[en] Initiatives have commenced, both in Europe and in the U.S.A., towards studies of very intense pulsed spallation neutron sources. Averaging proton beam powers of up to 5 MW are under consideration, representing an extrapolation of a factor of about 30 over the most intense existing source, ISIS (U.K.). Various options are discussed, and important design areas of the accelerators and targets are outlined

[en] The Fermilab Main Injector Project is a new 150 GeV synchrotron now under construction at the Fermi National Accelerator Laboratory. The FMI has been designed to support a luminosity in excess of 5x10³¹ cm^-2sec^-1 in the Tevatron proton-antiproton collider while simultaneously providing a 2 microAmp resonantly extracted 120 GeV beam which will present unique capabilities in the realm of rare neutral K decays and long baseline neutrino oscillation experiments. Expected performance characteristics of the Main Injector will be reviewed, and the status of the project and the schedule for completion will be discussed

[en] Results are shown of calculations and measurements of the effectiveness of the betatron stochastic cooling systems in the debuncher ring of the antiproton source at Fermilab. This system cools each batch of injected antiprotons from ca. 8 π mm mrad to less than 1 π mm mrad rms emittance in the 2.4 seconds between production cycles. The conclusions concerning future improvements are summarized

[en] The way of protons and heavy ions acceleration in ordinary proton synchrotrons with constant RF of an electrical field is proposed. It is carried out, if acceleration is realize with high harmonic number q, and RF voltage V is changed so, that the particles hit the new neighboring separatrix on the following turn. This way requires the application of RF systems providing the high acceleration rate 100 MeV/m, and working with the constant frequency approximately several tens of GHz

[en] Accelerator physicists today have access to computers that are far more powerful than those available just 10 years ago. In the early 1980's, desktop workstations performed less than one million floating point operations per second (Mflops), and the realized performance of vector supercomputers was at best a few hundred Mflops. Today vector processing is available on the desktop, providing researchers with performance approaching 100 Mflops at a price that is measured in thousands of dollars. Furthermore, advances in Massively Parallel Processors (MPP) have made performance of over 10 gigaflops a reality, and around mid-decade MPPs are expected to be capable of teraflops performance. Along with advances in MPP hardware, researchers have also made significant progress in developing algorithms and software for MPPs. These changes have had, and will continue to have, a significant impact on the work of computational accelerator physicists. Now, instead of running particle simulations with just a few thousand particles, researchers can perform desktop simulations with tens of thousands of simulation particles, and calculations with well over 1 million particles are being performed on MPPs. In the area of computational electromagnetics, simulations that used to be performed only on vector supercomputers now run in several hours on desktop workstations, and researchers are hoping to perform simulations with over one billion mesh points on future MPPs. In this paper the author discusses the latest advances, and what can be expected in the near future, in hardware, software and applications codes for advanced simulation of particle accelerators

[en] Generation of various space-charge waves due to localized perturbations on the beam parameters, namely the velocity, density, and current, is reported. Analytical solutions of one-dimensional fluid equations under such perturbations are presented and compared with the experimental results

[en] In accelerators with negatively charged beams, ions generated from the residual gas molecules may be trapped by the beam. Trapped ions may interact resonantly with the beam and cause a beam-ion coherent instability. This coherent instability bears many similarities to the resistive wall instability and can present important limitations to those machines' operation. A description of this effect requires a treatment of the beam coherent instability including both the normal machine wake field and the interaction with ions. The authors present a linear approach incorporating contributions from the machine impedance as well as ion forces. It also includes spreads in beam and ion frequencies and thus Landau damping. The analysis results in a modified stability diagram which will be used together with physical arguments to explain experimental observations in the Fermilab antiproton accumulator

[en] The authors present an overview of the calculated longitudinal and transverse coupled-bunch (CB) growth rates using the measured RF cavity higher order mode (HOM) impedance for the Advanced Light Source (ALS), a 1.5 GeV electron storage ring for producing synchrotron radiation. They also describe a visual method of representing the effective beam impedance and corresponding growth rates which is especially useful for understanding the dependence of growth rate on HOM frequency and Q, for determining the requirements of the CB feedback system, and for interpreting measured beam spectra

[en] An integral equation derived from the linearized Vlasov equation has been used to find the instability thresholds in the case of space-charge impedance alone for various distribution functions. It has been found that the thresholds for the instability which are caused by the coupling between m = ±1 azimuthal modes may be obtained analytically for many practically used distributions. Moreover, the criterion determining these thresholds appears to be the same as that for thresholds beyond which no stationary distribution can be found

[en] A double RF-cavity system with a passive higher-harmonic cavity is considered for the purpose of preventing coupled-bunch instabilities and/or increasing the bunch lifetime. Expressions are presented for the onset of the equilibrium phase instability, the frequency and damping rate of the Robinson instability, the synchrotron frequency, synchrotron frequency spread, and bunch length. An algorithm is presented for evaluating the performance of a passive higher-harmonic cavity, and applied to the SRRC electron storage ring, which is being installed