David C. Lizon

Novel cylindrical, air-coupled acoustic levitation/concentration devices

A new class of devices for levitation and/or concentration of aerosols and small liquid/solid samples (up to several millimeters in diameter) in air has been developed. The novelty of these devices is their simplicity in design. These are inexpensive, low-power, and, in their simplest embodiment, do not require accurate alignment of a resonant cavity. Best of all, these can be off-the-shelf items. The devices are constructed from a hollow, cylindrical piezoelectric tube. The main design criteria requires a resonant mode of the tube to match a resonant mode of the interior air-filled cavity. Once matched, it is shown that drops of water in excess of 1 mm in diameter may be levitated inside the cylinder cavity against the force of gravity for less than 1 Watt of input electrical power. Efficient concentration/agglomeration of aerosol particles in air is also demonstrated.

Capture of 2-10 keV Negative Hydrogen Ions into a Penning Trap

Negative Hydrogen ions from a duoplasmatron ion source at energies between 2 and 10 KeV have been captured in flight into a standard Penning Trap. A positive identification of the ion species was achieved with resonant excitation of the axial motion as well as the cyclotron motion. An exponential decay of the signal associated with the H- ions was observed. This decay was accompanied by an increase of a signal from a particle species stored in the trap at very low energy. These particles are interpreted as electrons liberated from the H- ions in collisions with residual gas molecules. The lifetime of H- ions under the specific circumstances has been studied, and the results were found to agree with estimates using the known rate constants and the pressures present inside the trap.

A non-contact technique for evaluation of elastic structures at large stand-off distances: applications to classification of fluids in steel vessels.

A novel technique for non-contact evaluation of structures in air at large stand-off distances (on the order of several meters) has been developed. It utilizes a recently constructed air-coupled, parametric acoustic array to excite the resonance vibrations of elastic, fluid-filled vessels. The parametric array is advantageous for NDE applications in that it is capable of producing a much narrower beamwidth and broader bandwidth than typical devices that operate under linear acoustic principles. In the present experiments, the array operates at a carrier frequency of 217 kHz, and the sound field several meters from the source is described spectrally by the envelope of the drive voltage. An operating bandwidth of more than 25 kHz at a center frequency of 15 kHz is demonstrated. For the present application, the array is used to excite vibrations of fluid-filled, steel containers at stand-off distances of greater than 3 m. The vibratory response of a container is detected with a laser vibrometer in a monostatic configuration with the acoustic source. By analyzing the change in the response of the lowest order, antisymmetric Lamb wave as the interior fluid loading conditions of the container are changed, the fluid contained within the steel vessel is classified.

Charging a Battery-Powered Device with a Fiber-Optically Connected Photonic Power System for Achieving High-Voltage Isolation

We are developing a system to provide isolated power to the filament power supply of an X-ray tube located at a potential of several hundred kilovolts. In this design a fiber-optically connected photonic power system (PPS) is used to recharge a lithium-ion battery pack, which will subsequently supply power to the rest of the system. This paper evaluates the suitability for using the commercially available JDSU Photonic Power System for charging Li-Ion batteries. The output of the PPC converter is characterized. The technical aspects of its use for charging a variety of Li-ion batteries are discussed. Battery charge protection requirements and safety concerns are also addressed.