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The design of an electrostatic variable energy positron beam for studies of defects in ceramic coatings and polymer films
(ScienceDirect, 2002-06-22) Abadjieva, E.; Schut, Henk; Alba García, A.; Escobar-Galindo, Ramón; Veen, A. van; Pimblott, S.M.; Universidad de Sevilla. Departamento de Física Aplicada I
An electrostatic variable energy positron beam for studying defects in ceramic coatings, polymer films and MOS-devices is developed for operation in Doppler-broadening (DB) and positron annihilation lifetime (PAL) modes. In DB mode the implantation energy can be varied between 3 and 30 keV with a beam diameter on the target ranging from 0.4 to 0.5 mm FWHM. In PAL mode the start-signal is given by secondary electron emission from a 25 nm thin carbon foil placed in front of the target. After passing the foil the positron beam is focused on the target with a spot size of 2 mm FWHM at 1 keV down to 0.6 mm FWHM at 30 keV. The target chamber is equipped with an in situ four-point bending device for studying defects introduced by tensile and compressive stresses.