0 Se p 20 02 The Dynamical Parameters of the Universe
The results of different analyses of the dynamical parameters of the Universe are converging towards agreement. Remaining disagreements reflect systematic errors coming either from the observations or from differences in the methods of analysis. Compiling the most precise parameter values with our estimates of such systematic errors added, we find the following best values: the baryonic density parameter Ω b h 2 = 0.019 ± 0.02, the density parameter of the matter component Ω m = 0.29 ± 0.06, the density parameter of the cosmological constant Ω λ = 0.71 ± 0.07, the spectral index of scalar fluctuations n s = 1.02 ± 0.08, the equation of state of the cosmological constant w λ < −0.86, and the deceleration parameter q 0 = −0.56 ± 0.04. We do not modify the published best values of the Hubble parameter H 0 = 0.73 ± 0.07 and the total density parameter Ω 0 +0.03 −0.02 .
A Cosmological Model
(I) IT is familiar that the Einstein equations for the density and pressure in a uniform universe: do not suffice to specify the model since there are two equations and three unknown functions, ρ, p and R. A very common assumption is p = 0, but models involving both positive and negative values of p have also been proposed. McCrea1 pointed out that there is no objection in principle to negative pressure and that the steady-state universe can be interpreted in this way.
Simulation study of high power microwave generation by virtual cathode oscillation in coaxial vircator
Summary form only given, as follows. We have numerically simulated the high power microwave generation by virtual cathode oscillation in a coaxial vircator with 3 dimensional PIC code Magic. It is noted that the coaxial vircator has the advantage of an enhancement of power efficiency and gaining of narrow bandwidth frequency. The study is focused on the design of a diode structure for a coaxial vircator suitable for Chundoong IREB pulser (Max. 600 kV, 85 kA, 60 ns). It consists of a center annular cathode, a cylindrical meshed-anode and a reflector. The simulation results showed that the coaxial vircator can indeed be operated at the selected frequency with the narrow bandwidth and the microwave output power strongly depends on the position and geometry of the reflector. From this simulation results we expect that the maximum microwave output power will be obtained by the reflector of 4 cm in width and also 4 cm in distance away from the IREB, where the resonant frequency of microwave from coaxial vircator is simulated to be 6.577 GHz.