Design studies of positron collection for the NLC

The positron source for the NLC project utilizes a 6.2 GeV electron beam interacting in a high-Z positron production target. The electromagnetic shower in the target results in large energy deposition which can cause damage to the target. Optimization of the collection system is required to insure long-term operation of the target with needed high positron yield into the 6-dimensional acceptance of the subsequent pre-damping ring. Positron tracking through the accelerating system indicates a dilution of the initial positron phase space density. Results of the studies on the development of the collector systems design are presented