The Coupled Cyclotron Facility (CCF) has been operating at the NSCL since 2001,providing up to 160MeV/u heavy ion beams for nuclear physics experiments.Recent steps,particularly the improvement of the ECR-to-K500 inje...The Coupled Cyclotron Facility (CCF) has been operating at the NSCL since 2001,providing up to 160MeV/u heavy ion beams for nuclear physics experiments.Recent steps,particularly the improvement of the ECR-to-K500 injection line,were taken to improve the CCF performance.For that purpose an off-line ECR source,ARTEMIS-B,was built and used to investigate the impact on beam brightness under various source operating conditions,different initial focusing systems and current analysis dipole.Beam dynamics simulations including space-charge and 3D electrostatic field effects were performed and beam diagnostics including emittance scanner were used,leading to a better understanding of the CCF beam injection process. New initial electrostatic focusing elements such as a large-bore quadrupole triplet and a quadrupole double- doublet with compensating octupole were tested,and a new beam tuning procedure was established to improve the beam brightness for the CCF.Following these efforts,a significant increase of primary beam power out of the CCF has been achieved.展开更多
An ion beam extracted from an ECRIS suffers from the inhomogeneous distribution of cold electrons within the minimum B configuration,necessary to confine the plasma.Especially for higher ion currents,the space charge ...An ion beam extracted from an ECRIS suffers from the inhomogeneous distribution of cold electrons within the minimum B configuration,necessary to confine the plasma.Especially for higher ion currents,the space charge force is not negligible any more,and because of the nonlinear force,emittance growth will occur. Measurements of the profile and the emittance of the beam directly behind the source show the complicated correlation between extraction voltage and plasma density.The emittance has been measured with a pepper pot device to account for the inhomogeneous azimuthal distribution of the beam.These results indicate that further information about the profile is required.To visualize the beam profile a tantalum foil with a thickness of 20μm has been used for an electrical beam power between 10 and 50W.Looking on the back side of the foil with a CCD camera it is possible to record the profile in real time.As a more sensitive diagnostic tool viewing targets made from BaF has been used. Three dimensional computer simulations have been used to identify the reason for the structures,observed in measurements.展开更多
基金Supported by National Science Foundation under grant PHY-0110253
文摘The Coupled Cyclotron Facility (CCF) has been operating at the NSCL since 2001,providing up to 160MeV/u heavy ion beams for nuclear physics experiments.Recent steps,particularly the improvement of the ECR-to-K500 injection line,were taken to improve the CCF performance.For that purpose an off-line ECR source,ARTEMIS-B,was built and used to investigate the impact on beam brightness under various source operating conditions,different initial focusing systems and current analysis dipole.Beam dynamics simulations including space-charge and 3D electrostatic field effects were performed and beam diagnostics including emittance scanner were used,leading to a better understanding of the CCF beam injection process. New initial electrostatic focusing elements such as a large-bore quadrupole triplet and a quadrupole double- doublet with compensating octupole were tested,and a new beam tuning procedure was established to improve the beam brightness for the CCF.Following these efforts,a significant increase of primary beam power out of the CCF has been achieved.
文摘An ion beam extracted from an ECRIS suffers from the inhomogeneous distribution of cold electrons within the minimum B configuration,necessary to confine the plasma.Especially for higher ion currents,the space charge force is not negligible any more,and because of the nonlinear force,emittance growth will occur. Measurements of the profile and the emittance of the beam directly behind the source show the complicated correlation between extraction voltage and plasma density.The emittance has been measured with a pepper pot device to account for the inhomogeneous azimuthal distribution of the beam.These results indicate that further information about the profile is required.To visualize the beam profile a tantalum foil with a thickness of 20μm has been used for an electrical beam power between 10 and 50W.Looking on the back side of the foil with a CCD camera it is possible to record the profile in real time.As a more sensitive diagnostic tool viewing targets made from BaF has been used. Three dimensional computer simulations have been used to identify the reason for the structures,observed in measurements.
