Patrick Krkotić
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View article: Assessing photon resilience of REBCO coated conductors under radiation-rich environments
Assessing photon resilience of REBCO coated conductors under radiation-rich environments Open
Rare-earth barium copper oxide (REBCO) coated conductors (CCs) are regarded as promising candidates for next-generation superconducting technologies operating in photon-rich environments, such as particle accelerators, fusion reactors, and…
View article: Impact of high-intensity LHC beam operation on warm vacuum modules
Impact of high-intensity LHC beam operation on warm vacuum modules Open
During the third run of the Large Hadron Collider in 2023, which had the highest intensity bunch population compared to previous runs, a beam dump incident with operational delays occurred due to increased losses attributed to pressure spi…
View article: Characterising the Surface Resistance of Laser-Treated LHC Beam Screens with the Shielded Pair Method
Characterising the Surface Resistance of Laser-Treated LHC Beam Screens with the Shielded Pair Method Open
The presence of strong electron clouds in the quadrupole magnetic field regions of the Large Hadron Collider (LHC) leads to considerable heating that poses challenges for the cryogenic cooling system, and under certain conditions to proton…
View article: Multimode Dielectric Resonator for Accurate Determination of Frequency and Temperature Dependence of Complex Permittivity in Small, High-Permittivity Cylinders
Multimode Dielectric Resonator for Accurate Determination of Frequency and Temperature Dependence of Complex Permittivity in Small, High-Permittivity Cylinders Open
We present a technique to measure permittivity and loss tangent in high-permittivity cylinders. This method utilizes a resonator to conduct concurrent measurements at the three lowest quasi-TE01p modes across various temperatures, combined…
View article: Selective laser processing of particle accelerator beam screen surfaces for electron cloud mitigation
Selective laser processing of particle accelerator beam screen surfaces for electron cloud mitigation Open
The material properties of laser-treated LHC beam screens with low SEY are examined to validate compatibility with the operation conditions of particle accelerators.
View article: Impact of a hybrid coating REBCO-CC-Cu to the resistive wall beam impedance of the FCC-hh beam screen
Impact of a hybrid coating REBCO-CC-Cu to the resistive wall beam impedance of the FCC-hh beam screen Open
The Future Circular Hadron Collider design studies proposed a novel dual chamber beam screen consisting of copper and stainless steel. However, one concern about the current design is the inherent resistive wall beam impedance of the beam …
View article: Influence of nanoparticulates and microgrooves on the secondary electron yield and electrical resistance of laser-treated copper surfaces
Influence of nanoparticulates and microgrooves on the secondary electron yield and electrical resistance of laser-treated copper surfaces Open
Laser surface structuring has proven to be an effective technique for achieving a copper surface with secondary electron yield (SEY) values close to or below unity. However, the attributes that minimize SEY, such as moderately deep grooves…
View article: Shielded Pair Method for Beam Screen Surface Resistance Measurement at Cryogenic Temperature
Shielded Pair Method for Beam Screen Surface Resistance Measurement at Cryogenic Temperature Open
The shielded pair resonator method is a useful tool in the measurement of accelerator components, such as the beam screens used in the Large Hadron Collider (LHC), the High-Luminosity (HL) LHC, or future accelerators. It can measure the re…
View article: Nonlinear Surface Impedance of HTS in High Magnetic Fields
Nonlinear Surface Impedance of HTS in High Magnetic Fields Open
Recently envisaged high-temperature superconductor (HTS) applications rely on their radio-frequency properties in very high magnetic fields. As an example, coating of surfaces facing particle beams with HTS for reducing the beam coupling i…
View article: Evaluation of the impact of REBCO-coated conductors on the resistive wall impedance of the FCC-hh
Evaluation of the impact of REBCO-coated conductors on the resistive wall impedance of the FCC-hh Open
The beam screen for the Future Circular hadron-hadron Collider (FCC-hh) has a baseline design based on a copper (Cu) coating. Calculations have indicated that the resistive wall impedance will be the major contributor to the beam impedance…
View article: RF Characterisation of Laser Treated Copper Surfaces for the Mitigation of Electron Cloud in Accelerators
RF Characterisation of Laser Treated Copper Surfaces for the Mitigation of Electron Cloud in Accelerators Open
In accelerator beam chambers and RF waveguides, electron cloud and multipacting can be mitigated effectively by reducing the secondary electron yield (SEY). In recent years, it has been established that laser-engineered surface structuring…
View article: Dielectric resonator to measure surface resistance of accelerator components at room temperature and 77 K
Dielectric resonator to measure surface resistance of accelerator components at room temperature and 77 K Open
We measured the surface resistance of titanium, amorphous carbon, and nonevaporable getter (NEG) coatings on copper samples, representative of surface treatments of beam-facing components in the High-Luminosity Large Hadron Collider at CER…
View article: Performance of high-temperature superconducting REBCO coated conductors under synchrotron irradiation for future circular colliders
Performance of high-temperature superconducting REBCO coated conductors under synchrotron irradiation for future circular colliders Open
The influence of medium-to-high energy synchrotron radiation (SR) (≈10–100 keV) produced by the ALBA Synchrotron Light Source on state-of-the-art REBCO coated conductors (CCs) has been studied to assess the feasibility of using high-temper…
View article: Electron Beam Characterization of REBCO-Coated Conductors at Cryogenic Conditions
Electron Beam Characterization of REBCO-Coated Conductors at Cryogenic Conditions Open
Particle accelerators with superconducting magnets operating at cryogenic temperatures use a beam screen (BS) liner that extracts heat generated by the circulating bunched charge particle beam before it can reach the magnets. The BS surfac…
View article: Potential impedance reduction by REBCO-coated conductors as beam screen coating for the Future Circular Hadron Collider
Potential impedance reduction by REBCO-coated conductors as beam screen coating for the Future Circular Hadron Collider Open
The Future Circular Collider study creates a conceptual design for a post-LHC particle accelerator using 16 T superconducting dipoles to achieve collision energies of up to 100 TeV in a 90 km circumference ring. A copper-coated beam screen…
View article: Evaluation of the surface impedance of ReBCO coated conductors and requirements for their use as beam screen materials for the FCC-hh
Evaluation of the surface impedance of ReBCO coated conductors and requirements for their use as beam screen materials for the FCC-hh Open
(English) The Future Circular Hadron Collider (FCC-hh) is a proposal for a 100-kilometre-long particle accelerator with collision energy substantially higher than previous colliders to expand the Large Hadron Collider (LHC) research. The s…
View article: Accurate Determination of Dielectric Properties in Small, High-Permittivity Dielectric Cylinders
Accurate Determination of Dielectric Properties in Small, High-Permittivity Dielectric Cylinders Open
We describe a method for performing cryogenic permittivity and loss tangent measurements of small (few mm), high-permittivity dielectric cylinders used in surface impedance measurement of superconductors. We combine the use of sapphire and…
View article: Evaluation of the nonlinear surface resistance of REBCO coated conductors for their use in the FCC-hh beam screen
Evaluation of the nonlinear surface resistance of REBCO coated conductors for their use in the FCC-hh beam screen Open
To assess the feasibility of using high-temperature superconductors for the beam screens of future circular colliders, we have undertaken a study of the power dependence of the microwave surface resistance in state-of-the-art REBCO coated …
View article: Algorithm for Resonator Parameter Extraction From Symmetrical and Asymmetrical Transmission Responses
Algorithm for Resonator Parameter Extraction From Symmetrical and Asymmetrical Transmission Responses Open
We describe an algorithm capable of extracting the unloaded quality factor and the resonant frequency of microwave resonators from vector S-parameters. Both symmetrical (Lorentzian) and asymmetrical (Fano) transmission responses are suppor…
View article: RF Characterisation of New Coatings for Future Circular Collider Beam Screens
RF Characterisation of New Coatings for Future Circular Collider Beam Screens Open
For the future high energy colliders being under the design at this moment, the choice of a low surface impedance beam screen coating material has become of fundamental importance to ensure sufficiently low beam impedance and consequently …
View article: High frequency response of thick REBCO coated conductors in the framework of the FCC study
High frequency response of thick REBCO coated conductors in the framework of the FCC study Open
A thorough microwave response study of high temperature superconductors, considered as an alternative beam screen coating, has become integral in the design decisions for CERN’s future research infrastructure. Here, we present the surface …
View article: Coated conductor technology for the beamscreen chamber of future high energy circular colliders
Coated conductor technology for the beamscreen chamber of future high energy circular colliders Open
The surface resistance of state-of-the-art REBa 2 Cu 3 O 7− x coated conductors has been measured at 8 GHz versus temperature and magnetic field. We show that the surface resistance of REBa 2 Cu 3 O 7− x strongly depends on the microstruct…