Comprehensive beam jitter study for the commissioning of the intermediate matching section and drift tube linac at ground test accelerator

An experiment on the Ground Test Accelerator (GTA) for the Neutral Particle Beam (NPB) at Los Alamos commissioned the intermediate matching section (IMS) and a single 3.2-MeV drift tube linac (DTL). A diagnostic platform or D-plate was used at the output of the DTL in order to measure various beam parameters. The D-plate and other diagnostic devices located in the IMS, provided measurement of the horizontal and vertical beam position, current, energy, and output phase. These instruments were installed to perform a complete beam jitter analysis based on the current beamline configuration to better understand the causes of any jitter sources as well as to prepare for the initial design of future feedback control systems. The study explored all types of jitter for various beamline configurations. Both interpulse jitter (jitter from pulse to pulse) and intrapulse jitter (jitter within each macropulse) were investigated. Spectral and statistical time analyses were used. Spectral analysis was employed to gain an understanding of the spectral contributions of various jitter sources to determine the degree of correction possible. Statistical time analysis gave a good overall representation of the jitter magnitude and allowed easy comparison of jitter for different beamline configurations, as well as an easy method for determining consistent problems

BEAM POSITION AND PHASE MONITORS FOR THE LANSCE LINAC*

Abstract New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center (LANSCE.) Transducers have been designed and are being installed. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We'll present the various options under consideration for instrumentation along with the advantages and shortcomings of these options

Log-ratio circuit for beam position monitoring

The logarithmic ratio of the signal amplitudes from beam-position probe-electrodes provides a normalized real-time analog signal that is more linear in beam displacement than other signal-processing techniques for circular cross-section, beam-position monitors. This paper describes work being done to develop a log-ratio circuit using an inexpensive, commercially available, logarithmic-response, integrated-circuit rf-amplifier. The circuit uses two amplifiers in a log (A) {minus} log (B) = log (A/B) configuration to provide the logarithmic ratio of the two rf input signals from the probe. The output is a real-time analog signal proportional to beam displacement. 4 refs., 7 figs

High energy beam transport beamline for LEDA

Here the authors describe the High Energy Beam Transport (HEBT) for the Low Energy Demonstration Accelerator (LEDA), which is part of the Accelerator Production of Tritium (APT) project. The authors used the TRACE 3-D linear design code for the first-order design and performed r-z and 3-D particle-in-cell (PIC) simulations to study the beam distribution and halo. TRACE 3-D predicts rms beam properties well. The PIC simulations are important for determining the presence of beam halo, which is present for some tunes. They propose halo experiments to help validate the simulation codes for modeling nonlinear space charge

Log-ratio circuit for beam position monitoring

A synopsis is given of work in progress on a new signal processing technique for obtaining real-time normalized beam position information from sensing electrodes in accelerator beam pipes. The circuit employs wideband logarithmic amplifiers in a configuration that converts pickup electrode signals to position signals that are substantially independent of beam current. The circuit functions as a ratio detector that computes the logarithm of (A/B) as (Log A-Log B), and presents the result in a video (real-time analog) format representing beam position. It has potential benefits of greater dynamic range and better linearity than other techniques currently used and it may be able to operate at substantially higher frequencies. 4 refs., 8 figs

Design and Development of the LEDA Slow Wire Scanner Profile Measurement

The Low Energy Demonstration Accelerator (LEDA) [1, 2] is being developed at Los Alamos National Laboratory as part of the Accelerator Production of Tritium (APT) project. One of the diagnostics being developed to commission LEDA [3] is a slow wire scanner beam profile measurement. Initial profile measurements will be made at 6.7 MeV beam energy and 100 mA beam current. The wire scanner is an interceptive device that will move two silicon carbide coated graphite mono-filament fibers (wires) through the beam, in order to obtain the profile. Some of the design considerations discussed are; Mechanical design, wire temperature analysis, secondary electron detection, signal processing, and system control