Large applications and challenges of state-of-the-art superconducting RF (SRF) technologies

Various applications of superconducting radio-frequency (SRF) accelerating structures in many fields around the world are introduced. These applications consist of high energy physics, nuclear physics, free electron lasers, energy amplifiers, nuclear materials and the treatment of radioactive wastes. A review of recent development of SRF technologies is presented. The authors also briefly discuss the future prospects of SRF technologies and applications

Eddy current and quench loads and stress of SSC collider 4-K liner and the bore tube during magnet quench

This paper describes the response of the eddy current and quench loads on a proposed Superconducting SuperCollider 4-K liner system. The liner within a bore tube is designed to remove the radiated power and the photodesorbed gas that impair the beam tube vacuum. The bimetallic liner tube is subjected to cooldown and eddy current loads. The square liner tube is a two-shell laminated Nitronic-40 steel is used for strength and a copper inner layer for low impedance to the image currents. Perforated holes are used to remove the photodesorbed gases for vacuum maintenance. The holes are located in a low-stress area of the liner. Rectangular holes in a four-pole symmetry pattern are required for beam dynamic stability. The liner is conductivity cooled by the round steel bore tube with a 2-mm wall. The copper layer must not be stressed over the yield strength limit because copper properties such as conductivity are known to change when the copper is stressed over yield strength. This analysis will address liner system response under thermal, eddy current, and vaporized liquid helium loads in a quenching dipole magnet

Design of three recirculating-linac SRF systems for a 4-TeV {mu}{sup +}-{mu}{sup {minus}} collider

In a conceptual design of the accelerating systems for a 4-TeV {mu}{sup +}-{mu}{sup {minus}} collider, three recirculating superconducting linacs (with energies reaching 70 GeV (with 350 MHz SRF), 250 GeV (800 MHz) and 2,000 GeV (1,300 GHz), respectively) are used. The authors briefly describe design concepts for the acceleration features, superconducting RF cavities, input couplers, RF control and RF power systems

High power coupler for the TESLA superstructure cavities

Published online on JACoWMore and more, accelerators are built with superconducting cavities operating at cryogenic temperatures, and the probability of a ceramic window failure presents increasing problems because of the resulting contamination of the cavities' surfaces and the resulting accelerating electric field degradation. Double ceramic window couplers are required to reduce this risk. The TESLA superstructure cavity requires a new coupler for the higher power input and the coupling characteristics. A cost effective design and fabrication method for these couplers has been developed to meet these demands. This new design presents an alternative to the present TESLA cylindrical ceramic windows, uses two planar disc windows separated by a vacuum space, and is optimized for RF input power, vacuum characteristics, and thermal properties. Two couplers with this design have been fabricated and are presently being tested at DESY, Germany on the RF high power testing stand and will also be tested on a test cryomodule. The design will be discussed in this paper

Micorrizas arbusculares, poblaciones de microbios rizosféricos y actividades enzimáticas del suelo en huertos de cítricos bajo dos tipos de manejo de suelos sin labranza

The arbuscular mycorrhizal (AM) status [total AM colonization (RLT), percentage of root length with arbuscules (RLA) and vesicles (RLV), spore density and hyphal length density], microbial populations and soil enzyme activities were investigated in citrus (Satsuma Mandarin grafted on Poncirus trifoliata L. Raf) orchards. Two types of no-tillage soil management, natural grass cover and use of herbicides, were employed in these orchards. The citrus AM colonization (37.26-70.09%) was high in all the experimental orchards sampled. The highest RLA (43.83%), spore density (384.63 spores/100 g soil), hyphal length density (4.09 m g–1 soil), rhizospheric microbial populations and enzyme activities were observed in the orchards with a natural grass cover, and the lowest values, except urease activity, were found in the orchards treated with herbicides. Spore density, hyphal length density, catalase activity and phosphatase activity varied notably between no-tillage/natural grass and no-tillage/herbicides treated orchards in the soil layers above 40 cm. A correlation analysis showed that the hyphal length density and organic matter were significantly positively correlated. Soil enzyme activities, except phosphatase, were strongly correlated with the bacteria populations. The data presented here demonstrates that the RLA, spore density, hyphal length density, rhizospheric microbe populations and enzyme activities were significantly better in the soil layers above 40 cm of orchards with a natural grass cover than herbicidetreated soils. So, the establishment of a natural grass cover benefits soil quality in citrus orchards in Southern China.Se investigó en huertos de mandarino Satsuma injertado sobre Poncirus trifoliata L. Raf el estado de las micorrizas arbusculares (AM) [colonización total de AM (RLT), % de longitud de la raíz con arbúsculos (RLA) y vesículas (RLV), densidad de esporas y de hifas], las poblaciones microbianas y las actividades enzimáticas del suelo. En estos huertos se emplea dos tipos de gestión del suelo sin labranza, uno mediante cubierta de césped natural y otro mediante uso de herbicidas. La colonización de AM en la raíz de los cítricos fue alta (37,26-70,09%) en todos los huertos muestreados. Se observó el mayor RLA (43,83%), densidad de esporas (384,63 esporas/100 g de suelo), densidad de longitud de hifas (4,09 m g–1 de suelo), poblaciones microbianas rizosféricas y actividades enzimáticas en los huertos con cubierta de césped natural. En las capas del suelo hasta los 40 cm, la densidad de las esporas y de las hifas, y la actividad de la catalasa y de la fosfatasa variaron notablemente entre los dos tratamientos. Un análisis de correlación mostró que la densidad de las hifas y la materia orgánica estaban significativamente correlacionadas. Las actividades enzimáticas del suelo, a excepción de la fosfatasa, estuvieron fuertemente correlacionadas con las poblaciones de bacterias. Por lo tanto, la no labranza y el establecimiento de una cobertura de césped beneficia la calidad del suelo en estos huertos de cítricos en el sur de China

Superconducting RF cavities and magnets for a 4-TeV energy muon collider

The accelerators must take the muon beams from {approximately} 100 MeV to 2 TeV energies within the muon lifetime for a 4 TeV energy muon collider. These constraints plus the muon decay heating seriously challenge the designs of the superconducting RF (SRF) cavities and magnets in the accelerators and collider ring. The multiple superconducting recirculation linac and the very rap8id-cycling superconducting synchrotron approach are both studied. The authors briefly introduce the technical considerations and preliminary designs of the SRF systems and magnets

High power coupler for the TESLA superstructure cavities

Published online on JACoWMore and more, accelerators are built with superconducting cavities operating at cryogenic temperatures, and the probability of a ceramic window failure presents increasing problems because of the resulting contamination of the cavities' surfaces and the resulting accelerating electric field degradation. Double ceramic window couplers are required to reduce this risk. The TESLA superstructure cavity requires a new coupler for the higher power input and the coupling characteristics. A cost effective design and fabrication method for these couplers has been developed to meet these demands. This new design presents an alternative to the present TESLA cylindrical ceramic windows, uses two planar disc windows separated by a vacuum space, and is optimized for RF input power, vacuum characteristics, and thermal properties. Two couplers with this design have been fabricated and are presently being tested at DESY, Germany on the RF high power testing stand and will also be tested on a test cryomodule. The design will be discussed in this paper