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Author Vnuchenko, A.; Esperante Pereira, D.; Gimeno, B.; Benedetti, S.; Catalan Lasheras, N.; Garlasch, M.; Grudiev, A.; McMonagle, G.; Pitman, S.; Syratchev, I.; Timmins, M.; Wegner, R.; Woolley, B.; Wuensch, W.; Faus-Golfe, A. doi  openurl
  Title High-gradient testing of an S-band, normal-conducting low phase velocity accelerating structure Type Journal Article
  Year 2020 Publication Physical Review Accelerators and Beams Abbreviated Journal Phys. Rev. Accel. Beams  
  Volume 23 Issue 8 Pages 084801 - 13pp  
  Keywords  
  Abstract A novel high-gradient accelerating structure with low phase velocity, v/c = 0.38, has been designed, manufactured and high-power tested. The structure was designed and built using the methodology and technology developed for CLIC 100 MV/m high-gradient accelerating structures, which have speed of light phase velocity, but adapts them to a structure for nonrelativistic particles. The parameters of the structure were optimized for the compact proton therapy linac project, and specifically to 76 MeV energy protons, but the type of structure opens more generally the possibility of compact low phase velocity linacs. The structure operates in S-band, is backward traveling wave (BTW) with a phase advance of 150 degrees and has an active length of 19 cm. The main objective for designing and testing this structure was to demonstrate that low velocity particles, in particular protons, can be accelerated with high gradients. In addition, the performance of this structure compared to other type of structures provides insights into the factors that limit high gradient operation. The structure was conditioned successfully to high gradient using the same protocol as for CLIC X-band structures. However, after the high power test, data analysis realized that the structure had been installed backwards, that is, the input power had been fed into what is nominally the output end of the structure. This resulted in higher peak fields at the power feed end and a steeply decreasing field profile along the structure, rather than the intended near constant field and gradient profile. A local accelerating gradient of 81 MV/m near the input end was achieved at a pulse length of 1.2 μs and with a breakdown rate (BDR) of 7.2 x 10(-7) 1 /pulse/m. The reverse configuration was accidental but the operating with this field condition gave very important insights into high-gradient behaviour and a comprehensive analysis has been carried out. A particular attention was paid to the characterization of the distribution of BD positions along the structure and within a cell.  
  Address [Vnuchenko, A.; Esperante Pereira, D.; Gimeno Martinez, B.] Inst Fsica Corpuscular IFIC, Valencia 46980, Spain, Email: anna.vnuchenko@cern.ch  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume (down) Series Issue Edition  
  ISSN 2469-9888 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000582958800002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4584  
Permanent link to this record
 

 
Author Woolley, B.; Burt, G.; Dexter, A.C.; Peacock, R.; Millar, W.L.; Catalan Lasheras, N.; Degiovanni, A.; Grudiev, A.; Mcmonagle, G.; Syratchev, I.; Wuensch, W.; Rodriguez Castro, E.; Giner Navarro, J. doi  openurl
  Title High-gradient behavior of a dipole-mode rf structure Type Journal Article
  Year 2020 Publication Physical Review Accelerators and Beams Abbreviated Journal Phys. Rev. Accel. Beams  
  Volume 23 Issue 12 Pages 122002 - 11pp  
  Keywords  
  Abstract A normal-conducting, X-band traveling wave structure operating in the dipole mode has been systematically high-gradient tested to gain insight into the maximum possible gradients in these types of structure. Measured structure conditioning, breakdown behavior, and achieved surface fields are reported as well as a postmortem analysis of the breakdown position and a scanning electron microscope analysis of the high-field surfaces. The results of these measurements are then compared to high-gradient results from monopole-mode cavities. Scaled to a breakdown rate of 10(-6), the cavities were found to operate at a peak electric field of 154 MV/m and a peak modified Poynting vector S-c of 5.48 MW/mm(2). The study provides important input for the further development of dipole-mode cavities for use in the Compact Linear Collider as a crab cavity and dipole-mode cavities for use in x-ray free-electron lasers as well as for studies of the fundamental processes in vacuum arcs. Of particular relevance are the unique field patterns in dipole cavities compared to monopole cavities, where the electric and magnetic fields peak in orthogonal planes, which allow the separation of the role of electric and magnetic fields in breakdown via postmortem damage observation. The azimuthal variation of breakdown crater density is measured and is fitted to sinusoidal functions. The best fit is a power law fit of exponent 6. This is significant, as it shows how breakdown probability varies over a surface area with a varying electric field after conditioning to a given peak field.  
  Address [Woolley, B.; Burt, G.; Dexter, A. C.; Peacock, R.; Millar, W. L.] Univ Lancaster, Lancaster LA1 4YW, England  
  Corporate Author Thesis  
  Publisher Amer Physical Soc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume (down) Series Issue Edition  
  ISSN 2469-9888 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000614886300002 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 4696  
Permanent link to this record
 

 
Author Diaz-Morcillo, A.; Barcelo, J.M.G.; Guerrero, A.J.L.; Navarro, P.; Gimeno, B.; Cuneáis, S.A.; Melcon, A.A.; Cogollos, C.; Calatroni, S.; Dobrich, B.; Gallego-Puyol, J.D.; Golm, J.; Irastorza, I.G.; Malbrunot, C.; Miralda-Escude, J.; Garay, C.P.; Redondo, J.; Wuensch, W. url  doi
openurl 
  Title Design of New Resonant Haloscopes in the Search for the Dark Matter Axion: A Review of the First Steps in the RADES Collaboration Type Journal Article
  Year 2022 Publication Universe Abbreviated Journal Universe  
  Volume 8 Issue 1 Pages 5 - 22pp  
  Keywords axions; dark matter detectors; haloscopes; resonant cavities  
  Abstract With the increasing interest in dark matter axion detection through haloscopes, in which different international groups are currently involved, the RADES group was established in 2016 with the goal of developing very sensitive detection systems to be operated in dipole magnets. This review deals with the work developed by this collaboration during its first five years: from the first designs-based on the multi-cavity concept, aiming to increase the haloscope volume, and thereby improve sensitivity-to their evolution, data acquisition design, and finally, the first experimental run. Moreover, the envisaged work within RADES for both dipole and solenoid magnets in the short and medium term is also presented.  
  Address [Diaz-Morcillo, Alejandro; Garcia Barcelo, Jose Maria; Lozano Guerrero, Antonio Jose; Navarro, Pablo; Alvarez Melcon, Alejandro] Univ Politecn Cartagena, Dept Informat & Commun Technol, Cartagena 30202, Spain, Email: alejandro.diaz@upct.es;  
  Corporate Author Thesis  
  Publisher Mdpi Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume (down) Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000746970600001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5086  
Permanent link to this record
 

 
Author Garcfa-Barcelo, J.M.; Melcon, A.A.; Cuendis, S.A.; Diaz-Morcillo, A.; Gimeno, B.; Kanareykin, A.; Lozano-Guerrero, A.J.; Navarro, P.; Wuensch, W. url  doi
openurl 
  Title On the Development of New Tuning and Inter-Coupling Techniques Using Ferroelectric Materials in the Detection of Dark Matter Axions Type Journal Article
  Year 2023 Publication IEEE Access Abbreviated Journal IEEE Access  
  Volume 11 Issue Pages 30360-30372  
  Keywords Tuning; Couplings; Permittivity; Dark matter; Magnetic resonance; Cryogenics; Receivers; Ferroelectrics; Microwave devices; Axion detection; axion-photon interaction; dark matter; ferroelectrics; haloscope; KTO; microwave resonator; STO; tuning  
  Abstract Tuning is an essential requirement for the search of dark matter axions employing haloscopes since its mass is not known yet to the scientific community. At the present day, most haloscope tuning systems are based on mechanical devices which can lead to failures due to the complexity of the environment in which they are used. However, the electronic tuning making use of ferroelectric materials can provide a path that is less vulnerable to mechanical failures and thus complements and expands current tuning systems. In this work, we present and design a novel technique for using the ferroelectric Potassium Tantalate (KTaO3 or KTO) material as a tuning element in haloscopes based on coupled microwave cavities. In this line, the structures used in the Relic Axion Detector Exploratory Setup (RADES) group are based on several cavities that are connected by metallic irises, which act as interresonator coupling elements. In this article, we also show how to use these KTaO3 films as interresonator couplings between cavities, instead of inductive or capacitive metallic windows used in the past. These two techniques represent a crucial upgrade over the current systems employed in the dark matter axions community, achieving a tuning range of 2.23% which represents a major improvement as compared to previous works (<0.1%) for the same class of tuning systems. The theoretical and simulated results shown in this work demonstrate the interest of the novel techniques proposed for the incorporation of this kind of ferroelectric media in multicavity resonant haloscopes in the search for dark matter axions.  
  Address [Garcia-Barcelo, J. M.; Melcon, A. Alvarez; Diaz-Morcillo, A.; Lozano-Guerrero, A. J.; Navarro, P.] Tech Univ Cartagena, Dept Informat & Commun Technol, Cartagena 30203, Spain, Email: josemaria.garcia@upct.es  
  Corporate Author Thesis  
  Publisher Ieee-Inst Electrical Electronics Engineers Inc Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume (down) Series Issue Edition  
  ISSN 2169-3536 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000966674500001 Approved no  
  Is ISI yes International Collaboration yes  
  Call Number IFIC @ pastor @ Serial 5513  
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