Development and performance of power processor system for 2-gigahertz, 200-watt amplifier for communications technology satellite

The electrical and environmental requirements for a power processor system (PPS) designed to supply the appropriate voltages and currents to a 200-watt traveling wave tube (TWT) for a communication technology satellite is described. A block diagram of the PPS, the interface requirements between the PPS and spacecraft, the interface requirements between the PPS and 200-watt TWT, and the environmental requirements of the PPS are presented. Also included are discussions of protection circuits, interlocking sequences, and transient requirements. Predictions of the flight performance, based on ground test data, are provided

Performance of field-emitting resonating carbon nanotubes as radio-frequency demodulators

International audienceWe report on a systematic study of the use of resonating nanotubes in a field emission (FE) configuration to demodulate radio frequency signals. We particularly concentrate on how the demodulation depends on the variation of the field amplification factor during resonance. Analytical formulas describing the demodulation are derived as functions of the system parameters. Experiments using AM and FM demodulations in a transmission electron microscope are also presented with a determination of all the pertinent experimental parameters. Finally we discuss the use of CNTs undergoing FE as nanoantennae and the different geometries that could be used for optimization and implementation. © 2011 American Physical Society

Kinetics of Moisture Sorption and Reverse Bias Degradation in Chip Tantalum Capacitors

Exposure of chip MnO2 tantalum capacitors to humid environments might result in increased ESR, leakage currents, and first turn-on failures. However, there is a lack of literature data on the effect of moisture on reverse bias behavior of the parts. The presence of moisture can also result in pop-corning when a high water vapor pressure develops when moisture absorbed in pores of tantalum slugs vaporizes instantly during soldering process resulting in damage to capacitors. A study of kinetics of moisture ingress to and release from active elements of capacitors would allow a better understanding of degradation mechanisms and is important for preventing failures. In this work, a technique for investigation of moisture sorption and desorption in solid chip tantalum capacitors that employs tantalum slugs as a humidity sensor have been developed and kinetics of the process analyzed for different types of capacitors at temperatures from room to 125 C. A model that relates diffusion characteristics of polymer cases and size of the slugs to characteristic times of moisture sorption has been developed. A strong effect of moisture on long-term degradation of reverse bias currents in MnO2 cathode capacitors has been demonstrated and physical mechanisms discussed

Space related biological and information studies Annual report, Mar. 1968 - Mar. 1969

Space related biotelemetry research - multichannel implantable telemeter, subcarrier oscillator, and ion concentration transducer

Practical quantum realization of the ampere from the electron charge

One major change of the future revision of the International System of Units (SI) is a new definition of the ampere based on the elementary charge \emph{e}. Replacing the former definition based on Amp\`ere's force law will allow one to fully benefit from quantum physics to realize the ampere. However, a quantum realization of the ampere from \emph{e}, accurate to within $10^{-8}$ in relative value and fulfilling traceability needs, is still missing despite many efforts have been spent for the development of single-electron tunneling devices. Starting again with Ohm's law, applied here in a quantum circuit combining the quantum Hall resistance and Josephson voltage standards with a superconducting cryogenic amplifier, we report on a practical and universal programmable quantum current generator. We demonstrate that currents generated in the milliampere range are quantized in terms of $ef_\mathrm{J}$ ($f_\mathrm{J}$ is the Josephson frequency) with a measurement uncertainty of $10^{-8}$. This new quantum current source, able to deliver such accurate currents down to the microampere range, can greatly improve the current measurement traceability, as demonstrated with the calibrations of digital ammeters. Beyond, it opens the way to further developments in metrology and in fundamental physics, such as a quantum multimeter or new accurate comparisons to single electron pumps.Comment: 15 pages, 4 figure

Evaluation of the energetic cost of bacterial elimination of E. Coli using the electroporation technique in cuvette vessels

In the last two years, the percentage of cases in Peru linked to diarrheal diseases in children has been considerably reduced, demonstrating that even in difficult times health must always be our greatest strength. Of course, fulfilling this desire requires that all Peruvians have access to treated water sources to comply with their personal hygiene duties. However, nearly 3 million Peruvians live without access to drinking water and leave their health to the fate of natural water sources with high probabilities of containing bacteria and viruses. Under this premise, the purpose of this thesis was to show the effectiveness of an alternative water sterilization treatment that could be of great help to these Peruvians in need. A methodology based on the 'electroporation' technique was developed through the application of low and high intensity electric field pulses, seeking to damage the cell membrane of Escherichia coli (E. coli) bacteria and inactivate their growth in contaminated water volumes. The E. coli cell was cultured in the laboratories of the University of Engineering and Technology and diluted in 9 ml of tap water to form a theoretical suspension of 480 CFU/ml of water. To meet the objective, pulses of 1, 5, 6, 10 and 15 kV/cm were applied to the contaminated water through cuvettes (400 μl) and the percentage of bacteria surviving the treatment was documented using the colony counting technique in Petri dishes. Respective measurements of pH, absorbance, and temperature of the water samples, as well as electrical measurements of the cuvettes, were performed moments before and after the application of the pulses. With this it was concluded that 1 kV/cm was sufficient to inactivate between 50-70 % of E. coli colonies when unipolar type pulses are applied in a time range of 20-22 μs. The minimum energy required to meet this result was simulated using MATLAB software and was 0.06092 J. This study did demonstrate that electric field is an effective physical phenomenon capable of sterilizing tap water samples using cuvette containers

Survey report on the state-of-the-art of cryogenic thermometry and signal conditioners and their potential for standardized space hardware

The possibility of standard low temperature detector(s) for use in upcoming cryogenically cooled satellite and Space Shuttle Payloads was investigated. These payloads operate from .3 Kelvin to 300 Kelvin. Standard detectors were selected and matching signal conditioning equipment were specified. This equipment will operate in a spacecraft environment and be compatible with the selected detector, typical spacecraft voltages, typical spacecraft telemetry systems, and the radiation encountered by a typical earth orbiting spacecraft. Work statements to better define and advance detector performance are presented