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The design study and the general aspect of a linear electron accelerator is described. Since this linear accelerator is used for the injector of the strong focusing synchrotron under construction, the spread of the output energy is desired to be as small as possible. For this purpose the cause of the energy spread has been reexamined and divided into two kinds; one is the different phase motions of the electrons injected at the various phase angles and the other is the variations of the microwave power, frequency, and other parameters. the careful design, especially on the buncher, and the use of the prebuncher and the stable power system, the output energy spread of about three percents has been obtained at the energy of 6.5 MeV.

The microware spectrum of the hyperfine components of the J =1←0 and J =2←1 rotational transitions of ICN molecule has been measured and the dependence of quadrupole coupling constant on the vibrational state was found. The values of ( e q Q ) I for each vibrational state are as follows

Zeeman effects in the absorption spectra of formaldehyde H 2 CO, HDCO, and D 2 CO were studied in microwave region with magnetic field of 1500∼300 oersteds. The effective g -values in several rotational states and the elements of g -tensor g a a , g b b , and g c c of these molecules were determined. Dependences of the effective g -values on the rotational quantum numbers J , τ were consistent among these isotopically substituted molecules. The components of the g -tensors of these molecules have been found to be g a a =2.86±0.04 for H 2 CO, 2.00±0.05 for HDCO, and 1.46±0.05 for D 2 CO. They are extraordinarily large compared to those of other molecules already known. A brief qualitative interpretation is given.

Resonance peaks observed near the ion cyclotron harmonics (\(n{\leqslant}5\)) of H + , H 2 + and H 3 + are studied in a low density plasma column. According to the dependences on r f voltage applied across a plasma column and electron temperature of the resonance frequency, it is conjectured that the behaviour of these resonances is caused by the electrostatic ion cyclotron waves propagating almost perpendicular to the magnetic field. Ions collected by ion collectors and electrodes are accelerated perpendicularly up to 3 keV, while the electron temperature displays little increase. The observed plasma loading indicates that the efficiency of power transfer between the electrodes and the plasma is greater than 50 per cent.

A power klystron amplifier and its driver system for a 6 MeV linear electron accelerator are described. The klystron is evacuated during its running by specially designed two oil diffusion pumps connected in series. Without using a liquid nitrogen trap the klystron works stable with the peak power output of 2–3 MW. The average life of the oxidecoated cathode was more than 500 hours. In order to keep a good frequency stability a feed back oscillator with an invar cavity and a travelling wave tube is used as a master oscillator. The output of this oscillator is 1–2 W at a frequency of 2759 Mc, with the fluctuation being less than 20 kc. The output signal of the oscillator is amplified by a pulsed travelling wave tube amplifier to drive the power klystron.

An explanation is presented for the existence of hydromagnetic waves in a partialiy ionized gas discharge that do not damp in a weak magnetic field and tend to have a phase velocity of the sound wave in a stronger field. Equation for a low frequency osciliation with smali amplitude in a plasma in a uniform magnetic field are used in the analysis. (C.E.S.)