Transverse electron guns for plasma excitation

Includes bibliographical references (page 4710).We report a plasma gun, which generates on a continuous basis, kilowatt electron beam discharges (e.g., 0.4 A at 4 kV) in an ambient pressure 0.1-1 Torr without differential pumping. Gun design characteristics, operating parameters, and measured beam profiles are given. Electron beam generation on a pulsed basis has also been studied. More than 100 A of beam current has been measured with a Faraday cup biased to - 100 V. A trapped electron beam scheme for achieving efficient deposition of the electron beam energy in a gas medium is described

Cw ion lasers pumped by electron beams

We have obtained cw laser radiation from singly ionized Hg, I, Cd, Se, and As by exciting He metal-vapor mixtures with a dc electron beam. The beam is generated by glow discharge electron guns located apart from the active medium. This is the first time that cw ion laser action has been obtained using electron beam excitation

Real-Time Parallel Trajectory Optimization with Spatiotemporal Safety Constraints for Autonomous Driving in Congested Traffic

Multi-modal behaviors exhibited by surrounding vehicles (SVs) can typically lead to traffic congestion and reduce the travel efficiency of autonomous vehicles (AVs) in dense traffic. This paper proposes a real-time parallel trajectory optimization method for the AV to achieve high travel efficiency in dynamic and congested environments. A spatiotemporal safety module is developed to facilitate the safe interaction between the AV and SVs in the presence of trajectory prediction errors resulting from the multi-modal behaviors of the SVs. By leveraging multiple shooting and constraint transcription, we transform the trajectory optimization problem into a nonlinear programming problem, which allows for the use of optimization solvers and parallel computing techniques to generate multiple feasible trajectories in parallel. Subsequently, these spatiotemporal trajectories are fed into a multi-objective evaluation module considering both safety and efficiency objectives, such that the optimal feasible trajectory corresponding to the optimal target lane can be selected. The proposed framework is validated through simulations in a dense and congested driving scenario with multiple uncertain SVs. The results demonstrate that our method enables the AV to safely navigate through a dense and congested traffic scenario while achieving high travel efficiency and task accuracy in real time.Comment: 8 pages, 7 figures, accepted for publication in the 26th IEEE International Conference on Intelligent Transportation Systems (ITSC 2023

Influence of electron collisions inside the cathode sheath upon the electron energy spectrum in the negative glow region of a gas discharge

Includes bibliographical references.Computer models have been developed to solve the Boltzmann equation for the electron energy spectrum in both the cathode sheath and the negative glow region of a glow discharge. Electron collisions occurring during acceleration inside the cathode sheath partially determine the structure of the electron energy distribution measured in the negative glow. The relative role of elastic, excitation, and ionization collisions are examined using the computer model. Good qualitative agreement was obtained between calculated electron energy distributions and previous experimental measurements both at the sheath-plasma interface as well as in the negative glow region of the discharge.This work was supported by the National Science Foundation. Quantum Electronics Waves and Beams (ECS-881505I, Dr. L. Goldberg) and the Naval Research Laboratory

Lithographic processing of polymers using plasma-generated electron beams

Includes bibliographical references.Pattern definition in polymer films is achieved using electron beams generated in soft vacuum (0.05-0.50 torr) glow discharges either on a continuous or pulsed (20-100 ns) basis. With the continuous- mode electron beam, 7- µm transmission mask features are replicated in both polymethyl methacrylate (PMMA) and polyimide resists. Using a pulsed electron-beam submicron (~0.5 µm) features are transferred from an electron-transmitting stencil mask into the PMMA. The soft-vacuum pulsed electron beam is also eminently suited for polymer stabilization. Pulsed electron-beam hardening of 0.05-3.5- µm-thick AZ-type and MacDermid resist patterns is also demonstrated with hardened resist patterns stable to temperatures between 200° and 350°C. The demonstrated replication and pattern stabilization technique may be applicable in microelectronics packaging lithography where the resist thickness is substantial, linewidths are 1-10 µm, and registration requirements are less stringent.This work was supported by the National Science Foundation (Quantum Electrorncs Waves and Beams) under Contract No. ECS-8815051, the Colorado Advanced Technology Institute, the Hewlett Packard Corporation, the Applied Electron Corporation, the IBM Corporation, and by MIS Buckbee-Mears of St. Paul, MN

Incremental Bayesian Learning for Fail-Operational Control in Autonomous Driving

Abrupt maneuvers by surrounding vehicles (SVs) can typically lead to safety concerns and affect the task efficiency of the ego vehicle (EV), especially with model uncertainties stemming from environmental disturbances. This paper presents a real-time fail-operational controller that ensures the asymptotic convergence of an uncertain EV to a safe state, while preserving task efficiency in dynamic environments. An incremental Bayesian learning approach is developed to facilitate online learning and inference of changing environmental disturbances. Leveraging disturbance quantification and constraint transformation, we develop a stochastic fail-operational barrier based on the control barrier function (CBF). With this development, the uncertain EV is able to converge asymptotically from an unsafe state to a defined safe state with probabilistic stability. Subsequently, the stochastic fail-operational barrier is integrated into an efficient fail-operational controller based on quadratic programming (QP). This controller is tailored for the EV operating under control constraints in the presence of environmental disturbances, with both safety and efficiency objectives taken into consideration. We validate the proposed framework in connected cruise control (CCC) tasks, where SVs perform aggressive driving maneuvers. The simulation results demonstrate that our method empowers the EV to swiftly return to a safe state while upholding task efficiency in real time, even under time-varying environmental disturbances.Comment: 8 pages, 8 figures, accepted for publication in the 22nd European Control Conference (ECC 2024

Process Simulation and Optimization of Fluid Catalytic Cracking Unit’s Rich Gas Compression System and Absorption Stabilization System

In a fuel-based refinery, rich gas in the fluid catalytic cracking (FCC) unit is further processed to separate dry gas and refinery products (i.e., stabilized gasoline and liquified petroleum gas). The process is utility-intensive and costly and includes a two-stage compressor, pumps, an absorber, a stripper, a stabilizer, and a re-absorber. The optimization was conducted with respect to the compressor outlet pressure from the gas compression system (GCS) and the flow rate of absorbent and supplementary absorbent from the Absorption-stabilization System (ASS) using the process simulation software Aspen Plus. Compared to the base case of a 725 kt/a rich gas FCC unit, a refinery can save 2.42% of utility costs under optimal operation. Through optimized operation, medium-pressure steam consumption has been reduced by 2.4% compared to the base case, resulting in a significant improvement in total operational cost. The optimization strategy can provide insightful guidance for the practical operation of GCS and ASS.</p

Bacterial Inactivation of Wound Infection in a Human Skin Model by Liquid-Phase Discharge Plasma

Background: We investigate disinfection of a reconstructed human skin model contaminated with biofilm-formative Staphylococcus aureus employing plasma discharge in liquid. Principal Findings: We observed statistically significant 3.83-log10 (p,0.001) and 1.59-log10 (p,0.05) decreases in colony forming units of adherent S. aureus bacteria and 24 h S. aureus biofilm culture with plasma treatment. Plasma treatment was associated with minimal changes in histological morphology and tissue viability determined by means of MTT assay. Spectral analysis of the plasma discharge indicated the presence of highly reactive atomic oxygen radicals (777 nm and 844 nm) and OH bands in the UV region. The contribution of these and other plasma-generated agents and physical conditions to the reduction in bacterial load are discussed. Conclusions: These findings demonstrate the potential of liquid plasma treatment as a potential adjunct therapy for chronic wounds