Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | 2021
Miniature source of accelerated ions with focusing ion-optical system
Abstract
Abstract The paper describes a small-sized accelerated ion source developed on the basis of the KLAN-10M technological source. Record values of the ion current density ( j ≈ \xa095 mA/cm2) were obtained, which made it possible to use this source for problems of deep correction of the shape of X-ray optical elements. Formation of small beam (FWHM ∼ 1.5\xa0mm) with a Gaussian distribution of the ion current along the output aperture without cut-off diaphragms is the main feature of this source. A focusing ion-optical system makes it possible to change the beam size depending on the distance and the value of the accelerating voltage. Thus, this source allows deep final correction of the shape errors of the surfaces of optical elements and bringing it to subnanometer accuracy in terms of the RMS parameter in the range of spatial frequencies up to 1 . 3 ∗ 10 −3 μ m−1 for the case of conductive and up to 9 . 5 ∗ 10 −4 μ m − 1 for the case of dielectric materials. The special design of the neutralizing unit allows to fully compensate for the positive ion flux, avoiding heating the sample to 50 degrees Celsius at a distance of 10\xa0mm from the source, which is a necessary condition in a number of tasks. The influence of the thermal cathode-neutralizer on the ion density distribution of the beam is shown and explained.