monte Carlo simulations. Two model systems are examined. In one, two identical current-carrying loops are coaxial and separated axially. In the second, two concentric and coplanar loops have different radii and carry equal currents. In both systems, a magnetic null circle is present between the current loops. Simulations are carried out for seven current loop separations for each system and at numerous values of magnetic field strength. Particle confinement is investigated at three locations between the loops at different distances from the magnetic null circle. Each simulated particle that did not escape the system exhibited one of four modes of confinement. Reduced results are given for both systems as the lowest magnetic field strength that exhibits complete confinement of all simulated particles for a particular loop separation.

Accelerator-based neutron source using a cold deuterium target with degenerate electrons

A neutron generator is considered in which a beam of tritons is incident on a hypothetical cold deuterium target with degenerate electrons. The energy efficiency of neutron generation is found to increase substantially with electron density. Recent reports of potential targets are discussed.

Charged particle reflection by a planar artificially structured boundary with electrostatic plugging

A classical trajectory Monte Carlo simulation is used to investigate an artificially structured boundary for confinement and control of charged particles. The artificially structured boundary considered here incorporates a planar sequence of conducting wires, where adjacent wires carry current in opposite directions. Such a configuration creates a sequence of magnetic cusps and was studied previously [C. A. Ordonez, J. Appl. Phys. 106, 024905 (2009)]. The effect of introducing a sequence of electrodes for electrostatic plugging of the cusps is investigated. The results of the simulations are used to identify regions of parameter space in which particle losses through the cusps may be negligible in the single particle limit. A trap based on a cylindrical generalization of the artificially structured boundary presented here may lead to a method for confining non-neutral and partially neutralized plasmas along the edge, such that the bulk of a confined plasma is effectively free of externally applied electro...