Nonuniform Electron Research Articles

Start-oscillation conditions of tapered backward-wave oscillators

Coupled-mode theory is employed to describe the interaction between nonuniform electron beams and circuits. It is then applied to determine the start-oscillation conditions of a tapered backward-wave oscillator. It is shown that under high space-charge operating conditions where the coupling to the fast space-charge wave is negligible and for weak circuit tapers, an approximate closed form solution of the coupled-mode equations can be obtained through a Wentzel-Kramers-Brillouin-Jeffreys approximation. The start-oscillation conditions are then determined approximately from such a solution.

The energy and the Dirac density matrix of a non-uniform electron gas

S>Dirac's density matrix is found in a self-consistent framework. The problem of electrons moving in a periodic lattice of protons is considered, and difficulties of introducing Hartree fields associated with inner electrons are circumvented. For the conduction electrons, a Hartree description is adopted essentially. Physical significance of the results is enhanced by including screening from the outset. (L.N.N.)

Dipole Resonant Modes of an Ionized Gas Column

It is shown by a quasi-static treatment there is not one but a multiplicity of plasma resonant modes which will emit dipole radiation in a cylindrical column of ionized gas with a radially symmetrical but non-uniform electron density. It is shown that the multiple resonances obtained by Romell in scattering of short waves from a gas discharge column may be qualitatively explained assuming a reasonable electron distribution.

Improvements in design and operation of image iconoscope type camera tubes

Television camera tubes using high-velocity electrons for scanning show a number of undesirable characteristics. These include spurious signals and edge flare, which are due to non-uniform secondary electron redistribution effects and, in addition, there is no true “black level” information in the picture signal.Effects due to uneven redistribution can be considerably reduced if the average storage surface potential is shifted negatively from that reached under normal operating conditions. In an improved design of the “Photicon” image iconoscope, this potential change is achieved by flooding the storage surface with low-velocity electrons, which are emitted from a large annular photo-emissive surface surrounding the storage plate. Suitably biased electrodes direct the low-velocity electron rain in such a manner as to compensate for the non-uniformity of the residual redistribution.The use of the new tube also allows simplification of the camera control unit. As the “black” picture signal is constant in relation to the interline pulses produced by beam suppression, it is no longer necessary to evaluate the blackest part of the picture signal in order to set the “black level”. A simple “clamp circuit” is sufficient and results in a very satisfactory transmission of the average brightness component of the picture.

The Admittance of High Frequency Gas Discharges

The admittance of a high frequency gaseous discharge between parallel plates has been measured as a function of pressure and discharge current. The susceptance is observed not to be proportional to the conductance. In fact the discharge susceptance changes sign from negative at low pressures and low electron densities to positive at high electron densities and high pressures. The discharge admittance is expressed as a volume integral over the complex conductivity. The non-linear relationship between discharge susceptance and conductance is shown to be a consequence of the non-uniform electron density along the direction of the field.