GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
IAP, Frankfurt am Main
CEA, Gif-sur-Yvette
Funding: We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 ‘‘Structuring the European Research Area’’ program (CARE, Contract No. RII3-CT-2003-506395).
Beam dynamics experiments with high intensity beams have been conducted at the GSI UNILAC in 2006-2008 with the goal of benchmarking four major simulation codes, i.e. DYNAMION, PARMILA, TraceWin/PARTRAN and LORASR with respect to transverse emittance growth along a DTL. The experiments comprised measurements of transverse phase space distributions in front of as well as behind the DTL. Additional longitudinal bunch length measurements at the DTL entrance allowed for estimate and control of mismatch in all three planes. Measured effects of mismatch and of theoretically predicted space charge resonances (equipartitioning and others) are compared with simulations for a wide range of transverse phase advance along the DTL. This contribution is the first report on the successful measurement of a space charge driven fourth order resonance in a linear accelerator.
GSI, Darmstadt
NSCL, East Lansing, Michigan
IAP, Frankfurt am Main
Funding: European Commission; contract number HPRI-CT-2001-50036 (HITRAP) German Ministry for Education and Research (BMBF; contract number 06 FY160I
Deceleration of heavy, highly charged ions from the ion storage ring ESR of the GSI accelerator facility with an rf-linear decelerator will provide ions up to bare uranium almost at rest for cutting edge experiments in atomic and nuclear physics. For this unique approach the beam has to be prepared well by electron cooling in the ESR to account for a 26 time increase of the transverse emittance during the following deceleration. An interdigital H-type (IH) structure and a radio-frequency quadrupole (RFQ) structure are operated in inverse to decelerate first from 4 MeV/u to 0.5 MeV/u and then to 6 keV/u. The quasi-continuous beam from the ESR is adapted, by using a double drift buncher, to match the longitudinal acceptance of the IH. Downstream from the IH-structure the 0.5 MeV/u beam is then fit with a spiral re-buncher to the RFQ, which finally decelerates the ions to 6 keV/u. First commissioning beam times have shown that the bunching works well and ions have been decelerated to 0.5 MeV/u in the IH structure. Extensive measurements of transversal emittance before and after deceleration can now be compared to beam dynamics calculations.