加速器物理
An electron beam passing through a tube which is lined on the inside with a dielectric layer will radiate energy in the THz range due to the interaction with the boundary. The resonant enhancement of certain frequencies is conditioned by…
Due to the tiny apertures of dielectric laser acceleration grating structures within the range of the optical wavelength, wakefields limit the bunch charge for relativistic electrons to a few femtocoulomb. In this paper, we present a…
Symplectic maps are routinely used to describe single-particle dynamics in circular accelerators. In the case of a linear accelerator map, the rotation number (the betatron frequency) can be easily calculated from the map itself. In the…
Thermal emittance and quantum efficiency (QE) are key figures of merit of photocathodes, and their uniformity is critical to high-performance photoinjectors. Several QE mapping technologies have been successfully developed; however, there…
Imaging systems have been an integral part of many beam monitors since the early days of accelerator diagnostics. The main application remains the observation of scintillating screens during commissioning, alignment and routine operation…
Superconducting radio-frequency (SRF) cavities cooled by superfluid helium-4 (He II) are building blocks of many modern particle accelerators due to their high quality factor. However, Joule heating from sub-millimeter surface defects on…
We propose an RF deflector in the THz regime to measure the bunch length of the ultrashort electron beam in GeV scale by using the dielectric-lined circular waveguide (DLW) structure. We show the design of the deflector and the possible…
This chapter takes a look at the ways tune, chromaticity and coupling can be measured in synchrotrons. After briefly introducing the importance of these parameters for machine operation, a broad overview of the various instrumentation and…
The Large Hadron Collider (LHC) uses a multi-stage collimator system to absorb the growing halo of circulating beams to protect and ensure reliable operation of superconducting magnets. A similar system is planned for the Future Circular…
It is well known that the tuning of a long radio-frequency quadrupole accelerator is demanding. This study investigated how to realize efficient long RFQ accelerators with multiple shorter and independent cavities. From the RF point of…
Slow extraction of beam from synchrotrons or storage rings as required by many fixed target experiments is performed by controlled excitation and feeding of a structural lattice resonance. Due to the sensitive nature of this resonant…
A superconducting Double Spoke Resonator (DSR) is the technology of choice in a low energy section of a high power proton linear accelerator. At the FREIA laboratory in Uppsala University, we have tested two DSRs in a prototype cryomodule…
The paper focuses on two issues important for design and operation of bunch-by-bunch transverse damper in a very large hadron collider, where fast damping is required to suppress beam instabilities and noise induced emittance growth. The…
This lecture gives an overview of the impacts on linear machine optics of machine imperfections due to incorrect field settings and misalignments. The effects of imperfections in dipole, quadrupole, and sextupole magnets are presented,…
After a short introduction of CLIC, the Compact Linear Collider, and its test facility CTF3 (CLIC Test Facility 3), this paper gives an overview and some examples of the diagnostics used at CTF3.
This paper gives a very brief summary of longitudinal beam dynamics for both linear and circular accelerators. After discussing synchronism conditions in linacs, it focuses on particle motion in synchrotrons. It summarizes the equations of…
In state of the art photoinjector electron sources, thermal emittance from photoemission dominates the final injector emittance. Therefore, low thermal emittance cathode developments and diagnostics are very important. Conventional thermal…
We propose to use Vavilov-Cherenkov (VC) and transition radiations as a source of twisted photons in a wide range of energies. The experimental setup to observe the orbital angular momentum of photons constituting those radiations is…
In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative collision scheme, the crab waist, has been successfully implemented during the years 2008-09. During operations for the Siddharta experiment an unusual synchrotron…
This paper presents history and evolution of the intra-bunch feedback system for circular accelerators. This pro-ject has been presented by John D. Fox (SLAC/Stanford Un.) at the IPAC2010 held in Kyoto. The idea of the pro-posal is to build…