Maximum Power Capability Research Articles

A versatile force balance for ultrasound power measurement

The passing decades have witnessed many designs of instrument for measuring the radiated power output from ultrasound equipment, both in the low power, diagnostic range and in the higher power range as used in therapy, for example. Criteria to be considered during design, encompass the following: high sensitivity/resolution- to microwatts; power handling to tens of watts; simplicity of use and calibration; quick response time; stability of readings and zero; the need for a frequency-independent linear response; ability to accept all current sizes of transducer; portability and ruggedness. The criteria must be accommodated in a single instrument. This paper starts with a brief review of but some of the previous designs, and identifies a fundamental problem with many. The instrument here described hopefully eliminates this problem and essentially meets the above criteria. Using the force-balance principle, the instrument has a 70 mm diameter reflecting target, plus a concentric absorber, in a water-filled chamber. The maximum sensitivity is 1 mW FSD, resolution better than 50 mu W and a maximum power capability of 10 W. The instrument is very portable, weighing only 3 kg.

4495136 Maximum power capability blanket for nuclear reactors : Thomas M Camden, William Orr assigned to Westinghouse Electric Corp

4495136 Maximum power capability blanket for nuclear reactors : Thomas M Camden, William Orr assigned to Westinghouse Electric Corp

RCA Satcom: An example of weight optimized satellite design for maximum communications capacity

The communications mission of RCA Satcom entails antenna beam coverage of all fifty states, with Hawaiian service provided by an offset spot from the primary beam for the contiguous 48 states and Alaska. To achieve minimum cost per channel in the competitive U.S. domestic market, Globcom and Alascom specified that their satellite should (1) incorporate 24 wide-band transponder channels in the commercial, 4 6 GHz band, (2) contain sufficient power and orbit control capacity to maintain all 24 channels operating continuously for a minimum of eight years, and (3) be compatible with the Delta 3914 launch vehicle, whose development they had funded jointly with the McDonnell-Douglas Astronautics Corporation at no cost to the U.S. government. This combination of requirements thus defined a communications satellite whose channel capacity is twice that of other current Delta class spacecraft but whose cost, including the launch vehicle, is significantly less than that of the corresponding 24-channel Atlas-Centaur class spacecraft designs. To meet these demands weight-optimized designs were needed in four key subsystem areas: antennas, transponder multiplexers, power supply, and attitude control as well as in the structure itself. The resultant three-axis stabilized spacecraft design with sun-oriented solar panels provides maximum power and weight capability to the primary communications payload within the launch vehicle envelope.

Q-Switching and Cavity Dumping of Nd:YAlG Lasers

Experiments in Q-switching and cavity dumping of a Nd:YAlG laser have been carried out. The system in either case is composed of a Nd:YAlG folded cavity laser and an intracavity acousto-optic modulator made of fused silica and Brewster cut. Q-switching is achieved by first feeding the modulator with an acoustic pulse of sufficient duration and intensity to keep the laser below threshold (hold off pulse). Termination of the acoustic pulse allows the power inside the laser cavity to build up. A second short acoustic pulse, introduced to the modulator at the time when the internal energy reaches its maximum, couples the energy out of the cavity. This pulse may also be the beginning of the hold off pulse. Cavity dumping is accomplished by feeding the modulator with short acoustic pulses at fixed intervals. In the Q switching mode the system can operate with a maximum repetition rate of about 30 kHz. In the cavity dumping mode of operation the repetition rate of the light pulses can be controlled from 125 kHz to several MHz. The minimum pulse duration obtained in both modes of operation was about 80 nsec. The average power can reach 2 W, which is the maximum cw power capability of the laser used.