Charge Transfer Losses Research Articles

Intracell charge-transfer structures for signal processing

An approach is presented for implementing a fully programmable transversal filter using surface charge-transfer techniques. Summation of the signals from each output tap is performed automatically by using common output electrodes, and fixed binary tap weights are Provided by selectively controlling the transfer of charge within each cell. Charge packets representing a sampled data input signal are inserted into individual cells where they remain until they are replaced by a new sample. Any combination of these packets can be nondestructively read during any clock cycle with the output being automatically summed. Since the charge does not leave the cell, but is simply sloshed back and forth within it during a read-out cycle, charge-transfer losses are not cumulative in this structure. The application of these structures in various familiar signal-processing functions is discussed, and both experimental results and theoretical expressions for their performance are presented. Experimental results on a simple test cell include reading the same charge more than 5 × 105times and demonstrating a charge-transfer loss of less than 10-7per transfer.

Trapping and Loss of Charged Particles in a Perturbed Magnetic Field

The properties of a nonadiabatic magnetic system for trapping and confining charged particles are derived. The trapping mechanism is a helical perturbation that matches the gyrations of an incoming particle beam. These particles, in resonance with the structure, convert their axial energy into transverse energy even in the absence of a magnetic mirror. By the same scheme, a spiraling beam could be straightened out. The best injection system is a four-conductor set, which is analyzed in detail. Once confined, the particles experience small and almost random nonadiabatic perturbations in their motion; they diffuse in both real and velocity space. A linear operator that governs this diffusion is presented; it is applicable to a uniform magnetic field with small perturbations. The velocity-space diffusion in a magnetic mirror is calculated for a general perturbation and in particular for a helical perturbation. For this last case, the injected particles can be confined for several hundred axial transits. If the charged particles are modified after being initially trapped (e.g., dissociation of molecular ions), the loss in physically realizable systems can be made virtually negligible compared with charge transfer and other conventional losses.