Transverse deflecting cavities

Transverse deflecting cavities are used for a number of applications in modern accelerators. In this paper we discuss the fields of these cavities, some of their applications, and some important aspects of their design.Comment: 11 pages, contribution to the CAS - CERN Accelerator School: Specialised Course on RF for Accelerators; 8 - 17 Jun 2010, Ebeltoft, Denmar

Inclusion is an action word

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Development and validation of the Just Community Gardening Survey: A measure of the social and dietary outcomes of community garden participation

Our aim was to develop and validate a survey measuring outcomes of community gardening related to food system equity. Face validity was assessed by six community gardening experts and resulted in minor changes to the survey. Weighted kappa and Cronbach’s alpha were used to determine test-retest reliability and internal consistency using a sample of community gardeners in New York City (n=38). Weighted kappa analyses revealed almost perfect agreement (mean = 0.981, range 0.498-1, p≤.001). Cronbach’s alpha was calculated for eight scales, most of which had excellent agreement. The resulting 25-item Just Community Gardening Survey consisted of demographic, garden participation, garden activities, social participation, social cohesion, collective efficacy, perceived impact on dietary intake, food access and security, horticultural and environmental knowledge and diet-related health questions. This validated survey not only measures the social and dietary outcomes of community gardening, it incorporates important aspects of food justice not assessed in previous research

Comparisons of the execution times and memory requirements for high-speed discrete fourier transforms and fast fourier transforms, for the measurement of AC power harmonics

Conventional wisdom dictates that a Fast Fourier Transform (FFT) will be a more computationally effective method for measuring multiple harmonics than a Discrete Fourier Transform (DFT) approach. However, in this paper it is shown that carefully coded discrete transforms which distribute their computational load over many frames can be made to produce results in shorter execution times than the FFT approach, even for large number of harmonic measurement frequencies. This is because the execution time of the presented DFT actually rises with N and not the classical N2 value, while the execution time of the FFT rises with Nlog2N

Developing and testing a generic micro-combined heat and power model for simulations of dwellings and highly distributed power systems

This paper elaborates an approach to the modelling of domestic micro-combined heat and power (μ-CHP) using a building simulation tool that can provide a detailed picture of the environmental performance of both the μ-CHP heating system and the dwelling it serves. The approach can also provide useful data for the modelling of highly distributed power systems (HDPS). At the commencement of the work described in this paper no μ-CHP device model that was compatible with a building simulation tool was available. The development of such a model is described along with its calibration and verification. The simulation tool with the device model was then applied to the analysis of a dwelling with a Stirling engine-based heating system. Different levels of thermal insulation and occupancy types were modelled. The energy and environmental performance of the μ-CHP device was quantified for each case; additionally, the potential for its participation in the control and operation of an HDPS was assessed. Analysis of the simulation results indicated that the parasitic losses associated with the μ-CHP system balance of plant reduced the overall heating system efficiency by up to 40 per cent. Performance deteriorated with increasing levels of insulation in the dwelling, resulting in reduced thermal efficiency and increased cycling, though overall fuel use was reduced. The analysis also indicated that the device was generally available to participate in HDPS control for greater than 90 per cent of the simulation time. The potential length of the participation time ranged from 1 to 800+min and depended upon the state of the μ-CHP system thermal buffer and prevailing heat loads. Probabilities for different participation times and modes were calculated

Asymmetric Dual Axis Energy Recovery Linac for Ultra-High Flux sources of coherent X-ray/THz radiation: Investigations Towards its Ultimate Performance

In order for sources of coherent high brightness and intensity THz and X-Ray radiation to be accepted by university or industrial R&D laboratories, truly compact, high current and efficient particle accelerators are required. The demand for compactness and efficiency can be satisfied by superconducting RF energy recovery linear accelerators (SRF ERL) allowing effectively minimising the footprint and maximising the efficiency of the system. However such set-ups are affected by regenerative beam-break up (BBU) instabilities which limit the beam current and may terminate the beam transport as well as energy recuperation. In this paper we suggest and discuss a SRF ERL with asymmetric configuration of resonantly coupled accelerating and decelerating cavities. In this type of SRF ERL an electron bunch is passing through accelerating and decelerating cavities once and, as we show in this case, the regenerative BBU instability can be minimised allowing high currents to be achieved. We study the BBU start current in such an asymmetric ERL via analytical and numerical models and discuss the properties of such a system

NEW CAVITY SHAPE DEVELOPMENTS FOR CRABBING APPLICATIONS

Deflecting mode cavities are required in several accelerators for use as crab cavities in colliders and light sources and as separators. The space requirements for these applications are extremely tight due to two or more beamlines being close together. In addition the dipole mode cavities have lower and same order modes as well as higher order modes which require damping to very low Q values. A number of designs are proposed for compact and/or strongly damped SRF crab cavities. This paper will discuss various coaxial type crab cavities which allow the design of compact crab cavities operating at frequencies below 500 MHz. In addition a number of novel damping schemes will be shown and evaluation of these designs including multipacting will be discussed

Modelling Gaia CCD pixels with Silvaco 3D engineering software

Gaia will only achieve its unprecedented measurement accuracy requirements with detailed calibration and correction for radiation damage. We present our Silvaco 3D engineering software model of the Gaia CCD pixel and two of its applications for Gaia: (1) physically interpreting supplementary buried channel (SBC) capacity measurements (pocket-pumping and first pixel response) in terms of e2v manufacturing doping alignment tolerances; and (2) deriving electron densities within a charge packet as a function of the number of constituent electrons and 3D position within the charge packet as input to microscopic models being developed to simulate radiation damage.Comment: 4 pages, 3 figures, contributed poster, appearing in proceedings of the ELSA conference: Gaia, at the frontiers of astrometry, 7-11 June 2010, S\`evres, Pari

Increasing security of supply by the use of a local power controller during large system disturbances

This paper describes intelligent ways in which distributed generation and local loads can be controlled during large system disturbances, using Local Power Controllers. When distributed generation is available, and a system disturbance is detected early enough, the generation can be dispatched, and its output power can be matched as closely as possible to local microgrid demand levels. Priority-based load shedding can be implemented to aid this process. In this state, the local microgrid supports the wider network by relieving the wider network of the micro-grid load. Should grid performance degrade further, the local microgrid can separate itself from the network and maintain power to the most important local loads, re-synchronising to the grid only after more normal performance is regained. Such an intelligent system would be a suitable for hospitals, data centres, or any other industrial facility where there are critical loads. The paper demonstrates the actions of such Local Power Controllers using laboratory experiments at the 10kVA scale