Status of the HIIF RF linac study based on H-mode cavities

The H-mode structure family was extended recently to gain access to velocity profiles ranging from beta similar to 0.002 to 0.6. This means that the (Heavy-Ion Inertial Fusion) (HIIF) relevant energy range is well included (beta less than or equal to 0.3). RF power tests show the capability of IH-cavities to withstand about 10 MV/m effective voltage gain. A linac lattice at 30 MeV/u and based on the (Kombinierte Null Grad Struktur) (KONUS) beam dynamics is investigated at beam intensities of up to 1 A. The use of multibeam cavities along the low energy linac sections is suggested. As the RF frequency along the H-type linac is changed from around 10 MHz up to around 400 MHz, typically 32 channels could be funneled into the single aperture high-energy linac section. This principle should open the possibility to get linac beam intensities as high as 2 A within norm, transverse emittances around 1 pi mm mrad and a final energy spread Delta W/W similar to +/- 2 x 10(-4). At the low-energy end beam intensities around 500 mA along each multi aperture cavity are feasible. Higher linac beam intensities give short RF pulse lengths. This will allow to develop RF power sources with significantly higher peak power levels. Additionally, the whole system will benefit from the time-averaged wall loss reduction. (C) 1998 Elsevier Science B.V. All rights reserved.