Design issues and fatigue lifetime of hypervapotron elements of the JET neutral beam injectors

Recent results on high heat flux testing of hypervapotron beam stopping elements are discussed. Two issues are being addressed: a) fatigue lifetime of components presently used at JET, and b) performance of the optimised hypervapotron element for the new Box Scraper. Results of the tests confirmed that a) beam stopping elements installed at JET can be used with confidence for several more years, and b) new hypervapotron element can sustain higher power load (peak power density of 13 MW/m/sup 2/ and total power of 0.7 MW) at moderately increased water flow velocity.