A statistical study of ®eld-aligned electron beams associated with up ̄owing ion conics is presented from Exos-D (Akebono) observations below 10 000 km. The electron beams are narrowly collimated along the ®eld line and generally have energies of several tens of eV. They are divided in the analysis into three types: up ̄owing, down ̄owing, and counterstreaming. All the types of electron beams are ...

Background: The purpose of this study was to determine the percentage depth dose (PDD) of PAGAT normoxic polymer gel dosimeter by electron beams using MRI technique for a standard clinically used Co-60 therapy unit and an electa linear accelerator. Materials and Methods: Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2(1/T2) was determined to be 4.5% N,...

Title of Dissertation: LONGITUDINAL DYNAMICS OF AN INTENSE ELECTRON BEAM John Richardson Harris, Ph.D., 2005 Dissertation Directed By: Professor Patrick G. O'Shea, Department of Electrical and Computer Engineering The dynamics of charged particle beams are governed by the particles' thermal velocities, external focusing forces, and Coulomb forces. Beams in which Coulomb forces play the dominant...

Introduction: In clinical electron beams, most of bremsstrahlung radiation is produced by various linac head structures. This bremsstrahlung radiation dose is influenced by the geometry and construction of every component of the linac treatment head structures. Thus, it can be expected that the amount of the contaminated photon dose due to bremsstrahlung radiation varies among different linacs,...

Impact of the various kVp settings used during computed tomography (CT) simulation that provides data for heterogeneity corrected dose distribution calculations in patients undergoing external beam radiotherapy with either high-energy photon or electron beams have been investigated. The change of the Hounsfield Unit (HU) values due to the influence of kVp settings and geometrical distribution o...

We propose an all-optical method of creating electron vortices utilizing the Kapitza-Dirac effect. This technique uses the transfer of orbital angular momentum from photons to free electrons creating electron vortex beams in the process. The laser intensities needed for this experiment can be obtained with available pulsed lasers and the resulting electron beams carrying orbital angular momentu...

Ionization-induced injection mechanism was introduced in 2010 to reduce the laser intensity threshold for controllable electron trapping in laser wakefield accelerators (LWFA). However, usually it generates electron beams with continuous energy spectra. Subsequently, a dual-stage target separating the injection and acceleration processes was regarded as essential to achieve narrow energy-spread...

Introduction: Radiation therapy using electron beams is a promising method due to its physical dose distribution. Monte Carlo (MC) code is the best and most accurate technique for forespeaking the distribution of dose in radiation treatment of patients.Materials and Methods: We report an MC simulation of a linac head and depth dose on central axis, along with profile calculations. The purpose o...

The resistive-wall instability of charged particle beams has been experimentally studied in space-charge dominated electron beams. The beam energy is in the range of 3 to 8.5 keV, the beam current is between 25 mA and 62 mA. In the experiment, electron beams produced from a thermionic cathode are passed through a 0.96 m long glass tube coated with a resistive material, and localized space-charg...

The secondary positron beams produced by linear electron accelerators are used in scattering experiments with stationary targets, in electron-positron colliding beam experiments, and in the production of annihilation photon beams : they now approach primary electron beams in their energy, intensity, and range of application. (To be published in physics Today) Work supported by the U.S. Atomic E...