The effect of a radial electrostatic field upon the resistance of tungsten in high vacua was reinvestigated employing lower pressures and better vacuum technique than in the original experiments of Worthing et al. Wires of 0.004-in. and 0.00045-in. diameter were subjected to negative and positive fields (retarding or assisting respectively electron motion from filament to plate) up to 9.0×${10}^6$ and 1.4×${10}^6$ volts/cm, respectively. The resistance abruptly decreased upon application of the electric field, increased slightly with time while the field was constant, and increased abruptly upon removal of the field regardless of the direction of the field. The abrupt increase was usually somewhat less than the abrupt decrease. The abrupt resistance changes satisfied the equation $\Delta R=\alpha E^{\frac{1}{2}}$, where $\Delta R$ is resistance change, $E$ is applied field in volts/cm×${10}^{-6\mathrm{}}$, and $\alpha =0.46\mathrm{}$. A large part of the small resistance change with constant field was due to an observed filament temperature increase resulting from bombardment by the electronic portion of the observed ion-, photo-, and field-emission current. It was found that the photo and ion currents were much larger than the field-emission currents. No observable electrostatic effect was found which could account for the abrupt resistance changes. It has not been possible to offer a theory for the observed effects.

Close

PrevNext

View figure in article