The radio-frequency quadrupole

Radio-frequency quadrupole (RFQ) linear accelerators appeared on the accelerator scene in the late 1970s and have since revolutionized the domain of low-energy proton and ion acceleration. The RFQ makes the reliable production of unprecedented ion beam intensities possible within a compact radio-frequency (RF) resonator which concentrates the three main functions of the low-energy linac section: focusing, bunching and accelerating. Its sophisticated electrode structure and strict beam dynamics and RF requirements, however, impose severe constraints on the mechanical and RF layout, making the construction of RFQs particularly challenging. This lecture will introduce the main beam optics, RF and mechanical features of a RFQ emphasizing how these three aspects are interrelated and how they contribute to the final performance of the RFQ.Comment: 17 pages, contribution to the CAS - CERN Accelerator School: Course on High Power Hadron Machines; 24 May - 2 Jun 2011, Bilbao, Spai

Radio Frequency Interference Mitigation

Radio astronomy observational facilities are under constant upgradation and development to achieve better capabilities including increasing the time and frequency resolutions of the recorded data, and increasing the receiving and recording bandwidth. As only a limited spectrum resource has been allocated to radio astronomy by the International Telecommunication Union, this results in the radio observational instrumentation being inevitably exposed to undesirable radio frequency interference (RFI) signals which originate mainly from terrestrial human activity and are becoming stronger with time. RFIs degrade the quality of astronomical data and even lead to data loss. The impact of RFIs on scientific outcome is becoming progressively difficult to manage. In this article, we motivate the requirement for RFI mitigation, and review the RFI characteristics, mitigation techniques and strategies. Mitigation strategies adopted at some representative observatories, telescopes and arrays are also introduced. We also discuss and present advantages and shortcomings of the four classes of RFI mitigation strategies, applicable at the connected causal stages: preventive, pre-detection, pre-correlation and post-correlation. The proper identification and flagging of RFI is key to the reduction of data loss and improvement in data quality, and is also the ultimate goal of developing RFI mitigation techniques. This can be achieved through a strategy involving a combination of the discussed techniques in stages. Recent advances in high speed digital signal processing and high performance computing allow for performing RFI excision of large data volumes generated from large telescopes or arrays in both real time and offline modes, aiding the proposed strategy.Comment: 26 pages, 10 figures, Chinese version accepted for publication in Acta Astronomica Sinica; English version to appear in Chinese Astronomy and Astrophysic

Radio frequency science considerations

Use of the 400 MHz telecommunications system to obtain scientific information, to provide backup information for the experiments flown, and to obtain measurements which aid in designing future probes is considered. Recommended objectives of such a program are summarized and include: measure 400 MHz amplitude to determine adsorption and perhaps scintillation (if data rate permits); measure noise strength near 400 MHz to reexamine 400 MHz choice and to observe thermal, cosmic, and local synchrotron noise trends; probe VSWR sensing to monitor integrity of system, icing, and possible plasma effects; after the probe is finished, have the bus radio occultation in the same region where the probe fell to evaluate the occultation

Radio-Frequency Single-Electron Refrigerator

We propose a cyclic refrigeration principle based on mesoscopic electron transport. Synchronous sequential tunnelling of electrons in a Coulomb-blockaded device, a normal metal-superconductor single-electron box, results in a cooling power of $\sim k_{\rm B}T \times f$ at temperature $T$ over a wide range of cycle frequencies $f$. Electrostatic work, done by the gate voltage source, removes heat from the Coulomb island with an efficiency of $\sim k_{\rm B}T/\Delta$, where $\Delta$ is the superconducting gap. The performance is not affected significantly by non-idealities, for instance by offset charges. We propose ways of characterizing the system and of its practical implementation.Comment: 5 pages, 4 figures; corrected typos, language improve

Radio frequency baseband recording technique

Technique uses a helical-scan video recorder with auxiliary signal-conditioning equipment to provide an inexpensive, high-capacity magnetic tape recording of a 112 channel, phase-locked, multiplexed, baseband signal

Radio-frequency Bloch-transistor electrometer

A quantum-limited electrometer based on charge modulation of the Josephson supercurrent in the Bloch transistor inserted into a superconducting ring is proposed. As this ring is inductive coupled to a high-Q resonance tank circuit, the variations of the charge on the transistor island (input signal) are converted into variations of amplitude and phase of radio-frequency oscillations in the tank. These variations are amplified and then detected. The output noise, the back-action fluctuations and their cross-correlation are computed. It is shown that our device enables measurements of the charge with a sensitivity which is determined by the energy resolution of its amplifier, that can be reduced down to the standard quantum limit of \hbar/2. On the basis of this setup a "back-action-evading" scheme of the charge measurements is proposed.Comment: 5 pages incl. 2 figure

Implementasi Teknologi Radio Frequency Identification Untuk Identifikasi Dan Autentikasi Pada Gerbang Masuk DiUniversitas Sam Ratulangi Manado

Lingkungan kampus Universitas Sam Ratuangi (UNSRAT) memiliki pengunjung pada saat jam kerja. Tetapi tidak semua pengunjung lingkungan kampus memiliki tujuan yang sama. Karena selain belajar dan mengajar, ada juga aktivitas lain yang dilakukan seperti misalnya hanya sekedar melewati jalan yang berada di lingkungan kampus untuk menghemat waktu. Hal ini membuat pihak kampus tidak dapat melihat dan mendata setiap pengunjung kampus dikarenakan tidak adanya metode atau cara yang digunakan untuk mendata pengunjung di lingkungan kampus UNSRAT. Untuk mengatasi masalah tersebut, penelitian ini akan membahas penggunaan teknologi Radio Frequency Identification (RFID) sebagai metode untuk mengidentifikasi dan mengautentikasi pengunjung. RFID reader akan di pasang pada setiap gerbang masuk untuk mendeteksi dan menerjemahkan ID tag pada kartu identitas pengunjung. Jika ID tag tersebut terdaftar, maka pengunjung tersebut akan diperbolehkan untuk masuk ke lingkungan kampus, namun jika tidak terdaftar di dalam database, maka pengunjung tidak diberi izin untuk masuk dan harus mendaftarkan ID tag tersebut agar memiliki hak akses masuk lingkungan kampus. Proses pendaftaran ID tag dan tampilan output akan disajikan dalam bentuk Graphical User Interface (GUI). Dengan menggunakan metode ini, pihak kampus akan lebih mudah untuk mengontrol dan mendata setiap pengunjung lingkungan kampus serta melihat jam masuk / keluar pengunjung