Congratulation to Meytal Siman Tov, Ph.D. student of Yakov Krasik, for winning the The Samuel Goldsmith Student Prize for her presentation in the 37th annual conference of the Israel Vacuum Society (IVS-IPSTA).

The topic of her presentation: Generation of Space Charge Self-Oscillations in a diode by Over-Injection.


Abstract: We propose a practical method to inject current higher than the space-charge limiting current into a vacuum diode . The current is produced in an arrangement of three electrodes (a triode) consisting of an accelerating voltage gap followed by a decelerating gap. The cathode emits a current lower than the space charge limit of the accelerating gap so that when the beam is not fully decelerated in the decelerating gap, it does not oscillate as it would in a reflex triode. This triode generated beam is then injected into a further gap which we consider to be an injected diode. When the injected current exceeds the space charge limited current of this gap a virtual cathode forms and the current self-oscillates by initiating triode oscillations. Electron bunches are formed at a frequency determined by the distance travelled in the triode.