Performance of a ballute decelerator towed behind a jet airplane

An F-104B airplane was modified to investigate the drag and stability characteristics of a ballute decelerator in the wake of an asymmetrical airplane. Decelerator deployments were initiated at a Mach number of 1.3 and an altitude of 15,240 meters (50,000 feet) and terminated when the airplane had decelerated to a Mach number of 0.5. The flight tests indicated that the decelerator had a short inflation time with relatively small opening forces. The drag levels attained with the subject decelerator were less than those obtained with other high-speed decelerators behind a symmetrical tow vehicle. The ballute demonstrated good stability characteristics behind the testbed airplane

Gyrotron experiments employing a field emission array cathode

The design and operation of a field emission array (FEA) cathode and the subsequent demonstration of the first FEA gyrotron are presented. Up to 10 mA from 30 000 tips was achieved reproducibly from each of ten chips in a gyrotron environment, namely, a vacuum 1 x 10(-8) mbar, -50 kV potential with multiple chip operation, The design parameters of the FEA gun were similar to those of a magnetron injection gun with an achievable electron beam current of 50-100 mA and measured power 720 W cw. Coherent microwave radiation was detected in both TE(02) at 30.1 GHz and TE(03) at 43.6 GHz, with a starting current of 1 mA

Numerical simulation of unconstrained cyclotron resonant maser emission

When a mainly rectilinear electron beam is subject to significant magnetic compression, conservation of magnetic moment results in the formation of a horseshoe shaped velocity distribution. It has been shown that such a distribution is unstable to cyclotron emission and may be responsible for the generation of Auroral Kilometric Radiation (AKR) an intense rf emission sourced at high altitudes in the terrestrial auroral magnetosphere. PiC code simulations have been undertaken to investigate the dynamics of the cyclotron emission process in the absence of cavity boundaries with particular consideration of the spatial growth rate, spectral output and rf conversion efficiency. Computations reveal that a well-defined cyclotron emission process occurs albeit with a low spatial growth rate compared to waveguide bounded simulations. The rf output is near perpendicular to the electron beam with a slight backward-wave character reflected in the spectral output with a well defined peak at 2.68GHz, just below the relativistic electron cyclotron frequency. The corresponding rf conversion efficiency of 1.1% is comparable to waveguide bounded simulations and consistent with the predictions of kinetic theory that suggest efficient, spectrally well defined radiation emission can be obtained from an electron horseshoe distribution in the absence of radiation boundaries.Publisher PD

Web-based Media Literacy to Prevent Tobacco Use among High School Students

Facilitator-led smoking media literacy (SML) programs have improved media literacy and reduced intention to smoke. However, these programs face limitations including high costs and barriers to standardization. We examined the efficacy of a Web-based media literacy program in improving smoking media literacy skills among adolescents. Sixty-six 9th grade students participated in a Web-based SML tobacco education program based on health behavior theory. Pre- and post-test assessments demonstrated statistically significant changes in the primary outcome of total SML as well as each of the individual SML items. However, there were inconsistent changes in other theory-based outcomes including attitudes and normative beliefs