Angular Distribution of Elastically Scattered Electrons Determined and Its Effect on Collector Performance Computed

It has been demonstrated that the suppression of secondary electron emission significantly improves the performance of electron beam collectors (ref. 1). However, a complete analysis of the effects of secondary electron emission with respect to collector performance has not been possible because of the lack of quantitative data on angular distributions of secondary electrons. Secondary electrons are emitted with energies ranging from near zero to the energy of the incident primary. For our purposes, we define elastically scattered electrons as secondary electrons within 20 percent of the incident energy. Elastically scattered electrons are of great concern because their energy allows them to follow trajectories that can carry them almost anywhere within the vacuum envelope. If these secondaries leave the collector and reenter the slow wave circuit, they can produce undesired signal distortion and oscillation.This apparatus, which was built by Krainsky (ref. 2), was used at the NASA Lewis Research Center to obtain detailed measurements of the angular distributions of elastically scattered secondaries. Data were obtained for three surfaces of significant interest to collector applications: highly polished copper, copper roughened by ion sputtering, and isotropic graphite. Lewis researchers discovered that elastically scattered electrons have a complex angular distribution that is strongly dependent on the atomic number and surface morphology of the target material, as well as the energy and angle of incidence of the primary beam. At low energies, secondary emission from polished copper in the chosen energy range is primarily directed back to the source of primary electrons (backscattering). Forward scattering increases with primary energy until, at high energies, forward scattering dominates the angular distribution. Although back-scattered secondaries dominate the distributions of the textured copper surface, the yield is substantially lower. From the standpoint of secondary emission, isotropic graphite is the most attractive material because it exhibits low yield and little back scattering

Sexuality in the Therapeutic Relationship: An Interpretative Phenomenological Analysis of the Experiences of Gay Therapists

This is an Accepted Manuscript of an article published by Taylor & Francis in Journal of Gay & Lesbian Mental Health on 17/10/2014 date, available online: DOI: 10.1080/19359705.2014.957882Lesbian, gay, bisexual, transgender, and queer (LGBTQ) clients have reported experiencing heterosexist/homophobic attitudes from heterosexual therapists, but this has seldom been discussed for gay therapists. Such experiences could impact the therapeutic process and a gay therapist’s willingness to self-disclose their sexuality. Self- disclosure of sexuality can be therapeutically beneficial for LGBTQ or heterosexual clients. Semi-structured interviews were conducted with seven gay male therapists and analyzed using Interpretative Phenomenological Analysis. Five themes emerged: affinity for work- ing with LGBTQ clients, heterosexual males’ resistance to the therapeutic process, the impact of homophobia within the therapeu- tic relationship, empathy through shared humanity, and utilizing therapist sexuality as a tool within the therapeutic relationship