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Proton therapy is an advanced particle radiotherapy technology. Lanzhou University recently designed a new linear accelerator system for proton therapy. In the system, a 750MHz radio frequency quadrupole (RFQ) accelerator was used to complete the initial acceleration of particles. The RFQ can accelerate a proton beam intensity of 1mA from 30keV to 3MeV kinetic energy within a length of 2m. This paper aims to complete the physical design of this high-frequency RFQ, including beam dynamics design, radio frequency (RF) design, and multiphysics analysis. In the dynamics design, a novel design strategy for controlling the longitudinal emittance was adopted to improve the output beam quality of the RFQ. The simulation results showed that the RFQ outlet longitudinal emittance was controlled below 0.1 $\pi$ mm mrad. In the RF design, the pi-mold rod structure was applied to RFQ at such high frequencies for the first time. After the whole cavity simulation, it was found that the separation between the operating frequency of the RFQ cavity and its closest dipole mode reached 58.3MHz, and its quality factor reached 6352. Finally, a multiphysics analysis was performed. The analysis showed that the maximum temperature rise of the RFQ cavity was less than $2.5^{\circ }$C and the frequency drift due to heating was 18kHz. This paper presents the current status of the design of this new linear accelerator. Compared with previous RFQs, the new RFQ has a very high transmission efficiency and higher RF stability.

We investigated theoretically the effect of an additional radio-frequency (rf) laser on the optical bistability (OB) behavior of the Pr${}^{3+}$: Y₂SiO₅ crystal. It is demonstrated that the rf field induces the OB behavior to the output of the system. It is shown that such OB behavior can be controlled by the intensity of either rf or coupling field.

Conventional CMOS switch uses NMOS as transistors in its main architecture requiring a control voltage of 5.0 V and a large resistance at the receivers and antennas (ANTs) to detect the signal. A CMOS integrated circuit switch uses FET transistors to achieve switching between multiple paths, because of its high value of control voltage. Hence it is not suitable for modern portable devices which demand lesser power consumption. Therefore, we proposed a new Double-Pole Four-Throw (DP4T) switch by using RF CMOS technology and analyzed its performance. Further, main objective is to provide a plurality of such switches arranged in a densely configured switch array, where the power and area could be reduced as compared to already existing switch configuration as SPDT and Double-Pole Double-Throw (DPDT) transceiver switches, which is simply a reduction of signal strength during transmission of the RF signals. The presented result for the proposed DP4T switch reveals the peak output currents (drain current) around 0.116–0.387 mA and a switching speed of 19–36 ps.

A radio frequency (RF) low voltage and low power down conversion mixer with high linearity using TSMC 0.18-μm technology is presented which operates in 2.4 GHz Industrial Scientific and Medical (ISM) band. The local oscillator (LO) frequency is 2.1 GHz with an input power of 5 dBm, whereas IF frequency is 300 MHz. Multiple gated transistors (MGTRs) method is used to increase the linearity of Gilbert cell mixer. In this method an auxiliary transistor is used parallel to the transconductance stage transistor. This increases linearity by decreasing of transconductance stage transistor. The simulation results show an IIP3 improvement of 16.55 dBm. The proposed low power and highly linear mixer consumes a power of 4.46 mW from 1.8 V a supply voltage. The noise figure (NF) and gain conversion are about 13.8 dB and 9.11 dB, respectively.

Wireless communication standard continues to evolve in order to fulfill the demand for high data rate operation. This leads to the exertion on the design of radio frequency power amplifier (RFPA) which consumes high DC power in order to support linear transmission of high data rate signal. Hence, operating the PA with low DC power consumption without trading-off the linearity is vital in order to achieve the goal of achieving fully integrated system-on-chip (SoC) solution for 4G and 5G transceivers. In this paper, the evolution of CMOS PA toward achieving a fully integrated transceiver solution is discussed through the review of multifarious CMOS PA design. This is categorized into the review of efficiency enhancement designs followed by linearity enhancement designs of the CMOS PA.

Dynamic range and spurious-free dynamic range are two of the most critical performance indexes in the field of radio frequency (RF). However, the definitions of both the indexes are ambiguous, and their characterization ability is insufficient, resulting in unfair, and even mutually incompatible, performance evaluation in practice. In this study, a new index named radio frequency distortion dynamic range and its corresponding evaluation method are proposed to achieve a fair and detailed dynamic range evaluation by unifying the existing definitions and improving the performance resolution ability. First, the sliding threshold selection method is introduced to replace the classification-based method of dynamic range definition to characterize more details of the dynamic range. Second, a dynamic range evaluation method of “performance body” is proposed to obtain a more comprehensive evaluation by generalizing the current evaluation from being based on a single condition to the one based on scanning critical conditions. Experiments show that the proposed radio frequency distortion dynamic range index with the proposed evaluation method reduces the ambiguity of dynamic range evaluation and can distinguish the performance difference that the current indexes cannot do.

Extended Air Showers produced by cosmic rays impinging on the earth atmosphere irradiate radio frequency radiation through different mechanisms. Upon certain conditions, the emission has a coherent nature, with the consequence that the emitted power is not proportional to the energy of the primary cosmic rays, but to the energy squared. The effect was predicted in 1962 by Askaryan and it is nowadays experimentally well established and exploited for the detection of ultra high energy cosmic rays.

In this paper, we discuss in detail the conditions for coherence, which in literature have been too often taken for granted, and calculate them analytically, finding a formulation which comprehends both the coherent and the incoherent emissions. We apply the result to the Cherenkov effect, obtaining the same conclusions derived by Askaryan, and to the geosynchrotron radiation.

For the radio frequency-based catalyst state monitoring of SCR catalysts, the dielectric properties of the used SCR catalyst materials are essential to design the measurement system and to adjust it to the given conditions. This work focuses on the experimental determination of the effective complex dielectric properties of zeolite coatings on cordierite substrates and the approximation of the latter to describe and transfer these systems in an easier manner. Therefore, different influences were investigated to approximate the real and the imaginary part of the complex permittivity of zeolite coatings on cordierite substrates.

Long time magnetization thermal switching under small amplitude high frequency excitation is analyzed. Approaches based upon conventional time-dependent energy barrier are not sufficient to describe magnetization nonvolatility under GHz excitations. Methods based upon large angle nonlinear magnetization dynamics are developed for both coherent and noncoherent magnetization switching. This dynamic approach is not only important for fundamental understanding of magnetization dynamics under combined radio frequency excitations and thermal fluctuations, but also critical for practical design of emerging spintronic devices. When applied to spin torque random access memory read operations, as sensing current duration reaches nanosecond, dynamic approach gives a switching probability estimation orders of magnitude different from that obtained from conventional time-dependent energy barrier approach.

The evolution of communication technologies with high-frequency radio-frequency (RF) devices increased the demand for compact and efficient designs. Micro-electromechanical systems (MEMS) technology revolutionized microwave and RF applications because of its ability to be engineered into miniaturized devices that are highly linear and power efficient. It is more challenging to perform numerical analysis and optimization of such complex MEMS devices. Electromagnetic (EM) simulation-based optimization software using different methodologies employing coupled domains and time domain analysis of MEMS devices requires repeated simulation, which makes it computationally expensive. The artificial neural network (ANN) model is an alternative to these conventional simulation-based design methodologies to expedite the design process. ANN models for RF and microwave modeling are known to be effective, precise, and flexible. ANN is capable of producing accurate results with less computational time than sophisticated EM models. An overview of various RF MEMS components and an introduction to ANN are provided in this chapter. In addition, this chapter presents the concept of modeling an RF MEMS shunt switch using ANN as a case study.

Firstly, by adopting the radio frequency magnetron sputtering system and the quartz glass as target materials, the SiO₂ thin film was prepared. Then, by the X-ray diffraction (the prepared flims are characterized by XRD techniques to study their structure and morphology and spectrophoto metric properties), the scanning electron microscopy (the prepared flims are characterized by SEM techniques to study their structure and morphology and spectrophoto metric properties) and the spectrophotometer, phase structure, the surface morphology and absorption spectrum characteristics of the film were analyzed. The results showed that: the surface of the SiO₂ film was smooth, the average size of the particles, with the non crystalline and disordered structure, was in the range of nanometer. The optimal process parameters were chosen as the sputtering power of 1.8KW and the sputtering time of 10 minutes, the average transmittance of the SiO₂ thin film increased more than 2%.