Improved masers for X-band and Ku band

Slow-wave structure of traveling-wave maser utilizes comb system which is comprised of ruby on one side and alumina on other; alumina also supports isolator material. Radiation at pump frequency is coupled to ruby through shaped alumina strips. Contact between ruby bars and comb completes conductance path for heat transfer

Resonant isolator for maser amplifier

An isolator is described for use in a low noise maser amplifier, which provides low loss across a wide bandwidth and which can be constructed at moderate cost. The isolator includes a train of garnet or ferrite elements extending along the length of a microwave channel parallel to the slow wave structure, with the elements being of staggered height, so that the thin elements which are resonant to the microwaves are separated by much thicker elements. The thick garnet or ferrite elements reduce the magnetic flux passing through the thin elements to permit altering of the shape of the thin elements so as to facilitate their fabrication and to provide better isolation with reduced loss, by increasing the thickness of the thin elements and decreasing their length and width

A 2.3-GHz maser at Usuda, Japan, for TDRSS-orbiting VLBI experiment

A 2.3 GHz traveling-wave maser/closed-cycle refrigerator (TWM/CCR) that is used in the DSN was installed and successfully operated on the 64 m antenna at Usuda, Japan. The TWM/CCR supported the first very long baseline interferometry (VLBI) experiment to use an orbiting spacecraft as one of the receiving antennas. The experiment required a 15 K receiving system over a 2271 to 2285 MHz bandwidth. The maser installation was made during June 1986, and successful VLBI measurements were made during July and August 1986 and again in January 1987

Dual-polarization 8.45 GHz traveling-wave maser

An 8.5 GHz dual-channel, dual-polarization traveling-wave maser (TWM) amplifier was installed in the XKR solar system radar cone at DSS 14. The TWM is based on the Blk IIA 8.45 GHz maser structure, with two of the four maser stages being used for each channel, and each maser half then followed by a high-performance GaAs FET amplifier to achieve the desired net gain. A shortened low-noise input waveguide and an orthogonal-mode junction which is cooled to 4.5 K feeds each amplifier chain. The rotation of an external polarizer permits the polarization of each channel to be defined as either linear or circular. A circular waveguide switch was also developed to provide for noise calibration and to protect the maser from incident transmitter power

Anisotropy in Fracking: A Percolation Model for Observed Microseismicity

Hydraulic fracturing (fracking) using high pressures and a low viscosity fluid allow the extraction of large quantiles of oil and gas from very low permeability shale formations. The initial production of oil and gas at depth leads to high pressures and an extensive distribution of natural fractures which reduce the pressures. With time these fractures heal, sealing the remaining oil and gas in place. High volume fracking opens the healed fractures allowing the oil and gas to flow the horizontal productions wells. We model the injection process using invasion percolation. We utilize a 2D square lattice of bonds to model the sealed natural fractures. The bonds are assigned random strengths and the fluid, injected at a point, opens the weakest bond adjacent to the growing cluster of opened bonds. Our model exhibits burst dynamics in which the clusters extends rapidly into regions with weak bonds. We associate these bursts with the microseismic activity generated by fracking injections. A principal object of this paper is to study the role of anisotropic stress distributions. Bonds in the $y$-direction are assigned higher random strengths than bonds in the $x$-direction. We illustrate the spatial distribution of clusters and the spatial distribution of bursts (small earthquakes) for several degrees of anisotropy. The results are compared with observed distributions of microseismicity in a fracking injection. Both our bursts and the observed microseismicity satisfy Gutenberg-Richter frequency-size statistics.Comment: 14 pages, 10 figure