IAP, Frankfurt am Main
The Frankfurt Neutron source FRANZ is under construction*. The ARMADILLO bunch compressor** as a part of it is composed of a 5MHz electric kicker, a magnetic dipole chicane and rf-rebunching cavities. The design phase of the bunch compressor has reached the final stage. A 175MHz 2MeV proton linac forms 100ns long beam pulses consisting of nineμbunches with 150mA. Deflected by the 5MHz kicker theμbunches are guided on different paths to arrive within 1ns at a n-production target. Due to high space charge forces rebuncher cavities are included***. The peak current at the target is expected to be in the range of 10A in a 1ns proton pulse, which is equivalent to a longitudinal pulse compression ratio of 45. A new code specific for complex magnetic multi aperture system and for high current applications has been developed. Hardware designs according to the beam dynamics results are in progress. Improved 3D magnetic and electric fields will be applied in the future beam dynamics studies including high space charge forces. The preliminary designs and the beam dynamics studies will be presented in this contribution.
* O. Meusel, et al.: LINAC06, Knoxville, Tennessee USA, 2006, pp. 159-161.
** L. P. Chau, et al.: EPAC08, Genoa, Italy, 2008, pp. 3578-3580.
*** D. Noll, another contribution at this conference.
IAP, Frankfurt am Main
Space charge lenses use a confined electron cloud for the focusing of ion beams. Due to the electric space charge field, focusing is independent of the particle mass. For this reason the application of the space charge lens especially in the field of heavy ion beams is advantageous. Moreover, the trapped non neutral plasma cloud compensates the space charge forces of the ion beam. The focusing strength is given by the confined electron density whereas the density distribution influences the mapping quality of the space charge lens. An important parameter for the focusing capability of the space charge lens is besides the homogeneous electron distribution a high electron density. In ongoing theoretical and experimental work methods have been developed to determine the most important parameters like electron temperature and electron density distribution for an optimized lens design. Based on the experimental results a new space charge lens has been designed to focus low energy heavy ion beams like 2,4 AkeV U4+ at the low energy transport section into the GSI High Current Injector. Experimental results will be presented and compared with numerical simulations.
*W. Barth, "THE INJECTOR SYSTEMS OF THE FAIR PROJECT", LINAC08, Victoria, BC, Canada
IAP, Frankfurt am Main
The Frankfurt Neutron source FRANZ is under construction*. The ARMADILLO bunch compressor** as a part of it is composed of a 5MHz electric kicker, a magnetic dipole chicane and rf-rebunching cavities. The design phase of the bunch compressor has reached the final stage. A 175MHz 2MeV proton linac forms 100ns long beam pulses consisting of nineμbunches with 150mA. Deflected by the 5MHz kicker theμbunches are guided on different paths to arrive within 1ns at a n-production target. Due to high space charge forces rebuncher cavities are included***. The peak current at the target is expected to be in the range of 10A in a 1ns proton pulse, which is equivalent to a longitudinal pulse compression ratio of 45. A new code specific for complex magnetic multi aperture system and for high current applications has been developed. Hardware designs according to the beam dynamics results are in progress. Improved 3D magnetic and electric fields will be applied in the future beam dynamics studies including high space charge forces. The preliminary designs and the beam dynamics studies will be presented in this contribution.
CEA, Gif-sur-Yvette
New PIC ray-tracing methods allows to design and simulate the transport of high intensity proton, H- and deuteron beam in the LEBT systems of future facilities like FAIR Proton Linac or IFMIF-EVADA and SPIRAL2 deuteron linacs. These techniques enable a precise prediction of the effect of residual gas ionisation and the consequent neutralisation of the large beam space charge on the beam emittances.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
CEA, Gif-sur-Yvette
Recent experiments at the Universal Linear Accelerator (UNILAC) at GSI provided evidence for space charge driven resonances along a periodic DTL. A transverse fourth order resonance has been detected by recording the four fold symmetry in phase space. As predicted in [D. Jeon et al., Phys. Rev. ST Accel. Beams 12, 054204 (2009)], the resonance dominates over the envelope instability. Additionally, evidence for resonant emittance transfer from the longitudinal to the transverse plane has been found for settings providing equal depressed tunes of the involved planes.
CERN, Geneva
Université Blaise Pascal, Clermont-Ferrand
The CERN LINAC4 commissioning will start in 2011, at first in a laboratory test stand where the 45 KeV H- source is already installed and presently tested, and later in the LINAC4 tunnel. A movable diagnostics bench will be equipped with the necessary sensors capable of characterizing the H- beam in different stages, from 3 MeV up to the first DTL tank at 12 MeV. In this paper we will discuss the accuracy of the transverse emittance measurement that will be performed with the slit-grid method. The system's mechanical and geometric parameters have been determined in order to achieve the required resolution and sensitivity. Space charge effects during the beam transfer from the slit to the grid and scattering effects at the slit have been considered to determine the overall emittance measurement accuracy.
IAP, Frankfurt am Main
For the development of high energy and high duty cycle RFQs accurate particle dynamic simulation tools are important for optimizing designs, especially in high current applications. To describe the external fields in RFQs as well as the internal space charge fields with image effect, the Poisson equation has to be solved taking the boundary conditions into account. In PteqHI a multigrid Poisson solver is used to solve the Poisson equation. This method will be described and compared to analytic solutions for the Two-term-potential to verify the answer of the Poisson solver.
LANL, Los Alamos, New Mexico
Particle-core interaction is the well-developed model of halo formation in high-intensity beams. In present paper an analytical solution for averaged single particle dynamics around uniformly charged beam core is obtained. The problem is analyzed through sequence of canonical transformations of Hamiltonian describing nonlinear particle oscillations. An analytical expression for maximum particle deviation from the axis is obtained. Results of the study are in good agreement with numerical simulations and with previously achieved data.
Fermilab, Batavia
Northern Illinois University, DeKalb, Illinois
Next generation accelerators, such as high-energy physics colliders and light sources, will be interested in phase space manipulations techniques within two degrees of freedom for enhanced performance. At the Fermilab A0 Photoinjector, a proof-of-principle experiment to demonstrate the exchange of the transverse and longitudinal emittances is ongoing. The emittance exchange beamline consists of a 3.9 GHz normal conducting deflecting mode cavity inserted between two doglegs. Electron bunches of varying charge levels from 250 pC to 1 nC and energy of 14.3 MeV are consistently sent through the exchange beamline. In this paper we will present our latest results on the effects of charge on the emittance exchange process.
ANL, Argonne
The proposed X-ray Free Electron Laser Oscillator* requires an ultra-low emittance gun that generates continuous electron bunches at 1 to 10 MHz. Recently, T. Shintake raised the possibility of using a pulsed triode gun with a thermionic cathode. In this paper, we investigate the feasibility for such a gun as part of an injector producing normalized emittances in the 0.1 μm range with 2 ps rms duration for 50 pC/bunch. We also explore some implementation concepts.
*K. J. Kim et al., Phys. Rev. Lett. 100, 244802 (2008)