The ANL HVEM-tandem accelerator facilities

Abstract

The ANL HVEM-TANDEM accelerator facilities are being developed to provide a unique combination of techniques for basic studies in the field of materials science. In addition to the methods of high voltage electron microscopy, the ion accelerator system will provide ion beam analysis and ion bombardment - implantation capability either in the HVEM or in an adjacent target area. The installation of the HVEM is completed and constitutes the first step in the development of a materials research laboratory, which will include a HVEM/ion beam interface with a 300 kV ion accelerator and a 2-MV tandem accelerator. The plan layout of these facilities is shown schematically in Figure 1.ANL's 1.2 MeV HVEM is an improved version of the AEI EM-7 and has a guaranteed resolution of 5 Å point-to-point. The design of the microscope contains a number of unique features. These include a specially designed ion beam access flight tube, instrumentation for two independently adjustable dark field conditions, 100 - 1200 kV continuous-mode accelerating voltage selection, a negative ion trap, and an ion- pumped specimen chamber.