加速器物理
Undesirable electron field emission (a.k.a. dark current) in high gradient RF photocathode guns deteriorates the quality of photoemission current and limits the operational gradient. To improve the understanding of dark current emission, a…
Knowledge of the transverse four-dimensional beam rms-parameters is essential for applications that involve lattice elements that couple the two transverse degrees of freedom (planes). Of special interest is the removal of inter-plane…
We develop analytical models of the longitudinal and transverse wakes, on and off axis for realistic structures, and then compare them with numerical calculations, and generally find good agreement. These analytical "first order" formulas…
We analyze the behavior of Free Electron Laser (FEL) oscillators operating in the deep saturated regime and point out the formation of sub-peaks of the optical pulse. They are very stable configurations, having a width corresponding to a…
In order to study the dynamic response of the material and the physical mechanism of the fluid dynamics, an accelerator scenario which can be applied to hard X-ray free electron laser and high energy electron radiography was proposed. This…
A new accelerator complex, HIAF (the High Intensity Heavy Ion Accelerator Facility), has been approved in China. It is designed to provide intense primary and radioactive ion beams for research in high energy density physics, nuclear…
Circular Electron-Positron Collider(CEPC) is one of the largest plans in high energy physics study at China, which would serve as Higgs Factory firstly and then upgrade to a hadron collider. In this paper we give the 50km and 100km design…
In the experiment of flash-radiography, the quality of acquired image strongly depends on the focal size of the x-ray source spot. A variety of techniques based on imaging of pinhole, slit and rollbar are adopted to measure the focal spot…
Within the framework of the LHC Injector Upgrade (LIU), the new LINAC4 is currently being commissioned to replace the existing LINAC2 proton source at CERN. After the expected completion at the end of 2016, the LINAC4 will accelerate H-…
After the successful completion of the SIDDHARTA experiment run with crab waist collisions, the electron- positron collider DA{\Phi}NE has started routine operations for the KLOE-2 detector. The new interaction region also exploits the crab…
A recent breakthrough in laser-plasma accelerators, based upon ultrashort high-intensity lasers, demonstrated the generation of quasi-monoenergetic GeV-electrons. With future Petawatt lasers ultra-high beam currents of ~100 kA in ~10 fs can…
Phase 1 of the vacuum ultra-violet (VUV) free-electron laser (FEL) at the TESLA Test Facility (TTF) recently concluded operation. It successfully demonstrated the saturation of a SASE FEL in the in the wavelength range of 80-120 nm. We…
The Rapid Cycling Synchrotron (RCS) in Chinese Spallation Neutron Source (CSNS) accelerates proton beam from 80Mev to 1.6GeV at a repetition rate of 25Hz. All dipole magnets of RCS are operated at AC with biased DC. Aiming at the properties…
Many particle accelerators operate with very high beam power and very high energy stored in particle beams as well as in magnet systems. In the future, the beam power in high intensity accelerators will further increase. The protection of…
The intensities and profiles of the muon beam behind the beam dump of the Fermilab test beam area when the facility is running in the "pion" beam mode are measured and summarized in this note. This muon beam with momenta in the range 10 -…
Previous work has demonstrated that the radio frequency surface resistance of niobium resonators is dramatically reduced when nitrogen impurities are dissolved as interstitial in the material. The origin of this effect is attributed to the…
Previous studies on magnetic flux expulsion as a function of cooling details have been performed for superconducting niobium cavities with the cavity beam axis placed parallel respect to the helium cooling flow, and findings showed that for…
Collimation systems in particle accelerators are designed to dispose of unavoidable losses safely and efficiently during beam operation. Different roles are required for different types of accelerator. The present state of the art in beam…
Since 2010 the Large Hadron Collider (LHC) is the accelerator with the highest stored energy per beam, with a record of 140 MJ at a beam energy of 4 TeV, almost a factor of 50 higher than other accelerators. With such a high stored energy,…
The radio-frequency (RF) system is the key element that generates electric fields for beam acceleration. To keep the system reliable, a highly sophisticated protection scheme is required, which also should be designed to ensure a good…