Active harmonic EU cavity: Commissioning and operation with beam

Low-level radio-frequency system upgrade for the IMP Heavy Ion Reach Facility in Lanzhou (HIRFL)

Within an increasingly connected world, the exponential growth in the deployment of Internet of Things (IoT) applications presents a significant challenge in power and data transfer optimisation. Currently, the maximization of Radio Frequency (RF) system power gain depends on the design of efficient, commercial chips, and on the integration of these chips by using complex RF simulations to verify bespoke configurations. However, even if a standard 50Ω transmitter’s chip has an efficiency of 90%, the overall power efficiency of the RF system can be reduced by 10% if coupled with a standard antenna of 72Ω. Hence, it is necessary for scalable IoT networks to have optimal RF system design for every transceiver: for example, impedance mismatching between a transmitter’s antenna and chip leads to a significant reduction of the corresponding RF system’s overall power efficiency. This work presents a versatile design framework, based on well-known theoretical methods (i.e., transducer gain, power wave approach, transmission line theory), for the optimal design in terms of power delivered to a load of a typical RF system, which consists of an antenna, a matching network, a load (e.g., integrated circuit) and transmission lines which connect all these parts. The aim of this design framework is not only to reduce the computational effort needed for the design and prototyping of power efficient RF systems, but also to increase the accuracy of the analysis, based on the explanatory analysis within our design framework. Simulated and measured results verify the accuracy of this proposed design framework over a 0–4 GHz spectrum. Finally, a case study based on the design of an RF system for Bluetooth applications demonstrates the benefits of this RF design framework.

The Proton Engineering Frontier Project (PEFP) low-level radio frequency (LLRF) system for the 3-MeV radio frequency quadrupole accelerator (RFQ) and the 20-MeV drift tube linear accelerator (DTL) has been developed. A stability of 1 % in the amplitude and 1 degree in the phase is required. Therefore, the drift of the analog components should be low enough to satisfy these requirements. An analog chassis, as a prototype of the LLRF system, was con gured and tested. RF components, including an IQ modulator, an RF switch, a mixer, RF splitters, RF lters, a circuit for measuring tank phase and a trip circuit for high voltage standing wave ratio (VSWR), have been installed in this chassis. The analog chassis performs an error compensation of the RF amplitude and phase from the IQ signal, a down-conversion to the 10 MHz IF signal, an interlock for the arc and the high VSWR and a distribution for the RF and the clock signals. The amplitude and the phase stability of each component were measured to check the e ect on the whole system's performance. In the test with dummy cavities, a uctuation of 5 degrees was measured in the 340 MHz LO signal, but the relative phase between the two cavities was maintained within 0.2 degrees because of the e ect being the same for the LO signals of the two cavities.

Upcoming Low Level Radio Frequency (LLRF) systems for particle accelerators are facing manifold challenges. Special purpose machines like the X-Ray Free Electron Laser (XFEL) demand for field stabilities of 0.01% in amplitude and 0.01° in phase for the pulsed operation of superconducting, high-Q resonators. Due to the large number of parameters in a LLRF systems, automated procedures for parameter optimization will be essential. Apart from the field stability, manageability is an important topic. The International Linear Collider (ILC) will exceed the number of 20000 superconducting resonators and several hundred LLRF control loops. It is clear, that automation for this enormous amount of LLRF stations is inevitable. This document describes a systematic approach to implement several automation tasks using the technique of finite state machines (FSM). It is general enough to be applicable on various types of accelerators. A prototype of such an implementation is currently tested at the VUV-FEL at DESY, Hamburg. Some test results will be presented.

Validation of a radio frequency identification system for monitoring the feeding patterns of feedlot cattle

To test and verify the performance of the digital low-level radio-frequency (LLRF) and tuner system designed by the IHEP RF group, an experimental platform with a retired KEK 1.3 GHz nine-cell cavity is set up. A radio-frequency (RF) field is established successfully in the cavity and the frequency of the cavity is locked by the tuner in ±0.5° (about ±1.2 kHz) at room temperature. The digital LLRF system performs well in a five-hour experiment, and the results show that the system achieves field stability at amplitude <0.1% (peak to peak) and phase <0.1° (peak to peak). This index satisfies the requirements of the International Linear Collider (ILC), and this paper describes this closed-loop experiment of the LLRF system.

In recent years there has been a growing interest in electronic design automation methodologies for the optimizationbased design of radiofrequency circuits and systems. While for simple circuits several successful methodologies have been proposed, these very same methodologies exhibit significant deficiencies when the complexity of the circuit is increased. The majority of the published methodologies that can tackle radiofrequency systems are either based on high-level system specification tools or use models to estimate the system performances. Hence, such approaches do not usually provide the desired accuracy for RF systems. In this work, a methodology based on hierarchical multilevel bottom-up design approaches is presented, where multi-objective optimization algorithms are used to design an entire radiofrequency system from the passive component level up to the system level. Furthermore, each level of the hierarchy is simulated with the highest accuracy possible: electromagnetic simulation accuracy at device-level and electrical simulations at circuit/system-level.

During the remainder of the 1980&apos;s and early 1990&apos;s, many technology improvements will be made to achieve high data rate satellite-to-satellite communications. Programs such as the Strategic Defense Initiative Organization&apos;s SDS (Strategic Defense System) have projected architecture requirements for data transfer rates ranging from hundreds of kilobits per second to hundreds of megabits per second on satellite crosslinks. The advanced technology required to realize these rates is being investigated even now, but a general solution for the communications problem, defined in part by unique operating environ-ments ranging from benign to highly perturbed, is not possible. This paper focuses on one aspect of the overall satellite communications problem. It begins by briefly comparing radio frequency (RF) with direct detection laser communications (lasercom) for application to high data rate SDS low and medium earth orbit crosslinks. This comparison is based on near term technology suitable for early deployment in the SDS. The RF system is a millimeter-wave system operating in the 60 GHz region of the electromagnetic spectrum. The Lasercom system is considered to operate in the near infrared, from 0.8 to 1.1 micrometers. The trades consider operation in benign as well as the very stressing environments postulated for the Strategic Defense System which includes low and high altitude nuclear bursts as well as the threat of spaced based jamming sources and directed energy weapons. Results of the trades are presented to show the advantages and disadvantages of each type of system. The advantages and disadvantages of the RF and Lasercom systems are of sufficient magnitude to consider combining the best features of each to create a truly new communication system with capabilities far exceeding those of either system. For example, maximum survivabilty results from carrying both systems (RF &amp; Lasercom) on the satellite. However, this approach is costly in terms of weight, power, and real estate. A better approach would be to carry the capabilities of both sys-tems. Such an approach is proposed in this paper. The combination of systems, termed the Dual Mode Communications System (DMCS), is the principal thrust of the remainder of the paper.

Harmonic cavities have been installed on various storage ring light sources to increase the Touschek lifetime by a factor of 2 to 4 by lengthening bunches. Several side effects have been observed, which limit the gain in lifetime. In the worst case, the beam stability can be altered, but harmonic cavities can also provide Landau damping of coherent motion. A multibunch multiparticle tracking code has been developed to evaluate the performance of harmonic RF systems under consideration of all longitudinal beam dynamics issues. Bunches with high intensities are already elongated by the interaction with the ring impedance. The computations indicate that a harmonic RF system provide significant additional lengthening. The application to the ESRF shows that an active superconducting harmonic system would constitute the only appropriate solution. Such a system would be useful in single bunch and sixteen-bunch operation to improve the beam lifetime by a factor of 2 and 3, respectively

Normal conducting linear particle accelerators consist of multiple rf stations with accelerating structure cavities. Low-level rf (LLRF) systems are employed to set the phase and amplitude of the field in the accelerating structure and to compensate for the pulse-to-pulse fluctuation of the rf field in the accelerating structures with a feedback loop. The LLRF systems are typically implemented with analog rf mixers, heterodyne-based architectures, and discrete data converters. There are multiple rf signals from each of the rf stations, so the number of rf channels required increases rapidly with multiple rf stations. With a large number of rf channels, the footprint, component cost, and system complexity of the LLRF hardware will increase significantly. To meet the design goals of being compact and affordable for future accelerators, we have designed the next-generation LLRF (NG-LLRF) with a higher integration level based on RFSoC technology. The NG-LLRF system samples rf signals directly and performs rf mixing digitally. The NG-LLRF has been characterized in loopback mode to evaluate the performance of the system and has also been tested with a standing-wave accelerating structure, a prototype for the Cool Copper Collider (C3) with a peak rf power level up to 16.45MW. The loopback test demonstrated amplitude fluctuation below 0.15% and phase fluctuation below 0.15°, which are considerably better than the requirements of C3. The rf signals from the different stages of the accelerating structure at different power levels are measured by the NG-LLRF, which will be critical references for the control algorithm designs. The NG-LLRF also offers flexibility in waveform modulation, so we have used rf pulses with various modulation schemes, which could be useful for controlling some of the rf stations in accelerators. In this paper, the high-power test results at different stages of the test setup will be summarized, analyzed, and discussed.

Laser communication (lasercom) can enable more efficient links across larger distances compared with radio frequency (RF) systems. However, lasercom systems are typically point-to-point connections that would have difficulty interacting with several concurrently active spatially diverse users, where RF systems can more easily support such scenarios. Lasercom pointing, acquisition and tracking (PAT) systems have traditionally relied on mechanical beam steering devices, such as fast steering mirrors (FSMs) or gimbals, both of which are subject to potential mechanical failure. In this work we investigate an alternative steering solution using liquid lenses. Liquid lenses are tunable lenses that can non-mechanically alter focal length based on an applied voltage or current. A series of liquid lenses, one on-axis to control beam divergence, and one each offset in the x and y-axes to steer, could be used to achieve laser pointing control. Currently available commercial off the shelf (COTS) liquid lenses are based on electrowetting (manufactured by Corning [1]) or pressure-driven (manufactured by Optotune [2]) operation. In this work, we analyze the suitability of both types of liquid lenses for use in a space-based multiple access lasercom terminal. Early liquid lens technology first surfaced in 1995 with the control of the shape of an oil droplet through electrowetting [3]. The technology then started to become commercially available with the founding of Varioptic in 2002. However, there is limited data on liquid lens survivability and operation in a space-like environment. Through vacuum testing, we have found that electrowetting-based liquid lenses not only survive, but continue to operate nominally in a very low-pressure environment. The pressure-driven liquid lenses appeared to have issues initially in vacuum testing, with gas bubbles forming in the lens aperture during pump-down. However, after extended exposure to vacuum of approximately two weeks, the gas bubbles diffuse through the lens membrane, and the lenses operate in vacuum. Steering transfer functions were developed both in ambient and in vacuum conditions for both lens types, and in each case, the differences between the two curves were largely negligible. The electrowetting lenses provide a steering range of 2.7°, both in and out of vacuum, with an approximate slope of 0.046°/V. In testing the Optotune lenses, the steering was limited by the camera detector size, but for a range of −92 mA to 144 mA on the steering lens, the lenses provided for approximately 8.6° of steering with a slope of 0.0367°/V. These steering ranges can be extended to near hemispherical coverage with the addition of a diffuser and wide-angle fisheye lens [4]. Maximum hysteresis error, the difference in steering angle response when increasing lens voltage or current as opposed to decreasing lens voltage or current, was identified at 0.02° for the Corning lenses and 0.05° for the Optotune lenses. A Zemax beam quality analysis was conducted to see how transmit gain would be affected by refraction through the liquid lenses. Through this analysis, the worst-case link penalties were determined to be −0.5 dB for the Corning lenses at _0.8° steering and −0.4 dB for the Optotune lenses at _1.0° steering. Thus, we see that liquid lenses are likely good candidates for space applications and may perform well in nonmechanical beam steering. We discuss next steps in environmental testing as well as optical layout and control approaches for using liquid lenses in PAT systems for a nanosatellite based optical antenna.

As the demand for faster, more efficient, and durable electronic devices surges in the age of 5G, electric vehicles, and quantum technologies, researchers are turning to unconventional materials to push the boundaries of what is possible. Among these materials, diamond, long admired for its unmatched thermal conductivity, extreme hardness, and wide bandgap, has emerged as a game-changing contender. When combined with advanced heterojunction architectures, diamond-based heterojunction devices offer a groundbreaking platform that surpasses the limitations of traditional semiconductors like silicon, GaN, and SiC. With potential applications spanning from ultra-fast power electronics to next-generation quantum computing and high-frequency radio frequency (RF) systems, diamond heterojunction devices hold the key to revolutionizing electronics in ways previously unimaginable. This review delves into the remarkable advancements in diamond-based heterojunction devices, highlighting their applications in power electronics, RF systems, quantum technologies, and extreme-environment sensors. Finally, we summarize the current challenges facing diamond heterojunctions and provide an outlook on their transformative potential across the future landscape of high-performance electronics.

The specific absorption rate (SAR) induced by wireless radiofrequency (RF) systems depends on different parameters. Previously, SAR was mainly assessed under conditions of a single frequency and technology and for a limited number of localized RF sources. The current and emerging mobile systems involve a wider range of usage scenarios and are frequently used simultaneously, leading to combined exposures for which almost no exposure evaluation exists. The aim and novelty of this study is to close this gap of knowledge by developing new methods to rapidly evaluate the SAR induced by RF systems in such scenarios at frequencies from 50MHz to 5.5GHz. To this aim, analytical methods for SAR estimation in several usage scenarios were derived through a large-scale numerical study. These include subject-specific characteristics, properties of the RF systems and provide an estimation of the SAR in the whole body, tissues and organs, and different brain regions.

Radiofrequency Thawing of Frozen Minced Fish Based on the Dielectric Response Mechanism

Considerations in design of commercial radio frequency treatments for postharvest pest control in in-shell walnuts