Decoupling Ion Efficiency from Impedance in Pulsed Power Diodes.
NAVAL RESEARCH LAB WASHINGTON DC
Pagination or Media Count:
Classical axial diode theory links the impedance of a diode to its ion production efficiency i.e., the fraction of diode power carried by ions. This linkage stems from the dependence of both impedance and efficiency on the aspect ratio of the given device. This ratio is defined as the cathode outer radius, R, divided by the axial anode-cathode A-K gap, D. Numerical simulations and experiments have been completed which demonstrate that the ion efficiency, eta sub i, is strictly proportional only to the typical pathlength, L, of electrons in the A-K gap and that this length need not be related to R. Specifically, a radial pinch-reflex diode geometry is examined in which the anode is a cylindrical shell of radius, R D and of length 2L. For this device, eta sub i is found to vary as LD while the impedance, Z sub d, varies as RD. This decoupling of eta sub i from Z sub diode offers significant new possibilities for high powerhigh voltage intense ion beam sources as well as for high powerlow voltage intense electron beam sources. A series of numerical simulations using the PREMAS diode-modeling code have been completed for diode geometries which demonstrate both of these applications. Preliminary experimental results confirm the theory as well as the numerical predictions. Author
- Electrical and Electronic Equipment
- Theoretical Mathematics
- Electricity and Magnetism