Design issues in the scanning and beam extraction devices in high power accelerators

High Power Electron Accelerators with more than 100 kW power in the energy range 0.7-2.5 MeV are used in environmental applications like treatment of flue gas and industrial wastewater. The electron beam is extracted from vacuum into atmosphere through a thin Titanium foil for this purpose. For a cost-effective industrial process, the power loss in the extraction window needs to be minimized as far as possible. The 20-30 mm diameter beam is also scanned along and across the foil to distribute the loss and to impart correct dose to the job. In this paper, we discuss the design considerations for the scanning system and extraction devices in such accelerators. (author)