DEVELOPMENT OF A BI-ION-DRIVEN IGNITION FACILITY( SOURCE FOR A HEAVY)

As part of a conceptual design for an inertial fusion ignition facilit y, a prototype driver is being developed for Bit production. The sourc e is driven by an are discharge ionizing bismuth atoms which are evapo rated from an oven inside the source chamber. The fraction of the sing ly ionized bismuth is above 92%. Emittance growth from the ion source to the target is crucial but inevitable. Therefore, although the requi red beam current is high, the initial ion source emittance still shoul d be low. For that purpose, a multi aperture extraction system was cho sen. Seven holes with a radius of 3 mm each make up for an overall emi ssion area of 1.98 cm(2). For that system, the perveance limit was ach ieved at a beam current of 70 mA and an extraction voltage of 27.5 kV. The corresponding emission current density amounts to 35 mA/cm(2). Fu rthermore, the effective emittance of a 21 mA - 18.2 keV beam has been measured. It amounts to 0.27 pi mm mrad (80%, normalized, 4 rms). Thi s paper will give a description of the source regarding its prospectiv e use in a heavy-ion-driven ignition facility. In addition, various de pendencies between the plasma parameters and the beam composition are presented. The use of other heavy-ions is considered as well as the in fluence of the extraction geometry on the effective emittance. (C) 199 8 Elsevier Science B.V. All rights reserved.