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AbstractMechanical energy‐induced CO2 reduction is a promising strategy for reducing greenhouse gas emissions and simultaneously harvesting mechanical energy. Unfortunately, the low energy conversion efficiency is still an open challenge. Here, multiple‐pulse, flow‐type triboelectric plasma with dual functions of harvesting mechanical energy and driving chemical reactions is introduced to efficiently reduce CO2. CO selectivity of 92.4% is achieved under normal temperature and pressure, and the CO and O2 evolution rates reach 12.4 and 6.7 µmol h−1, respectively. The maximum energy conversion efficiencies of 2.3% from mechanical to chemical energy and 31.9% from electrical to chemical energy are reached. The low average electron energy in triboelectric plasma and vibrational excitation dissociation of CO2 with low barrier is revealed by optical emission spectra and plasma simulations, which enable the high energy conversion efficiency. The approach of triboelectric plasma reduction reported here provides a promising strategy for efficient utilization of renewable and dispersed mechanical energy.

Nuclear fusion is a process that occurs naturally in stars and has the potential to provide a clean, safe, and virtually limitless source of energy for humanity. Research and development of nuclear fusion technology have been ongoing for several decades, with the aim of creating a functional fusion reactor that can generate electricity on a commercial scale. The primary challenge in achieving this goal is the need to control the extreme temperatures and pressures required to initiate and maintain the fusion reaction. However, recent advancements in materials science, superconducting magnets, and computer simulations have brought the prospect of a functioning fusion reactor closer than ever before. If successful, fusion energy could provide a sustainable and low-carbon source of electricity for the world's growing energy needs, while mitigating the environmental and safety risks associated with traditional fission-based nuclear power.

MHD turbulence has numerous applications in space and astrophysical plasmas. In this paper, the eddy-damped quasi-normal Markovian (EDQNM) model is used to perform a preliminary study of the nonlinear transfer process in three-dimensional MHD turbulence. Both twoand three-dimensional contour plots of the triadic transfer functions are presented for the case of assumed energy spectra corresponding to Kolmogorov inertial subrange scaling. Introduction The magnetohydrodynamic (MHD) approximation has been quite successful in space physics and astrophysics. In particular, the manifestation of turbulence and other nonlinear phenomena in astrophysical plasmas is explainable from an MHD turbulence perspective. The MHD description has been shown to be an excellent starting point for describing plasma motions when the macroscopic level of motions are well separated from the Coulomb collision/particle gyro-scales. * Copyright © 2001 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. The application of MHD turbulence to the solar wind illustrates how the understanding of basic plasma physics and the universe can be improved. The existence of the solar wind was deduced in 1896 by Birkeland and later theoretically predicted by Parker. Subsequent observations confirmed the presence of hot. supersonic outflows of electrons, protons, and alpha particles from the upper limits of the corona of the Sun. The solar wind streams past the magnetosphere of the Earth, and is the means by which mechanical energy is transmitted from the Sun to the Earth. Solar wind spacecraft observations provide a readily available 'laboratory' for testing theories and assumptions. For example, spacecraft observations demonstrated that the solar wind can be characterized as a turbulent magnetofluid. Reduced power spectra constructed from Mariner 10 spacecraft magnetometer data revealed a steady power-law spectrum spanning nearly three decades in frequency, with an o;~/ powerlaw, where u; is the spacecraft rest frequency. Relating time measurements to spatial scales using the Taylor frozen-in-flow hypothesis, this translates to a fr~/ wavenumber spectrum, reminiscent of the well-known kinetic energy spectrum in fullydeveloped homogeneous, isotropic fluid turbulence. (c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization. Fyfe. Montgomery, and Joyce argued that the original Kolmogorov scaling, and its associated fc~/ power-law, is also applicable to MHD turbulence. Kraichnan. however, proposed that the usual phenomenological argument should be modified to include magnetic field effects, which leads to a k~/ spectrum. Unquestionably, spacecraft observations have strongly motivated the study of turbulence in MHD models describing the dynamics of the solar wind. Much MHD turbulence research has focused on the spectra of three quadratic, integral 'rugged invariants-. These invariants are deduced from the incompressible, non-dissipative approximation of the MHD equations in the absence of a mean magnetic field. In three-dimensional MHD turbulence, these invariants are the energy (per unit mass), the cross helicity. and the magnetic helicity. Some interesting applications of MHD turbulence to the solar wind include the evolution of cross helicity. the development of anisotropies. the decay of magnetic helicity with a mean magnetic field, and nearly-incompressible dynamics. While significant progress has been made, some fundamental aspects of MHD turbulence must be investigated and understood regarding the energy transfer and interacting scales. One can appreciate this point by noting that nearly all MHD turbulence, including its applications to the solar wind" rely on assumptions regarding the energy transfer process through the inertial range. Spacecraft observations may be able to indicate the total energy at a given scale in the spectrum, and detailed information on the energy transfer and interacting scales can be obtained by an analysis similar to that carried out for fluid turbulence". In this paper, we will develop the basic concepts and equations for the energy transfer and interacting scale analysis. After forming the transfer spectra, we will formulate the principal quantitative measurements for describing the spectral locality, strength, and anisotropies of the nonlinear modal couplings. All of these analyses can be carried out with direct numerical simulation (DNS) databases of MHD turbulence. The main limitation of DNS data is that the fluid and magnetic Reynolds numbers are restricted to relatively moderate values. Here, we present an alternative method for performing the energy transfer analysis using transfer spectra constructed from the eddydamped quasi-normal Markovian (EDQNM) closure model'. The EDQNM closure can achieve very high Reynolds numbers, and therefore, a wide range of spectral scales for the analysis. The MHD Equations The standard, unforced MHD equations are the Navier-Stokes equation o \ — i/V ) u = -Vr>+ b V b u Vu (1) dt ) and the magnetic field equation | — _ £ v J b — v x (u x b) (2) \ / with V • u = V • b = 0. (3) where the kinematic viscosity and magnetic diffusivity are v and £. respectively. For homogeneous turbulence, the MHD equations in wavenumber space are

The Norman Rostoker Memorial Symposium brought together approximately 150 attendees to share their recent work and to reflect on the contributions of Norman Rostoker to the field of plasma physics and the advancement of fusion as a source of renewable clean energy. The field has changed considerably in a few short decades, with theoretical advances and technological innovations evolving in lock step. Over those same decades, our understanding of human induced climate change has also evolved; measurable changes in Earth’s physical, chemical, and biological processes have already been observed, and these will likely intensify in the coming decades. Never before has the need for clean energy been more pronounced, or the need for transformative solutions more pressing. As scientists work with legislators, journalists, and the public to take actions to address the threat of climate change, there is much to be learned from the legacies of innovators like Norman Rostoker, who have tackled complex problems with scientific insight and determination even when the odds were stacked against them. I write this from the perspective on an Earth system scientist who studies photosynthesis and the biogeochemistry of the oceans, and my statements about plasma physics and Norman Rostoker are based on information I gathered from the colloquium and from many enjoyable conversations with his friends and colleagues.

This report provides the U.S. Department of Energy (DOE) and the public with information on the level of radioactive and non-radioactive pollutants (if any) that are added to the environment as a result of Princeton Plasma Physics Laboratory's (PPPL) operations. The results of the 2004 environmental surveillance and monitoring program for PPPL's are presented and discussed. The report also summarizes environmental initiatives, assessments, and programs that were undertaken in 2004.

Key among various issues of ignited plasmas is understanding the physics of energy transfer between thermal plasma particles and magnetically confined, highly energetic charged ions in a tokamak device. The superthermal particles are products of fusion reactions. The efficiency of energy transfer by collisions, from charged fusion products (e.g., {alpha}-particles) to plasma ions, grossly determines whether or not plasma conditions are self-sustaining without recourse to auxiliary heating. Furthermore, should energy transfer (efficiency be poor, and substantial auxiliary heating power is required to maintain reacting conditions within the plasma, economics may preclude commercial viability of fusion reactors. The required charged fusion product information is contained in the energy distribution function of these particles. Knowledge of temporal variations of the superthermal particle energy distribution function could be used by a fusion reactor control system to balance plasma conditions between thermal runaway and a modicum of fusion product energy transfer. Therefore, diagnostics providing data on the dynamical transfer of alpha-particle and other charged fusion product energy to the plasma ions are essential elements for a fusion reactor control system to insure that proper plasma conditions are maintained. The objective of this work is to assess if spectral analysis of rf radiation emitted bymore » charged fusion products confined in a magnetized plasma, called ion cyclotron emission (ICE), can reveal the vital data of the distribution function of the superthermal particles.« less

Owing to the storage and transportation problems of hydrogen fuel, exploring new methods of the realtime hydrogen production from ammonia becomes attractive. In this paper, non-thermal arc plasma (NTAP) combining with NiO/Al2O3 catalyst is developed to produce hydrogen from ammonia with high efficiency and large scale. The effects of ammonia gas flow rate and discharge power on the gas temperature, electron density, the hydrogen production rate, and energy efficiency were investigated. Experimental results show that the optical emission spectrum of NTAP working with pure ammonia medium was dominated by the atom spectrum of Hα, Hβ, and molecular spectrum of NH component. Under the optimum experimental condition of plasma discharge, the highest energy efficiency of hydrogen production reached 783.4 L/kW·h at NH3 gas flow rate of 30 SLM. When the catalyst was added, and heated by the NTAP simultaneously, the energy efficiency further increased to 1080.0 L/kW·h. Owing to the storage and transportation problems of hydrogen fuel, exploring new methods of the realtime hydrogen production from ammonia becomes attractive. In this paper, non-thermal arc plasma (NTAP) combining with NiO/Al2O3 catalyst is developed to produce hydrogen from ammonia with high efficiency and large scale. The effects of ammonia gas flow rate and discharge power on the gas temperature, electron density, the hydrogen production rate, and energy efficiency were investigated. Experimental results show that the optical emission spectrum of NTAP working with pure ammonia medium was dominated by the atom spectrum of Hα, Hβ, and molecular spectrum of NH component. Under the optimum experimental condition of plasma discharge, the highest energy efficiency of hydrogen production reached 783.4 L/kW·h at NH3 gas flow rate of 30 SLM. When the catalyst was added, and heated by the NTAP simultaneously, the energy efficiency further increased to 1080.0 L/kW·h.

Progress is reported on the following programs: geothermal and geosciences; controlled thermonuclear research; chemical processing; instrument development; environment; energy use and conservation; energy analysis; and engineering sciences.