Author: Wolf, C.R.
Paper Title Page
WEPPT021 Columbus - A Simple Ion Source 364
  • M. J. Frank, E. Held, C.R. Wolf
    Ernes, Coburg, Germany
  An ion source provides a cyclotron with charged particles which can be accelerated by an electric field. The simpelst possibility is a thermionic ion-source. Electrons emitted from a white-hot tungsten filament, placed in a ceramic block of macor, are accelerated by a dc voltage of 100 - 150 V and constraint to a spiral path by the homogenous magnetic field of the cyclotron. They collide with hydrogen atoms and ionisize them. The ceramic block is covered by tube made of copper in which the ions raise up. They enter the gap between the dees through a small aperture in tube. The ion source is mounted under the dummy-dee, so its position can be changed to find the best place. The hydrogen gas is stored in a Hydro-stick, a small tube which contains 10 l of Hydrogen under a pressure of 10 bar. From here it enters the ion source by a mass-flow controller which enables accurate dosing.  
poster icon Poster WEPPT021 [1.640 MB]  
WE1PB03 COLUMBUS - A Small Cyclotron for School and Teaching Purposes 296
  • C.R. Wolf
    FZJ, Jülich, Germany
  • M. J. Frank, E. Held
    Ernes, Coburg, Germany
  A small cyclotron has been constructed for school- and teaching purposes. The cyclotron uses a water-cooled magnet with adjustable pole-pieces. The magnet provides a field up to 0,7 T. Between the two poles the vacuum chamber is positioned. The vacuum chamber provides ports for the different subsystems, measuring tools and some viewports. A turbo molecular pump backed up by a dry compressor vacuum pump is used to evacuate the chamber to a pressure of 10-5 mbar. The ions will be accelerated between two brass RF electrodes, called dee and dummy-dee. In the center of the chamber there is a thermionic ion source. A massflow controller fills it with hydrogen gas ionized by electrons from a cathode. The required 5,63 MHz RF power is supplied by a RF transceiver. A matchingbox adjusts the output impedance of the transceiver to the input impedance of the cyclotron. The expected final energies of the protons are 24 keV after 12 revolutions. At these energies there is no radiation outside the chamber. In addition to the design of this cyclotron it is the purpose of this dissertation to use standard devices to realize a low-cost solution.  
slides icon Slides WE1PB03 [6.246 MB]