The transient highly excited solar flare plasma

Recent observations of the energetic particles produced in solar flares indicate that the production of electrons, with energies up to about 100 keV, is a fairly common feature of small flares. In those flares the acceleration of protons and other nuclei does not extend beyond about 1 MeV.The X-ray emission often exhibits two distinct components of which the first one is produced by non-thermal, the second by thermal electrons through bremsstrahlung collisions with the ambient ions. Along with these X rays, radio emission, in the microwave region, is observed. This radio emission is usually interpreted as due to gyrosynchrotron radiation from the same electrons.In this review a discussion is presented of the processes occurring in solar flares with special reference to the acceleration and radiation processes.     

Scientific ballooning services

The services available for scientific ballooning are described with special emphasis on the facilities of the NCAR Balloon Flight Station at Palestine, Texas. The preparations for a typical launching, the operations during the launch, the flight and the recovery are described for illustrative purposes. Considerations on the future development of scientific ballooning are given; technological problems for extended flights are considered to be less serious than the political problems.     

A Pulsewidth-Modulated Dc-to-Dc Converter That Utilizes a Small Number of Components

In general, circuit reliability can be enhanced by either incorporating redundancy or by minimizing a circuits component count. Conventional nonregulating converters generally require two active devices, whereas in regulating converters or switching regulators as many as 10 transistors, either integrated or discrete, is not uncommon. A regulating dc-to-dc converter which provides useful regulation and which can be constructed with either two or three transistors is described.     

Effect of Observation Errors on Satellite Attitude Estimation

A study of the effect of observation errors on the best least squares estimate of satellite attitude based on two sets of direction measurements, where one set contains two independent measurements which are corrupted by zero-mean normally distributed additive errors, is summarized. Using Monte-Carlo techniques, the statistics of the estimated rotation of the satellite, from a known reference, were obtained. It was found that one of the parameterizations of the rotation, namely, the vector z, is best suited for estimation, since ?z is normally distributed with zero mean and its standard deviation is independent of the two direction measurements.     

A Test of the Effect of Satellite Spin on Two-Way Doppler Range-Rate Measurements

Analysis indicates that the rotation of a satellite can cause an error in the range-rate measurements of a two-way Doppler tracking system. The error is proportional to the rotation rate, and the constant of proportionality depends on the polarization of the satellite transponder antennas. Measurements made by ground-based simulation confirmed the analytical prediction.