[en] This report discusses the follow topics on radio frequency quadrupole accelerators: RFQ characteristics; low velocity accelerators; alternating-gradient focusing; acceleration; RFQ accelerator; bunching; adiabatic capture; injectors; transverse input matching; rf structures; mechanical designs; structure stabilization; rf considerations; space-charge effects; beam dynamics codes; cavity design codes; some real machines; heavy ions; and future directions

[en] Numerical calculations made by several groups have always shown that an asymptotic lower exit emittance exists for linacs operating with high beam current as the input emittance is reduced to zero. In this paper, a mechanism for this limit is shown to be spread in the betatron frequencies of the individual particles due to the combination of space charge and rf gap forces, causing different transverse trajectories correlated with the instaneous longitudinal position of the particle. These trajectories cannot all be simultaneously matched to the average restoring forces, resulting in an overall emittance increase if the the space charge force is a large fraction of the restoring force. In principle, equilibrium distributions may exist which would not grow. Raising the linac frequency or reducing longitudinal emittance improves the situation, but higher injection energy does not

[en] The LUX femtosecond light source concept would support pump-probe experiments that need to synchronize laser light pulses with electron-beam-generated X-ray pulses to less than 50 fs at the experimenter endstations. To synchronize multiple endstation lasers with the X-ray pulse, we are developing a fiber-distributed optical timing network. A high frequency clock signal is distributed via fiber to RF cavities (controlling X-ray probe pulse timing) and mode-locked lasers at endstations (controlling pump pulse timing). The superconducting cavities are actively locked to the optical clock phase. Most of the RF timing error is contained within a 10 kHz bandwidth, so these errors and any others affecting X-ray pulse timing (such as RF gun phase) can be detected and transmitted digitally to correct laser timing at the endstations. Time delay through the fibers will be stabilized by comparing a retro-reflected pulse from the experimenter endstation end with a reference pulse from the sending en d, and actively controlling the fiber length

[en] Long-term phase drifts of less than a femtosecond per hour have been demonstrated in a 2 km length of single-mode optical fiber, stabilized interferometrically at 1530 nm. Recent improvements include a wide-band phase detector that reduces the possibility of fringe jumping due to fast external perturbations of the fiber and locking of the master CW laser wavelength to an atomic absorption line. Mode-locked lasers may be synchronized using two wavelengths of the comb, multiplexed over one fiber, each wavelength individually interferometrically stabilized

[en] A new high-mass, high intensity injector for the SuperHILAC has been approved and is under construction at LBL. A high power intermediate charge state ion source and accompanying low-velocity linac will provide beams for subsequent acceleration by the SuperHILAC. Both axially and radially extracted ion sources will be accommodated and charge state analyzed in the 750 kV, 100 kHz Cockcroft-Walton terminal. The LEBT will provide isotopic analysis to 1 part in 300. A 5m long, 23.4 MHz Wideroe linac, operating in the π -3 π mode based on the GSI design accelerates typically a U⁺⁵ ion to 113 keV/a where it is stripped to U⁺¹¹ by a perfluoropolyether vapor stripper and further accelerated by the SuperHILAC. The space charge limit of the system is several electrical mA which will be approached in the intermediate mass range

No abstract available

[en] The LBL Wideroe-based high-intensity heavy-ion injector for the SuperHILAC will be operational by April 1981. It will provide several emA of low charge state ions up through uranium at high duty factor to the SuperHILAC. Several of the subsystems have already operated to specification and will be described

[en] The photoinjector for the LBNL LUX project, a femtosecond-regime X-ray source, is a room-temperature 1.3 GHz 4 cell structure producing a 10 MeV, nominal 30 psec, 1 nanocoulomb electron bunch at a 10 kHz rate. The first cell is of reentrant geometry, with a peak field of 64MV/m at the photocathode surface, the geometry of which will be optimized for minimum beam emittance. The high repetition rate and high peak power results in a high average surface power density. The design of the cavity, its cooling structure and power couplers, is coordinated with the configuration of the RF system, including a short, highpower driving pulse and active removal of stored energy after the beam pulse to reduce the average power dissipated in the cavity. An RF and thermal analysis of the photoinjector will be presented

[en] New scientific applications require phase-stabilized RF distribution to multiple remote locations. These include phased-array radio telescopes and short pulse free electron lasers. RF modulated onto a CW optical carrier and transmitted via fiber is capable of low noise, but commercially available systems aren't long term stable enough for these applications. Typical requirements are for less than 50fs long term temporal stability between receivers, which is 0.05 degrees at 3GHz. Good results have been demonstrated for RF distribution schemes based on transmission of short pulses, but these require specialized free-space optics and high stability mechanical infrastructure. We report a method which uses only standard telecom optical and RF components, and achieves less than 20fs RMS error over 300m of standard single-mode fiber. We demonstrate stable transmission of 3GHz over 300m of fiber with less than 0.017 degree (17fs) RMS phase error. An interferometer measures optical phase delay, providing information to a feed-forward correction of RF phase.

[en] We consider beams which are described by a 4D transverse distribution f(x, y, x(prime), y(prime)), where x(prime) (triple_bond) p_x/p_z and z is the axial coordinate. A two-slit scanner is commonly employed to measure, over a sequence of shots, a 2D projection of such a beam's phase space, e.g., f(x, x(prime)). Another scanner might yield f(y, y(prime)) or, using crossed slits, f(x, y). A small set of such 2D scans does not uniquely specify f(x, y, x(prime), y(prime)). We have developed ''tomographic'' techniques to synthesize a ''reasonable'' set of particles in a 4D phase space having 2D densities consistent with the experimental data. These techniques are described in a separate document [A. Friedman, et. al., submitted to Phys. Rev. ST-AB, 2002]. Here we briefly summarize one method and describe progress in validating it, using simulations of the High Current Experiment at Lawrence Berkeley National Laboratory