Feedbacks on Tune and Chromaticity

Feedbacks on tune, coupling and chromaticity are becoming an integral part of safe and reliable accelerator operation. Tight tolerances on beam parameters typically constrain the allowed oscillation amplitudes to the micrometre range, leaving only a small margin for the transverse beam and momentum excitations required for tune and chromaticity measurements. This contribution presents an overview of these beam-based feedback systems, their architecture and design choices involved. It discusses performance limitations due to cross constraints, non-linearities, the coupling between multiple nested loops, and the interdependence of beam parameters

Real-timefeedback on beam parameters

Traditionally, tight beam parameter stability requirements were most pronounced for light sources and lepton colliders but have now become increasingly important for present and future hadron accelerator operation, not only for performance but also for reasons of machine protection, as recent improvements have led to significantly increased stored beam energies. In the latest generation machines, performance depends critically on the stability of the beam. In order to counteract disturbances due to magnetic imperfections, misalignments, ground motion, temperature changes and other dynamic effects, fully automated control of the key beam parameters â orbit, tune, coupling, chromaticity and energy â becomes an increasingly important aspect of accelerator operation. This contribution presents an overview of beam-based feedback systems, their architecture, performance limitations and design choices involved

LHC Beam Stability and Feedback Control - Orbit and Energy -

This report presents the stability and control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The LHC, presently being built at CERN, will store, accelerate and provide particle collisions with a maximum particle momentum of 7TeV/c and a nominal luminosity of L = 10^34 cm^â2s^â1. The presence of two beams, with both high intensity as well as high particle energies, requires excellent control of particle losses inside a superconducting environment, which will be provided by the LHC Cleaning and Machine Protection System. The performance and function of this and other systems depends critically on the stability of the beam and may eventually limit the LHC performance. Environmental and accelerator-inherent sources as well as failure of magnets and their power converters may perturb and reduce beam stability and may consequently lead to an increase of particle loss inside the cryogenic mass. In order to counteract these disturbances, control of the key beam parameters â orbit, tune, energy, coupling and chromaticity â will be an integral part of LHC operation. Since manual correction of these parameters may reach its limit with respect to required precision and expected time-scales, the LHC is the first proton collider that requires automatic feedback control systems for safe and reliable machine operation. The aim of this report is to help and contribute towards these efforts

Study of the costs and benefits of composite materials in advanced turbofan engines

Composite component designs were developed for a number of applicable engine parts and functions. The cost and weight of each detail component was determined and its effect on the total engine cost to the aircraft manufacturer was ascertained. The economic benefits of engine or nacelle composite or eutectic turbine alloy substitutions was then calculated. Two time periods of engine certification were considered for this investigation, namely 1979 and 1985. Two methods of applying composites to these engines were employed. The first method just considered replacing an existing metal part with a composite part with no other change to the engine. The other method involved major engine redesign so that more efficient composite designs could be employed. Utilization of polymeric composites wherever payoffs were available indicated that a total improvement in Direct Operating Cost (DOC) of 2.82 to 4.64 percent, depending on the engine considered, could be attained. In addition, the percent fuel saving ranged from 1.91 to 3.53 percent. The advantages of using advanced materials in the turbine are more difficult to quantify but could go as high as an improvement in DOC of 2.33 percent and a fuel savings of 2.62 percent. Typically, based on a fleet of one hundred aircraft, a percent savings in DOC represents a savings of four million dollars per year and a percent of fuel savings equals 23,000 cu m (7,000,000 gallons) per year

Analysis of Fouling Data Based on Prior Knowledge

Conventional regression methods are generally unable to analyse extremely complicated processes involving a considerable number of independent variables with poorly understood interaction. These methods use a defined equation for which the parameters of this equation have to be determined. It is however questionable whether any arbitrarily chosen equation is the best. This study aims to implement the powerful neural network architecture for a comprehensive data bank. The HTRI data bank contains a large and unique set of experimental data for cooling water fouling. Only a selection of the data bank is being used at the present time, due to the large number of independent variables investigated in this experimental study

The alignment of the LHC

The Large Hadron Collider (LHC) has been aligned using both classical and non-standard techniques. The results of these alignments were seen on September 10th, 2008 when the beam made several turns in the machine with very few correctors activated. This paper will present the different steps of the alignment as well the techniques used to obtain the alignment accuracy required for beam operation. The correlation of these results with the position recorded by the beam position monitors (BPM) will be presented

Heat Exchanger Fouling in Phosphoric Acid Evaporators - Evaluation of Field Data -

Multistage evaporators are frequently used in phosphoric acid plants to increase the concentration of dilute phosphoric acid to 52-55 wt% P2O5. The concentrated phosphoric acid solution is supersaturated with respect to calcium sulfate. As a result, part of the calcium sulfate in the liquor deposits on the heat exchanger tube walls. Since the thermal conductivity of these scales is very low, thin deposits can create a significant resistance to heat transfer. Therefore, regular cleaning of heat exchangers is required, frequently at less than biweekly intervals. As the major costs in modern phosphoric acid plants are the cost of energy, a thorough understanding of the fouling kinetics and of the effects of various operational parameters on the behavior of calcium sulfate is required to improve operation and design of the shell and tube heat exchangers, which are extensively used. In this investigation, a large number of heat exchanger data were collected from shell and tube heat exchangers of the phosphoric acid plant of the Razi Petrochemical Complex (Iran) and the fouling deposits were analyzed with respect to appearance and composition. The overall heat transfer coefficients and fouling resistances were evaluated at different times and a kinetic model for the crystallization fouling was developed. It is shown that the crystallization rate constant obeys an Arrhenius relationship with activation energy of 57 kJ/mol. The predictions of the suggested model are in good agreement with the plant data

The FPGA-based Continious FFT Tune Measurement System for the LHC and its test at the CERN SPS

A base band tune (BBQ) measurement system has been developed at CERN. This system is based on a high-sensitivity direct-diode detection technique followed by a high resolution FFT algorithm implemented in an FPGA. The system allows acquisition of continuous real-time spectra with 32-bit resolution, while a digital frequency synthesiser (DFS) can provide an acquisition synchronised chirp excitation. All the implemented algorithms support dynamic reconfiguration of processing and excitation parameters. Results from both laboratory measurements and tests performed with beam at the CERN SPS are presented

LHC Beam Stability and Feedback Control - Orbit and Energy -

This report presents the stability and control of the Large Hadron Collider's (LHC) two beam orbits and their particle momenta using beam-based feedback systems. The LHC, presently being built at CERN, will store, accelerate and provide particle collisions with a maximum particle momentum of 7TeV/c and a nominal luminosity of L = 10^34 cm^â2s^â1. The presence of two beams, with both high intensity as well as high particle energies, requires excellent control of particle losses inside a superconducting environment, which will be provided by the LHC Cleaning and Machine Protection System. The performance and function of this and other systems depends critically on the stability of the beam and may eventually limit the LHC performance. Environmental and accelerator-inherent sources as well as failure of magnets and their power converters may perturb and reduce beam stability and may consequently lead to an increase of particle loss inside the cryogenic mass. In order to counteract these disturbances, control of the key beam parameters â orbit, tune, energy, coupling and chromaticity â will be an integral part of LHC operation. Since manual correction of these parameters may reach its limit with respect to required precision and expected time-scales, the LHC is the first proton collider that requires automatic feedback control systems for safe and reliable machine operation. The aim of this report is to help and contribute towards these efforts