CUSTOM-TAILORED DOSE WITH THE IMPELA ELECTRON IRRADIATOR

For maximum utilization of the electron beam, the exposure dose should be tailored to match the geometric and density variations in the prod uct. Such tailoring has already been demonstrated [1] with the spot sc anner, which lays down a series of overlapping ''spots'' of controlled intensity across the product. Tbe new IMPELA macroscanner sweeps ever y beam pulse across the entire width of the product, and can also be a djusted to provide a non-uniform surface dose. Experience with the spo t scanner is summarized, and new experimental results with the macrosc anner are presented. The experiments illustrate the flexibility in exp osure-dose distribution that can be achieved by varying the beam pulse duration and timing relative to the scan waveform.