extraction

Paper	Title	Other Keywords	Page
MOP05	The HITRAP-Decelerator for Heavy Highly-Charged Ions	ion, rfq, emittance, storage-ring	39
	L. Dahl, W. Barth, T. Beier, W. Vinzenz GSI, Darmstadt C. A. Kitegi, U. Ratzinger, A. Schempp IAP, Frankfurt-am-Main
	The GSI accelerator facility provides highly charged ions up to U92+ by stripping the ions at 400 MeV/u in the transfer line from the SIS18 (Heavy Ion Synchrotron) to the ESR (Experimental Storage Ring). The ESR provides high quality beams by means of stochastic cooling and electron cooling. Deceleration down to 4 MeV/u was already successfully demonstrated. After suitable rebunching, further deceleration down to 6 keV/u, neccessary for the capture of the ions by a penning trap, is done by IH/RFQ-structures. All cavities are operated at 108 MHz. Recently the HITRAP-project (Heavy Ion Trap), described in a Technical Design Report, was approved. The layout of the decelerator and the beam dynamics in different sections are reported.
MOP73	Development of a Permanent Magnet ECR Source to Produce a 5 mA Deuteron Beam at CEA/Saclay	plasma, emittance, simulation, permanent-magnet	192
	R. Gobin, D.D. De Menezes, O. Delferriere, R. Ferdinand, F. Harrault CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex P.-Y. Beauvais, G. Charruau, Y. Gauthier CEA/DSM/DAPNIA, Gif-sur-Yvette N. Comte CEA/Saclay, Gif-sur-Yvette P. Lehérissier, J.Y. Pacquet GANIL, Caen
	The high intensity light ion source, SILHI, is an ECR ion source operating at 2.45 GHz which produces high intensity (over 100 mA) proton or deuteron beams at 95 keV. It has been moved in the IPHI building after a complete dismantling. At the beginning of 2003, after tuning the source parameters at standard values, the first extracted beam reached more than 70 mA within a few minutes. This encouraged us to propose a permanent magnet source based on the SILHI design to fit in with the injector of the Spiral2 project, requesting 5 mA of D+ beam with an energy of 40 keV and a normalized rms emittance lower than 0.2 π·mm·mrad. The new source has been recently assembled and the first beam (proton) extracted. After a brief source description, the preliminary results will be reported and discussed.
MOP74	Recent Results of the 2.45 GHz ECR Source Producing H- Ions at CEA/Saclay	plasma, ion, electron, ion-source	195
	R. Gobin, K. Benmeziane, O. Delferriere, R. Ferdinand, F. Harrault CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex A. Girard CEA DSM Grenoble, Grenoble
	Low frequency ECR plasma sources have demonstrated their efficiency, reproducibility and long life time for the production of positive light ions. In 2003, the new 2.45 GHz ECR test stand based on a pure volume H- ion production, developed at CEA/Saclay, showed a dramatic increase of the H- extracted ion beam. In fact, a stainless steel grid now divides the plasma chamber in two different parts: the plasma generator zone and the negative ion production zone. By optimizing the grid position and its potential with respect to the plasma chamber, the negative ion current reached close to 1 mA. Ceramic plates, covering the plasma chamber walls help electron density and lead to an optimisation of the ion production. A 50 % improvement has been observed. A new 6 kW magnetron RF generator now replaces the 1.2 kW previous one and the current will be soon plotted versus the RF power. New Langmuir probe measurements are also expected on both sides of the grid. The last results will be reported and discussed.
	Transparencies
MOP75	Hminus Distribution in the HERA RF-Volume Source	laser, electron, plasma, acceleration	198
	J. Peters DESY, Hamburg
	The HERA RF-Volume Source is the only source available that delivers routinely an Hminus current of 40 mA without Cs. The production mechanism for Hminus ions in this type of source is still under discussion. Laser photodetachment measurements have been started at DESY in order to measure the Hminus distribution in the source. The measurements have also been done under extraction conditions at high voltage. The results of the measurements with and without extraction are a basis for the development of a theory for the transition between plasma and vacuum (sheath), a cornerstone for beam transport programs. Knowledge of the H- distribution and where they are produced makes further source improvements possible.
TUP09	The Heidelberg High Current Injector: A Versatile Injector for Storage Ring Experiments	ion, rfq, ion-source, storage-ring	309
	R. von Hahn, M. Grieser, R. Repnow, D. Schwalm, C.P. Welsch MPI-K, Heidelberg
	The High Current Injector (HCI) was designed and built as a dedicated injector for the Test Storage Ring in Heidelberg to deliver mainly singly charged Li- and Be-ions. After start for routine operation in 1999 the HCI delivered stable beams during the following years for about 50 % of the experiments with very high reliability. Due to the requirements from the experiment the HCI changed during that period from a machine for singly charged positive ions to an injector for a large variety of molecules as well as positively or negatively charged light ions. After successful commissioning of the custom built 18 GHz high power ECR-source at its present test location various modifications and additions were made in preparation of a possible conversion into an injector for highly charged heavy ions as a second phase. This paper gives an overview of the experience gained in the passed 5 years and presents the status of the upgrade of the HCI.
TUP79	A New RF System for the CEBAF Normal Conducting Cavities	simulation, feedback, linac, electron	456
	C. Hovater, H. Dong, A. Hofler, G. Lahti, J. Musson, T. Plawski TJNAF, Newport News, Virginia
	The CEBAF Accelerator at Jefferson Lab is a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. CEBAF also has numerous normal conducting cavities for beam conditioning in the injector and for RF extraction to the experimental halls. The RF systems that presently control these cavities are becoming expensive to maintain, therefore a replacement RF control system is now being developed. For the new RF system, cavity field control is maintained digitally using an FPGA which contains the feedback algorithm. The system incorporates digital down conversion, using quadrature under-sampling at an IF frequency of 70 MHz. The VXI bus-crate was chosen as the operating platform because of its excellent RFI/EMI properties and its compatibility with the EPICS control system. The normal conducting cavities operate at both the 1497 MHz accelerating frequency and the sub-harmonic frequency of 499 MHz. To accommodate this, the new design will use different receiver-transmitter daughter cards for each frequency. This paper discuses the development of the new RF system and reports on initial results.
THP71	First Experience with Dry-Ice Cleaning on SRF Cavities	superconductivity, site, acceleration	776
	D. Reschke, A. Brinkmann DESY, Hamburg G. Müller BUW, Wuppertal D. Werner IPA, Stuttgart
	The surface of superconducting (s.c.) accelerator cavities must be cleaned from any kind of contaminations, like particles or chemical residues. Contaminations might act as centers for field emission, thus limiting the maximum gradient. Today's final cleaning is based on high pressure rinsing with ultra pure water. Application of dry-ice cleaning might result in additional cleaning potential. Dry-ice cleaning using the sublimation-impulse method removes particulate and film contaminations without residues. As a first qualifying step intentionally contaminated niobium samples were treated by dry ice cleaning. It resulted in a drastic reduction of DC field emission up to fields of 100 MV/m as well as in the reduction of particle numbers. The dry ice jet caused no observable surface damage. First cleaning tests on single-cell cavities showed Q-values at low fields up to 4x1010 at 1.8 K. Gradients up to 32 MV/m were achieved, but field emission still is the limiting effect. Further tests are planned to optimize the dry-ice cleaning technique.