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.

$\gamma$-ray generation by Compton backscattering in an optical lens series with periodic focal points is considered to produce a polarized positron beam for a linear collider. The lens series is composed of 20 unit cells with a length of 210 mm. Each lens has a hole to pass an electron beam with an energy of 5.8 GeV and the generated $\gamma$ rays. It is shown by diffraction analysis that laser beam loss in the series is very small, and the beam size is periodically reduced to $26\mu \mathrm{m}$. Electron beam size is reduced to $34\mu \mathrm{m}$ in a superconducting solenoid with a field of 15 T. To get a required $\gamma$-ray yield of $7\times {10}^{15}\gamma /\mathrm{s}$, only one circularly polarized ${\mathrm{CO}}_2$ laser source with a power of 24 kW is needed.

A new accelerator, LACARA (laser-driven cyclotron autoresonance accelerator), under construction at the Accelerator Test Facility at Brookhaven National Laboratory, is to be powered by a 1 TW ${\mathrm{CO}}_2$ laser beam and a 50 MeV injected electron pulse. LACARA will produce inside a 2 m, 6 T solenoid a 100 MeV gyrating electron bunch, with $\sim 3\%$ energy spread, approximately 1 psec in length with particles advancing in phase at the laser frequency, executing one cycle each 35 fsec. A beamstop with a small off axis channel will transmit a short beam pulse every optical cycle, thereby producing a train of about 30, 3.5 fsec long, 1–3 pC microbunches for each laser pulse. We describe here a novel accelerator, a micron-scale dielectric wake field accelerator driven by a 500 MeV LACARA-type injector that takes the output train of microbunches and transforms them into a near-rectangular cross section having a narrow dimension of $\sim 10\mu \mathrm{m}$ and height of $\sim 150\mu \mathrm{m}$ using a magnetic quadrupole; these bunches may be injected into a planar dielectric-lined waveguide (slightly larger than the bunch) where cumulative buildup of wake fields can lead to an accelerating gradient $>1\mathrm{}\mathrm{GV}/\mathrm{m}$. This proposed vacuum-based wake field structure is physically rigid and capable of microfabrication accuracy, factors important in staging a large number of accelerator modules. Furthermore, the accelerating gradients it promises are comparable with those for plasma accelerators. A LACARA unit for preparing suitable bunches at 500 MeV is described. Physics issues are discussed, including bunch spreading and transport, bunch shaping, coherent diffraction radiation from the aperture, dielectric breakdown, and bunch stability in the rectangular wake field structure.

We consider the dynamical properties of a particle-core model for a uniformly filled triaxial ellipsoid in a periodic lattice of a high intensity linac. The mismatched oscillation modes are analytically computed in the smooth approximation and are compared with the numerical results of a tracking program. The study of the phase space in the mismatched case is performed by the frequency map analysis. In particular, we can analyze the effect of the nonlinear resonances between the envelope modes and the single particle sincrobetatron frequencies. A chaoticity criterion based on the frequency map analysis allows one to compute the stability region around the beam core. An estimate of the transport and its enhancement due to mismatch is provided by tracking orbits at the border of the stability region.

At the Cornell Electron/Positron Storage Ring, a fast luminosity monitor has been implemented. The monitor works by measuring the amplitude of oscillation of selected bunches while the corresponding opposing bunches are shaken. Signal-to-noise ratios of better than 100:1 have been obtained with 1 sec averaging times. A software normalization program ameliorates the unwanted dependence of the signal upon certain vertical lattice parameters such as the vertical tune.

The visible-infrared self-amplified spontaneous emission amplifier (VISA) free electron laser (FEL) is an experimental device designed to show self-amplified spontaneous emission (SASE) to saturation in the near infrared to visible light energy range. It generates a resonant wavelength output from 800–600 nm, so that silicon detectors may be used to characterize the optical properties of the FEL radiation. VISA is designed to show how SASE FEL theory corresponds with experiment in this wavelength range, using an electron beam with emittance close to that planned for the future Linear Coherent Light Source at SLAC. VISA comprises a 4 m pure permanent magnet undulator with four 99 cm segments, each of 55 periods, 18 mm long. The undulator has distributed focusing built into it, to reduce the average beta function of the 70–85 MeV electron beam to about 30 cm. There are four FODO cells per segment. The permanent magnet focusing lattice consists of blocks mounted on either side of the electron beam, in the undulator gap. The most important undulator error parameter for a free electron laser is the trajectory walk-off, or lack of overlap of the photon and electron beams. Using pulsed wire magnet measurements and magnet shimming, we were able to control trajectory walk-off to less than $\pm 50\mu \mathrm{m}$ per field gain length.

A compact proton synchrotron using combined function magnets is proposed to help realize the wider availability of charged particle cancer therapy facilities. This combined function magnet was designed with the help of three-dimensional magnetic field calculations to take account of a realistic fringe and the interference among the magnetic poles. An evaluation scheme for tune values based on particle tracking was developed to improve the magnet design. To verify the magnet design, a model magnet was fabricated and measured. In order to achieve a tune value evaluation from the measured magnetic field, schemes for accurate field mapping and field interpolation were developed. From the tune value evaluation of the measured magnetic field, it was thought that the performance of the model magnet was good enough to construct a synchrotron. In this paper, we report details of the design and the evaluation scheme for the combined function magnet and the results of the field measurements of the model magnet.

Because of a long-range resistive wake, the closed orbit may experience an unstable drift. Unlike the conventional betatron instabilities, this closed orbit instability is not sensitive to the spread of the betatron frequencies. For bunched beams, feedback appears to be the only way to stabilize the closed orbit above threshold. This new instability can be significant for both existing and designed high-intensity rings.

A calculation method of emittance growth of an electron beam due to intrabeam scattering is described. The 3 degrees of freedom are equally treated in the beam rest frame, and the couplings between them are included in a natural way. This formalism is suitable for the calculation of the emittance growth with the beam-envelope method.

The cavities of choice for high-energy synchrotrons and for medium-beta and high-beta accelerating superconducting structures around the world are $\pi$-mode structures. A coupled-circuit analysis, allowing for errors in cell frequencies and cell coupling constants, has been used to determine relative on-axis electric field amplitudes between cells, operating frequencies, end-cell tuning, relative on-axis field phase shifts, and field tilts when operated off resonance. Formulas are given for the above information as well as specific examples showing sensitivities and machining/assembly/control tolerances. A method to determine relative field amplitudes on the basis of the mode spectra was developed.