The problem of the wakefields generated by an ultrarelativistic particle traveling in a long beam tube with a periodic rough surface has been revisited by means of a standard theory based on the hybrid modes excited in a periodically corrugated rectangular waveguide. Slow surface waves synchronous with the particle can be excited in the structure, producing wakefields whose frequency and amplitude depend on the depth of the corrugation. We apply our results to the case of the CERN Large Hadron Collider beam screen and the Linac Coherent Light Source undulator.

Effects caused by misalignment of undulator segments on the gain of a free electron laser (FEL) based on the process of self-amplified spontaneous emission are theoretically studied. The well-known FEL equations are solved analytically and numerically with boundary conditions describing the misalignment effect in order to obtain the amplification gain as a function of the distance from the undulator entrance. The two worst cases of alignment are considered. One is that the phase slip over the drift section between the adjacent segments is $\pi$, and the other is that the radiation is cut off at the drift section. Calculations show that if the undulator segment is several times as long as the gain length, the radiation power is close to that of no segmentation in both cases.

Beam losses due to half-integer resonance have been observed in the Heavy Ion Medical Accelerator in Chiba synchrotron, along with exciting the harmonic component of gradient field errors. During operation, while varying the defocusing quadrupole to cross a half-integer tune in the vertical space, the region of bare tunes which causes the half-integer resonance was evaluated. When the initial beam intensity was high, the bare tune where the beam loss occurred became higher. The beam loss occurred rapidly when the half-integer tune was crossed upward, but gradually when it was crossed downward. Those results mean that the half-integer resonance is affected by space-charge-induced tune shifts. This fact was verified experimentally for the first time. The results from a one-dimensional multiparticle simulation agreed with those characteristics. Finally, the beam-size growth and the change in distribution were studied by a simulation.

We propose a scheme for bright sub-100-fs x-ray radiation generation using small-angle Thomson scattering. Coupling high-brightness electron bunches with high-power ultrafast laser pulses, radiation with photon energies between 8 and 40 keV can be generated with pulse duration comparable to that of the incoming laser pulse and with peak spectral brightness close to that of the third-generation synchrotron light sources of $\sim {10}^{20}\mathrm{photons}{\mathrm{s}}^{-1\mathrm{}}{\mathrm{mm}}^{-2\mathrm{}}{\mathrm{mrad}}^{-2\mathrm{}}$ per ${10}^{-3\mathrm{}}$ bandwidth. A preliminary dynamic calculation is performed to understand the property of this novel scattering scheme with relativistic laser intensities.

The Rare Isotope Accelerator (RIA) facility project includes a cw 1.4 GeV driver linac and a 100 MV postaccelerator both based on superconducting (SC) cavities operating at frequencies from 48 to 805 MHz. In these linacs more than 99% of the total voltage is provided by SC cavities. An initial acceleration is provided by room temperature radio frequency quadrupoles. The driver linac is designed for acceleration of any ion species, from protons up to 900 MeV to uranium up to 400 MeV/u. The novel feature of the driver linac is an acceleration of multiple charge-state heavy-ion beams in order to achieve 400 kW beam power. This paper presents design features of a medium-energy SC heavy-ion linac taking the RIA driver linac as an example. The dynamics of single and multiple charge-state beams are detailed, including the effects of possible errors in rf field parameters and misalignments of transverse focusing elements. The important design considerations of such linac are presented. Several new conceptual solutions in beam dynamics in SC accelerating structures for heavy-ion applications are discussed.

The delay line distribution system is an alternative to conventional pulse compression, which enhances the peak power of rf sources while matching the long pulse of those sources to the shorter filling time of accelerator structures. We present an implementation of this scheme that combines pairs of parallel delay lines of the system into single lines. The power of several sources is combined into a single waveguide delay line using a multimode launcher. The output mode of the launcher is determined by the phase coding of the input signals. The combined power is extracted from the delay line using mode-selective extractors, each of which extracts a single mode. Hence, the phase coding of the sources controls the output port of the combined power. The power is then fed to the local accelerator structures. We present a detailed design of such a system, including several implementation methods for the launchers, extractors, and ancillary high power rf components. The system is designed so that it can handle the 600 MW peak power required by the Next Linear Collider design while maintaining high efficiency.

We have built a 4-cell prototype plane wave transformer (PWT) linac structure. We discuss here details of the design and fabrication of the PWT linac structure. We present results from superfish and gdfidl simulations as well as cold tests, which are in good agreement with each other. We also present detailed tolerance maps for the PWT structure. We discuss beam dynamics simulation studies performed using parmela.

Nonlinear harmonic generation can be a very useful and important phenomenon for single-pass free-electron lasers (FELs) operating in the high-gain regime. Strong bunching at the fundamental wavelength and its associated higher harmonic content allow significant radiation at shorter wavelengths to be emitted without serious effects upon the output power at the fundamental. Here, we analyze the relative sensitivities to beam quality variations of the output fundamental and harmonic powers for a visible-wavelength FEL operating in the high-gain regime.

Since its birth, the laser has been extraordinarily effective in the study and applications of laser-matter interaction at the atomic and molecular level and in the nonlinear optics of the bound electron. In its early life, the laser was associated with the physics of electron volts and of the chemical bond. Over the past fifteen years, however, we have seen a surge in our ability to produce high intensities, 5 to 6 orders of magnitude higher than was possible before. At these intensities, particles, electrons, and protons acquire kinetic energy in the megaelectron-volt range through interaction with intense laser fields. This opens a new age for the laser, the age of nonlinear relativistic optics coupling even with nuclear physics. We suggest a path to reach an extremely high-intensity level ${10}^{26–28}\mathrm{W}/{\mathrm{cm}}^2$ in the coming decade, much beyond the current and near future intensity regime ${10}^{23}\mathrm{W}/{\mathrm{cm}}^2$, taking advantage of the megajoule laser facilities. Such a laser at extreme high intensity could accelerate particles to frontiers of high energy, teraelectron volt, and petaelectron volt, and would become a tool of fundamental physics encompassing particle physics, gravitational physics, nonlinear field theory, ultrahigh-pressure physics, astrophysics, and cosmology. We focus our attention on high-energy applications, in particular, and the possibility of merged reinforcement of high-energy physics and ultraintense laser.

High beam current can be achieved by longitudinally compressing bunched beams. The objective of drift compression is to compress a long beam bunch by imposing an initial longitudinal velocity distribution over the length of the beam in the beam frame. The longitudinal dynamics of drift compression and pulse shaping for high intensity particle beams are studied using a one-dimensional warm-fluid model. Two self-similar drift compression solutions admitted by the one-dimensional warm-fluid equations are derived. The pulse shaping problem is also solved such that an arbitrary input pulse shape can be shaped into the pulse shapes required by the self-similar drift compression solutions.

The Very Large Hadron Collider design is converging on a program where a 233 km circumference tunnel would first be occupied by a low field dipole system producing 40 TeV in the center of mass, followed by a higher field magnet system producing nearly 200 TeV in the center of mass. We consider the possibility of first using the tunnel for a large $e^{+}{e}^{-}$ collider. We assume that the total radiated synchrotron power will be limited to 100 MW. We describe the design strategy, the luminosity and energy reach, the factors that limit the machine performance, the scaling laws that apply to its design, and the technology that would be required for its implementation.

A detailed study of the influence of space charge on the crossing of second-order resonances is presented and associated with the space-charge limit of high-intensity rings. Two-dimensional simulation studies are compared with envelope models, which agree in the finding of an increased intensity limit due to the coherent frequency shift. This result is also found for realistic bunched beams with multiturn injection painting. Characteristic features such as the influence of tune splitting, structure resonances, and the role of envelope instabilities are discussed in detail. The theoretical limits are found to be in good agreement with the performance of high-intensity proton machines.

We develop the method of weighted macroparticle tracking (WMPT) for simulating the time evolution of the moments of the phase space densities of two beams which are coupled via the collective (strong-strong) beam-beam interaction in the absence of diffusion and damping. As an initial test we apply this method to study the $\pi$ mode and the $\sigma$ mode in three different 1D limits of the beam-beam interaction. The three limits are flat beams and transverse motion in the direction of the small width, round beams, and flat beams and motion in the direction of the large width. We have written a code (BBDeMo1D) based on WMPT, which allows testing of all three limits and is suited for extension to 2 degrees of freedom.

Projected next-generation linac-based light sources, such as PERL or the TESLA free-electron laser, generally assume, as essential components of their injector complexes, long-pulse photocathode rf electron guns. These guns, due to their design rf pulse durations of many milliseconds to continuous wave, may be more susceptible to ion bombardment damage of their cathodes than conventional rf guns, which typically use rf pulses of microsecond duration. This paper explores this possibility in terms of ion propagation within the gun, and presents a basis for future study of the subject.

Edge radiation may be extracted within a straight section of an electron storage ring by using a tilted mirror with a hole (or slot) for passage of the electron beam and its velocity field. At wavelengths much greater than the critical wavelength of the ring’s synchrotron radiation, the flux distribution upon the mirror is almost independent of wavelength. When the reflected radiation is extracted through a nearby window, diffraction reduces the extracted flux at wavelengths exceeding $\sim 2\pi$ times the hole radius. For the Aladdin 800 MeV electron storage ring, the extracted edge radiation may find application as a broadband source for wavelengths of $1\mu \mathrm{m}–60\mathrm{mm}$ or as a diagnostic of the bunch dimensions.

A Hamiltonian approach to the solution of the Vlasov-Poisson equations has been developed. Based on a nonlinear canonical transformation, the rapidly oscillating terms in the original Hamiltonian are transformed away, yielding a new Hamiltonian that contains slowly varying terms only. The formalism has been applied to the dynamics of an intense beam propagating through a periodic focusing lattice, and to the coherent beam-beam interaction. A stationary solution to the transformed Vlasov equation has been obtained.

A self-consistent theory of periodic hole structures in coasting beams in synchrotrons and storage rings is presented, extending the theory on localized holes. The analysis reveals new intrinsic nonlinear modes which owe their existence to a deficiency of particles trapped in the self-sustained potential well, showing up as notches in the thermal range of the distribution function. It is therefore the full set of Vlasov-Poisson equations which is invoked; linearized treatments as well their nonlinear extensions fundamentally fail to cope with this strongly nonthermodynamic phenomenon. Qualitative agreement with the holes recently found at the CERN proton synchrotron booster is shown.

BL11, the most recently installed wiggler in the SPEAR storage ring at the Stanford Synchrotron Radiation Laboratory, produces a large nonlinear perturbation of the electron beam dynamics, which was not directly evident in the integrated magnetic field measurements. Measurements of tune shifts with betatron oscillation amplitude and closed orbit shifts were used to characterize the nonlinear fields. Because of the narrow pole width in BL11, the nonlinear fields seen along the wiggling electron trajectory are dramatically different from the magnetic measurements made along a straight line with a stretched wire. This difference explains the tune shift measurements and the observed degradation in dynamic aperture. Because of the relatively large dispersion (1.2 m) at BL11, the nonlinearities particularly reduced the off-energy dynamic aperture. Because of the nature of these nonlinear fields, it is impossible, even theoretically, to cancel them completely with short multipole correctors. Magic finger corrector magnets were built, however, that partially correct the nonlinear perturbation, greatly improving the storage ring performance.

The concept of using short plasma sections several meters in length to double the energy of a linear collider just before the collision point is proposed and modeled. In this scenario the beams from each side of a linear collider are split into pairs of microbunches with the first driving a plasma wake that accelerates the second. The luminosity of the doubled collider is maintained by employing plasma lenses to reduce the spot size before collision.

The measurement of emittance in space-charge dominated, high brightness beam systems is investigated from conceptual, computational, and experimental viewpoints. As the self-field-induced collective motion in the low energy, high brightness beams emitted from photoinjector rf guns are more important in determining the macroscopic beam evolution than thermal spreads in transverse velocity; traditional methods for phase space diagnosis fail in these systems. We discuss the role of space charge forces in a traditional measurement of transverse emittance, the quadrupole scan. The mitigation of these effects by use of multislit- or pepper-pot-based techniques is explained. The results of a direct experimental comparison between quadrupole scanning and slit-based determination of the emittance of a 5 MeV high brightness electron beam are presented. These data are interpreted with the aid of both envelope and multiparticle simulation codes. It is shown that the ratio of the beam’s $\beta$ function to its transverse plasma wavelength plays a central role in the quadrupole scan results. Methods of determining the presence of systematic errors in quadrupole scan data are discussed.