Accession Number : AD0089979

Title :   THE CYCLOTRON RESONANCE OF FREE ELECTRONS IN WEAK MAGNETIC FIELDS.

Descriptive Note : Technical rept.,

Corporate Author : RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ SCHOOL OF CHEMISTRY

Personal Author(s) : Torrey, H. C. ; Codrington, R. S.

Report Date : 1954

Pagination or Media Count : 19

Abstract : An investigation was made of the cyclotron resonance of free electrons as a means of providing a sensitive indication of magnetic field changes at low fields of the order of the earth's field. The electrons were produced by a thermionic emitter and were accelerated at resonance in the presence of a magnetic field by a RF electric field. The absorption by the electrons of power from the RF field was detected directly. The apparatus consisted of a RF head which includes a vacuum chamber in which an electron beam is passed between the rectangular plates of a condenser. The electron beam is produced by an electron gun consisting of a thoriated tungsten filament, an accelerating grid, and a decelerating cylindrical electrode. One of the plates of the condenser is grounded to the wall of the chamber; a lead from the other is brought out through a vacuum seal. The condenser is connected in parallel to a RF coil and a variable tuning condenser. The whole array forms a tank circuit of a regenerative oscillator to the Pound-Watkins type. The RF head is placed at the center of a pair of large-precision Helmholtz coils with a field-to-current ratio of 11.193 gauss/amp. The theory is discussed for 3 processes by which the life of an electron may be terminated: the electron drifts out of the absorbing field, the electron strikes an electrode, or the electron strikes a residual gas molecule. The tests demonstrated that narrow resonances of high intensity can be obtained from the free electron-cyclotron effect at fields comparable to that of the earth.

Descriptors :   *ELECTRONS, *RESONANCE ABSORPTION, DETERMINATION, RADIOFREQUENCY, RESONANCE.

Distribution Statement : APPROVED FOR PUBLIC RELEASE