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Experimental results from the Cadarache
1 MV test bed with SINGAP accelerators
L. Svensson, D. Boilson*, H.P.L. de Esch, R.S. Hemsworth, and A. Krylov
Association EURATOM-CEA, CEA/DSM/DRFC, CEA-Cadarache,
13108 ST PAUL-LEZ-DURANCE (France)
*Association EURATOM-DCU , PRL/NCPST, Glasnevin, Dublin 13, Ireland
Abstract: A prototype accelerator based on a pre-accelerator normally used for positive ion acceleration
was used on the Cadarache MV negative ion beam facility up to 2004. Even though this
accelerator demonstrated the feasibility of SINGAP (SINgle GAP, SINGle APerture)
accelerators it was not possible to produce beams with the optical quality required for ITER.
A new “ITER-like” accelerator, which is a scaled down version of the ITER SINGAP
accelerator, has been built and installed on the Cadarache 1 MV test bed. The objective with
the “ITER-like” is to demonstrate reliable D- beam acceleration as close as possible to 1 MeV
with a current density j- » 200 A/m² with the beam optics required for ITER, i.e. a beamlet
divergence of £7 mrad and beamlet steering within ±2 mrad of that specified. High voltage
hold-off tests have been performed and 940 kV has been held without breakdowns. Beams up
to 850 keV (D-, 15 A/m²) were obtained after 4 weeks of experiments and the highest current
density that has been obtained so far is 150 A/m² (D-, 580 keV). The required beam optics for
ITER has been obtained but a larger than expected halo has been measured.
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Synopsis (pdf)