Linearity testing of LED transmitter and corresponding voltage to current op-amp configuration [abstract]

Abstract only availableThe LM7171 operational amplifier is made for high electrostatic discharge and fast signal performance. In a configuration using the diode in the transmitter and a resistor on the negative op-amp terminal, the op amp will convert the voltage measurement to a current value, which will then be sent linearly via the HFBR-1414MZ optical transmitter over optical fiber. First, the transmitter and receiver pair will be tested for linearity using a variable current source. Should data confirm linearity, the voltage to current op amp configuration will be tested. This paper presents the results of these tests. This project is sponsored by Los Alamos National Laboratory.Los Alamos National Laborator

Development of a RF Class E amplifier to power a ferroelectric plasma thruster [abstract]

Abstract only availableClass E amplifiers are a special class of electronic amplifiers which are highly efficient at delivering power at high frequencies. Class E amplifiers consist of a signal generator, switch, and two LC resonant circuits. The resonant circuits are tuned to a specific frequency, which requires the amplifier to be designed to a particular frequency. This amplifier is being developed to power the Ferroelectric Plasma Thruster (FEPT) which creates plasma when excited by a high voltage, high frequency signal. The FEPT has a piezoelectric resonance near 400 kHz, so an operating frequency of 375 kHz was selected for optimal performance. The goal of this project is to reduce the size and amount of equipment to operate the FEPT. Design goals require volume, weight, and electrical inputs to be kept to a minimum so that the amplifier and FEPT can be merged together into a small package

Characterization of runtime and jitter on a megavolt laser triggered spark gap switch [abstract]

Abstract only availableLaser triggering has been utilitzed in spark gap switches to initiate switch breakdown resulting in more reliable and repeatable switching. Many studies have focused on how various parameters of the switch or the laser triggering system affect the timing of the breakdown in an attempt to minimize the jitter associated with the switch. In preparation for a future study characterizing runtime and jitter with respect to switch and laser parameters, an extensive literature review of laser triggered spark gap switches has been completed. The focus of the study has consisted mainly on large megavolt switches similar to the 1 MV, SF6 filled, laser triggered gas switch installed at the University of Missouri pulsed power test stand. Factors including the applied field, rate of rise and gas pressure of the switch along with the laser power, focused intensity, and Rayleigh range have been examined to determine their relation to jitter and runtime. The end goal of research is to understand the factors contributing to increased jitter and runtime and thereby provide paths to improved switch performance.College of Engineering Undergraduate Research Optio

Avaliação da atividade sexual pré-zigótica de populações de Anastrepha fraterculus (Wiedmann, 1830) (Diptera: Tephritidae).

Neste trabalho foi avaliada a competitividade sexual pré-zigótica das populações de A. fraterculus: 1) selvagem; 2) laboratório (78° geração) e 3) laboratório esterilizadas

Disciplinarization of the mouth, the autonomy of the individual in a working society

Objectives: To analyze the dental health-illness process using the buccality concept proposed by Botazzo

Dynamics of electron beam ablation of silicon dioxide measured by dye laser resonance absorption photography

The dynamics of electron beam ablation plumes have been characterized through the application of dye laser resonance absorption photography. The ablation of fused silica by a channelspark electron beam was studied by probing the near-ground state, 3p2 1D−4s 1P03p21D−4s1P0 neutral Si transition at 288.158 nm. Necessary background gases (Ar or N2)N2) were tested at pressures of 15 or 30 mTorr. A two-lobed, Si atom plume shape was discovered that is hydrodynamically more complex than laser ablation plumes. These plumes merge into a single-lobed plume at about 400 ns after the e-beam current pulse rise. Plume front expansion velocities of Si atoms were measured at nearly 1 cm/μs, and are comparable to the expansion of laser ablated metal atom plumes with laser fluences of a few J/cm2. © 1998 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70034/2/APPLAB-73-18-2576-1.pd

Electron beam ablation of materials

The channelspark, a low accelerating voltage, high current electron beam accelerator, has been used for ablation of materials applied to thin film deposition. The channelspark operates at accelerating voltages of 10 to 20 kV with ∼1500 A beam currents. The electron beam ionizes a low-pressure gas fill (10–20 mTorr Ar or N2)N2) to compensate its own space charge, allowing ion focused transport. Ablation of TiN, Si, and fused silica has been studied through several plasma diagnostics. In addition, thin films of SiO2SiO2 have been deposited and analyzed. Strong optical emission from ionized species, persisting for several microseconds, was observed in the electron beam ablated plumes. Free electron temperatures were inferred from relative emission intensities to be between 1.1 and 1.2 eV. Dye-laser-resonance-absorption photography showed Si atom plume expansion velocities from 0.38 to 1.4 cm/μs for several pressures of Ar or N2N2 background gas. A complex, multilobed plume structure was also observed, yielding strong indications that an electron beam instability is occurring, which is dependent upon the conductivity of the target. Nonresonant interferometry yielded line-averaged electron densities from 1.6 to 3.7×1023 m−33.7×1023m−3 near the target surface. Resonant UV interferometry performed on Si neutral atoms generated in the ablation plumes of fused silica targets measured line integrated densities of up to 1.6×1016 cm−2,1.6×1016cm−2, with the total number of ablated silicon neutrals calculated to be in the range 2.0×10152.0×1015 to 5.0×1013.5.0×1013. Electron beam deposited films of fused silica were microscopically rough, with a thickness variation of 7%. The average SiO2SiO2 deposition rate was found to be about 0.66 nm/shot. The electron beam-deposited fused silica films had accurately maintained stoichiometry. Ablated particulate had an average diameter near 60 nm, with a most probable diameter between 40 and 60 nm. For SiO2SiO2 targets, the mass of material ablated in the form of particulate made up only a few percent of the deposited film mass, the remainder being composed of atomized and ionized material. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70186/2/JAPIAU-86-12-7129-1.pd

Competitividade sexual pré-zigótica em Mosca-das-frutas Anastrepha Fraterculus (Wiedmann, 1830) (Diptera: Tephritidae).

A mosca-das-frutas Anastrepha fraterculus é a principal praga da maçã e a técnica do inseto estéril seria uma alternativa para seu controle. O presente trabalho avaliou a competitividade sexual pré-zigótica entre três populações de A. fraterculus: selvagens, de laboratório e laboratório esterilizadas. O estudo foi conduzido em gaiolas teladas na Estação Experimental de Fruticultura de Clima Temperado (EEFCT), Vacaria, RS. A população selvagem foi obtida dos frutos de Feijoa sellowiana e as de laboratório obtidas da criação experimental do Laboratório de Entomologia da EEFTC, criadas artificialmente. O processo de esterilização foi realizado pelo Centro de Energia Nuclear na Agricultura, Piracicaba, SP, em pupas 24 horas antes da emergência, a uma taxa de 135,65 Gy/h. Logo após a emergência os adultos foram separados por sexo e alimentados de acordo com o sistema de criação. No dia anterior ao teste foram identificados com tinta. Os ensaios foram conduzidos às 8:00 da manhã liberando-se 30 machos de cada população e 30 minutos depois as respectivas fêmeas. Para população de laboratório foram usados adultos de 8 a 10 dias de idade e para selvagem de 15 a 18 dias. Para cada combinação foram realizadas oito repetições. Foram observados e capturados os casais formados registrando a cor e a duração das cópulas. Todas as observações foram realizadas do interior da gaiola durante 3 horas. Os casais foram separados em gaiolas de acordo com sua combinação para avaliação da viabilidade dos ovos. Os resultados foram analisados de acordo com o Índice de Isolamento Sexual (ISI) e os relativos à viabilidade de ovos foram comparados ao padrão da espécie. Os resultados indicaram que há compatibilidade sexual entre as populações, mas que o processo de radioesterilização afetou a competitividade sexual. Os ovos obtidos de cópulas envolvendo a população esterilizada geraram ovos inviáveis e as fêmeas estéreis não produziram ovos