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The radiation produced by a hollow, non‐neutral, rotating, relativistic E layer propagating inside a coaxial cylindrical drift tube has been investigated theoretically and experimentally. The measured radiation spectrum is very broadband in agreement with theory, though a shift in the spectrum can be achieved by a preloaded azimuthal density structure.

The production of high power microwave radiation at high harmonics of the electron cyclotron frequency by the interaction of a rotating electron beam with a magnetron‐type conducting boundary has been studied theoretically and experimentally using a 2‐MeV, 1–2‐kA, 10‐ns electron beam pulse. Approximately 10% of the electron beam power has been converted to microwave radiation at the 12th harmonic, and about 2% at the 20th harmonic. Radiation characteristics are in good agreement with a theoretical analysis of the resonant interaction of a beam mode with the modes of the conducting boundary system. Radiation from rotating beams in ‘‘glide‐symmetric’’ boundary systems is also reported.

Studies of the production of microwave and millimeter wave radiation at high harmonics of the relativistic electron cyclotron frequency by the interaction of a rotating E-layer with a multiresonator magnetron boundary system have been conducted. The interaction of a 2 MeV, 1-2 kA, 5 ns cusp injected E layer of radius 6 cm with 12, 20, and 40 slot magnetron type waveguides are studied. Approximately 10% of the injected electron beam power is converted to microwaves at 12c (10 GHz), 2% at 20c (17 GHz), and 1% at 40?c (34 GHz). We have theoretically examined this system via analyzing the resonant interaction of a doppler shifted electron beam mode with the modes of the conducting boundary system. The location of these resonant interactions in frequency agrees well with the observed spectrum.

The generation of high‐power bursts of microwave radiation from hollow, relativistic E layers injected through a cusped magnetic field into a magnetron‐type conducting boundary configuration has been studied experimentally. Using a 2‐MeV, 2‐kA, 5‐ns injected beam pulse, approximately 250 MW of radiated power have been generated at 9.6 GHz.

Research on microwave generation from rotating electron beams in various conducting boundary systems has been pursued with the major emphasis being on the production of radiation from rotating electron beams in magnetron like conducting boundary systems. These experimental configurations are new recognized as an entirely new type of microwave tube, referred to in the literature as a Gyromagnetron, High Harmonic Gyrotron, or Cusp Injected Magnetron (Cusptron). The interest in this new device has centered around its potential to reduce the required magnetic field in microwave tubes by an order of magnitude by allowing operation at a high harmonic of the electron cyclotron frequency. Results from research on millimeter and submillimeter waves produced by rotating electron beams in rippled magnetic fields, are also summarized in this report.

A high proportion of Cree and other North American Indian children have a chronic cough and many have bronchial wall thickening on radiographs, reminiscent of white children with asthma, mild cystic fibrosis, or immune deficiency. When compared to postmortem studies, radiographs underestimate the degree of bronchial wall thickening present. As compared to white children, Indian children in the first two years of life are more susceptible to recurrent bronchitis and pneumonia, are much more likely to develop pneumonia with rubeola and pertussis, and are more likely to develop chronic lung disease after adenovirus infections. Staphylococcal complications with pneumatocele formation are more common. A greater number acquire pneumonia while in hospital with other medical or surgical problems. Indian children with pneumonia recover more slowly, and some continue to deteriorate even after admission to hospital.