Overview of SRF Deflecting and Crabbing Cavities

Developments over the past few years on novel superconducting deflecting and crabbing cavities have introduced advanced rf geometries with improved performance, in comparison to the typical squashed elliptical cavities operating in TM110 type mode. These new structures are compact geometries operating in either TEM type or TE11-like mode. One of the key applications of such cavities is the use of crabbing systems for circular colliders in increasing the luminosity. Crabbing systems are an essential component in future colliders with intense beams and proposed electron-ion colliders. High luminosity upgrade of LHC is planned to implement crabbing systems at two interaction points. Recently, a two-cavity cryomodule with double quarter wave crabbing cavity was installed in SPS at CERN and successfully tested with the proton beam. We present the details of different superconducting deflecting and crabbing cavities and their applications, as well as the recent results of the crabbing systems test at SPS

Compact Superconducting Crabbing and Deflecting Cavities

Recently, new geometries for superconducting crabbing and deflecting cavities have been developed that have significantly improved properties over those the standard TM110 cavities. They are smaller, have low surface fields, high shunt impedance and, more importantly for some of them, no lower-order-mode with a well-separated fundamental mode. This talk will present the status of the development of these cavities

Superconducting RF-Dipole Deflecting and Crabbing Cavities

Recent interests in compact deflecting and crabbing structures for future accelerators and colliders have initiated the development of novel rf structures. The superconducting rf-dipole cavity is one of the first compact designs with attractive properties such as high gradients, high shunt impedance, the absence of lower order modes, and widely separated higher order modes. Two rf-dipole cavities at 400 MHz and 499 MHz have been designed, fabricated and tested as proof-of-principle designs of compact deflecting and crabbing cavities for the LHC high luminosity upgrade and Jefferson Lab 12 GeV upgrade. The first rf tests have been performed on the rf-dipole geometries at 4.2 K and 2.0 K in a vertical test assembly with excellent results. The cavities have achieved high gradients with high intrinsic quality factors, and multipacting levels were easily processed

II Encontro Internacional de Formação na Docência (INCTE): livro de resumos

O II Encontro Internacional de Formação na Docência apresenta os seguintes objetivos: problematizar, no quadro do processo de Bolonha, as estruturas curriculares da formação de educadores e professores; debater propostas didáticas inovadoras na formação para a docência; refletir sobre as práticas formativas nos diversos contextos; analisar o contributo da formação na dinamização das instituições; aprofundar a comunicação entre os diferentes intervenientes na formação numa perspetiva de educação para o desenvolvimento. O Encontro está estruturado em quatro grandes eixos temáticos: Currículo e formação de educadores e professores (CFEP) Este eixo temático integra as questões do currículo, da inovação curricular e as novas perspetivas curriculares, no âmbito da formação inicial ou continuada de educadores e professores, incluindo a discussão de modelos e processos curriculares de diferente natureza e de trabalhos ou propostas de formação de educadores e professores, nos diversos contextos. Didática e formação de educadores e professores (DFEP) Este eixo temático integra aspetos dos diferentes saberes disciplinares em contexto escolar, abarcando a reflexão sobre os contributos da didática na formação de educadores e professores para uma construção progressiva de formas de compreender e agir conscientemente em situações educativas. Práticas educativas e supervisão pedagógica (PESP) Este eixo temático integra o desenvolvimento de práticas de formação de educadores e professores nas escolas, compreendendo a problematização dos papéis a desempenhar pelos diversos intervenientes, numa perspetiva de trabalho colaborativo e da construção de uma identidade profissional consciente, empenhada e responsável. Formação docente e educação para o desenvolvimento (FDED) Este eixo temático integra aspetos formativos do ensino e da aprendizagem relacionados com a promoção de uma cidadania global responsável, abrangendo a discussão de projetos e práticas educativas potenciadoras de uma educação para o desenvolvimento

II Encontro Internacional de Formação na Docência (INCTE): livro de atas

Este livro contém os artigos do I Encontro Internacional de Formação na Docência (INCTE), realizado nos dias 5 e 6 de maio de 2017 no Instituto Politécnico de Bragança

Measurement of Surface Resistance Properties With Coaxial Resonators - Review

Achieving ever decreasing surface resistance at higher field in superconducting RF accelerating structures is one of most outstanding developments in modern accelerators. The BCS theory has been used widely to estimate the surface resistance and to direct the technology. However, recent research results show that the behavior of the surface resistance further deviates from the BCS theory. So far the study on surface resistance was performed usually with cavities of single frequency which limited the study of frequency dependent surface resistance. The Center for Accelerator Science at Old Dominion University has designed and built several half wave coaxial cavities to study the frequency, temperature, and RF field dependence of surface resistance. TRIUMF in Canada also joined this line of research using such multi frequency quarter wave and half wave coaxial cavities. This type of multi mode cavity will allow us to systematically study the parameters affecting surface resistance on the same cavity surface. In this paper, we review the results ODU and TRIUMF collected so far and proper analysis methods

Measurements of Frequency, Temperature, RF Field Dependent Surface Resistance Using Superconducting Half-Wave Cavity

A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its own frequency. A superconducting half wave cavity is a cavity that enables us to collect the surface resistance data across frequencies of interest for particle accelerators and evaluate preparation techniques. This paper will present the design of the half wave cavity, its electromagnetic mode characteristics and experimental results

Investigation of the Surface Resistance of Niobium Between 325 MHz and 1300 MHz Using a Coaxial Half-wave Cavity

The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test procedure, results and we will explore underlying physics of the phenomenon. * H. Park et al., MOPB003, Proc. SRF2015, http://jacow.org/** H. Park et al., THPB080, Proc. SRF2017, http://jacow.org

Lessons learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box

Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box