High Power microwave vacuum windows are an essential component in developing 1 MW/CW gyrotrons. The thesis focuses on thermal and mechanical analysis of three different microwave window designs. These include the present double disk window, a distributed window being developed by General Atomics and a single-disk diamond window design. The output microwave window is currently the limiting facto...

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β < 2...

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β > 2...

The method of constructing of rotation curve for our galactic disk is developed. Simple physical model shows that the velocity of the Sun around the center of the Galaxy must be less than currently accepted IAU value 220 km/s. Independently obtained result for neutral hydrogen (λ = 21.1 cm) confirms the previous statement. The values of the Sun’s velocity is about 110 km/s. As a consequence, th...

Active galaxies are thought to be both fueled and obscured by neutral gas removed from the host galaxy and funneled into a central accretion disk. We performed a VLA imaging survey of 21 cm absorption in Seyfert and starburst nuclei to study the neutral gas in the near-nuclear environment. With the exception of NGC 4151, the absorbing gas traces 100 pc scale, rotating disks aligned with the out...

The feasibility of mid-infrared (MIR) lasing in erbium-doped gallium lanthanum sulfide (GLS) micro-disks was examined. Lasing condition at 4.5 µm signal using 800 nm pump source was simulated using rate equations, mode propagation and transfer matrix formulation. Cavity quality (Q) factors of 1.48 × 10(4) and 1.53 × 10(6) were assumed at the pump and signal wavelengths, respectively, based on s...

We present a radiative transfer model which computes the spectral energy distribution of a passive, irradiated circumstellar disk, assuming the grains are in radiative equilibrium. Dependence on the radial density profile, grain temperature estimation, and optical depth profiles on the output SED are discussed. The best fit model for HR 4796A has a minimum and maximum spherical grain size of 2....

Exhibiting a very high surface area, good electrical conductivity and density of active sites, nitrogen-doped graphenic materials are considered as promising catalysts for the oxygen reduction reaction (ORR). Seldom studied in acidic media, N-doped foams were tested here cathode polymer electrolyte membrane fuel cell (PEMFC). The prepared via solvothermal-based process, by reacting either cyclo...

We report a high resolution (0: 00 2), 15 GHz survey of a sample of 48 low-luminosity active galactic nuclei with the Very Large Array 1. Compact radio emission has been detected above a ux density of 1.1 mJy in 57% (17 of 30) of low-ionization nuclear emission-line region (LINER) nuclei and low-luminosity Seyferts. The 2 cm radio power is signiicantly correlated with the emission-line ((O I] 6...

A new molecular hydrogen cloud is found in the sub-damped Lyα absorber [logN(H i) = 19.88± 0.05] at the redshift zabs = 1.15 toward the bright quasar HE 0515–4414 (zem = 1.71). More than 30 absorption features in the Lyman band system of H2 are identified in the UV spectrum of this quasar obtained with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope. The H2-bea...