8,918 research outputs found
High-power Ka-band amplifier
Development of a high-power tube suitable to power a Ka-band (34.5-GHz) antenna transmitter located at the Goldstone, California, tracking station is continuing. The University of Maryland Laboratory for Plasma Research and JPL are conducting a joint effort to test the feasibility of phase locking a second-harmonic gyrotron both by direct injection at the output cavity and by using a priming cavity to bunch the electrons in the beam. This article describes several design options and the results of computer simulation testing
Voltage source ac-to-dc converters for high-power transmitters
This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters
Metric Perturbations and Inflationary Phase Transitions
We study the out of equilibrium dynamics of inflationary phase transitions
and compute the resulting spectrum of metric perturbations relevant to
observation. We show that simple single field models of inflation may produce
an adiabatic perturbation spectrum with a blue spectral tilt and that the
precise spectrum depends on initial conditions at the outset of inflation.Comment: 4 pages, 3 figures, COSMO-99 Proceeding
The 250-kW CW klystron amplifier for planetary radar
The design, construction, and performance testing is described of two Varian klystrons, model VKX-7864A, which replaced the aging and less efficient VA-949J klystrons in the X band planetary radar transmitter on the Goldstone, CA, 70 meter antenna. The project was carried out jointly by the JPL and Varian Assoc. Output power was increased from 200 to 250 kW continuous wave per klystron, and full dc beam power is dissipated in the collector (it was not possible to operate the VA-949J klystrons without RF drive because of limited collector dissipation capability). Replacements were made with a minimum of transmitter modifications. The planetary radar transmitter is now operating successfully with these two klystrons
Design and test of a 2.25-MW transformer rectifier assembly
A new 2.25-MW transformer rectifier assembly was fabricated for DSS-13 at Goldstone, California. The transformer rectifier will provide constant output power of 2.25 MW at any voltage from 31 kV to 125 kV. This will give a new capability of 1 MW of RF power at X-band, provided appropriate microwave tubes are in the power amplifier. A description of the design and test results is presented
2015 Valedictory Address: Nicholas R. Cormier \u2715
Speech given by valedictorian Nicholas Cormier at the 169th Commencement Exercises of the College of the Holy Cross, May 22, 2015.https://crossworks.holycross.edu/valedictory/1002/thumbnail.jp
- …