arXiv subjects

Alfred Y. Wong

Publications and source records attributed to Alfred Y. Wong.

5 recordsLinked to original sources

arXiv2025

Performance Characteristics of the Battery-Operated Si PIN Diode Detector with Integrated Preamplifier and Data Acquisition Module for Fusion Particle Detection

We present the performance and application of a commercial off-the shelf Si PIN diode (Hamamatsu S14605) as a charged particle detector in a compact ion beam system (IBS) capable of generating D-D and p-B fusion charged particles. This detector is inexpensive, widely available, and operates in photoconductive mode under a reverse bias voltage of 12 V, supplied by an A23 battery. A charge-sensitive preamplifier (CSP) is powered by two 3 V lithium batteries (A123), providing +/-3 V rail voltages. Both the detector and preamplifier circuits are integrated onto the same 4-layer PCB and housed on the vacuum side of the IBS, facing the fusion target. The system employs a CF-2.75 flanged DB-9 connector feedthrough to supply the signal, bias voltage, and rail voltages. To mitigate the high sensitivity of the detector to optical light, a thin aluminum foil assembly is used to block optical emissions from the ion beam and target. Charged particles generate step responses on the preamplifier output, with pulse rise times on the order of 0.2 to 0.3 us. These signals are recorded using a custom-built data acquisition unit, which features an optical fiber data link to ensure electrical isolation of the detector electronics. Subsequent digital signal processing is employed to optimally shape the pulses using a CR-RC^4 filter to produce Gaussian-shaped signals, enabling accurate extraction of energy information. Performance results show that the signal-to-noise ratios (S/N) for D-D fusion charged particles - protons, tritons, and helions - are approximately 30, 10, and 5, respectively, with a shaping time constant of 4 us.

physics.ins-det↗

arXiv2024

Compact Ion Beam System for Fusion Demonstration

We demonstrate a compact ion beam device capable of accelerating H$^+$ and D$^+$ ions up to 75keV energy, on to a solid target, with sufficient beam current to study fusion reactions. The ion beam system uses a microwave driven plasma source to generate ions that are accelerated to high energy with a direct current (DC) acceleration structure. The plasma source is driven by pulsed microwaves from a solid-state radiofrequency (RF) amplifier, which is impedance matched to the plasma source chamber at the ISM band frequency (2.4-2.5GHz). The plasma chamber is held at high positive DC potential and is isolated from the impedance matching structure (at ground potential) by a dielectric-filled gap. To facilitate the use of high-energy-particle detectors near the target, the plasma chamber is biased to a high positive voltage, while the target remains grounded. A target loaded with deuterium is used to study D-D fusion and a B$_4$C or LaB$_6$ target is used to study p-$^{11}$B fusion. Detectors include solid-state charged particle detector and a scintillation fast neutron detector. The complete ion beam system can fit on a laboratory table and is a useful tool for teaching undergraduate and graduate students about the physics of fusion.

physics.ins-det↗

arXiv2021

Enhanced D-D Fusion Rates when the Coulomb Barrier Is Lowered by Electrons

A profusion of unbound, low-energy electrons creates a local electric field that reduces Coulomb potential and increases quantum tunneling probability for pairs of nuclei. Neutral beam-target experiments on deuterium-deuterium fusion reactions, observed with neutron detectors, show percentage increases in fusion products are consistent with electron-screening predictions from Schrodinger wave mechanics. Experiments performed confirm that observed fusion rate enhancement with a negatively biased target is primarily due to changes to the fusion cross section, rather than simply acceleration due to electrostatic forces.

physics.plasm-ph↗

arXiv2020

Ponderomotive Screening of Nuclear Fusion Reactions Based on Localized Surface Plasmon Resonance

A scheme is presented to catalyze nuclear fusion by the excitation of the localized surface plasmon resonance (LSPR) of an Au nanobipyramid (NBP) by ultrafast (femtosecond) laser pulses. The effect utilizes the exceptionally high electric field enhancement provided by the Au NBP LSPR, localized to nm^3 volumes and fs time scales, to produce a ponderomotive force that in turn provides for screening energies near the Au NBP tip. Discrete-dipole approximation (DDA) simulations are presented to support the proposed scheme. Calculations made with conservative parameters suggest that the effect should be observable in a laboratory setting using commercially available ultrafast lasers.

physics.gen-ph↗

arXiv2019

Approach to Nuclear Fusion Utilizing Dynamics of High-Density Electrons and Neutrals

An approach to achieve nuclear fusion utilizing the formation of high densities of electrons and neutrals is described. The profusion of low energy electrons provides high dynamic electric fields that help reduce the Coulomb barrier in nuclear fusion; high-density neutrals provide the stability and reaction rates to achieve break-even fusion where charged particles are the main products. Interactions of energetic charged particles with high-density background produce positive feedbacks with enhanced cross sections. Experiments in a rotating geometry illustrate the advantages of this approach, which discriminates against neutronic fusion.

physics.plasm-ph↗