Chopping and transport of high-intensity ion beams

  • In this thesis, a novel 257 kHz chopper device was numerically developed, technically designed and experimentally commissioned; a 4-solenoid, low-energy ion beam transport line was numerically investigated, installed and experimentally commissioned; and a novel massless beam-separation system was numerically developed. The chopper combines a pulsed electric field with a static magnetic field in an ExB or Wien-filter type field configuration. Chopped beam pulses with a 257 kHz repetition rate and rise times of 110 ns were experimentally achieved using a 14 keV helium beam. Due to the achieved results, the complete LEBT line for the future Frankfurt Neutron Source FRANZ is ready to deliver a dc or a pulsed beam. At the same time, the LEBT section represents an attractive test stand for the study of low-energy ion beams. It combines magnetic lenses, which allow space-charge compensated beam transport, and a chopper system capable of producing short beam pulses in the hundred nanosecond range. Since these beam pulses are transported onwards, their longitudinal and transverse properties can be analyzed. The pulse duration and time of flight are well below the rise time for the space-charge compensation through residual gas ionization. This opens the possibility for dedicated investigations of the transport of short, low-energy beam pulses including longitudinal and transverse space-charge effects and of relevant issues like the dynamics of space-charge compensation and electron effects in short pulses.

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Author:Christoph Wiesner
Place of publication:Frankfurt am Main
Referee:Ulrich RatzingerORCiD, Oliver KesterORCiD, Shaukat Khan
Advisor:Ulrich Ratzinger
Document Type:Doctoral Thesis
Date of Publication (online):2014/12/18
Year of first Publication:2014
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Granting Institution:Johann Wolfgang Goethe-Universität
Date of final exam:2014/07/18
Release Date:2014/12/18
Chopper; Ion Beam; Particle Accelerator; Septum
Page Number:208
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht