sa11a3925 effects of a relativistic electron beam interaction...

8/27/2015 2014 AGU Fall Meeting https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/9649 1/2 An artificial beam of relativistic (0.510 MeV) electrons has been proposed as an active experiment in the ionosphere and magnetosphere, with applications to magnetic fieldline tracing, studies of waveparticle interactions, and beamatmosphere interactions. The beamatmosphere interaction, while a scientific endeavor of its own, also provides key diagnostics for other experiments. We present results of Monte Carlo simulations of the interaction of a beam of relativistic electrons with the upper atmosphere as they are injected downwards from a notional high altitude (thermospheric / ionospheric) injection platform. The beam parameters, defined by realistic parameters of a compact linear accelerator, are used to create a distribution of thousands of electrons. Each electron is injected downwards from 300 km altitude towards the dense atmosphere, where it undergoes elastic and inelastic collisions, leading to secondary ionization, optical emissions, and Xrays via bremsstrahlung. Here we describe the Monte Carlo model and present calculations of diagnostic outputs, including optical emissions, Xray fluxes, secondary ionization, and backscattered energetic electron fluxes. Optical emissions are propagated to the ground through the lower atmosphere, including the effects of atmospheric absorption and scattering, to estimate the brightness of the emission column for a given beam current and energy. Similarly, Xray fluxes are propagated to hypothetical detectors on balloons and satellites, taking into account Compton scattering and photoabsorption. Secondary ionization is used to estimate the radar signal returns from various groundbased radar facilities. Finally, simulated backscattered electron fluxes are measured at the injection location. The simulation results show that for realizable accelerator parameters, each of these diagnostics should be readily detectable by appropriate instruments. Monday, 15 December 2014 08:00 AM 12:20 PM Moscone South Poster Hall Authors Robert Marshall Stanford University Michael Nicolls SRI International Ennio Sanchez SRI International Nikolai Lehtinen Stanford University Jeffrey Neilson SLAC National Accelerator Laboratory Back to: Nikolai Lehtinen SA11A3925 Effects of a Relativistic Electron Beam Interaction with the Upper Atmosphere: Ionization, XRays, and Optical Emissions

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Page 1: SA11A3925 Effects of a Relativistic Electron Beam Interaction ...nlpc.stanford.edu/nleht/Science/talks/2014/AGU/SA11A...emissions, and X rays via bremsstrahlung. Here we describe the

8/27/2015 2014 AGU Fall Meeting

https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/9649 1/2

An artificial beam of relativistic (0.510 MeV) electrons has been proposed as an activeexperiment in the ionosphere and magnetosphere, with applications to magnetic fieldlinetracing, studies of waveparticle interactions, and beamatmosphere interactions. Thebeamatmosphere interaction, while a scientific endeavor of its own, also provides keydiagnostics for other experiments. We present results of Monte Carlo simulations of theinteraction of a beam of relativistic electrons with the upper atmosphere as they areinjected downwards from a notional high altitude (thermospheric / ionospheric) injectionplatform. The beam parameters, defined by realistic parameters of a compact linearaccelerator, are used to create a distribution of thousands of electrons. Each electron isinjected downwards from 300 km altitude towards the dense atmosphere, where itundergoes elastic and inelastic collisions, leading to secondary ionization, opticalemissions, and Xrays via bremsstrahlung. Here we describe the Monte Carlo model andpresent calculations of diagnostic outputs, including optical emissions, Xray fluxes,secondary ionization, and backscattered energetic electron fluxes. Optical emissions arepropagated to the ground through the lower atmosphere, including the effects ofatmospheric absorption and scattering, to estimate the brightness of the emission columnfor a given beam current and energy. Similarly, Xray fluxes are propagated tohypothetical detectors on balloons and satellites, taking into account Compton scatteringand photoabsorption. Secondary ionization is used to estimate the radar signal returnsfrom various groundbased radar facilities. Finally, simulated backscattered electronfluxes are measured at the injection location. The simulation results show that forrealizable accelerator parameters, each of these diagnostics should be readily detectableby appropriate instruments.

Monday, 15 December 2014 08:00 AM 12:20 PMMoscone SouthPoster Hall

AuthorsRobert MarshallStanford University

Michael NicollsSRI International

Ennio SanchezSRI International

Nikolai LehtinenStanford University

Jeffrey NeilsonSLAC National Accelerator Laboratory

Back to: Nikolai Lehtinen

SA11A3925 Effects of a Relativistic Electron Beam Interaction with the UpperAtmosphere: Ionization, XRays, and Optical Emissions

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