The superconducting split ring resonator as an accelerating structure (original) (raw)
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Split Ring Resonator Experiment - Simulation Results
2021
FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a compact linac-based test facility for accelerator and diagnostics R&D. An example for a new accelerator diagnostics tool currently studied at FLUTE is the split-ring-resonator (SRR) experiment, which aims to measure the longitudinal bunch profile of fs-scale electron bunches. Laser-generated THz radiation is used to excite a high frequency oscillating electromagnetic field in the SRR. Particles passing through the SRR gap are time-dependently deflected in the vertical plane, which allows a vertical streaking of an electron bunch. This principle allows a diagnosis of the longitudinal bunch profile in the femtosecond time domain and will be tested at FLUTE. This contribution presents an overview of the SRR experiment and the results of various tracking simulations for different scenarios as a function of laser pulse length and bunch charge. Based on these results possible working points for the experiments at FLUTE will be proposed.
Design and test of a superconducting structure for high-velocity ions
Following the successful development of a niobium coaxial half-wave structure we have designed, built and tested a new half-wave geometry: the spoke resonator. This geometry is better suited for high frequency resonators and for the acceleration of high velocity ions. The prototype cavity is a 2-gap structure resonating at 855 MHz, and optimized for particle velocity of 0.30 c. It is easier to manufacture than the coaxial half-wave resonator and the geometry can be straightforwardly extended to multigap designs. Rf-tests have been performed on this cavity both prior to and after high temperature annealing. An accelerating gradient of 7.2 MV/m (cw) and 7.8 MV/m (pulsed) was observed at 4.2 K. After annealing, a low power Q{sub 0} of 1.2 {times}10{sup 8} was observed with small Q degradation due to field emission at high accelerating fields.
Superconducting accelerating structures for very low velocity ion beams
Physical Review Special Topics - Accelerators and Beams, 2008
Super-conducting TEMof independentlyof different ion species. y designs presented here arge state. Several types icle velocities above 0.06c. Superconducting four-gap quarter-wave r veloped about two decades ago and have been successfully operated at the ATLAS SC linac at Argonne National Lab e, progress in simulation tools, cavity fabrication and processing have increased SC cavity gradients by a fa r applies these tools to optimize the design of a four-gap quarter-1+ or a 2+ charge state efficiency, be able injectors have been Radio Frequency Quadrupole (RFQ) injecting a near accelerator. The latter must be capable to accept and accelerate rare isotopes with charge-to-mass ratio in the range from 1/238 to 1/6. The SC linac is required after the gas stripping for q/A≥1/66 ions in the energy range from 75 keV/u to ~1 MeV/u. Superconducting four-gap quarter-wave resonators, also known as "fork" or inter-digital cavities, are a proven type of SC cavity for application in the energy range from ~30 keV/u to ~1.0 MeV/u [2]. At very low velocities, the greater length of 4-gap cavities compared with 2-gap cavities provides more voltage per cavity, while at the same time, the number of gaps remains small enough to provide a wide velocity acceptance, VERY LOW VELOCITY ION BE
Beam dynamics studies of four-gap low-beta superconducting resonators
1993
The four-ga p superconducting resonators which have been developed st Azsonne for use in the low-beta positive ion-_ 2 injector for ATLAS [I] have potential applications for ions ]"[-.... ";ta. with velocities less than 0.007c and q/m less than 0.1. It _-_ ! was previously observed that at low velodties these strut-_ _ tuzes cn be focussing in both longitudinal sad trans-_ vezqe phase spaces due to an inherent altetnating-phasefocusdn 8 property [2]. Studies are underway to determine the optimum combination of multi-gap struct_es and solenoids st low velocity and low q/ro. In this paper we present the results of accept,ace studies for the first t_ee resonators at the front of the positive-ion injector linac, with sad without the focussin 8 solenoids. These studies include the effects of higher-order distortions in longitudinal and trsasveme phase spaces since minim_in 8 such aberration, is very important for most nuclear physics sppllcations of such accelerators.
A superconducting quarter-wave resonator for high-brightness ion beam acceleration
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A niobium resonant cavity optimized for phase velocity P, = 0.15 was constructed based on a coaxial quarter-wave geometry adapted for high-brightness ion beams. This cavity, which resonates at 400 MHz in the fundamental mode, operated at an average (wall-to-wall) accelerating gradient of 12.9 MV/m under continuous-wave fields. This is the highest average accelerating gradient achieved to date in low-velocity structures designed for cw operation. At this gradient, a cavity Q of 1.4 x 108 was measured.
Superconducting travelling wave ring with high gradient accelerating section
2007 IEEE Particle Accelerator Conference (PAC), 2007
Use of a superconducting travelling wave accelerating (STWA) structure [1] instead of a standing wave cavity has major advantages in increasing the accelerating gradient in the ILC. In contrast with standing wave cavity STWA requires feedback loop, which sends wave from the structure output to input, making a superconducting travelling wave ring (STWR). One or few input couplers need to excite STWR and compensate power dissipations due to beam loading. To control travelling wave regime in the structure two independent knobs can be used for tuning both resonant ring frequency and backward wave. We discuss two variants of the STWR with one and two feed couplers.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2010
We obtain band diagrams for a two-dimensional periodic structure consisting of an infinite square array of infinitely thin concentric circles (split rings) with narrow gaps. Our approach exploits the narrowness of the gaps and yields algebraic equations relating the frequency to the Bloch wavenumber and geometric properties of the array. Further asymptotic analysis indicates that the gravest mode has a frequency that scales in an inverse logarithmic fashion with the size of the gap and that exhibits anomalous dispersion. Near the origin of the Brillouin zone this ‘acoustic’ mode is dispersionless. Numerical solution of the eigenvalue problem in the single-gap case confirms these conclusions. The two lowest modes of the split ring can be interpreted as a splitting of the gravest propagating Rayleigh mode.
Beam steering in superconducting quarter-wave resonators: An analytical approach
Physical Review Special Topics - Accelerators and Beams, 2011
, p. 1095], where an analytical formula describing it was proposed and the influence of cavity geometry was discussed. Since then, the importance of this effect was recognized and effective correction techniques have been found [P. N. Ostroumov and K. W. Shepard, Phys. Rev. ST Accel. Beams 4, 110101 (2001)]. This phenomenon was further studied in the following years, mainly with numerical methods. In this paper we intend to go back to the original approach and, using well established approximations, derive a simple analytical expression for QWR steering which includes correction methods and reproduces the data starting from a few calculable geometrical constants which characterize every cavity. This expression, of the type of the Panofski equation, can be a useful tool in the design of superconducting quarter-wave resonators and in the definition of their limits of application with different beams.