USTC/NSRL, Hefei, Anhui
IHEP Beijing, Beijing
SINAP, Shanghai
USTC/NSRL, Hefei, Anhui
In this paper, HLS (Hefei light Source) bunch-by-bunch measurement and feedback system will be introduced. This system is integrated with longitudinal oscillation measurement system, fast vector control, fiber notch filter and bunch current detection system. The detail of the two fronts will be shown. Some experimental results by this system are also present in this paper, as phase-space tracing, mode dumping rate, and feedback experiments.
LBNL, Berkeley, California
ICST, Harbin
The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory (RAL) in the UK. The MICE RF and Coupling Coil Module comprises a superconducting solenoid mounted around four normal conducting 201.25-MHz RF cavities. Each cavity has a pair of thin curved beryllium windows to close the conventional open beam irises. The coil package that surrounds the RF cavities is to be mounted on the outside of a 1.4 m diameter vacuum vessel. The coupling coil confines the beam in the cavity module and, in particular, within the radius of the cavity beam windows. The two MICE coupling solenoids will be operated in series using a 300 A, 10 V power supply. The maximum longitudinal force that will be carried by the cold mass support system is 0.5 MN during the expected operating and failure modes of the experiment. The detailed design and analysis of the two coupling coils has been completed, and the fabrication of the magnets is under way. The primary magnetic and mechanical design features of the coils are presented along with a summary of key fabrication issues.
LLNL, Livermore, California
A compact proton accelerator for medical applications is being developed at Lawrence Livermore National Laboratory. The accelerator architecture is based on the dielectric wall accelerator (DWA) concept. One critical area to consider is the switch region. Electromagnetic field simulations and thermal calculations of the switch area were performed to help determine the operating limits of the SiC switches. Different geometries were considered for the field simulation including the shape of the thin indium solder meniscus between the electrodes and SiC, and possible misalignment of electrodes and SiC during manufacturing. Electromagnetic field simulations were also utilized to demonstrate how the field stress could be reduced. Both transient and steady-state thermal simulations were analyzed to find the average power capability of the switches.
LLNL, Livermore, California
University of Missouri - Rolla, Rolla, Missouri
University of Missouri, Columbia, Columbia, Missouri
TPL, Albuquerque, NM
Progress in the development of compact induction accelerators employing advanced vacuum insulators and dielectrics will be described. These machines will have average accelerating gradients at least an order of magnitude higher than existing machines and can be used for a variety of applications including flash x-ray radiography and medical treatments. Research describing an extreme variant of this technology aimed at proton therapy for cancer will be described.
SLAC, Menlo Park, California
CERN, Geneva
The ILC positron damping ring comprises hundreds of meters of wiggler sections, where many more photons than in the arcs are emitted, and with the smallest beam-pipe aperture of the ring. A significant electron-cloud density can therefore be accumulated via photo-emission and via beam-induced multipacting. In field-free regions the electron-cloud build up may be suppressed by adding weak solenoid fields, but the electron cloud remaining in the wigglers as well as in the arc dipole magnets can still drive single-bunch and multi-bunch beam instabilities. This paper studies the electron-cloud formation in an ILC wiggler section for various scenarios, as well as its character, and possible mitigation schemes.
SLAC, Menlo Park, California
PSI, Villigen
Possible remedies for the electron cloud in the Damping Ring of the International Linear collider includes conditioning of the surface and chamber with grooves. We installed chambers in PEP-II to test the secondary electron yield (SEY) of coated TiN and TiZrV NEG samples and study the effect of electron and photon conditioning in situ. We have also installed vacuum chambers with rectangular groove profile in straight sections to test this possible mitigation technique. In this paper, we will describe the PEP-II test layout, results and impact on impedance.
USTC/NSRL, Hefei, Anhui
USTC, Hefei, Anhui
USTC/NSRL, Hefei, Anhui
USTC, Hefei, Anhui
USTC/NSRL, Hefei, Anhui
USTC, Hefei, Anhui
USTC/NSRL, Hefei, Anhui
USTC, Hefei, Anhui
USTC/NSRL, Hefei, Anhui
Some model cavities have been further developed and investigated for a X-band (f=9.37GHz) hybrid dielectric-iris-loaded accelerating structure based on the calculated results about the effect of the dimension tolerance on the RF properties. The dispersion curve fitted by using the measurement value is consistent with the one calculated. The r/Q values of the dipole modes have been calculated by the Mafia code. The theoretical results show that the r/Q values of dipole modes for the new accelerating structure are lower than those for the iris-load accelerating structure.
SLAC, Menlo Park, California
Grooved surface is proposed to reduce the secondary emission yield in a dipole and wiggler magnet of International Linear Collider. An analysis of the impedance of the grooved surface based on adaptive finite element is presented in this paper. The performance of the adaptive algorithms, based on an element-element h-refinement technique, is assessed. The features of the refinement indictors, adaptation criteria and error estimation parameters are discussed.
SLAC, Menlo Park, California
The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit machine performance. The suppression of electrons in a magnet is a challenge for the positron damping ring of the International Linear Collider (ILC) as well as the Large Hadron Collider. Simulation show that grooved surfaces can significantly reduce the electron yield in a magnet. Some of the secondary electrons emitted from the grooved surface return to the surface within a few gyrations, resulting in a low effective secondary electron yield (SEY) of below 1.0 A triangular surface is an effective, technologically attractive mitigation with a low SEY and a weak dependence on the scale of the corrugations and the external magnetic field. A chamber with triangular grooved surface is proposed for the dipole and wiggler sections of the ILC and will be tested in PEP-II in 2007. The strategy of electron cloud control in ILC and the optimization of the grooved chamber such as the SEY, impedance as well as the manufacturing of the chamber, are also discussed.
SLAC-PUB-11933 & NIMA in publication
SLAC, Menlo Park, California
Ion induced beam instability is one critical issue for the electron damping ring of the International Linear Collider (ILC) due to its ultra small emittance of 2pm. Bunch train filling pattern is proposed to mitigate the instability and bunch-by-bunch feedback is applied to suppress it. Multi-bunch train fill pattern is introduced in the electron beam to reduce the number of trapped ions. Our study shows that the ion effects can be significantly mitigated by using multiple gaps. However, the beam can still suffer from the beam-ion instability driven by the accumulated ions that cannot escape from the beam during the gaps. The effects of beam fill pattern, emittance, vacuum and various damping mechanism are studied using self-consistent program, which includes the optics of the ring.
SLAC, Menlo Park, California
BNL, Upton, Long Island, New York
SLAC, Menlo Park, California
The effects of the round edge beam hole on the frequency and wake field are studied using variational method, which allows for rounded iris disk hole without any approximation in shape treatment. The frequency and wake field of accelerating mode and dipole mode are studied for different edge radius cases, including the flat edge shape that is often used to approximately represent the actual structure geometry. The edge hole shape has weak effect on the frequency, but much effect on the wake field. Our study shows that the amounts of wake fields are not precise enough with the assumption of the flat edge beam hole instead of round edge.
USTC/NSRL, Hefei, Anhui
USTC, Hefei, Anhui
A method of injection analysis of small electron storage ring is introduced, and several medium emittance lattices are proposed. By analyzing the injection, working point of the lattice is selected at the vicinity of half integer resonance lines, and emittance is around 60nmrad, the linear and nonlinear properties can be satisfied for injection and store.
LIU Zu-Ping, Li Wei-Min. Progress of the NSRL Phase Two Project. In proceedings of the Second Asia Particle Accelerator Conference, Beijing, China, 2001, 235-238