The novel ultrastable HVEE 3.5 MV Singletron ™ accelerator for nanoprobe applications

Abstract

Recently, HVEE has completed a novel 3.5 MV single ended accelerator (Singletron ™) for the University of Leipzig, Germany. For one of the main applications, the system will be connected to a nanobeamline to achieve submicron resolution. Because the energy stability and ripple of the beam, and beam brightness are of vital importance for the performance of a nanoprobe, special care has been taken in optimizing these parameters. The system consists of an RF source which is directly mounted on the accelerator tube, a switching magnet to bend the beam into a chamber for standard analysis purposes and an analysis magnet that directs the beam into the nanoprobe. The stability of the beam energy was measured at a terminal voltage of 1.881 MV. These measurements were taken during factory acceptance with large production equipment operational, which negatively influenced the stability of the mains. The measured stability was found to be approx. ±50 eV over 5 h, but it is anticipated that this figure will be as good as ±20 eV (i.e. ∼ 10 −5) under normal laboratory conditions. The terminal voltage ripple was measured at 2.25 MV to be 25 V pp (i.e. ∼ 1.1 × 10 −5). Finally, the beam brightness of a 2.25 MeV hydrogen beam was measured by the use of two micrometer slit systems. A brightness of approx. 18 Amps · rad −2 m −2 eV −1 was obtained. In this article we will describe the considerations which have led to the layout of the present system.