R Mcadams A J T Holmes D B King E Surrey
A 1d analytical model of the sheath in a negative ion source, such as those proposed for heating and diagnostic beams on present and future fusion devices, has been developed. The model describes the transport of surface produced negative ions from a cathode, across the sheath to a plasma containing electrons, positive ions and negative ions. It ac…
PublishedR. Mcadams M. P. S. Nightingale D. Godden A. J. T. Holmes G. Proudfoot
Cost optimisation studies are carded out for an accelerator based neutron source consisting of a series of linear accelerators. The characteristics of the lowest cost design for a given beam current and energy machine such as power and length are found to depend on the lifetime envisaged for it. For a fixed neutron yield it is preferable to have a …
PublishedS. B. Wells Y. Takeiri A. F. Newman R. Mcadams A. J. T. Holmes
A rf ion source with a large extraction area suitable for fusion applications is considered. The source is a metallic magnetic multipole bucket with an internal antenna to couple the rf (at a frequency of 2 MHz) to the plasma. The source is diagnosed by an array of Langmuir probes to measure uniformity, density, and temperature and a small probe ac…
PublishedR. Mcadams R. F. King A. F. Newman
Two designs of electron suppressor have been tested in a volume negative ion source operating dc with a large extraction aperture diameter (16 mm). Both suppressors employ magnetic fields to divert the electrons near the extraction aperture onto collector electrodes. However, while one suppressor uses a fixed field produced by permanent magnets, th…
PublishedR. Mcadams R. F. King A. F. Newman
This paper reports tests of an electron suppressor, for volume negative ion sources with variable electric and magnetic fields. The experiments have been carried out with a source and accelerator operating d.c. and with an extraction aperture of 16 mm diameter. The results are compared to those obtained with a permanent magnet suppressor and to a t…
Published