THE NOVEL ULTRASTABLE HVEE 3.5 MV SINGLETRON(TM) ACCELERATOR FOR NANOPROBE APPLICATIONS

Recently, HVEE has completed a novel 3.5 MV single ended accelerator ( Singletron((TM))) for the University of Leipzig, Germany. For one of t he main applications, the system will be connected to a nanobeamline t o achieve submicron resolution. Because the energy stability and rippl e of the beam, and beam brightness are of vital importance for the per formance of a nanoprobe, special care has been taken in optimizing the se parameters. The system consists of an RF source which is directly m ounted on the accelerator tube, a switching magnet to bend the beam in to a chamber for standard analysis purposes and an analysis magnet tha t directs the beam into the nanoprobe. The stability of the beam energ y was measured at a terminal voltage of 1.881 MV. These measurements w ere taken during factory acceptance with large production equipment op erational, 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. simi lar to 10(-5)) under normal laboratory conditions. The terminal voltag e ripple was measured at 2.25 MV to be 25 V-pp (i.e. similar to 1.1 x 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 ap prox. 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 p resent system.