The operational characteristics of the Cosmotron were reviewed in brief. Since a rather complete account of this machine is now available in the September 1953 issue of Rev. Sci. Inst., this summary will include only the more recent utilization of the machine as a research instrument.

A comparison between the performance of the d-c unit as a pump and as a generator is presented.

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A summary of operating experience and observations obtained during approximately 5OO hrs of running time on the PuP lead-bismuth forced circulation system is given. (auth)

A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup6} watts peak at 202.5 mo. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type. Output currents are 3 x 10 {sup-9} ampere average, and 50 {mu}a peak. The beam has a diameter of 1 cm and an angular divergence of 10{sup-3} radians.