Commissioning experience with the PEP-II low-level RF system

International Nuclear Information System (INIS)

Corredoura, P.; Allison, S.; Claus, R.; Ross, W.; Sapozhnikov, L.; Schwarz, H.D.; Tighe, R.; Yee, C.; Ziomek, C.

1997-05-01

The low-level RF system for PEP-II is a modular design housed in a VXI environment and supported by EPICS. All signal processing and control is done at baseband using in-phase and quadrature (IQ) techniques. Remotely configurable RF feedback loops are used to control coupled-bunch instabilities driven by the accelerating mode of the RF cavities. A programmable DSP based feedback loop is implemented to control phase variations across the klystron due to the required adjustment of the cathode voltage to limit cathode power dissipation. The DSP loop also adaptively cancels modulations caused by klystron power supply ripple at selected power line harmonics between 60 Hz and 10 kHz. The system contains a built-in baseband network analyzer which allows remote measurement of the RF feedback loop transfer functions and automated configuration of these loops. This paper presents observations and measured data from the system

Control Loops for the J-PARC RCS Digital Low-Level RF Control

CERN Document Server

Schnase, Alexander; Ezura, Eizi; Hara, Keigo; Nomura, Masahiro; Ohmori, Chihiro; Takagi, Akira; Tamura, Fumihiko; Yamamoto, Masanobu; Yoshii, Masahito

2005-01-01

The low-level radiofrequency control for the Rapic Cycling Synchrotron of J-PARC is based on digital signal processing. This system controls the acceleration voltages of 12 magnetic alloy loaded cavities. To achive a short overall delay, mandatory for stable loop operation, the data-processing is based on distributed arithmetics in FPGA. Due to the broadband characteristic of the acceleration cavities, no tuning loop is needed. To handle the large beam current, the RF system operates simultaneously with dual harmonics (h=2) and (h=4). The stability of the amplitude loops is limited by the delay of the FIR filters used after downconversion. The phase loop offers several operation modes to define the phase relation of (h=2) and (h=4) between the longitudinal beam signal and the vector-sum of the cavity voltages. Besides the FIR filters, we provide cascaded CIC filters with smoothly varying coefficients. Such a filter tracks the revolution frequency and has a substantially shorter delay, thereby increasing the s...

New low-level rf system for the Fermilab Booster synchrotron

International Nuclear Information System (INIS)

Kerns, C.; Crisp, J.; Kerns, Q.; Miller, H.

1987-03-01

This paper describes the Booster low-level rf system that was constructed to meet these recently added requirements: (1) synthesizer controlled capture frequency at injection, (2) very low-phase noise over the machine cycle, (3) smooth phase-lock of beam to an external reference frequency and (4) ability to accelerate either a full turn or partial turn of beam

Low-level rf control of Spallation Neutron Source: System and characterization

Directory of Open Access Journals (Sweden)

Hengjie Ma

2006-03-01

Full Text Available The low-level rf control system currently commissioned throughout the Spallation Neutron Source (SNS LINAC evolved from three design iterations over 1 yr intensive research and development. Its digital hardware implementation is efficient, and has succeeded in achieving a minimum latency of less than 150 ns which is the key for accomplishing an all-digital feedback control for the full bandwidth. The control bandwidth is analyzed in frequency domain and characterized by testing its transient response. The hardware implementation also includes the provision of a time-shared input channel for a superior phase differential measurement between the cavity field and the reference. A companion cosimulation system for the digital hardware was developed to ensure a reliable long-term supportability. A large effort has also been made in the operation software development for the practical issues such as the process automations, cavity filling, beam loading compensation, and the cavity mechanical resonance suppression.

Development of EPICS Input Output Controller and User Interface for the PEFP Low Level RF Control System

International Nuclear Information System (INIS)

Song, Young Gi; Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub

2010-01-01

The Low-Level RF (LLRF) control system of the Proton Engineering Frontier Project (PEFP) was developed for handling the driving frequency for Quadrupole (RFQ) and the Draft Tube Linac (DTL) cavities in 2006. The RF amplitude and phase of the accelerating field were controlled within 1% and 1 degree by stability requirements, respectively. Operators have been using the LLRF control system under the windows based text console mode as an operator interface. The LLRF control system could not be integrated with Experimental Physics Industrial Control System (EPICS) Input Output Controllers (IOC) for each subsection of PEFP facility. The main objective of this study is to supply operators of the LLRF control system with user friendly and convenient operating environment. The new LLRF control system is composed of a Verse Module Eurocard (VME) baseboard, a PCI Mezzanine Card (PMC), Board Support Package (BSP), EPICS software tool and a Real-Time Operating System (RTOS) VxWorks. A test with a dummy cavity of the new LLRF control system shows that operators can control and monitor operation parameters for a desired feedback action by using EPICS Channel Access (CA).

Development of EPICS Input Output Controller and User Interface for the PEFP Low Level RF Control System

Energy Technology Data Exchange (ETDEWEB)

Song, Young Gi; Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2010-05-15

The Low-Level RF (LLRF) control system of the Proton Engineering Frontier Project (PEFP) was developed for handling the driving frequency for Quadrupole (RFQ) and the Draft Tube Linac (DTL) cavities in 2006. The RF amplitude and phase of the accelerating field were controlled within 1% and 1 degree by stability requirements, respectively. Operators have been using the LLRF control system under the windows based text console mode as an operator interface. The LLRF control system could not be integrated with Experimental Physics Industrial Control System (EPICS) Input Output Controllers (IOC) for each subsection of PEFP facility. The main objective of this study is to supply operators of the LLRF control system with user friendly and convenient operating environment. The new LLRF control system is composed of a Verse Module Eurocard (VME) baseboard, a PCI Mezzanine Card (PMC), Board Support Package (BSP), EPICS software tool and a Real-Time Operating System (RTOS) VxWorks. A test with a dummy cavity of the new LLRF control system shows that operators can control and monitor operation parameters for a desired feedback action by using EPICS Channel Access (CA).

Low Level RF Including a Sophisticated Phase Control System for CTF3

CERN Document Server

Mourier, J; Nonglaton, J M; Syratchev, I V; Tanner, L

2004-01-01

CTF3 (CLIC Test Facility 3), currently under construction at CERN, is a test facility designed to demonstrate the key feasibility issues of the CLIC (Compact LInear Collider) two-beam scheme. When completed, this facility will consist of a 150 MeV linac followed by two rings for bunch-interleaving, and a test stand where 30 GHz power will be generated. In this paper, the work that has been carried out on the linac's low power RF system is described. This includes, in particular, a sophisticated phase control system for the RF pulse compressor to produce a flat-top rectangular pulse over 1.4 µs.

Intelligent low-level RF system by non-destructive beam monitoring device for cyclotrons

Science.gov (United States)

Sharifi Asadi Malafeh, M. S.; Ghergherehchi, M.; Afarideh, H.; Chai, J. S.; Yoon, Sang Kim

2016-04-01

The project of a 10 MeV PET cyclotron accelerator for medical diagnosis and treatment was started at Amirkabir University of Technology in 2012. The low-level RF system of the cyclotron accelerator is designed to stabilize acceleration voltage and control the resonance frequency of the cavity. In this work an Intelligent Low Level Radio Frequency Circuit or ILLRF, suitable for most AVF cyclotron accelerators, is designed using a beam monitoring device and narrow band tunable band-pass filter. In this design, the RF phase detection does not need signal processing by a microcontroller.

The Design and Performance of the Spallation Neutron Source Low-Level RF Control System

CERN Document Server

Champion, M; Kasemir, K; Ma, H; Piller, C

2004-01-01

The Spallation Neutron Source linear accelerator low-level RF control system has been developed within a collaboration of Lawrence Berkeley, Los Alamos, and Oak Ridge national laboratories. Three distinct generations of the system, described in a previous publication [1], have been used to support beam commissioning at Oak Ridge. The third generation system went into production in early 2004, with installation in the coupled-cavity and superconducting linacs to span the remainder of the year. The final design of this system will be presented along with results of performance measurements.

Low Level RF System for Jefferson Lab Cryomodule Test Facility

International Nuclear Information System (INIS)

Tomasz Plawski; Trent Allison; Jean Delayen; J. Hovater; Thomas Powers

2003-01-01

The Jefferson Lab Cryomodule Test Facility (CMTF) has been upgraded to test and commission SNS and CEBAF Energy Upgrade cryomodules. Part of the upgrade was to modernize the superconducting cavity instrumentation and control. We have designed a VXI based RF control system exclusively for the production testing of superconducting cavities. The RF system can be configured to work either in Phase Locked Loop (PLL) or Self Excited Loop (SEL) mode. It can be used to drive either SNS 805 MHz or CEBAF Energy Upgrade 1497 MHz superconducting cavities and can be operated in pulsed or continuous wave (CW) mode. The base design consists of RF-analog and digital sections. The RF-analog section includes a Voltage Control Oscillator (VCO), phase detector, IandQ modulator and ''low phase shift'' limiter. The digital section controls the analog section and includes ADC, FPGA, and DAC . We will discuss the design of the RF system and how it relates to the support of cavity testing

Low power RF beam control electronics for the LEB

International Nuclear Information System (INIS)

Mestha, L.K.; Mangino, J.; Brouk, V.; Uher, T.; Webber, R.C.

1993-05-01

Beam Control Electronics for the Low Energy Booster (LEB) should provide a fine reference phase and frequency for the High Power RF System. Corrections applied on the frequency of the rf signal will reduce dipole synchrotron oscillations due to power supply regulation errors, errors in frequency source or errors in the cavity voltage. It will allow programmed beam radial position control throughout the LEB acceleration cycle. Furthermore the rf signal provides necessary connections during, adiabatic capture of the beam as injected into the LEB by the Linac and will guarantee LEB rf phase synchronism with the Medium Energy Booster (MEB) rf at a programmed time in the LEB cycle between a unique LEB bucket and a unique MEB bucket. We show in this paper a design and possible interfaces with other subsystems of the LEB such as the beam instrumentation, High Power RF Stations, global accelerator controls and the precision timing system. The outline of various components of the beam control system is also presented followed by some test results

Digital Low-Level RF Controls for Future Superconducting Linear Colliders

CERN Document Server

Simrock, Stefan

2005-01-01

The requirements for RF Control Systems of Superconducting Linear Colliders are not only defined in terms of the quality of field control but also with respect to operability, availability, and maintainability of the RF System, and the interfaces to other subsystems. The field control of the vector-sum of many cavities driven by one klystron in pulsed mode at high gradients is a challenging task since severe Lorentz force detuning, microphonics and beam induced field errors must be suppressed by several orders of magnitude. This is accomplished by a combination of local and global feedback and feedforward control. Sensors monitor individual cavity probe signals, and forward and reflected wave as well as the beam properties including beam energy and phase while actuators control the incident wave of the klystron and individual cavity resonance frequencies. The operability of a large llrf system requires a high degree of automation while the high availability requires robust algorithms, redundancy, and extremel...

Versatile rf controller

International Nuclear Information System (INIS)

Howard, D.

1985-05-01

The low level rf system developed for the new Bevatron local injector provides precise control and regulation of the rf phase and amplitude for three 200 MHz linac cavities. The main features of the system are: extensive use of inexpensive, off-the-shelf components, ease of maintenance, and adaptability to a wide range of operation frequencies. The system utilizes separate function, easily removed rf printed circuit cards interconnected via the edge connectors. Control and monitoring are available both locally and through the computer. This paper will describe these features as well as the few component changes that would be required to adapt the techniques to other operating frequencies. 2 refs

Design and development of low level S-Band RF control system for IRFEL injector LINAC

International Nuclear Information System (INIS)

Mohania, Praveen; Mahawar, Ashish; Singh, Adarsh Pratap; Namdeo, Rajkumar; Baxy, Deodatta; Shrivastava, Purushottam

2015-01-01

A low level RF system has been designed and developed for phase and amplitude stabilization of S- Band microwave power being fed to fundamental buncher cavity and the injector LINAC structure of the Infra Red Free Electron Laser being developed at RRCAT Indore. The system uses analog phase shifters and voltage variable attenuators to control the phase and amplitude respectively, the control voltages for phase shifters and attenuators are generated using a 12 Bit ADC and is software controlled. The system has a slow feedback to correct phase and amplitude drifts occurring due to thermal variations and a fast feed forward mechanism to vary amplitude and phase of the output pulse to compensate beam loading and to shape the klystron output power. The present paper describes the design aspects of the LLRF system. (author)

Development of digital low level rf system

International Nuclear Information System (INIS)

Michizono, Shinichiro; Anami, Shozo; Katagiri, Hiroaki; Fang, Zhigao; Matsumoto, Toshihiro; Miura, Takako; Yano, Yoshiharu; Yamaguchi, Seiya; Kobayashi, Tetsuya

2008-01-01

One of the biggest advantages of the digital low level rf (LLRF) system is its flexibility. Owing to the recent rapid progress in digital devices (such as ADCs and DACs) and telecommunication devices (mixers and IQ modulators), digital LLRF system becomes popular in these 10 years. The J-PARC linac LLRF system adopted cPCI crates and FPGA based digital feedback system. Since the LLRF control of the normal conducting cavities are more difficult than super conducting cavities due to its lower Q values, fast processing using the FPGA was the essential to the feedback control. After the successful operation of J-PARC linac LLRF system, we developed the STF (ILC test facility in KEK) LLRF system. Since the klystron drives eight cavities in STF phase 1, we modified the FPGA board. Basic configuration and the performances of these systems are summarized. The future R and D projects (ILC and ERL) is also described from the viewpoints of LLRF. (author)

Timing and low-level rf system for an x-ray laser

Directory of Open Access Journals (Sweden)

Yuji Otake

2016-02-01

Full Text Available An x-ray free-electron laser (XFEL, SACLA, designed to open up new science, was constructed for generating coherent x rays with a peak power of more than 10 GW and a very short pulse of below 30 fs. This feature demands a very highly short-term temporal stability of less than 50 fs to the acceleration rf field of SACLA. For this reason, we developed a timing and low-level rf (LLRF system for SACLA based on that of the SPring8 compact SASE source (SCSS test accelerator for verifying the feasibility of an XFEL. The performance of the system using the in-phase and quadrature rf manipulation method was improved from SCSS’s system. Since the facility length of SACLA is 700 m, which is 10 times longer than that of the SCSS test accelerator, a phase-stabilized optical-fiber system designed to transmit time standard rf signals with low loss was also developed and deployed. This optical-fiber system equips fiber optical-length feedback control in order to mitigate environmental effects, such as temperature and humidity changes. On the other hand, the demanded maximum rf temporal stability is less than 50 fs, which is almost 10 times smaller than that of the SCSS test accelerator. Hence, reducing electric noise and increasing the temperature stability around timing and LLRF instruments were necessary and realized with a very low-noise power supply and a hemathermal 19-inch enclosure. The short-term temporal performance of the timing LLRF system finally attained a temporal stability of less than 13.6 fs in rms measured by a beam arrival-time measurement. This stability greatly helps to achieve the stable x-ray lasing of SACLA for routine operation during user experiments.

Architecture design of the application software for the low-level RF control system of the free-electron laser at Hamburg

International Nuclear Information System (INIS)

Geng, Z.; Ayvazyan, V.; Simrock, S.

2012-01-01

The superconducting linear accelerator of the Free-Electron Laser at Hamburg (FLASH) provides high performance electron beams to the lasing system to generate synchrotron radiation to various users. The Low-Level RF (LLRF) system is used to maintain the beam stabilities by stabilizing the RF field in the superconducting cavities with feedback and feed forward algorithms. The LLRF applications are sets of software to perform RF system model identification, control parameters optimization, exception detection and handling, so as to improve the precision, robustness and operability of the LLRF system. In order to implement the LLRF applications in the hardware with multiple distributed processors, an optimized architecture of the software is required for good understandability, maintainability and extendibility. This paper presents the design of the LLRF application software architecture based on the software engineering approach for FLASH. (authors)

Lessons learned from positron-electron project low level rf and longitudinal feedback

Directory of Open Access Journals (Sweden)

J. Fox

2010-05-01

Full Text Available The Positron-Electron Project II (PEP-II B Factory collider ended the final phase of operation at nearly twice the design current and 4X the design luminosity. In the ultimate operation state, eight 1.2 MW radio-frequency (rf klystrons and 12 accelerating cavities were added beyond the original implementation, and the two storage rings were operating with longitudinal instability growth rates roughly 5X in excess of the original design estimates. From initial commissioning there has been continual adaptation of the low level rf (LLRF control strategies, configuration tools, and some new hardware in response to unanticipated technical challenges. This paper offers a perspective on the original LLRF and longitudinal instability control design, and highlights via two examples the system evolution from the original design estimates through to the final machine with 1.2×10^{34} luminosity. The impact of unanticipated signals in the coupled-bunch longitudinal feedback and the significance of nonlinear processing elements in the LLRF systems are presented. We present valuable “lessons learned” which are of interest to designers of next generation feedback and impedance controlled LLRF systems.

Digital Low Level RF Systems for Fermilab Main Ring and Tevatron

Science.gov (United States)

Chase, B.; Barnes, B.; Meisner, K.

1997-05-01

At Fermilab, a new Low Level RF system is successfully installed and operating in the Main Ring. Installation is proceeding for a Tevatron system. This upgrade replaces aging CAMAC/NIM components for an increase in accuracy, reliability, and flexibility. These VXI systems are based on a custom three channel direct digital synthesizer(DDS) module. Each synthesizer channel is capable of independent or ganged operation for both frequency and phase modulation. New frequency and phase values are computed at a 100kHz rate on the module's Analog Devices ADSP21062 (SHARC) digital signal processor. The DSP concurrently handles feedforward, feedback, and beam manipulations. Higher level state machines and the control system interface are handled at the crate level using the VxWorks operating system. This paper discusses the hardware, software and operational aspects of these LLRF systems.

Participants of the LLRF05 : Workshop on Low Level RF, CERN 10-13 October 2005

CERN Multimedia

Maximilien Brice

2005-01-01

Sophisticated Low Level RF systems are needed in modern particle accelerators to deal with the characteristics of state-of-the-art RF accelerating structures and their power sources, and to meet unprecedented levels of performance. The goal of the LLRF05 workshop is to share experience between linac and synchrotron projects (SNS, J-PARC, ILC, LHC etc.) and to discuss the best engineering practice.

Low power rf system for the ALS Linac

International Nuclear Information System (INIS)

Lo, C.C.; Taylor, B.; Lancaster, H.

1991-05-01

The Linear Accelerator (Linac) in the Advanced Light Source (ALS) is designed to provide either single or multiple bunchers of 50 MeV electrons for the booster synchrotron. Three cavities are used in the Linac for electron bunching. The two subharmonic bunching cavities operate at 124.914 MHz and 499.654 MHz respectively. The S Band buncher operates at 2.997924 GHz. The low level RF system includes a master signal source, RF burst generators, signal phase control, timing trigger generators and a water temperature control system. The design and performance of the system will be described. 7 refs., 3 figs

Design and construction of the advanced photon source 352-MHz rf system switching control

International Nuclear Information System (INIS)

Horan, D.; Solita, L.; Reigle, D.; Dimonte, N.

1997-01-01

A switching control system has been designed and built to provide the capability of rapidly switching the waveguide and low-level cabling between different klystrons to operate the Advanced Photon Source storage ring in the event of a failure of a klystron system or to perform necessary repairs and preventative maintenance. The twelve possible modes of operation allow for complete redundancy of the booster synchrotron rf system and either a maximum of two storage ring rf systems to be completely off-line or one system to be used as a power source for an rf test stand. A programmable controller is used to send commands to intermediate control panels which interface to WR2300 waveguide switches and phase shifters, rf cavity interlock and low-level rf distribution systems, and klystron power supply controls for rapid reconfiguration of the rf systems in response to a mode-selection command. Mode selection is a local manual operation using a keyswitch arrangement which prevents more than one mode from being selected at a time. The programmable controller also monitors for hardware malfunction and guards against open-quotes hot-switchingclose quotes of the rf systems. The rf switching controls system is monitored via the Experimental Physics and Industrial Control System (EPICS) for remote system status check

Modeling and simulation of Indus-2 RF feedback control system

International Nuclear Information System (INIS)

Sharma, D.; Bagduwal, P.S.; Tiwari, N.; Lad, M.; Hannurkar, P.R.

2012-01-01

Indus-2 synchrotron radiation source has four RF stations along with their feedback control systems. For higher beam energy and current operation amplitude and phase feedback control systems of Indus-2 are being upgraded. To understand the behaviour of amplitude and phase control loop under different operating conditions, modelling and simulation of RF feedback control system is done. RF cavity baseband I/Q model has been created due to its close correspondence with actual implementation and better computational efficiency which makes the simulation faster. Correspondence between cavity baseband and RF model is confirmed by comparing their simulation results. Low Level RF (LLRF) feedback control system simulation is done using the same cavity baseband I/Q model. Error signals are intentionally generated and response of the closed loop system is observed. Simulation will help us in optimizing parameters of upgraded LLRF system for higher beam energy and current operation. (author)

Fast digital feedback control systems for accelerator RF system using FPGA

International Nuclear Information System (INIS)

Bagduwal, Pritam Singh; Sharma, Dheeraj; Tiwari, Nitesh; Lad, M.; Hannurkar, P.R.

2012-01-01

Feedback control system plays important role for proper injection and acceleration of beam in particle accelerators by providing the required amplitude and phase stability of RF fields in accelerating structures. Advancement in the field of digital technology enables us to develop fast digital feedback control system for RF applications. Digital Low Level RF (LLRF) system offers the inherent advantages of Digital System like flexibility, adaptability, good repeatability and reduced long time drift errors compared to analog system. To implement the feedback control algorithm, I/Q control scheme is used. By properly sampling the down converted IF signal using fast ADC we get accurate feedback signal and also eliminates the need of two separate detectors for amplitude and phase detection. Controller is implemented in Vertex-4 FPGA. Codes for control algorithms which controls the amplitude and phase in all four quadrants with good accuracy are written in the VHDL. I/Q modulator works as common actuator for both amplitude and phase correction. Synchronization between RF, LO and ADC clock is indispensable and has been achieved by deriving the clock and LO signal from RF signal itself. Control system has been successfully tested in lab with phase and amplitude stability better then ±1% and ±1° respectively. High frequency RF signal is down converted to IF using the super heterodyne technique. Super heterodyne principal not only brings the RF signal to the Low IF frequency at which it can be easily processed but also enables us to use the same hardware and software for other RF frequencies with some minor modification. (author)

High-power RF controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddl, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kw cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference

Simulations of S-band RF gun with RF beam control

Science.gov (United States)

Barnyakov, A. M.; Levichev, A. E.; Maltseva, M. V.; Nikiforov, D. A.

2017-08-01

The RF gun with RF control is discussed. It is based on the RF triode and two kinds of the cavities. The first cavity is a coaxial cavity with cathode-grid assembly where beam bunches are formed, the second one is an accelerating cavity. The features of such a gun are the following: bunched and relativistic beams in the output of the injector, absence of the back bombarding electrons, low energy spread and short length of the bunches. The scheme of the injector is shown. The electromagnetic field simulation and longitudinal beam dynamics are presented. The possible using of the injector is discussed.

High-power rf controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddle, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kW cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. A block diagram of this system is shown, as is a subset of the complete system on which the measurements reported in this paper were performed. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference. 4 refs., 8 figs

Embedded control system for high power RF amplifiers

International Nuclear Information System (INIS)

Sharma, Deepak Kumar; Gupta, Alok Kumar; Jain, Akhilesh; Hannurkar, P.R.

2011-01-01

RF power devices are usually very sensitive to overheat and reflected RF power; hence a protective interlock system is required to be embedded with high power solid state RF amplifiers. The solid state RF amplifiers have salient features of graceful degradation and very low mean time to repair (MTTR). In order to exploit these features in favour of lowest system downtime, a real-time control system is embedded with high power RF amplifiers. The control system is developed with the features of monitoring, measurement and network publishing of various parameters, historical data logging, alarm generation, displaying data to the operator and tripping the system in case of any interlock failure. This paper discusses the design philosophy, features, functions and implementation details of the embedded control system. (author)

Serum LH-RF and LH levels after synthetic LH-RF administration in man as measured by radioimmunoassays

International Nuclear Information System (INIS)

Shiina, Masaki; Makino, Tsunehisa; Nakamura, Yukio; Iizuka, Rihachi

1975-01-01

Using a radioimmunoassay (RIA) which is sensitive and highly specific to lutenizing hormone releasing factors (LRF, LH-RF), diminution of an exogeously administered synthetic LH-RF in the blood and the movement of LH released into the blood from the anterior lobe of hypopysis were examined on healthy adult males. The blood LH-RF level after an intravenous administration of 200 μg of synthetic LH-RF reached a maximum (mean, 35.0 ng/ml serum) 2.5 minutes after administration, followed by a rapid decrease, and was as low as 1.0 ng/ml serum 30 minutes after administration. The diminution of the exogenous LH-RF from the blood was rapidest 2.5-15 minutes after administration (t1/2=3.9 minutes) and slowest (t1/2=7.9 minutes) 15-30 minutes after administration. On the other hand, when 200 μg of the synthetic LH-RF was administered intramuscularly, LH-RF appeared only slightly in the blood 2.5 minutes after administration, and the maximum level (10 minutes after administration) was only 1.6 ng/ml serum. It diminished from the blood drawing lenient curve. The blood LH level continued to rise significantly starting 5 minutes after administration of 200 μg of the synthetic LH-RF both in intravenous and intramuscular cases, showing hardly any differences between them. The blood endogenous LH-RF level prior to the synthetic LH-RF administration was below the measurable sensitivity (10 pg/tupe). (Mukohata, S.)

RF control hardware design for CYCIAE-100 cyclotron

Energy Technology Data Exchange (ETDEWEB)

Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Fu, Xiaoliang; Ji, Bin; Zhao, Zhenlu; Zhang, Tianjue; Li, Pengzhan; Wei, Junyi; Xing, Jiansheng; Wang, Chuan

2015-11-21

The Beijing Radioactive Ion-beam Facility project is being constructed by BRIF division of China Institute of Atomic Energy. In this project, a 100 MeV high intensity compact proton cyclotron is built for multiple applications. The first successful beam extraction of CYCIAE-100 cyclotron was done in the middle of 2014. The extracted proton beam energy is 100 MeV and the beam current is more than 20 μA. The RF system of the CYCIAE-100 cyclotron includes two half-wavelength cavities, two 100 kW tetrode amplifiers and power transmission line systems (all above are independent from each other) and two sets of Low Level RF control crates. Each set of LLRF control includes an amplitude control unit, a tuning control unit, a phase control unit, a local Digital Signal Process control unit and an Advanced RISC Machines based EPICS IOC unit. These two identical LLRF control crates share one common reference clock and take advantages of modern digital technologies (e.g. DSP and Direct Digital Synthesizer) to achieve closed loop voltage and phase regulations of the dee-voltage. In the beam commission, the measured dee-voltage stability of RF system is better than 0.1% and phase stability is better than 0.03°. The hardware design of the LLRF system will be reviewed in this paper.

A low-power RF system with accurate synchronization for a S-band RF-gun using a laser-triggered photocathode

International Nuclear Information System (INIS)

Otake, Y.; Naito, T.; Shintake, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

1992-01-01

An S-band RF-gun using a laser-triggered photocathode and its low-power RF system have been constructed. The main elements of the low-power RF system comprise a 600-W amplifier, an amplitude modulator, a phase detector, a phase shifter and a frequency-divider module. Synchronization between the RF fields for acceleration and the mode-locked laser pulses for beam triggering are among the important points concerning the RF-gun. The frequency divider module which down-converts from 2856 MHz(RF) to 89.25 MHz(laser), and the electrical phase-shifter were specially developed for stable phase control. The phase jitter of the frequency divider should be less than 10 ps to satisfy our present requirements. The first experiments to trigger and accelerate beams with the above-mentioned system were carried out in January, 1992. (Author) 6 figs., 5 refs

Frequency control of RF booster cavity in TRIUMF

International Nuclear Information System (INIS)

Fong, K.; Laverty, M.

1993-01-01

A booster is used in the TRIUMF cyclotron to increase the energy gain per turn for beam orbits corresponding to energies greater than 370 MeV. It operates at 92.24 MHz, the 4 th harmonic of the cyclotron main rf, and at a nominal voltage of 150 kV. Excitation is provided by a 90 kW rf system that is phase locked to the main rf. When the main rf is interrupted due to sparking or other causes, a controller built into the low frequency source of the booster rf system disables the phase-locked loop, and reconfigures the source as a temperature stabilized oscillator operating at the last locked frequency. When the cyclotron rf is restored it usually will be at different frequency. The oscillator tunes automatically to this new frequency. The acquisition time is extended by the controller to match the response time of the mechanical tuner in the cavity

EPICS based low-level radio frequency control system in LIPAc

Energy Technology Data Exchange (ETDEWEB)

Calvo, Julio, E-mail: julio.calvo@ciemat.es [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Ciemat (Spain); Rivers, Mark L. [Department of Geophysical Sciences and Center for Advanced Radiation Sources, The University of Chicago (United States); Patricio, Miguel A. [Departamento de Informatica, Universidad Carlos III de Madrid (Spain); Ibarra, Angel [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Ciemat (Spain)

2012-11-15

Highlights: Black-Right-Pointing-Pointer The system proposed can control amplitude and phase of each cavity. Black-Right-Pointing-Pointer Rapid diagnostics are refreshed in milliseconds. Black-Right-Pointing-Pointer Increasing control parameters will not increase consumed time neither complexity. Black-Right-Pointing-Pointer IQ demodulation can be achieved thanks to the transformed values at driver level. - Abstract: The IFMIF-EVEDA (International Fusion Materials Irradiation Facility - Engineering Validation and Engineering Design Activity) linear accelerator, known as Linear IFMIF Prototype Accelerator (LIPAc), will be a 9 MeV, 125 mA continuous wave (CW) deuteron accelerator prototype to validate the technical options of the accelerator design for IFMIF. The primary mission of such facility is to test and verify materials performance when subjected to extensive neutron irradiation of the type encountered in a fusion reactor to prepare for the design, construction, licensing and safe operation of a fusion demonstration reactor (DEMO). The radio frequency (RF) power system of IFMIF-EVEDA consists of 18 RF chains working at 175 MHz with three amplification stages each. The low-level radio frequency (LLRF) controls the amplitude and phase of the signal to be synchronized with the beam and it also controls the resonance frequency of the cavities. The system is based on a commercial compact peripheral component interconnect (cPCI) field programmable gate array (FPGA) board, provided by Lyrtech and controlled by a Windows host PC. For this purpose, it is mandatory to communicate the cPCI FPGA board from EPICS Channel Access [1]. A software architecture on EPICS framework in order to control and monitor the LLRF system is presented.

DEMONSTRATION OF AN ATCA BASED RF CONTROL SYSTEM AT FLASH

CERN Document Server

Simrock, S N; Jezynski, T; Koprek, W; Butkowski, L; Jablonski, G W; Jalmuzna, W; Makowski, D R; Piotrowski, A; Czuba, K

2009-01-01

Future rf control systems will require simultaneous data acquisition of up to 100 fast ADC channels at sampling rates of around 100 MHz and real time signal processing within a few hundred nanoseconds. At the same time the standardization of Low-Level RF systems are common objectives for all laboratories for cost reduction, performance optimization and machine reliability. Also desirable are modularity and scalability of the design as well as compatibility with accelerator instrumentation needs including the control system. All these requirements can be fulfilled with the new telecommunication standard ATCA when adopted to the domain of instrumentation. We describe the architecture and design of an ATCA based LLRF system for the European XFEL. The operation of a prototype capable of controlling the vectorsum of 24-cavities and providing measurements of forward and reflected power are presented.

Low frequency rf current drive

International Nuclear Information System (INIS)

Hershkowitz, N.

1992-01-01

An unshielded antenna for rf heating has been developed and tested during this report period. In addition to design specifications being given, some experimental results are presented utilizing: (1) an unprotected Faraday shield, (2) insulating guard limiters, (3) unshielded antenna experiments, (4) method for detecting small rf driven currents, (5) rf fast wave current drive experiments, (6) alfven wave interactions with electrons, and (7) machine conditioning, impurity generation and density control

Control electronics of the PEP RF system

International Nuclear Information System (INIS)

Pellegrin, J.L.; Schwarz, H.

1981-01-01

The operation of the major components used for controlling the phase and field level of the PEP RF cavities is described. The control electronics of one RF station is composed of several control loops: each cavity has a tuners' servo loop which maintains the frequency constant and also keeps the fields of each cavity balanced; the total gap voltage developed by a pair of cavities is regulated by a gap voltage controller; finally, the phase variation along the amplification chain, the klystron and the cavities are compensated by a phase lock loop. The design criteria of each loop are set forth and the circuit implementation and test results are presented

Control system analysis for the perturbed linear accelerator rf system

CERN Document Server

Sung Il Kwon

2002-01-01

This paper addresses the modeling problem of the linear accelerator RF system in SNS. Klystrons are modeled as linear parameter varying systems. The effect of the high voltage power supply ripple on the klystron output voltage and the output phase is modeled as an additive disturbance. The cavity is modeled as a linear system and the beam current is modeled as the exogenous disturbance. The output uncertainty of the low level RF system which results from the uncertainties in the RF components and cabling is modeled as multiplicative uncertainty. Also, the feedback loop uncertainty and digital signal processing signal conditioning subsystem uncertainties are lumped together and are modeled as multiplicative uncertainty. Finally, the time delays in the loop are modeled as a lumped time delay. For the perturbed open loop system, the closed loop system performance, and stability are analyzed with the PI feedback controller.

CONTROL SYSTEM ANALYSIS FOR THE PERTURBED LINEAR ACCELERATOR RF SYSTEM

International Nuclear Information System (INIS)

SUNG-IL KWON; AMY H. REGAN

2002-01-01

This paper addresses the modeling problem of the linear accelerator RF system in SNS. Klystrons are modeled as linear parameter varying systems. The effect of the high voltage power supply ripple on the klystron output voltage and the output phase is modeled as an additive disturbance. The cavity is modeled as a linear system and the beam current is modeled as the exogenous disturbance. The output uncertainty of the low level RF system which results from the uncertainties in the RF components and cabling is modeled as multiplicative uncertainty. Also, the feedback loop uncertainty and digital signal processing signal conditioning subsystem uncertainties are lumped together and are modeled as multiplicative uncertainty. Finally, the time delays in the loop are modeled as a lumped time delay. For the perturbed open loop system, the closed loop system performance, and stability are analyzed with the PI feedback controller

Low-temperature, low-loss zero level packaging techniques for RF applications by using a photopatternable dry film

International Nuclear Information System (INIS)

Kim, J; Seok, S; Rolland, N; Rolland, P-A

2012-01-01

This paper presents a low-temperature zero-level packaging technique using a dry film type of PerMX polymer for RF devices. Silicon cap packaging with PerMX sealing ring and PerMX cap packaging through multilayer lamination have been implemented. All of the fabrication process has been performed at temperature less than 150 °C. The influence of each packaging cap on the packaged coplanar waveguide was first investigated using the HFSS electromagnetic simulation. The RF measurement results showed that both packaging caps did not have significant influence on the performance of transmission lines. The insertion loss changes before and after packaging were almost negligible up to 30 GHz, and the return losses were better than 20 dB. Also, the deformation of PerMX structures concerning the packaging processes has been studied. For silicon capping, the volumetric compression of PerMX sealing ring by the bonding process has been observed. For PerMX cap packaging, the deflection of the polymer cap has been investigated as a function of sealing ring width for the different cap size. Measured results had good agreement with the ANSYS simulated ones. (paper)

New digital low-level rf system for heavy-ion synchrotrons

Directory of Open Access Journals (Sweden)

Harald Klingbeil

2011-10-01

Full Text Available In the scope of the Facility for Antiproton and Ion Research (FAIR project, several new synchrotrons and storage rings will be built. The existing heavy-ion synchrotron SIS18 has to be upgraded to serve as an injector for the FAIR accelerators. All this imposes new requirements on the low-level rf (LLRF systems. These requirements include fast ramping modes, arbitrary ion species, and complex beam manipulations such as dual-harmonic operation, bunch merging/splitting, barrier bucket operation, or bunch compression. In order to fulfill these tasks, a completely new and unique system architecture has been developed since 2002, and the system is now used in SIS18 operation. The presentation of this novel system architecture is the purpose of this paper. We first describe the requirements and the design of the LLRF system. Afterwards, some key components and key interfaces of the system are summarized followed by a discussion of technological aspects. Finally, we present some beam experiment results that were obtained using the new LLRF system.

An updated overview of the LEB RF system

International Nuclear Information System (INIS)

Rogers, J.D.; Ferrell, J.H.; Curbow, J.E.; Friedrichs, C.

1992-01-01

Each of the Low Energy Booster (LEB) rf systems consists of the following major subsystems: a vacuum tube final rf amplifier driven by a solid state rf amplifier, a ferrite-tuned rf cavity used to bunch and accelerate the beam, a low-level rf system including rf feedback systems, a computer-based supervisory control system, and associated power supplies. The LEB rf system is broadband with the exception of the rf cavity, which is electronically tuned from approximately 47.5 MHz to 59.7 MHz in 50 ms. The design and development status of the LEB rf system is presented, with particular emphasis on the cavity and tuner, and the tuner bias power supply

The New RF Control System for the CERN SPS Accelerator

CERN Document Server

Baudrenghien, P; Linnecar, Trevor Paul R; Marty, H; Molendijk, J C; Pilchen, Y; Wehrle, U; Weierud, F

1996-01-01

The old SPS RF control system designed in 1972 has been replaced completely, i.e. both hardware and software. The new system has to control both RF equipment conceived during the last 23 years and future (modern) equipment. Using information analysis methods, we derived a model of an RF command and designed a data base accordingly (ORACLE®). Information from this data base is used for command generation and processing and also for archiving settings. The advantage is purely generic software, i.e. the same computer code is used for switching on an RF amplifier, as for setting a frequency synthesizer. New equipment is added very simply by entering new records in the data base. Additional features include a reservation scheme whereby a user can take private control of any piece of equipment, a reporting facility notifying the user of the simultaneous control activity by other users on RF equipment, and a capability scheme assigning a level of expertise to each user restricting action on the equipment.

ACCELERATORS: RF system design and measurement of HIRF-CSRe

Science.gov (United States)

Xu, Zhe; Zhao, Hong-Wei; Wang, Chun-Xiao; Xia, Jia-Wen; Zhan, Wen-Long; Bian, Zhi-Bin

2009-05-01

An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections: ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB interface and has three feedback loops. Finally we give the results of the measurement on our system.

Low-level feedback control for the phase regulation of CLIC Drive Beam Klystrons

CERN Document Server

AUTHOR|(SzGeCERN)752526

2015-01-01

The requirement of luminosity loss below 1% raises tight tolerances for the phase and power stability of the CLIC drive beam (DB) klystrons and consequently for the high voltage pulse ripple of the modulators. A low-level RF (LLRF) feedback system needs to be developed and combined with the modulator in order to guarantee the phase and amplitude tolerances. To this aim, three feedback control strategies were investigated, i) Proportional Integral (PI) controller, ii) Linear Quadratic Integral Regulator (LQI) and iii) Model Predictive Controller (MPC). The klystron, as well as the incident phase noise were modelled and used for the design and evaluation of the controllers. First simulation results are presented along with future steps and directions.

3 GHz digital rf control at the superconducting Darmstadt electron linear accelerator: First results from the baseband approach and extensions for other frequencies

Directory of Open Access Journals (Sweden)

A. Araz

2010-08-01

Full Text Available The low level rf system for the superconducting Darmstadt electron linear accelerator (S-DALINAC developed 20 years ago and operating since converts the 3 GHz signals from the cavities down to the baseband and not to an intermediate frequency. While designing the new, digital rf control system this concept was kept: the rf module does the I/Q and amplitude modulation/demodulation while the low frequency board, housing an field programmable gate array analyzes and processes the signals. Recently, the flexibility of this concept was realized: By replacing the modulator/demodulators on the rf module, cavities operating at frequencies other than the one of the S-DALINAC can be controlled with only minor modifications: A 6 GHz version, needed for a harmonic bunching system at the S-DALINAC and a 324 MHz solution to be used on a room temperature cavity at GSI, are currently under design. This paper reviews the concept of the digital low level rf control loops in detail and reports on the results gained during first operation with a superconducting cavity.

Broadband direct RF digitization receivers

CERN Document Server

Jamin, Olivier

2014-01-01

This book discusses the trade-offs involved in designing direct RF digitization receivers for the radio frequency and digital signal processing domains.  A system-level framework is developed, quantifying the relevant impairments of the signal processing chain, through a comprehensive system-level analysis.  Special focus is given to noise analysis (thermal noise, quantization noise, saturation noise, signal-dependent noise), broadband non-linear distortion analysis, including the impact of the sampling strategy (low-pass, band-pass), analysis of time-interleaved ADC channel mismatches, sampling clock purity and digital channel selection. The system-level framework described is applied to the design of a cable multi-channel RF direct digitization receiver. An optimum RF signal conditioning, and some algorithms (automatic gain control loop, RF front-end amplitude equalization control loop) are used to relax the requirements of a 2.7GHz 11-bit ADC. A two-chip implementation is presented, using BiCMOS and 65nm...

RF-Station control crate

International Nuclear Information System (INIS)

Beuzekom, M.G. van; Es, J.T. van.

1992-01-01

This report gives a description of the electronic control-system for the RF-station of AmPS. The electronics form the connection between the computer-system and the hardware of the RF-station. Only the elements of the systems which are not described in the other NIKHEF-reports are here discussed in detail. (author). 7 figs

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

Energy Technology Data Exchange (ETDEWEB)

Guo, Jiquan [Stanford Univ., CA (United States)

2008-12-01

In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

The Digital Feedback RF Control System of the RFQ and DTL1 for 100 MeV Proton Linac of PEFP

CERN Document Server

Yu In Ha; Cho, Yong-Sub; Han, Yeung-Jin; Kang Heung Sik; Kim, Sung-Chul; Kwon, Hyeok-Jung; Park, In-Soo; Tae Kim, Do; Tae Seol, Kyung

2005-01-01

The 100 MeV Proton linear accelerator (Linac) for the PEFP (Proton Engineering Frontier Project) will include 1 RFQ and 1 DTL1 at 350 MHz as well as 7 DTL2 cavities at 700 MHz. The low level RF system with the digital feedback RF control provides the field control to accelerate a 20mA proton beam from 50 keV to 20 MeV with a RFQ and a DTL1 at 350M Hz. The FPGA-based digital feedback RF control system has been built and is used to control cavity field amplitude within ± 1% and relative phase within ± 1°. The fast digital processing is networked to the EPICS-based control system with an embedded processor (Blackfin). In this paper, the detailed description of the digital feedback RF control system will be described with the performance test results.

Reaction of the immune system to low-level RF/MW exposures

International Nuclear Information System (INIS)

Szmigielski, Stanislaw

2013-01-01

Radiofrequency (RF) and microwave (MW) radiation have been used in the modern world for many years. The rapidly increasing use of cellular phones in recent years has seen increased interest in relation to the possible health effects of exposure to RF/MW radiation. In 2011 a group of international experts organized by the IARC (International Agency for Research on Cancer in Lyon) concluded that RF/MW radiations should be listed as a possible carcinogen (group 2B) for humans. The incomplete knowledge of RF/MW-related cancer risks has initiated searches for biological indicators sensitive enough to measure the “weak biological influence” of RF/MWs. One of the main candidates is the immune system, which is able to react in a measurable way to discrete environmental stimuli. In this review, the impacts of weak RF/MW fields, including cell phone radiation, on various immune functions, both in vitro and in vivo, are discussed. The bulk of available evidence clearly indicates that various shifts in the number and/or activity of immunocompetent cells are possible, however the results are inconsistent. For example, a number of lymphocyte functions have been found to be enhanced and weakened within single experiments based on exposure to similar intensities of MW radiation. Certain premises exist which indicate that, in general, short-term exposure to weak MW radiation may temporarily stimulate certain humoral or cellular immune functions, while prolonged irradiation inhibits the same functions

Reaction of the immune system to low-level RF/MW exposures

Energy Technology Data Exchange (ETDEWEB)

Szmigielski, Stanislaw, E-mail: szmigielski@wihe.waw.pl

2013-06-01

Radiofrequency (RF) and microwave (MW) radiation have been used in the modern world for many years. The rapidly increasing use of cellular phones in recent years has seen increased interest in relation to the possible health effects of exposure to RF/MW radiation. In 2011 a group of international experts organized by the IARC (International Agency for Research on Cancer in Lyon) concluded that RF/MW radiations should be listed as a possible carcinogen (group 2B) for humans. The incomplete knowledge of RF/MW-related cancer risks has initiated searches for biological indicators sensitive enough to measure the “weak biological influence” of RF/MWs. One of the main candidates is the immune system, which is able to react in a measurable way to discrete environmental stimuli. In this review, the impacts of weak RF/MW fields, including cell phone radiation, on various immune functions, both in vitro and in vivo, are discussed. The bulk of available evidence clearly indicates that various shifts in the number and/or activity of immunocompetent cells are possible, however the results are inconsistent. For example, a number of lymphocyte functions have been found to be enhanced and weakened within single experiments based on exposure to similar intensities of MW radiation. Certain premises exist which indicate that, in general, short-term exposure to weak MW radiation may temporarily stimulate certain humoral or cellular immune functions, while prolonged irradiation inhibits the same functions.

Programmable optical processor chips: toward photonic RF filters with DSP-level flexibility and MHz-band selectivity

Directory of Open Access Journals (Sweden)

Xie Yiwei

2017-12-01

Full Text Available Integrated optical signal processors have been identified as a powerful engine for optical processing of microwave signals. They enable wideband and stable signal processing operations on miniaturized chips with ultimate control precision. As a promising application, such processors enables photonic implementations of reconfigurable radio frequency (RF filters with wide design flexibility, large bandwidth, and high-frequency selectivity. This is a key technology for photonic-assisted RF front ends that opens a path to overcoming the bandwidth limitation of current digital electronics. Here, the recent progress of integrated optical signal processors for implementing such RF filters is reviewed. We highlight the use of a low-loss, high-index-contrast stoichiometric silicon nitride waveguide which promises to serve as a practical material platform for realizing high-performance optical signal processors and points toward photonic RF filters with digital signal processing (DSP-level flexibility, hundreds-GHz bandwidth, MHz-band frequency selectivity, and full system integration on a chip scale.

Development of a multichannel RF field detector for the low-level RF control of the free-electron laser at Hamburg

International Nuclear Information System (INIS)

Hoffmann, Matthias

2008-10-01

Modern free electron lasers produce synchrotron radiation with constantly shortening wavelengths of up to 6 nm and pulse widths of up to 100 fs. That requires a constantly increasing stability of the beam energy and arrival time of the electron beam at the undulator entrance which is situated at the end of the accelerator. At the same time, the increasing speed of digital signal processing and data acquisition facilitates new possibilities for the digital radio frequency control and field detection. In this thesis the development of a multichannel radio frequency field detector for the low level radio frequency (LLRF) control of the superconducting cavities of the Free-Electron Laser at Hamburg (FLASH) is described. The applied method of IF sampling is state of the technology and is utilized in many areas of digital communication. It is evaluated concerning its applicability for the LLRF control. Analytical and numerical investigations of the noise behavior and transport in the control loop have been accomplished to define the requirements for the measurement accuracy of the field detector that was to be developed. Therefore, simplified models of the noise behavior of each system component of the control loop, e.g. amplifier, radio frequency mixer and analog-to-digital converter, were established and subsequently assorted to a the model of the control loop. Due to the application of the vector-sum control, where several separately measured field vectors are added to a vector-sum, requirements concerning the allowable compression error of the detector nonlinearity were defined. These were investigated by analytical and numerical methods, as well. Requirements for the hardware that was to be developed were compiled from the simulation results. For the development of the field detector, a modular and EMC-compatible concept with a high-level passive front-end for an improvement of the signal-to-noise ratio was chosen. The following tests in the lab delivered the

Development of a multichannel RF field detector for the low-level RF control of the free-electron laser at Hamburg

Energy Technology Data Exchange (ETDEWEB)

Hoffmann, Matthias

2008-10-15

Modern free electron lasers produce synchrotron radiation with constantly shortening wavelengths of up to 6 nm and pulse widths of up to 100 fs. That requires a constantly increasing stability of the beam energy and arrival time of the electron beam at the undulator entrance which is situated at the end of the accelerator. At the same time, the increasing speed of digital signal processing and data acquisition facilitates new possibilities for the digital radio frequency control and field detection. In this thesis the development of a multichannel radio frequency field detector for the low level radio frequency (LLRF) control of the superconducting cavities of the Free-Electron Laser at Hamburg (FLASH) is described. The applied method of IF sampling is state of the technology and is utilized in many areas of digital communication. It is evaluated concerning its applicability for the LLRF control. Analytical and numerical investigations of the noise behavior and transport in the control loop have been accomplished to define the requirements for the measurement accuracy of the field detector that was to be developed. Therefore, simplified models of the noise behavior of each system component of the control loop, e.g. amplifier, radio frequency mixer and analog-to-digital converter, were established and subsequently assorted to a the model of the control loop. Due to the application of the vector-sum control, where several separately measured field vectors are added to a vector-sum, requirements concerning the allowable compression error of the detector nonlinearity were defined. These were investigated by analytical and numerical methods, as well. Requirements for the hardware that was to be developed were compiled from the simulation results. For the development of the field detector, a modular and EMC-compatible concept with a high-level passive front-end for an improvement of the signal-to-noise ratio was chosen. The following tests in the lab delivered the

Simplified RF power system for Wideroe-type linacs

International Nuclear Information System (INIS)

Fugitt, J.; Howard, D.; Crosby, F.; Johnson, R.; Nolan, M.; Yuen, G.

1981-03-01

The RF system for the SuperHILAC injector linac was designed and constructed for minimum system complexity, wide dynamic range, and ease of maintenance. The final amplifier is close coupled to the linac and operates in an efficient semilinear mode, eliminating troublesome transmission lines, modulators, and high level regulators. The system has been operated at over 250 kW, 23 MHz with good regulation. The low level RF electronics are contained in a single chassis adjacent to the RF control computer, which monitors all important operating parameters. A unique 360 0 phase and amplitude modular is used for precise control and regulation of the accelerating voltage

Commissioning of the 400 MHz LHC RF System

CERN Document Server

Ciapala, Edmond; Baudrenghien, P; Brunner, O; Butterworth, A; Linnecar, T; Maesen, P; Molendijk, J; Montesinos, E; Valuch, D; Weierud, F

2008-01-01

The installation of the 400 MHz superconducting RF system in LHC is finished and commissioning is under way. The final RF system comprises four cryo-modules each with four cavities in the LHC tunnel straight section round IP4. Also underground in an adjacent cavern shielded from the main tunnel are the sixteen 300 kW klystron RF power sources with their high voltage bunkers, two Faraday cages containing RF feedback and beam control electronics, and racks containing all the slow controls. The system and the experience gained during commissioning will be described. In particular, results from conditioning the cavities and their movable main power couplers and the setting up of the low level RF feedbacks will be presented.

THE Low-level Radio Frequency System for the superconducting cavities of National Synchrotron Light Source II

International Nuclear Information System (INIS)

Ma, H.; Rose, J.; Holub, B.; Cupolo, J.; Oliva, J.; Sikora, R.; Yeddulla, M.

2011-01-01

A digital low-level radio frequency (LLRF) field controller has been developed for the storage ring of The National Synchrotron Light Source-II (NSLS-II). The primary performance goal for the LLRF is to support the required RF operation of the superconducting cavities with a beam current of 500mA and a 0.14 degree or better RF phase stability. The digital field controller is FPGA-based, in a standard format 19-inch/I-U chassis. It has an option of high-level control support with MATLAB running on a local host computer through a USB2.0 port. The field controller has been field tested with the high-power superconducting RF (SRF) at Canadian light Source, and successfully stored a high beam current of 250 mA. The test results show that required specifications for the cavity RF field stability are met. This digital field controller is also currently being used as a development platform for other functional modules in the NSLS-II RF systems.

Electronics for the control of the rf system

International Nuclear Information System (INIS)

Pellegrin, J.L.; Schwarz, H.

1980-03-01

This note describes the operation of the major components used for controlling the phase and the field level of the PEP rf cavities. The block diagram of one rf station is decomposed into several control loops: each cavity has a tuners' servo loop which maintains the frequency constant and also keeps the field of each cell at the same level; the total gap voltage developed by a pair of cavities is obeying the command of the gap voltage controller; finally, the phase variation along the amplification chain and the klystron are compensated by a phase lock loop. The design criteria of each loop are set forth and the circuit implementation and test results are presented. The purpose of this report is to acquaint interested people with the design philosophy and to allow them to evaluate the capabilities of this system and its behavior during operation of the machine. 5 refs., 16 figs

Rf beam control for the AGS Booster

International Nuclear Information System (INIS)

Brennan, J.M.

1994-01-01

RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made

Rf beam control for the AGS Booster

Energy Technology Data Exchange (ETDEWEB)

Brennan, J.M.

1994-09-26

RF beam control systems for hadron synchrotrons have evolved over the past three decades into an essentially standard design. The key difference between hadron and lepton machines is the absence of radiation damping and existence of significant frequency variation in the case of hadrons. Although the motion of the hadron in the potential well of the rf wave is inherently stable it is not strongly damped. Damping must be provided by electronic feedback through the accelerating system. This feedback is typically called the phase loop. The technology of the rf beam control system for the AGS Booster synchrotron is described. First, the overall philosophy of the design is explained in terms of a conventional servo system that regulates the beam horizontal position in the vacuum chamber. The concept of beam transfer functions is fundamental to the mathematics of the design process and is reviewed. The beam transfer functions required for this design are derived from first principles. An overview of the beam signal pick-ups and high level rf equipment is given. The major subsystems, the frequency program, the heterodyne system, and beam feedback loops, are described in detail. Beyond accelerating the beam, the rf system must also synchronize the bunches in the Booster to the buckets in the AGS before transfer. The technical challenge in this process is heightened by the need to accomplish synchronization while the frequency is still changing. Details of the synchronization system are given. This report is intended to serve two purposes. One is to document the hardware and performance of the systems that have been built. The other is to serve as a tutorial vehicle from which the non-expert can not only learn the details of this system but also learn the principles of beam control that have led to the particular design choices made.

Cancer risks related to low-level RF/MW exposures, including cell phones.

Science.gov (United States)

Szmigielski, Stanislaw

2013-09-01

For years, radiofrequency (RF) and microwave (MW) radiations have been applied in the modern world. The rapidly increasing use of cellular phones called recent attention to the possible health risks of RF/MW exposures. In 2011, a group of international experts organized by IARC (International Agency for Research on Cancer in Lyon) concluded that RF/MW radiations should be listed as a possible carcinogen (group 2B) for humans. Three meta-analyses of case-control studies have concluded that using cell phones for more than ten years was associated with an increase in the overall risk of developing a brain tumor. The Interphone Study, the largest health-related case-control international study of use of cell phones and head and neck tumors, showed no statistically significant increases in brain cancers related to higher amounts of cell phone use, but excess risk in a small subgroup of more heavily exposed users associated with latency and laterality was reported. So far, the published studies do not show that mobile phones could for sure increase the risk of cancer. This conclusion is based on the lack of a solid biological mechanism, and the fact that brain cancer rates are not going up significantly. However, all of the studies so far have weaknesses, which make it impossible to entirely rule out a risk. Mobile phones are still a new technology and there is little evidence about effects of long-term use. For this reason, bioelectromagnetic experts advise application of a precautionary resources. It suggests that if people want to use a cell phone, they can choose to minimize their exposure by keeping calls short and preferably using hand-held sets. It also advises discouraging children from making non essential calls as well as also keeping their calls short.

RF Control System Upgrade at CAMD

CERN Document Server

Suller, Victor P; Jines, Paul; Launey, Daren

2005-01-01

A description is given of the new control system for the RF system of the CAMD light source. The new design being implemented brings all RF signals into the data acquisition system via a modular, custom made, RF detector and renders the amplitude and tune control loops in the VME computer. On line calculations ensure monitoring of proper operation and display the information to the user in an efficient way. In addition, an advanced load impedance monitoring diagnostic has been implemented, being displayed as a Smith Chart, which is based on the system used at the SRS in Daresbury, England.

RF System description for the ground test accelerator radio-frequency quadrupole

International Nuclear Information System (INIS)

Regan, A.H.; Brittain, D.; Rees, D.E.; Ziomek, D.

1992-01-01

This paper describes the RF system being used to provide RF power and to control the cavity field for the ground test accelerator (GTA) radio-frequency quadrupole (RFQ). The RF system consists of a low-level RF (LLRF) control system, and RF Reference generation subsystem, and a tetrode as a high-power amplifier (HPA) that can deliver up to 300 kW of peak power to the RFQ cavity at a 2% duty factor. The LLRF control system implements in-phase and quadrature (I and Q) control to maintain the cavity field within tolerances of 0.5% in amplitude and 0.5 degrees in phase in the presence of beam-induced instabilities

Directions for rf-controlled intelligent microvalve

Science.gov (United States)

Enderling, Stefan; Varadan, Vijay K.; Abbott, Derek

2001-03-01

In this paper, we consider the novel concept of a Radio Frequency (RF) controllable microvalve for different medical applications. Wireless communication via a Surface Acoustic Wave Identification-mark (SAW ID-tag) is used to control, drive and locate the microvalve inside the human body. The energy required for these functions is provided by RF pulses, which are transmitted to the valve and back by a reader/transmitter system outside of the body. These RF bursts are converted into Surface Acoustic Waves (SAWs), which propagate along the piezoelectric actuator material of the microvalve. These waves cause deflections, which are employed to open and close the microvalve. We identified five important areas of application of the microvalve in biomedicine: 1) fertility control; 2) artificial venous valves; 3) flow cytometry; 4) drug delivery and 5) DNA mapping.

Global voltage control for the LEP RF system

International Nuclear Information System (INIS)

Ciapala, E.; Butterworth, A.; Peschardt, E.

1993-01-01

The LEG RF system is installed as independent 16 cavity units. In addition to the eight copper cavity units originally installed 12 units with super-conducting cavities are being added for the LEP200 energy upgrade. The total RF voltage determines the synchrotron tune (Qs) and must be controlled precisely during energy ramping. Local function generators in each of the RF units are pre-loaded such that when triggered simultaneously by ramp timing events transmitted over the general timing system the total voltage varies to give the Qs function required. A disadvantage is that loss of RF in a unit at any time after the loading process cannot be corrected. As the number of RF units increases automatic control of the total RF voltage and its distribution around LEP becomes desirable. A global voltage control system, based on a central VME controller, has recently been installed. It has direct and rapid access to the RF units over the LEP time division multiplexing system. Initial tests on operation and performance at fixed energy and during energy ramping are described, as well as the implementation of a Qs loop in which Qs can be set directly using on-line synchrotron frequency measurements

Rf system specifications for a linear accelerator

International Nuclear Information System (INIS)

Young, A.; Eaton, L.E.

1992-01-01

A linear accelerator contains many systems; however, the most complex and costly is the RF system. The goal of an RF system is usually simply stated as maintaining the phase and amplitude of the RF signal within a given tolerance to accelerate the charged particle beam. An RF system that drives a linear accelerator needs a complete system specification, which should contain specifications for all the subsystems (i.e., high-power RF, low-level RF, RF generation/distribution, and automation control). This paper defines a format for the specifications of these subsystems and discusses each RF subsystem independently to provide a comprehensive understanding of the function of each subsystem. This paper concludes with an example of a specification spreadsheet allowing one to input the specifications of a subsystem. Thus, some fundamental parameters (i.e., the cost and size) of the RF system can be determined

Practical use of the amplitude and phase modulation of a high-power RF pulse via feed-forward control

International Nuclear Information System (INIS)

Kawase, Keigo; Kato, Ryukou; Irizawa, Akinori; Isoyama, Goro; Kashiwagi, Shigeru

2013-01-01

A new feed-forward control system to precisely control the amplitude and phase of the pulsed RF power in an electron linear accelerator (linac) is developed to make the accelerating field constant. Fast variations and ripples in the amplitude and phase in the RF pulses are compensated by modulating the amplitude and phase in the low-level system with a variable attenuator and phase shifter. The system is innovated the overdrive technique, which is commonly used in analog circuits, to speed up the slow response of the phase shifter, while the control signals are digitally processed; thus, the method is a hybrid of analog and digital techniques. By using the new control system, we find that the peak-to-peak variations in the amplitude and phase are reduced from 11.6% to 0.4% and from 6.1 degrees to 0.3 degrees, respectively, in 7.6-μs-long RF pulses for the L-band electron linac at Osaka University. (author)

A self-adaptive feedforward rf control system for linacs

International Nuclear Information System (INIS)

Zhang Renshan; Ben-Zvi, I.; Xie Jialin

1993-01-01

The design and performance of a self-adaptive feedforward rf control system are reported. The system was built for the linac of the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. Variables of time along the linac macropulse, such as field or phase are discretized and represented as vectors. Upon turn-on or after a large change in the operating-point, the control system acquires the response of the system to test signal vectors and generates a linearized system response matrix. During operation an error vector is generated by comparing the linac variable vectors and a target vector. The error vector is multiplied by the inverse of the system's matrix to generate a correction vector is added to an operating point vector. This control system can be used to control a klystron to produce flat rf amplitude and phase pulses, to control a rf cavity to reduce the rf field fluctuation, and to compensate the energy spread among bunches in a rf linac. Beam loading effects can be corrected and a programmed ramp can be produced. The performance of the control system has been evaluated on the control of a klystron's output as well as an rf cavity. Both amplitude and phase have been regulated simultaneously. In initial tests, the rf output from a klystron has been regulated to an amplitude fluctuation of less than ±0.3% and phase variation of less than ±0.6deg. The rf field of the ATF's photo-cathode microwave gun cavity has been regulated to ±5% in amplitude and simultaneously to ±1deg in phase. Regulating just the rf field amplitude in the rf gun cavity, we have achieved amplitude fluctuation of less than ±2%. (orig.)

Embedded software for the CEBAF RF Control Module

International Nuclear Information System (INIS)

Lahti, G.; Ashkenazi, I.; West, C.; Morgan, B.

1991-01-01

The CEBAF accelerator control system employs a distributed computer strategy. As part of this strategy, the RF control sub-system uses 342 RF Control Modules, one for each of four warm section beam forming cavities (i.e., choppers, buncher, capture) and 338 superconducting accelerating cavities. Each control module has its own microprocessor, which provides local intelligence to automatically control over 100 parameters, while keeping the user interface simple. The microprocessor controls analog and digital I/O, including the phase and gradient section, high power amplifier (HPA), and interlocks. Presently, the embedded code is used to commission the 14 RF control modules in the injector. This paper describes the operational experience of this complex real-time control system

Study of Control Grid Thermionic Cathode RF Gun

CERN Document Server

Xiao, Jin; Ming, Li; Xinfan, Yang; Xumin, Shen; Yanan, Chen; Zhou, Xu

2004-01-01

In this paper, the beam loading effect of RF Gun was analyzed. To minimize the energy spread, the grid control RF Gun was introduced. The result shows that the grid congrol RF Gun can increase electron beam within 1% energy spread.

Design and development of RF system for vertical test stand for characterization of superconducting RF cavities

International Nuclear Information System (INIS)

Mohania, Praveen; Rajput, Vikas; Baxy, Deodatta; Agrawal, Ankur; Mahawar, Ashish; Adarsh, Kunver; Singh, Pratap; Shrivastava, Purushottam

2011-01-01

RRCAT is developing a Vertical Test Stand (VTS) to test and qualify 1.3 GHz/650 MHz, SCRF Cavities in collaboration with Fermi National Accelerator Laboratory (FNAL) under Indian Institutions' Fermilab Collaboration. The technical details for VTS is being provided by FNAL, USA. The RF System of VTS needs to provide stable RF power to SCRF cavity with control of amplitude, relative phase and frequency. The incident, reflected, transmitted power and field decay time constant of the cavity are measured to evaluate cavity performance parameters (E, Qo). RF Power is supplied via 500 W Solid State amplifier, 1270-1310 MHz being developed by PHPMS, RRCAT. VTS system is controlled by PXI Platform and National Instruments LabVIEW software. Low Level RF (LLRF) system is used to track the cavity frequency using Phase Locked Loop (PLL). The system is comprised of several integrated functional modules which would be assembled, optimized, and tested separately. Required components and instruments have been identified and procurement for the same is underway. Inhouse development for the Solid State RF amplifier and instrument interfacing is in progress. This paper describes the progress on the development of the RF system for VTS. (author)

Investigation and reduction of excess low-frequency noise in rf superconducting quantum interference devices

International Nuclear Information System (INIS)

Mueck, M.; Heiden, C.; Clarke, J.

1994-01-01

A detailed study has been made of the low-frequency excess noise of rf superconducting quantum interference devices (SQUIDs), fabricated from thin niobium films and operated at 4.2 K, with rf bias frequencies of 0.15, 1.7, and 3 GHz. When the SQUIDs were operated in an open-loop configuration in the absence of low-frequency flux modulation, the demodulated rf voltage exhibited a substantial level 1/f noise, which was essentially independent of the rf bias frequency. As the rf bias frequency was increased, the crossover frequency at which the 1/f noise power was equal to the white noise power moved to higher frequencies, because of the reduction in white noise. On the other hand, when the SQUID was flux modulated at 50 kHz and operated in a flux locked loop, no 1/f noise was observed at frequencies above 0.5 Hz. A detailed description of how the combination of rf bias and flux modulation removes 1/f noise due to critical current fluctuations is given. Thus, the results demonstrate that the 1/f noise observed in these SQUIDs is generated by critical current fluctuations, rather than by the hopping of flux vortices in the niobium films

Performance analysis of a low power low noise tunable band pass filter for multiband RF front end

International Nuclear Information System (INIS)

Manjula, J.; Malarvizhi, S.

2014-01-01

This paper presents a low power tunable active inductor and RF band pass filter suitable for multiband RF front end circuits. The active inductor circuit uses the PMOS cascode structure as the negative transconductor of a gyrator to reduce the noise voltage. Also, this structure provides possible negative resistance to reduce the inductor loss with wide inductive bandwidth and high resonance frequency. The RF band pass filter is realized using the proposed active inductor with suitable input and output buffer stages. The tuning of the center frequency for multiband operation is achieved through the controllable current source. The designed active inductor and RF band pass filter are simulated in 180 nm and 45 nm CMOS process using the Synopsys HSPICE simulation tool and their performances are compared. The parameters, such as resonance frequency, tuning capability, noise and power dissipation, are analyzed for these CMOS technologies and discussed. The design of a third order band pass filter using an active inductor is also presented. (semiconductor integrated circuits)

The RF voltage dependence of the electron sheath heating in low pressure capacitively coupled rf discharges

International Nuclear Information System (INIS)

Buddemeier, U.; Kortshagen, U.; Pukropski, I.

1995-01-01

In low pressure capacitively coupled RF discharges two competitive electron heating mechanisms have been discussed for some time now. At low pressures the stochastic sheath heating and for somewhat higher pressures the Joule heating in the bulk plasma have been proposed. When the pressure is increased at constant RF current density a transition from concave electron distribution functions (EDF) with a pronounced cold electron group to convex EDFs with a missing strong population of cold electrons is found. This transition was interpreted as the transition from dominant stochastic to dominant Joule heating. However, a different interpretation has been given by Kaganovich and Tsendin, who attributed the concave shaped EDFs to the spatially inhomogeneous RF field in combination with the nonlocality of the EDF

RF compensation of single Langmuir probe in low density helicon plasma

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Soumen, E-mail: soumen@ipr.res.in; Chattopadhyay, Prabal K.; Ghosh, Joydeep; Bora, Dhiraj

2016-11-15

Highlights: • Appropriate density and temperature measurement with Langmuir probe in RF Eenvironment. • Necessity of large auxiliary electrode for RF compensation at low densities (∼10{sup 16} m{sup −3}). • Measured two temperature electrons in low pressure helicon antenna produced RF plasma. • Tail electrons are localized only at off-axis in our cylindrical plasma system. - Abstract: Interpretations of Single Langmuir probe measurements in electrode-less radio frequency (RF) plasmas are noteworthy tricky and require adequate compensation of RF. Conventional RF compensation technique is limited only at high density (>10{sup 17} m{sup −3}) RF plasmas. RF compensation of single Langmuir probe at low density RF plasmas (∼10{sup 16} m{sup −3}) is presented in this paper. In RF driven plasmas, where the RF voltage is high (∼50 V) and density is in the range (∼10{sup 16} m{sup −3}), the primary RF compensation condition (Z{sub ck} > >Z{sub sh}) is very difficult to fulfill, because of high sheath impedance (Z{sub sh}) at 13.56 MHz and the construction limitation of a self-resonant tiny chock (Z{sub ck}) with very high impedance. Introducing a large auxiliary electrode (A{sub x}), (A{sub x} >>> A{sub p}), close to the small Langmuir probe (A{sub p}) tip, connected in parallel with probe via a coupling capacitor (C{sub cp}), significantly reduces the effective sheath impedance (Z{sub sh}) and allows probe bias to follow the RF oscillation. Dimensional requirements of the auxiliary electrode and the role of suitable coupling capacitor are discussed in this paper. Observations show proper compensation leads to estimation of more positive floating potentials and lower electron temperatures compared to uncompensated probe. The electron energy probability function (EEPF) is also obtained by double differentiating the collected current with respect to the applied bias voltage using an active analog circuit.

RF control system of the HIMAC synchrotron

International Nuclear Information System (INIS)

Kanazawa, M.; Sato, K.; Itano, A.

1992-01-01

An RF control system of the HIMAC synchrotron has been constructed. In this control system we have adopted a digital feed back system with a digital synthesizer (DS). Combining a high power system, performance of the control system have been tested in a factory (Toshiba) with a simulator circuit of the synchrotron oscillation. Following this test, We had beam acceleration test with this control system at TARN-II in INS (Institute for Nuclear Study, University of Tokyo). This paper describes the RF control system and its tested results. (author)

RF emittance in a low energy electron linear accelerator

Science.gov (United States)

Sanaye Hajari, Sh.; Haghtalab, S.; Shaker, H.; Kelisani, M. Dayyani

2018-04-01

Transverse beam dynamics of an 8 MeV low current (10 mA) S-band traveling wave electron linear accelerator has been studied and optimized. The main issue is to limit the beam emittance, mainly induced by the transverse RF forces. The linac is being constructed at Institute for Research in Fundamental Science (IPM), Tehran Iran Labeled as Iran's First Linac, nearly all components of this accelerator are designed and constructed within the country. This paper discusses the RF coupler induced field asymmetry and the corresponding emittance at different focusing levels, introduces a detailed beam dynamics design of a solenoid focusing channel aiming to reduce the emittance growth and studies the solenoid misalignment tolerances. In addition it has been demonstrated that a prebuncher cavity with appropriate parameters can help improving the beam quality in the transverse plane.

RF control at transient beamloading for high-duty-factor linacs

Energy Technology Data Exchange (ETDEWEB)

Chernogubovsky, M.A.; Sugimoto, Masayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-08-01

An effective RF control with the transient beamloading is the major issue in the operation of the high-duty-factor linacs to suppress the undesirable beam loss. The RF control method is considered to obtain the control principle and the state equation, under the analysis of electrodynamical properties of the excitation in the resonator of the linac due to the transient beamloading. The concept of the directional selective coupling is applied for the RF system to define the main characteristics and to optimize the RF control parameters. (author)

Rf control system for a rocket-borne accelerator

International Nuclear Information System (INIS)

Lynch, M.T.; Sorum, L.N.; Keffeler, D.R.

1987-01-01

The Beam Experiments Aboard Rockets (BEAR) accelerator experiment imposes several nonstandard requirements on the rf control system. The experiment is entirely hands-off and must operate under local computer control. The rf control system must be extremely reliable, which implies excellence in design and fabrication as well as redundancy whenever possible. This paper describes the design of the frequency-source, frequency-control, and amplitude-control systems for the BEAR experiment

Wafer-level packaging technology for RF applications based on a rigid low-loss spacer substrate

NARCIS (Netherlands)

Polyakov, A.

2006-01-01

As mobile portable devices such as cellular system/phones, smart handheld devices and laptop computers acquire wireless connectivity there is a growing demand for greater levels of RF integration. The holy grail of integration is to have a whole set of different components integrated into one chip.

RF control at SSCL - an object oriented design approach

International Nuclear Information System (INIS)

Dohan, D.A.; Osberg, E.; Biggs, R.; Bossom, J.; Chillara, K.; Richter, R.; Wade, D.

1994-01-01

The Superconducting Super Collider (SSC) in Texas, the construction of which was stopped in 1994, would have represented a major challenge in accelerator research and development. This paper addresses the issues encountered in the parallel design and construction of the control systems for the RF equipment for the five accelerators comprising the SSC. An extensive analysis of the components of the RF control systems has been undertaken, based upon the Schlaer-Mellor object-oriented analysis and design (OOA/OOD) methodology. The RF subsystem components such as amplifiers, tubes, power supplies, PID loops, etc. were analyzed to produce OOA information, behavior and process models. Using these models, OOD was iteratively applied to develop a generic RF control system design. This paper describes the results of this analysis and the development of 'bridges' between the analysis objects, and the EPICS-based software and underlying VME-based hardware architectures. The application of this approach to several of the SSCL RF control systems is discussed. ((orig.))

Beam test with the HIMAC RF control system

International Nuclear Information System (INIS)

Kanazawa, M.; Sato, K.; Itano, A.

1992-01-01

RF system of the HIMAC synchrotron has been developed and tested in the factory. With the high power system, we could sweep the acceleration frequency from 1MHz to 8MHz with the acceleration voltage of 6KV. The performance of the RF control system has been confirmed with a developed simulator of the synchrotron oscillation. Following these two tests in the factory, we had a beam test of the RF control system at TARN-II in INS (Institute for Nuclear Study, University of Tokyo). This paper describes the beam test and its results. (author)

Analog techniques in CEBAF's RF control system

International Nuclear Information System (INIS)

Hovater, C.; Fugitt, J.

1989-01-01

Recent developments in high-speed analog technology have progressed into the areas of traditional RF technology. Diode related devices are being replaced by analog IC's in the CEBAF RF control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. RF signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

Analog techniques in CEBAF'S RF control system

International Nuclear Information System (INIS)

Hovater, C.; Fugitt, J.

1989-01-01

Recent developments in high-speed analog technology have progressed into the areas of traditional rf technology. Diode-related devices are being replaced by analog IC's in the CEBAF rf control system. Complex phase modulators and attenuators have been successfully tested at 70 MHz. They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity. Rf signal conditioning components and how to implement the new analog IC's will be covered in this paper. 4 refs., 5 figs

The system of RF beam control for electron gun

International Nuclear Information System (INIS)

Barnyakov, A.M.; Levichev, A.E.; Chernousov, Yu.D.; Ivannikov, V.I.; Shebolaev, I.V.

2015-01-01

The system of RF control of three-electrode electron gun current is described. It consists of a source of microwave signal, coaxial line, coaxial RF switch and RF antenna lead. The system allows one to get the electron beam in the form of bunches with the frequency of the accelerating section to achieve the capture of particles in the acceleration mode close to 100%. The results of calculation and analysis of the elements of the system are presented. Characteristics of the devices are obtained experimentally. The results of using RF control in three-electrode electron gun at electron linear accelerator are described

Analysis of RF thrusters with TOPICA and a global system-level model

NARCIS (Netherlands)

Lancellotti, V.; Vecchi, G.; Maggiora, R.; Pavarin, D.; Rocca, S.; Bramanti, C.

2007-01-01

Recent advances in plasma-based propulsion systems have led to the development of electromagnetic (RF) generation and acceleration systems, capable of providing highly controllable and wide-ranging exhaust velocities, and potentially enabling a wide range of missions from KWs to MWs levels. In this

Method of electron emission control in RF guns

International Nuclear Information System (INIS)

Khodak, I.V.; Kushnir, V.A.

2001-01-01

The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described

Method of electron emission control in RF guns

CERN Document Server

Khodak, I V

2001-01-01

The electron emission control method for a RF gun is considered.According to the main idea of the method,the additional resonance system is created in a cathode region where the RF field strength could be varied using the external pulse equipment. The additional resonance system is composed of a coaxial cavity coupled with a RF gun cylindrical cavity via an axial hole. Computed results of radiofrequency and electrodynamic performances of such a two-cavity system and results of the RF gun model pilot study are presented in. Results of particle dynamics simulation are described.

Rf system description for the ground test accelerator radio-frequency quadrupole

International Nuclear Information System (INIS)

Regan, A.H.; Brittain, D.; Rees, D.E.; Ziomek, D.

1992-01-01

This paper describes the RF system being used to provide RF power and to control the cavity field used for the ground test accelerator (GTA) radio-frequency quadrupole (RFQ). The RF system consists of a low-level RF (LLRF) control system that uses a tetrode as a high-power amplifier (HPA) as part of its plant to deliver up to 300 kW of peak power to the RFQ at a 2% duty factor. The LLRF control system implements in-phase and quadrature (I ampersand Q) control to maintain the cavity field within tolerances of 0.5% in amplitude and 0.5 degrees in phase in the presence of beam-induced instabilities. This paper describes the identified components and presents measured performance data. The user interface with the systems is described, and cavity field measurements are included

The Spallation Neutron Source RF Reference System

CERN Document Server

Piller, Maurice; Crofford, Mark; Doolittle, Lawrence; Ma, Hengjie

2005-01-01

The Spallation Neutron Source (SNS) RF Reference System includes the master oscillator (MO), local oscillator(LO) distribution, and Reference RF distribution systems. Coherent low noise Reference RF signals provide the ability to control the phase relationships between the fields in the front-end and linear accelerator (linac) RF cavity structures. The SNS RF Reference System requirements, implementation details, and performance are discussed.

Controlling the dynamics of a self-organized structure using a rf-field

International Nuclear Information System (INIS)

Talasman, S.J.; Ignat, M.

2004-01-01

We investigate the influence of an external rf-field upon a plasma self-organized structure. We show that depending on the intensity of this field, though it is at very low values, the dynamics of the structure can be easily controlled over a wide range of the state parameters values. This could be considered as a non-feedback method of dynamics control

Control of total voltage in the large distributed RF system of LEP

CERN Document Server

Ciapala, Edmond

1995-01-01

The LEP RF system is made up of a large number of independent RF units situated around the ring near the interaction points. These have different available RF voltages depending on their type and they may be inactive or unable to provide full voltage for certain periods. The original RF voltage control system was based on local RF unit voltage function generators pre-loaded with individual tables for energy ramping. This was replaced this year by a more flexible global RF voltage control system. A central controller in the main control room has direct access to the units over the LEP TDM system via multiplexers and local serial links. It continuously checks the state of all the units and adjusts their voltages to maintain the desired total voltage under all conditions. This voltage is distributed among the individual units to reduce the adverse effects of RF voltage asymmetry around the machine as far as possible. The central controller is a VME system with 68040 CPU and real time multitasking operating syste...

Pc based RF control system for the Vincy cyclotron

International Nuclear Information System (INIS)

Samardzic, B.J.; Drndarevic, V.R.

1999-01-01

The concept and design procedure for the RF control system of the VINCY cyclotron are described. Special attention has been paid to the choice of computer support of this system. The merits and limitations of the chosen solution have been analyzed. A PC type computer has been selected as the platform for performing the functions of initiation, control, and supervision of the RF system. The integration of the hardware is carried out by direct connection to the PC bus via standard communication interfaces. The system software operates under a graphic oriented Windows operating system applying the modern concept of virtual instrumentation. The application of this concept allowed considerable simplification of the operator-RF system interaction and resulted in additional flexibility of the software to further extensions or modifications of the system. The selected open architecture of the computer platform allows a simple and economic upgrading of the realized system in accordance with future requirements. Tests of the realized RF control system prototype are in progress. (authors)

Operational experience with the new LEIR digital low-level RF System

CERN Document Server

Angoletta, ME

2010-01-01

The LEIR Low-Level (LLRF) system is the first all-digital low LLRF system that has been put into operation in a CERN circular machine. It is a very compact system, composed of one VME64x crate and of few NIM modules. System capabilities include typical beam control tasks, such as frequency program, beam phase, radial and extraction synchronization feedback loops, as well as cavity voltage/phase feedback loops. The system is also capable of coping with the large variation of the revolution frequency during an acceleration cycle as well as with the high dynamic range required by the LEIR cavities operation. Extensive diagnostics and observation capabilities are built-in and the system’s control parameters are fully configurable remotely and in-between cycles. Over the various LEIR runs, the LLRF system has proven to be reliable and reproducible as well as extremely flexible and powerful. These characteristics are essential for a LLRF system and LEIR is already profiting from them. Moreover, high beam availabi...

Estimate of radiation damage to low-level electronics of the RF system in the LHC cavities arising from beam gas collisions.

Science.gov (United States)

Butterworth, A; Ferrari, A; Tsoulou, E; Vlachoudis, V; Wijnands, T

2005-01-01

Monte Carlo simulations have been performed to estimate the radiation damage induced by high-energy hadrons in the digital electronics of the RF low-level systems in the LHC cavities. High-energy hadrons are generated when the proton beams interact with the residual gas. The contributions from various elements-vacuum chambers, cryogenic cavities, wideband pickups and cryomodule beam tubes-have been considered individually, with each contribution depending on the gas composition and density. The probability of displacement damage and single event effects (mainly single event upsets) is derived for the LHC start-up conditions.

CORPORATE FEED WITH DUAL SEGMENT CIRCULAR POLARIZED ARRAY RECTENNA FOR LOW POWER RF ENERGY HARVESTING

Directory of Open Access Journals (Sweden)

CHIA CHAO KANG

2016-06-01

Full Text Available This paper focuses on the investigation of the level powers that can be scavenged from the ambient environment by using corporate feed with dual segment circular polarized antenna array . It will converts the received power to direct current (DC. Being a circular polarized antenna, it has higher inductance per unit area, a good Q-factor and compact capability. The design of corporate-series feed rectenna array is to achieve a high gain antenna and maximize the RF energy received by the rectenna system at ultra low power levels. The entire structure was investigated using a combination of harmonic balance nonlinear analysis and full wave electromagnetic field analysis. The results show that 5.0 dBi gain for circular polarized antenna array can be achieved at frequency 956 MHz. When the input power of 20 dBm fed into the transmitting antenna, the maximum distance for radio frequency (RF harvesting is 5.32m. The output DC voltage for various values of incident RF power is also presented. There are noticed reasonable agreements between the simulated and measured result and the works concludes that the investigation of RF energy harvesting system was successful.

Summary of the 3rd workshop on high power RF-systems for accelerators

International Nuclear Information System (INIS)

Sigg, P.K.

2005-01-01

The aim of this workshop was to bring together experts from the field of CW and high average power RF systems. The focus was on operational and reliability issues of high-power amplifiers using klystrons and tubes, large power supplies; as well as cavity design and low-level RF and feedback control systems. All these devices are used in synchrotron radiation facilities, high power linacs and collider rings, and cyclotrons. Furthermore, new technologies and their applications were introduced, amongst other: high power solid state amplifiers, IOT amplifiers, and high voltage power supplies employing solid state controllers/crowbars. Numerical methods for complete rf-field modeling of complex RF structures like cyclotrons were presented, as well as integrated RF-cavity designs (electro-magnetic fields and mechanical structure), using numerical methods. (author)

AN INTERNET RACK MONITOR-CONTROLLER FOR APS LINAC RF ELECTRONICS UPGRADE

Energy Technology Data Exchange (ETDEWEB)

Ma, Hengjie; Smith, Terry; Nassiri, Alireza; Sun, Yine; Doolittle, Lawrence; Ratti, Alex

2016-06-01

To support the research and development in APS LINAC area, the existing LINAC rf control performance needs to be much improved, and thus an upgrade of the legacy LINAC rf electronics becomes necessary. The proposed upgrade plan centers on the concept of using a modern, network-attached, rackmount digital electronics platform –Internet Rack Monitor-Controller (or IRMC) to achieve the goal of modernizing the rf electronics at a lower cost. The system model of the envisioned IRMC is basically a 3-tier stack with a high-performance DSP in the mid-layer to perform the core tasks of real-time rf data processing and controls. The Digital Front-End (DFE) attachment layer at bottom bridges the applicationspecific rf front-ends to the DSP. A network communication gateway, together with an embedded event receiver (EVR) in the top layer merges the Internet Rack MonitorController node into the networks of the accelerator controls infrastructure. Although the concept is very much in trend with today’s Internet-of-Things (IoT), this implementation has actually been used in the accelerators for over two decades.

Adaptive feedforward in the LANL rf control system

International Nuclear Information System (INIS)

Ziomek, C.D.

1992-01-01

This paper describes an adaptive feedforward system that corrects repetitive errors in the amplitude and phase of the RF field of a pulsed accelerator. High-frequency disturbances that are beyond the effective bandwidth of the RF field feedback control system can be eliminated with a feedforward system. Many RF field disturbances for a pulsed accelerator are repetitive, occurring at the same relative time in every pulse. This design employs digital signal processing hardware to adaptively determine and track the control signals required to eliminate the repetitive errors in the feedback control system. In order to provide the necessary high-frequency response, the adaptive feedforward hardware provides the calculated control signal prior to the repetitive disturbance that it corrects. This system has been demonstrated to reduce the transient disturbances caused by beam pulses. Furthermore, it has been shown to negate high-frequency phase and amplitude oscillations in a high-power klystron amplifier caused by PFN ripple on the high-voltage. The design and results of the adaptive feedforward system are presented

EXCESS RF POWER REQUIRED FOR RF CONTROL OF THE SPALLATION NEUTRON SOURCE (SNS) LINAC, A PULSED HIGH-INTENSITY SUPERCONDUCTING PROTON ACCELERATOR

International Nuclear Information System (INIS)

Lynch, M.; Kwon, S.

2001-01-01

A high-intensity proton linac, such as that being planned for the SNS, requires accurate RF control of cavity fields for the entire pulse in order to avoid beam spill. The current design requirement for the SNS is RF field stability within ±0.5% and ±0.5 o [1]. This RF control capability is achieved by the control electronics using the excess RF power to correct disturbances. To minimize the initial capital costs, the RF system is designed with 'just enough' RF power. All the usual disturbances exist, such as beam noise, klystron/HVPS noise, coupler imperfections, transport losses, turn-on and turn-off transients, etc. As a superconducting linac, there are added disturbances of large magnitude, including Lorentz detuning and microphonics. The effects of these disturbances and the power required to correct them are estimated, and the result shows that the highest power systems in the SNS have just enough margin, with little or no excess margin

Evaluation of gamma ray durability and its application of shielded RF tags

International Nuclear Information System (INIS)

Teraura, Nobuyuki; Ito, Kunio; Kobayashi, Daisuke; Sakurai, Kouichi

2015-01-01

In this study, the RF (Radio Frequency) tag with radiation shield is developed and its gamma ray durability is evaluated. RFID (RF Identification) is a radio-wave-based identification technology that can be used for various items. RF tags find use in many applications, including item tracing, access control, etc. RF tags can be classified as active RF tags, which have inbuilt voltaic cells, and passive RF tags without these cells. Passive RF tags, known for their low price and durability, are used in various fields. For instance, they are used for equipment maintenance in factories and thermal power plants. Several frequencies are used for RF tags. Further, RF tagging on the UHF (Ultra High Frequency) frequencies allows a communication range of approximately 10 m, and thus, remote reading is possible. When used in radiation environments such as in nuclear power plants, remote reading can contribute to the reduction of radiation exposure. However, because semiconductors are the primary elements used in the manufacture of RF tags, they can be damaged by radiation, and operational errors can occur. Therefore, this technology has not been used in environments affected by relatively high radiation levels. Therefore, in nuclear power plants, the use of RF tags is limited in areas of low radiation levels. In our study, we develop and manufacture a new RF tag with a radiation shield cover that provides error correction functionality. It is expected that radiation shielded RF tags will improve the radiation-proof feature, and its application range will be expanded. Using the radiation-proof RF tag, we have conducted radiation durability tests. These tests are of two types: one using low energy gamma ray, and the other using high-energy gamma ray. Experimental results are then analyzed. The number of applications for radiation shielded RF tags is considerably increasing, because it can be used in various radiation environments other than nuclear power plants as well, such as

An Implantable Cardiovascular Pressure Monitoring System with On-Chip Antenna and RF Energy Harvesting

Directory of Open Access Journals (Sweden)

Yu-Chun Liu

2015-08-01

Full Text Available An implantable wireless system with on-chip antenna for cardiovascular pressure monitor is studied. The implantable device is operated in a batteryless manner, powered by an external radio frequency (RF power source. The received RF power level can be sensed and wirelessly transmitted along with blood pressure signal for feedback control of the external RF power. The integrated electronic system, consisting of a capacitance-to-voltage converter, an adaptive RF powering system, an RF transmitter and digital control circuitry, is simulated using a TSMC 0.18 μm CMOS technology. The implanted RF transmitter circuit is combined with a low power voltage-controlled oscillator resonating at 5.8 GHz and a power amplifier. For the design, the simulation model is setup using ADS and HFSS software. The dimension of the antenna is 1 × 0.6 × 4.8 mm3 with a 1 × 0.6 mm2 on-chip circuit which is small enough to place in human carotid artery.

Auto-tuning systems for J-PARC LINAC RF cavities

International Nuclear Information System (INIS)

Fang, Z.; Kobayashi, T.; Fukui, Y.; Futatsukawa, K.; Michizono, S.; Yamaguchi, S.; Anami, S.; Suzuki, H.; Sato, F.; Shinozaki, S.; Chishiro, E.

2014-01-01

The 400-MeV proton linear accelerator (LINAC) at the Japan Proton Accelerator Research Complex (J-PARC) consists of 324-MHz low-β and 972-MHz high-β accelerator sections. From October 2006 to May 2013, only the 324-MHz low-β accelerator section was in operation. From the summer of 2013 the J-PARC LINAC was upgraded by installing the 972-MHz high-β accelerator section, and the proton beam was successfully accelerated to 400 MeV in January 2014. Auto-tuning systems for the J-PARC LINAC RF cavities have been successfully developed. A first generation design, an auto-tuning system using a mechanical tuner controller, was developed and operated for the first 3 years. Then the second-generation auto-tuning system was developed using a new approach to the RF cavity warm-up process, and this was applied to the accelerator operation for the subsequent 4 years. During the RF cavity warm-up process in this system, the mechanical tuner is constantly fixed and the input RF frequency is automatically tuned to the cavity resonance frequency using the FPGA (Field-Programmable Gate Array) of the digital feedback RF control system. After the input power level reaches the required value, input RF frequency tuning is stopped and it is switched to the operation frequency. Then, the mechanical tuner control begins operation. This second-generation auto-tuning system was extremely effective for the 324-MHz cavity operation. However, if we apply this approach to the 972-MHz RF cavities, an interlock due to the RF cavity reflection amplitude occasionally occurs at the end of the warm-up process. In order to solve this problem a third generation novel auto-tuning system was successfully developed in December 2013 and applied to the operation of the J-PARC LINAC, including the 972-MHz ACS RF cavities. During the warm-up process both the mechanical tuner controller and the input RF frequency tuning are in operation, and good matching between the input RF frequency and the RF cavity is

Auto-tuning systems for J-PARC LINAC RF cavities

Energy Technology Data Exchange (ETDEWEB)

Fang, Z., E-mail: fang@post.kek.jp [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Kobayashi, T.; Fukui, Y.; Futatsukawa, K.; Michizono, S.; Yamaguchi, S.; Anami, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Suzuki, H.; Sato, F.; Shinozaki, S.; Chishiro, E. [Japan Atomic Energy Agency (JAEA), 2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

2014-12-11

The 400-MeV proton linear accelerator (LINAC) at the Japan Proton Accelerator Research Complex (J-PARC) consists of 324-MHz low-β and 972-MHz high-β accelerator sections. From October 2006 to May 2013, only the 324-MHz low-β accelerator section was in operation. From the summer of 2013 the J-PARC LINAC was upgraded by installing the 972-MHz high-β accelerator section, and the proton beam was successfully accelerated to 400 MeV in January 2014. Auto-tuning systems for the J-PARC LINAC RF cavities have been successfully developed. A first generation design, an auto-tuning system using a mechanical tuner controller, was developed and operated for the first 3 years. Then the second-generation auto-tuning system was developed using a new approach to the RF cavity warm-up process, and this was applied to the accelerator operation for the subsequent 4 years. During the RF cavity warm-up process in this system, the mechanical tuner is constantly fixed and the input RF frequency is automatically tuned to the cavity resonance frequency using the FPGA (Field-Programmable Gate Array) of the digital feedback RF control system. After the input power level reaches the required value, input RF frequency tuning is stopped and it is switched to the operation frequency. Then, the mechanical tuner control begins operation. This second-generation auto-tuning system was extremely effective for the 324-MHz cavity operation. However, if we apply this approach to the 972-MHz RF cavities, an interlock due to the RF cavity reflection amplitude occasionally occurs at the end of the warm-up process. In order to solve this problem a third generation novel auto-tuning system was successfully developed in December 2013 and applied to the operation of the J-PARC LINAC, including the 972-MHz ACS RF cavities. During the warm-up process both the mechanical tuner controller and the input RF frequency tuning are in operation, and good matching between the input RF frequency and the RF cavity is

Low reflectance high power RF load

Science.gov (United States)

Ives, R. Lawrence; Mizuhara, Yosuke M.

2016-02-02

A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

Multi-level RF identification system

Science.gov (United States)

Steele, Kerry D.; Anderson, Gordon A.; Gilbert, Ronald W.

2004-07-20

A radio frequency identification system having a radio frequency transceiver for generating a continuous wave RF interrogation signal that impinges upon an RF identification tag. An oscillation circuit in the RF identification tag modulates the interrogation signal with a subcarrier of a predetermined frequency and modulates the frequency-modulated signal back to the transmitting interrogator. The interrogator recovers and analyzes the subcarrier signal and determines its frequency. The interrogator generates an output indicative of the frequency of the subcarrier frequency, thereby identifying the responding RFID tag as one of a "class" of RFID tags configured to respond with a subcarrier signal of a predetermined frequency.

Estimate of radiation damage to low-level electronics of the RF system in the LHC cavities arising from beam gas collisions

International Nuclear Information System (INIS)

Butterworth, A.; Ferrari, A.; Tsoulou, E.; Vlachoudis, V.; Wijnands, T.

2005-01-01

Monte Carlo simulations have been performed to estimate the radiation damage induced by high-energy hadrons in the digital electronics of the RF low-level systems in the LHC cavities. High-energy hadrons are generated when the proton beams interact with the residual gas. The contributions from various elements - vacuum chambers, cryogenic cavities, wideband pickups and cryo-module beam tubes - have been considered individually, with each contribution depending on the gas composition and density. The probability of displacement damage and single event effects (mainly single event upsets) is derived for the LHC start-up conditions. (authors)

Development of low emittance high brightness electron beams and rf accelerating structures

International Nuclear Information System (INIS)

Pellegrini, C.

1991-01-01

The main goals of this project were the construction of an S-band RF photoinjector for the production of a high brightness electron beam, and the development of a new type of RF accelerator structure; the Plane wave transformer. By the end of October 1991 the photoinjector had been built, its RF characteristics had been measured at low power, and an initial test of the gun at high RF power had been done. The Plane Wave Transformer had also been built and tested at lower power. In both cases the results obtained are mostly in agreement with the expected and calculated behavior

Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

International Nuclear Information System (INIS)

Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

2010-01-01

Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

In Depth Diagnostics for RF System Operation in the PEP-II B Factory

International Nuclear Information System (INIS)

Van Winkle, Daniel; Fox, John; Teytelman, Dmitry; SLAC

2005-01-01

The PEP-II RF systems incorporate numerous feedback loops in the low-level processing for impedance control and operating point regulation. The interaction of the multiple loops with the beam is complicated, and the systems incorporate online diagnostic tools to configure the feedback loops as well as to record fault files in the case of an RF abort. Rapid and consistent analysis of the RF-related beam aborts and other failures is critical to the reliable operation of the B-Factory, especially at the recently achieved high beam currents. Procedures and algorithms used to extract diagnostic information from time domain fault files are presented and illustrated via example interpretations of PEP-II fault file data. Example faults presented will highlight the subtle interpretation required to determine the root cause. Some such examples are: abort kicker firing asynchronously, klystron and cavity arcs, beam loss leading to longitudinal instability, tuner read back jumps and poorly configured low-level RF feedback loop

Effect of low-frequency ambient magnetic fields on the control unit and RF head of a commercial SQUID magnetometer

Science.gov (United States)

Marcus, C. M.

1984-01-01

The control unit and RF head of the SHE model 330XRFSQUID system are shown to be sensitive to ambient ac magnetic fields below 1 HZ, which cause the appearance of false signals corresponding to a magnetometer signal of 0.000001 phi(0) per gauss of field applied. The control unit shows a sensitivity that is linear with frequency, suggesting that the signal is generated by Faraday induction. In contrast, the RF head response is independent of frequency and shows a strong second-harmonic coversion. This response may be due to the magnetic field sensitivity of the ferrite core inductor in the tuned amplifier of the RF head. These signals induced by ambient fields are a potential source of error in Stanford's Relativity Gyroscope experiment, which uses SQUID's on board a rolling satellite as part of the gyroscope readout system. The extent of the magnetic field sensitivity in these components necessitates the use of additional magnetic shielding aboard the satellite.

Modeling the interaction of a heavily beam loaded SRF cavity with its low-level RF feedback loops

Science.gov (United States)

Liu, Zong-Kai; Wang, Chaoen; Chang, Lung-Hai; Yeh, Meng-Shu; Chang, Fu-Yu; Chang, Mei-Hsia; Chang, Shian-Wen; Chen, Ling-Jhen; Chung, Fu-Tsai; Lin, Ming-Chyuan; Lo, Chih-Hung; Yu, Tsung-Chi

2018-06-01

A superconducting radio frequency (SRF) cavity provides superior stability to power high intensity light sources and can suppress coupled-bunch instabilities due to its smaller impedance for higher order modes. Because of these features, SRF cavities are commonly used for modern light sources, such as the TLS, CLS, DLS, SSRF, PLS-II, TPS, and NSLS-II, with an aggressive approach to operate the light sources at high beam currents. However, operating a SRF cavity at high beam currents may result with unacceptable stability problems of the low level RF (LLRF) system, due to drifts of the cavity resonant frequency caused by unexpected perturbations from the environment. As the feedback loop gets out of control, the cavity voltage may start to oscillate with a current-dependent characteristic frequency. Such situations can cause beam abort due to the activation of the interlock protection system, i.e. false alarm of quench detection. This malfunction of the light source reduces the reliability of SRF operation. Understanding this unstable mechanism to prevent its appearance becomes a primary task in the pursuit of highly reliable SRF operation. In this paper, a Pedersen model, including the response of the LLRF system, was used to simulate the beam-cavity interaction of a SRF cavity under heavy beam loading. Causes for the onset of instability at high beam current will be discussed as well as remedies to assure the design of a stable LLRF system.

Low modulation index RF signal detection for a passive UHF RFID transponder

International Nuclear Information System (INIS)

Liu Zhongqi; Zhang Chun; Li Yongming; Wang Zhihua

2009-01-01

In a typical RFID system the reader transmits modulated RF power to provide both data and energy for the passive transponder. Low modulation index RF energy is preferable for an adequate tag power supply and increase in communication range but gives rise to difficulties for near-field conventional demodulation. Therefore, a novel ASK demodulator for minimum 20% modulation index RF signal detection over a range of 23 dB is presented. Thanks to the proposed innovative divisional linear conversion from the power into voltage signal, the detection sensitivity is ensured over a wide power range with low power consumption of 8.6 μW. The chip is implemented in UMC 0.18 μm mix-mode CMOS technology, and the chip area is 0.06 mm 2 .

Origin of high carrier mobility and low residual stress in RF superimposed DC sputtered Al doped ZnO thin film for next generation flexible devices

Science.gov (United States)

Kumar, Naveen; Dubey, Ashish; Bahrami, Behzad; Venkatesan, S.; Qiao, Qiquan; Kumar, Mukesh

2018-04-01

In this work, the energy and flux of high energetic ions were controlled by RF superimposed DC sputtering process to increase the grain size and suppress grain boundary potential with minimum residual stress in Al doped ZnO (AZO) thin film. AZO thin films were deposited at different RF/(RF + DC) ratios by keeping total power same and were investigated for their electrical, optical, structural and nanoscale grain boundaries potential. All AZO thin film showed high crystallinity and orientation along (002) with peak shift as RF/(RF + DC) ratio increased from 0.0, pure DC, to 1.0, pure RF. This peak shift was correlated with high residual stress in as-grown thin film. AZO thin film grown at mixed RF/(RF + DC) of 0.75 showed high electron mobility, low residual stress and large crystallite size in comparison to other AZO thin films. The nanoscale grain boundary potential was mapped using Kelvin Probe Force Microscopy in all AZO thin film and it was observed that carrier mobility is controlled not only by grains size but also by grain boundary potential. The XPS analysis confirms the variation in oxygen vacancies and zinc interstitials which explain the origin of low grain boundaries potential and high carrier mobility in AZO thin film deposited at 0.75 RF/(RF + DC) ratio. This study proposes a new way to control the grain size and grain boundary potential to further tune the optoelectronic-mechanical properties of AZO thin films for next generation flexible and optoelectronic devices.

Rf stability, control and bunch lengthening in electron synchrotron storage rings

International Nuclear Information System (INIS)

Wachtel, J.M.

1989-09-01

A self-consistent theory for nonlinear longitudinal particle motion and rf cavity excitation in a high energy electron storage ring is developed. Coupled first order equations for the motion of an arbitrary number of particles and for the field in several rf cavities are given in the form used in control system theory. Stochastic quantum excitation of synchrotron motion is included, as are the effects of rf control system corrections. Results of computations for double cavity bunch lengthening are given. 11 refs., 4 figs., 1 tab

Adaptive feed forward in the LANL RF control system

International Nuclear Information System (INIS)

Ziomek, C.D.

1992-01-01

This paper describes an adaptive feed forward system that corrects repetitive errors in the amplitude and phase of the RF field of a pulsed accelerator. High-frequency disturbances that are beyond the effective bandwidth of the RF-field feedback control system can be eliminated with a feed forward system. Many RF-field disturbances for a pulsed accelerator are repetitive, occurring at the same relative time in every pulse. This design employs digital signal processing hardware to adaptively determine and track the control signals required to eliminate the repetitive errors in the feedback control system. In order to provide the necessary high-frequency response, the adaptive feed forward hardware provides the calculated control signal prior to the repetitive disturbance that it corrects. This system has been demonstrated to reduce the transient disturbances caused by beam pulses. Furthermore, it has been shown to negate high-frequency phase and amplitude oscillations in a high-power klystron amplifier caused by PFN ripple on the high-voltage. The design and results of the adaptive feed forward system are presented. (Author) 3 figs., 2 refs

Low power microwave tests on RF gun prototype of the Iranian Light Source Facility

Directory of Open Access Journals (Sweden)

A Sadeghipanah

2017-08-01

Full Text Available In this paper, we introduce RF electron gun of Iranian Light Source Facility (ILSF pre-injection system. Design, fabrication and low-power microwave tests results of the prototype RF electron gun have been described in detail. This paper also explains the tuning procedure of the prototype RF electron gun to the desired resonant frequency. The outcomes of this project brighten the path to the fabrication of the RF electron gun by the local industries  

Design of electronic modules for the low-level RF systems at CERN. With particular regard to a new trigger unit for the Super Proton Synchrotron.

CERN Document Server

Levens, Thomas Edward; Knox, Andrew

This report presents the work completed while the author was working for the BE-RF-FB group at the European Organization for Nuclear Research during the period of June to December 2010. The placement was completed as part of the University of Glasgow course ‘Industrial Project EE5’ which is requirement during the final year of the Degree of Master of Engineering. The report will pay particular attention to the hardware and firmware design of the ‘Dual Trigger Unit’, a new electronic module for the low-level RF system of the Super Proton Synchrotron accelerator which generates delayed timing pulses in order to trigger other hardware. In addition to this, the report will cover other projects completed during the period, including work on a prototype of the ‘VME Peak Detector’ card for the Large Hadron Collider beam observation system.

Low modulation index RF signal detection for a passive UHF RFID transponder

Energy Technology Data Exchange (ETDEWEB)

Liu Zhongqi [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China); Zhang Chun; Li Yongming; Wang Zhihua, E-mail: liu-zq04@mails.tsinghua.edu.c [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

2009-09-15

In a typical RFID system the reader transmits modulated RF power to provide both data and energy for the passive transponder. Low modulation index RF energy is preferable for an adequate tag power supply and increase in communication range but gives rise to difficulties for near-field conventional demodulation. Therefore, a novel ASK demodulator for minimum 20% modulation index RF signal detection over a range of 23 dB is presented. Thanks to the proposed innovative divisional linear conversion from the power into voltage signal, the detection sensitivity is ensured over a wide power range with low power consumption of 8.6 {mu}W. The chip is implemented in UMC 0.18 {mu}m mix-mode CMOS technology, and the chip area is 0.06 mm{sup 2}.

Clinical diagnostic value of combined determination of serum RF, AKA and anti-CCP antibody levels in patients with rheumatoid arthritis

International Nuclear Information System (INIS)

Zhao Hongcan; Xiang Guoqian

2005-01-01

Objective; To investigate the clinical usefulness of combined determination of serum rheumatic factor (RF), anti-keratin antibody (AKA) and anti-cyclic citrullinated peptide antibody (anti-CCP antibody) levels for early diagnosis in patients with rheumatoid arthritis (RA). Methods: Serum RF ( with rate-nephelometry), AKA (with indirect immuno-fluorescence) and anti-CCP antibody (with ELISA) levels were determined in 40 patients with RA, 30 patients with SLE and 30 controls. Results: For diagnosis of RA; the sensitivity and specificity of RF was 70.0% and 90.0% respectively, the sensitivity and specificity of AKA was 35.0% and 96.7%, the sensitivity and specificity of anti-CCP-antibody was 85% and 93.3% respectively. With combined determination of RF, AKA and anti-CCP antibody, the sensitivity and specificity would be the highest, being 97.07 and 99.8% respectively. Conclusion: RF, AKA and anti-CCP antibody were useful diagnostic serum markers for rheumatoid arthritis and combined determination of these markers would be very useful for early diagnosis. (authors)

The IPNS second harmonic RF upgrade

International Nuclear Information System (INIS)

Middendorf, M.E.; Brumwell, F.R.; Dooling, J.C.; Horan, D.; Kustom, R.L.; Lien, M.K.; McMichael, G.E.; Moser, M.R.; Nassiri, A.; Wang, S.

2008-01-01

The intense pulsed neutron source (IPNS) rapid cycling synchrotron (RCS) is used to accelerate protons from 50 MeV to 450 MeV, at a repetition rate of 30 Hz. The original ring design included two identical rf systems, each consisting of an accelerating cavity, cavity bias supply, power amplifiers and low-level analog electronics. The original cavities are located 180 degrees apart in the ring and provide a total peak accelerating voltage of ∼21 kV over the 2.21-MHz to 5.14-MHz revolution frequency sweep. A third rf system has been constructed and installed in the RCS. The third rf system is capable of operating at the fundamental revolution frequency for the entire acceleration cycle, providing an additional peak accelerating voltage of up to ∼11 kV, or at the second harmonic of the revolution frequency for the first ∼4 ms of the acceleration cycle, providing an additional peak voltage of up to ∼11 kV for bunch shape control. We describe here the hardware implementation and operation to date of the third rf cavity in the second harmonic mode.

DDS-based control loops for the RF system at INFN-LNS

International Nuclear Information System (INIS)

Caruso, A.; Calabretta, L.; Cosentino, G.; Sparta, A.; Speziale, F.

2005-01-01

In the last two years a new radio-frequency source generator has been working to synthesize the driving sinusoidal signals of the RF systems at LNS. This device is based on Direct Digital Synthesis (DDS) technique. Every time you need a constant relation of phase between several RF signals, our DDS-based multiple frequencies generator produces these high frequency waveforms. The good results of this DDS synthesizer technique, make us feel confident that we can develop a new DDS control system for the various RF equipment. The AD9852/54 a commercial DDS microchip, will be the core of this new control system. The component allows, through digital ports, the manipulation of the frequency, amplitude and phase of the developed RF-carrier without any interruption to the latter. In this way we would have a complete DDS control system capable of stabilizing amplitude, phase and tuning ensuring the present stability of the analog control loops. The remaining operations, such as turning on/off and protection of the system will be performed at the same time. The prototype of this new DDS control, its technical performances and the experimental results will be presented in this paper. (author)

Development of RF non-IQ sampling module for Helium RFQ LLRF system

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hae-Seong; Ahn, Tae-Sung; Kim, Seong-Gu; Kwon, Hyeok-Jung; Kim, Han-Sung; Song, Young-Gi; Seol, Kyung-Tae; Cho, Yong-Sub [KOMAC, Gyeongju (Korea, Republic of)

2015-05-15

KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the helium irradiation system. This system includes the Ion source, LEBT, RFQ, MEBT systems to transport helium particles to the target. Especially, the RFQ (Radio Frequency Quadrupole) system should receive the 200MHz RF within 1% amplitude error stability. For supplying stable 200MHz RF to the RFQ, the low-level radio frequency (LLRF) should be controlled by control system. The helium RFQ LLRF control system adopted non- IQ sampling method to sample the analog input RF. Sampled input data will be calculated to get the I, Q values. These I, Q values will be used to monitor the amplitude and phase of the RF signal. In this paper, non-IQ sampling logic and amplitude and phase calculating logic of the FPGA will be introduced. Using Xilinx ISE design suite which is tool for developing the FPGA logic module, non-IQ sampling module and amplitude and phase computing module developed. In the future, PI gain module and frequency error computing module will be developed.

Interaction between beam control and rf feedback loops for high Q cavities an heavy beam loading. Revision A

International Nuclear Information System (INIS)

Mestha, L.K.; Kwan, C.M.; Yeung, K.S.

1994-04-01

An open-loop state space model of all the major low-level rf feedback control loops is derived. The model has control and state variables for fast-cycling machines to apply modern multivariable feedback techniques. A condition is derived to know when exactly we can cross the boundaries between time-varying and time-invariant approaches for a fast-cycling machine like the Low Energy Booster (LEB). The conditions are dependent on the Q of the cavity and the rate at which the frequency changes with time. Apart from capturing the time-variant characteristics, the errors in the magnetic field are accounted in the model to study the effects on synchronization with the Medium Energy Booster (MEB). The control model is useful to study the effects on beam control due to heavy beam loading at high intensities, voltage transients just after injection especially due to time-varying voltages, instability thresholds created by the cavity tuning feedback system, cross coupling between feedback loops with and without direct rf feedback etc. As a special case we have shown that the model agrees with the well known Pedersen model derived for the CERN PS booster. As an application of the model we undertook a detailed study of the cross coupling between the loops by considering all of them at once for varying time, Q and beam intensities. A discussion of the method to identify the coupling is shown. At the end a summary of the identified loop interactions is presented

An improved phase-control system for superconducting low-velocity accelerating structures

International Nuclear Information System (INIS)

Bogaty, J.M.; Clifft, B.E.; Shepard, K.W.; Zinkann, G.P.

1989-01-01

Microphonic fluctuations in the rf eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the rf phase. The tuning system must handle a reactive power proportional to the product of the tuning range and the rf energy content of the resonant cavity. The accelerating field level of many of the SC cavities forming the ATLAS linac has been limited by the rf power capacity of the presently used PIN-diode based fast-tuner. A new system has been developed, utilizing PIN diodes operating immersed in liquid nitrogen, with the diodes controlled by a high-voltage VMOS FET driver. The system has operated at reactive power levels above 20 KVA, a factor of four increase over an earlier design. 7 refs., 2 figs

An improved phase-controlled system for superconducting low-velocity accelerating structures

International Nuclear Information System (INIS)

Bogaty, J.M.; Clifft, B.E.; Shepard, K.W.; Zinkann, G.P.

1989-01-01

Microphonic fluctuations in the RF eigenfrequency of supeconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the tuning range and the RF energy content of the resonant cavity. The accelerating field level of many of the SC cavities forming the ATLAS linac has been limited by the RF power capacity of the presently used PIN-diode based fast-tuner. A new system has been developed, utilizing PIN diodes operating immersed in liquid nitrogen, with the diodes controlled by a high-voltage VMOS FET driver. The system has operated at reactive power levels above 20 KVA, a factor of four increase over an earlier design. 7 refs., 2 figs

An improved phase-control system for superconducting low-velocity accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Bogaty, J.M.; Clifft, B.E.; Shepard, K.W.; Zinkann, G.P.

1989-01-01

Microphonic fluctuations in the rf eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the rf phase. The tuning system must handle a reactive power proportional to the product of the tuning range and the rf energy content of the resonant cavity. The accelerating field level of many of the SC cavities forming the ATLAS linac has been limited by the rf power capacity of the presently used PIN-diode based fast-tuner. A new system has been developed, utilizing PIN diodes operating immersed in liquid nitrogen, with the diodes controlled by a high-voltage VMOS FET driver. The system has operated at reactive power levels above 20 KVA, a factor of four increase over an earlier design. 7 refs., 2 figs.

Rf and space-charge induced emittances in laser-driven rf guns

International Nuclear Information System (INIS)

Kim, Kwang-Je; Chen, Yu-Jiuan.

1988-10-01

Laser-driven rf electron guns are potential sources of high-current, low-emittance, short bunch-length electron beams, which are required for many advanced accelerator applications, such as free-electron lasers and injectors for high-energy machines. In such guns the design of which was pioneered at Los Alamos National Laboratory and which is currently being developed at several other laboratories, a high-power laser beam illuminates a photo-cathode surface placed on an end wall of an rf cavity. The main advantages of this type of gun are that the time structure of the electron beam is controlled by the laser, eliminating the need for bunchers, and that the electric field in rf cavities can be made very strong, so that the effects due to space-charge repulsion can be minimized. In this paper, we present an approximate but simple analysis for the transverse and longitudinal emittances in rf guns that takes into account both the time variation of the rf field and the space-charge effect. The results are compared and found to agree well with those from simulation. 7 refs., 6 figs

Control system for RF-driven negative ion source experimental setup at HUST

Energy Technology Data Exchange (ETDEWEB)

Li, Dong; Wang, Xiaomin, E-mail: xm_wang@hust.edu.cn; Zhao, Peng; Liu, Kaifeng; Zhang, Lige; Yue, Haikun; Chen, Dezhi; Zuo, Chen

2017-03-15

Highlights: • The CompactRIO system is reliable and could achieve high-speed data collection. • The queue and event software structure allows the control code to be flexible. • TCP/IP performs better than shared variable method for mass data transmission. • The method for lowering the peak RF reflected power has been discussed and given. - Abstract: An experimental setup of RF-driven negative ion source has been built at the Huazhong University of Science and Technology (HUST). The control system for this setup is responsible for RF loading, gas feeding, filament heating, filament DC bias, data collection and Langmuir probe triggering during plasma production. To research influences on the plasma ignition of gas puff and RF power loading, the control system should be of flexible operating sequence, high-speed data collection and reliable data transmission. The general control unit (GCU) adopts a CompactRIO system, which performs high-speed data collection for gas pressure and RF power. The host control program adopts a queue and event structure for flexible operation, and TCP/IP method is applied for mass data transmission. The development of the host control program is described in detail. The test results of the shared variable and TCP/IP methods are presented, as well as data showing the advantages of the TCP/IP method. The experiment results with two different sequences of plasma production are given and discussed here.

Digital base-band rf control system for the superconducting Darmstadt electron linear accelerator

Directory of Open Access Journals (Sweden)

M. Konrad

2012-05-01

Full Text Available The accelerating field in superconducting cavities has to be stabilized in amplitude and phase by a radio-frequency (rf control system. Because of their high loaded quality factor superconducting cavities are very susceptible for microphonics. To meet the increased requirements with respect to accuracy, availability, and diagnostics, the previous analog rf control system of the superconducting Darmstadt electron linear accelerator S-DALINAC has been replaced by a digital rf control system. The new hardware consists of two components: An rf module that converts the signal from the cavity down to the base-band and a field-programmable gate array board including a soft CPU that carries out the signal processing steps of the control algorithm. Different algorithms are used for normal-conducting and superconducting cavities. To improve the availability of the control system, techniques for automatic firmware and software deployment have been implemented. Extensive diagnostic features provide the operator with additional information. The architecture of the rf control system as well as the functionality of its components will be presented along with measurements that characterize the performance of the system, yielding, e.g., an amplitude stabilization down to (ΔA/A_{rms}=7×10^{-5} and a phase stabilization of (Δϕ_{rms}=0.8° for superconducting cavities.

RF and microwave microelectronics packaging II

CERN Document Server

Sturdivant, Rick

2017-01-01

Reviews RF, microwave, and microelectronics assembly process, quality control, and failure analysis Bridges the gap between low cost commercial and hi-res RF/Microwave packaging technologies Engages in an in-depth discussion of challenges in packaging and assembly of advanced high-power amplifiers This book presents the latest developments in packaging for high-frequency electronics. It is a companion volume to “RF and Microwave Microelectronics Packaging” (2010) and covers the latest developments in thermal management, electrical/RF/thermal-mechanical designs and simulations, packaging and processing methods, and other RF and microwave packaging topics. Chapters provide detailed coverage of phased arrays, T/R modules, 3D transitions, high thermal conductivity materials, carbon nanotubes and graphene advanced materials, and chip size packaging for RF MEMS. It appeals to practicing engineers in the electronic packaging and high-frequency electronics domain, and to academic researchers interested in underst...

Controlling low-level radioactive waste

International Nuclear Information System (INIS)

1990-01-01

This series of information sheets describes at a popular level the sources of low-level radioactive wastes, their associated hazards, methods of storage, transportation and disposal, and the Canadian regulations that cover low-level wastes

Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting.

Science.gov (United States)

Chaour, Issam; Fakhfakh, Ahmed; Kanoun, Olfa

2017-03-09

For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from -40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions.

Low-Power RF SOI-CMOS Technology for Distributed Sensor Networks

Science.gov (United States)

Dogan, Numan S.

2003-01-01

The objective of this work is to design and develop Low-Power RF SOI-CMOS Technology for Distributed Sensor Networks. We briefly report on the accomplishments in this work. We also list the impact of this work on graduate student research training/involvement.

Design of resonant converter based DC power supply for RF amplifier

International Nuclear Information System (INIS)

Mohan, Kartik; Suthar, Gajendra; Dalicha, Hrushikesh; Agarwal, Rohit; Trivedi, R.G.; Mukherjee, Aparajita

2017-01-01

ITER require 20 MW of RF power to a large variety of plasmas in the Ion Cyclotron frequency range for heating and driving plasma current. Nine RF sources of 2.5MW RF power level each collectively will accomplish the above requirement. Each RF source consists of SSPA, driver and end stage, above which driver and end stage amplifier are tube (Tetrode/Diacrode) based which requires auxiliary DC power source viz. filament, screen grid and control grid DC power supply. DC power supply has some stringent requirements like low stored energy, fast turn off, and low ripple value, etc. This paper will focus only on Zero Current Switching (ZCS) resonant converter based buck converter. This can serve the purpose of control grid and screen grid DC power supply for above requirement. IGBT switch will be used at 20 kHz so as to lower the filter requirement hence low stored energy and ripple in the output voltage. ZCS operation will also assist us in reducing EMI/EMC effect. Design of resonant tank circuit is important aspect of the converter as it forms the backbone of the complete system and basis of selection of other important parameters as well hence mathematical model analysis with the help of circuit equations for various modes have been shown as a part of selection criteria. Peak current through the switch, duty cycle, switching frequency will be the design parameters for selecting resonant tank circuit

Design study of a low-emittance high-repetition rate thermionic rf gun

Directory of Open Access Journals (Sweden)

A. Opanasenko

2017-05-01

Full Text Available We propose a novel gridless continuous-wave radiofrequency (rf thermionic gun capable of generating nC ns electron bunches with a rms normalized slice emittance close to the thermal level of 0.3 mm mrad. In order to gate the electron emission, an externally heated thermionic cathode is installed into a stripline-loop conductor. Two high-voltage pulses propagating towards each other in the stripline-loop overlap in the cathode region and create a quasielectrostatic field gating the electron emission. The repetition rate of pulses is variable and can reach up to one MHz with modern solid-state pulsers. The stripline attached to a rf gun cavity wall has with the wall a common aperture that allows the electrons to be injected into the rf cavity for further acceleration. Thanks to this innovative gridless design, simulations suggest that the bunch emittance is approximately at the thermal level after the bunch injection into the cavity provided that the geometry of the cathode and aperture are properly designed. Specifically, a concave cathode is adopted to imprint an Ƨ-shaped distribution onto the beam transverse phase-space to compensate for an S-shaped beam distribution created by the spherical aberration of the aperture-cavity region. In order to compensate for the energy spread caused by rf fields of the rf gun cavity, a 3rd harmonic cavity is used. A detailed study of the electrodynamics of the stripline and rf gun cavity as well as the beam optics and bunch dynamics are presented.

“Virtual IED sensor” at an rf-biased electrode in low-pressure plasma

Energy Technology Data Exchange (ETDEWEB)

Bogdanova, M. A.; Zyryanov, S. M. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, SINP MSU, Moscow (Russian Federation); Faculty of Physics, Moscow State University, MSU, Moscow (Russian Federation); Lopaev, D. V.; Rakhimov, A. T. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, SINP MSU, Moscow (Russian Federation)

2016-07-15

Energy distribution and the flux of the ions coming on a surface are considered as the key-parameters in anisotropic plasma etching. Since direct ion energy distribution (IED) measurements at the treated surface during plasma processing are often hardly possible, there is an opportunity for virtual ones. This work is devoted to the possibility of such indirect IED and ion flux measurements at an rf-biased electrode in low-pressure rf plasma by using a “virtual IED sensor” which represents “in-situ” IED calculations on the absolute scale in accordance with a plasma sheath model containing a set of measurable external parameters. The “virtual IED sensor” should also involve some external calibration procedure. Applicability and accuracy of the “virtual IED sensor” are validated for a dual-frequency reactive ion etching (RIE) inductively coupled plasma (ICP) reactor with a capacitively coupled rf-biased electrode. The validation is carried out for heavy (Ar) and light (H{sub 2}) gases under different discharge conditions (different ICP powers, rf-bias frequencies, and voltages). An EQP mass-spectrometer and an rf-compensated Langmuir probe (LP) are used to characterize plasma, while an rf-compensated retarded field energy analyzer (RFEA) is applied to measure IED and ion flux at the rf-biased electrode. Besides, the pulsed selfbias method is used as an external calibration procedure for ion flux estimating at the rf-biased electrode. It is shown that pulsed selfbias method allows calibrating the IED absolute scale quite accurately. It is also shown that the “virtual IED sensor” based on the simplest collisionless sheath model allows reproducing well enough the experimental IEDs at the pressures when the sheath thickness s is less than the ion mean free path λ{sub i} (s < λ{sub i}). At higher pressure (when s > λ{sub i}), the difference between calculated and experimental IEDs due to ion collisions in the sheath is observed in the low

RF field control for KAON Factory booster cavities

International Nuclear Information System (INIS)

Craig, S.T.; de Jong, M.S.

1990-11-01

A conceptual design is developed for control of the KAON Factory Booster rf accelerating fields. This design addresses control of cavity: tuning, voltage amplitude, and voltage phase angle. Time-domain simulations were developed to evaluated the proposed controllers. These simulations indicated that adequate tuning performance can be obtained with the combination of adaptive feed-forward and proportional feedback control. Voltage amplitude and voltage phase can be adequately controlled using non-adaptive feedforward and proportional feedback control

Low-level wastewater treatment facility process control operational test report

International Nuclear Information System (INIS)

Bergquist, G.G.

1996-01-01

This test report documents the results obtained while conducting operational testing of a new TK 102 level controller and total outflow integrator added to the NHCON software that controls the Low-Level Wastewater Treatment Facility (LLWTF). The test was performed with WHC-SD-CP-OTP 154, PFP Low-Level Wastewater Treatment Facility Process Control Operational Test. A complete test copy is included in appendix A. The new TK 102 level controller provides a signal, hereafter referred to its cascade mode, to the treatment train flow controller which enables the water treatment process to run for long periods without continuous operator monitoring. The test successfully demonstrated the functionality of the new controller under standard and abnormal conditions expected from the LLWTF operation. In addition, a flow totalizer is now displayed on the LLWTF outlet MICON screen which tallies the process output in gallons. This feature substantially improves the ability to retrieve daily process volumes for maintaining accurate material balances

Low jitter RF distribution system

Science.gov (United States)

Wilcox, Russell; Doolittle, Lawrence; Huang, Gang

2012-09-18

A timing signal distribution system includes an optical frequency stabilized laser signal amplitude modulated at an rf frequency. A transmitter box transmits a first portion of the laser signal and receive a modified optical signal, and outputs a second portion of the laser signal and a portion of the modified optical signal. A first optical fiber carries the first laser signal portion and the modified optical signal, and a second optical fiber carries the second portion of the laser signal and the returned modified optical signal. A receiver box receives the first laser signal portion, shifts the frequency of the first laser signal portion outputs the modified optical signal, and outputs an electrical signal on the basis of the laser signal. A detector at the end of the second optical fiber outputs a signal based on the modified optical signal. An optical delay sensing circuit outputs a data signal based on the detected modified optical signal. An rf phase detect and correct signal circuit outputs a signal corresponding to a phase stabilized rf signal based on the data signal and the frequency received from the receiver box.

RF field control for Kaon Factory booster cavities

International Nuclear Information System (INIS)

Craig, S.T.; de Jong, M.S.

1992-08-01

A conceptual design is developed for control of the Kaon Factory booster rf accelerating fields. This design addresses control of cavity: tuning, voltage amplitude, and voltage phase angle. Time-domain simulations were developed to evaluate the proposed controllers. These simulations indicate that adequate tuning performance can be obtained with the combination of adaptive feed forward and proportional feedback control. Voltage amplitude and voltage phase can be adequately controlled using non-adaptive feed forward and proportional feedback control. (Author) (figs., tabs.)

RF beam control system for the Brookhaven Relativistic Heavy Ion Collider, RHIC

International Nuclear Information System (INIS)

Brennan, J.M.; Campbell, A.; DeLong, J.; Hayes, T.; Onillon, E.; Rose, J.; Vetter, K.

1998-01-01

The Relativistic Heavy Ion Collider, RHIC, is two counter-rotating rings with six interaction points. The RF Beam Control system for each ring will control two 28 MHz cavities for acceleration, and five 197 MHz cavities for preserving the 5 ns bunch length during 10 hour beam stores. Digital technology is used extensively in: Direct Digital Synthesis of rf signals and Digital Signal Processing for, the realization of state-variable feedback loops, real-time calculation of rf frequency, and bunch-by-bunch phase measurement of the 120 bunches. DSP technology enables programming the parameters of the feedback loops in order to obtain closed-loop dynamics that are independent of synchrotron frequency

RF Beam control system for the Brookhaven relativistic heavy ion collider, RHIC

International Nuclear Information System (INIS)

Brennan, J.M.; Campbell, A.; Delong, J.; Hayes, T.; Onillon, E.; Rose, J.; Vetter, K.

1998-01-01

The Relativistic Heavy Ion Collider, RHIC, is two counter-rotating rings with six interaction points. The RF Beam Control system for each ring will control two 28 MHz cavities for acceleration, and five 197 MHz cavities for preserving the 5 ns bunch length during 10 hour beam stores. Digital technology is used extensively in: Direct Digital Synthesis of rf signals and Digital Signal Processing for, the realization of state-variable feedback loops, real-time calculation of rf frequency, and bunch-by-bunch phase measurement of the 120 bunches. DSP technology enables programming the parameters of the feedback loops in order to obtain closed-loop dynamics that are independent of synchrotron frequency

Real-time cavity simulator-based low-level radio-frequency test bench and applications for accelerators

Science.gov (United States)

Qiu, Feng; Michizono, Shinichiro; Miura, Takako; Matsumoto, Toshihiro; Liu, Na; Wibowo, Sigit Basuki

2018-03-01

A Low-level radio-frequency (LLRF) control systems is required to regulate the rf field in the rf cavity used for beam acceleration. As the LLRF system is usually complex, testing of the basic functions or control algorithms of this system in real time and in advance of beam commissioning is strongly recommended. However, the equipment necessary to test the LLRF system, such as superconducting cavities and high-power rf sources, is very expensive; therefore, we have developed a field-programmable gate array (FPGA)-based cavity simulator as a substitute for real rf cavities. Digital models of the cavity and other rf systems are implemented in the FPGA. The main components include cavity baseband models for the fundamental and parasitic modes, a mechanical model of the Lorentz force detuning, and a model of the beam current. Furthermore, in our simulator, the disturbance model used to simulate the power-supply ripples and microphonics is also carefully considered. Based on the presented cavity simulator, we have established an LLRF system test bench that can be applied to different cavity operational conditions. The simulator performance has been verified by comparison with real cavities in KEK accelerators. In this paper, the development and implementation of this cavity simulator is presented first, and the LLRF test bench based on the presented simulator is constructed. The results are then compared with those for KEK accelerators. Finally, several LLRF applications of the cavity simulator are illustrated.

Real-time cavity simulator-based low-level radio-frequency test bench and applications for accelerators

Directory of Open Access Journals (Sweden)

Feng Qiu

2018-03-01

Full Text Available A Low-level radio-frequency (LLRF control systems is required to regulate the rf field in the rf cavity used for beam acceleration. As the LLRF system is usually complex, testing of the basic functions or control algorithms of this system in real time and in advance of beam commissioning is strongly recommended. However, the equipment necessary to test the LLRF system, such as superconducting cavities and high-power rf sources, is very expensive; therefore, we have developed a field-programmable gate array (FPGA-based cavity simulator as a substitute for real rf cavities. Digital models of the cavity and other rf systems are implemented in the FPGA. The main components include cavity baseband models for the fundamental and parasitic modes, a mechanical model of the Lorentz force detuning, and a model of the beam current. Furthermore, in our simulator, the disturbance model used to simulate the power-supply ripples and microphonics is also carefully considered. Based on the presented cavity simulator, we have established an LLRF system test bench that can be applied to different cavity operational conditions. The simulator performance has been verified by comparison with real cavities in KEK accelerators. In this paper, the development and implementation of this cavity simulator is presented first, and the LLRF test bench based on the presented simulator is constructed. The results are then compared with those for KEK accelerators. Finally, several LLRF applications of the cavity simulator are illustrated.

Computer control of rf at SLAC

International Nuclear Information System (INIS)

Schwarz, H.D.

1985-03-01

The Stanford Linear Accelerator is presently upgraded for the SLAC Linear Collider project. The energy is to be increased from approximately 31 GeV to 50 GeV. Two electron beams and one positron beam are to be accelerated with high demands on the quality of the beams. The beam specifications are shown. To meet these specifications, all parameters influencing the beams have to be under tight control and continuous surveillance. This task is accomplished by a new computer system implemented at SLAC which has, among many other functions, control over rf accelerating fields. 13 refs., 8 figs., 2 tabs

Experience with the New Digital RF Control System at the CESR Storage Ring

CERN Document Server

Liepe, Matthias; Dobbins, John; Kaplan, Roger; Strohman, Charles R; Stuhl, Benjamin K

2005-01-01

A new digital control system has been developed, providing great flexibility, high computational power and low latency for a wide range of control and data acquisition applications. This system is now installed in the CESR storage ring and stabilizes the vector sum field of two of the superconducting CESR 500 MHz cavities and the output power from the driving klystron. The installed control system includes in-house developed digital and RF hardware, very fast feedback and feedforward control, a state machine for automatic start-up and trip recovery, cw and pulsed mode operation, fast quench detection, and cavity frequency control. Several months of continuous operation have proven high reliability of the system. The achieved field stability surpasses requirements.

Proceedings, CAS - CERN Accelerator School: RF for Accelerators, Ebeltoft, Denmark, 8 - 17 Jun 2010

CERN Document Server

Bailey, R

2012-01-01

These proceedings present the lectures given at the twenty-fourth specialized course organized by the CERN Accelerator School (CAS). The course was held in Ebeltoft, Denmark, from 8-17 June, 2010 in collaboration with Aarhus University, with the topic 'RF for Accelerators' While this topic has been covered by CAS previously, early in the 1990s and again in 2000, it was recognized that recent advances in the field warranted an updated course. Following introductory courses covering the background physics, the course attempted to cover all aspects of RF for accelerators; from RF power generation and transport, through cavity and coupler design, electronics and low level control, to beam diagnostics and RF gymnastics. The lectures were supplemented with several sessions of exercises, which were completed by discussion sessions on the solutions.

Subjective annoyance caused by indoor low-level and low frequency noise and control method

Institute of Scientific and Technical Information of China (English)

DI Guo-qing; ZHANG Bang-jun; SHANG Qi

2005-01-01

The influence of low-level noise has not been widely noticed. This paper discovered that low-level and low frequency noise(Aweighted equivalent level Leq ＜ 45 dB) causes higher probability of subjective annoyance. The fuzzy mathematic principle was applied to deal with the threshold level of subjective annoyance from noise in this study; there is preferable relationship between the indoor noise and noise annoyance at low frequency noise level. Study indicated at the same centered noise level, the change of annoyance probability is mainly caused by the change of the frequency spectrum characteristic of the indoor noise. Under low noise level environment, without change of the medium-low frequency noise, the slight increase of medium-high frequency noise level with the help of noise sheltering effect can significantly reduce the noise annoyance. This discovery brings a new resolution on how to improve the environmental quality of working or living places. A noise control model is given in this study according to the acoustic analysis.

Wafer-level packaged RF-MEMS switches fabricated in a CMOS fab

NARCIS (Netherlands)

Tilmans, H.A.C.; Ziad, H.; Jansen, Henricus V.; Di Monaco, O.; Jourdain, A.; De Raedt, W.; Rottenberg, X.; De Backer, E.; Decoussernaeker, A.; Baert, K.

2001-01-01

Reports on wafer-level packaged RF-MEMS switches fabricated in a commercial CMOS fab. Switch fabrication is based on a metal surface micromachining process. A novel wafer-level packaging scheme is developed, whereby the switches are housed in on-chip sealed cavities using benzocyclobutene (BCB) as

16 kanałowy układ sterownika silników krokowych przesuwników fazy RF 1,3 GHz zasilających nadprzewodzące wnęki rezonansowe lasera na swobodnych elektronach FLASH

CERN Document Server

Kielar, E; Wierba, W

2011-01-01

The LLRF (Low Level Radio Frequency) System has to control also the RF coupling with the FLASH accelerator cavities. It is done remotely by controlling RF Phase Shifters driven by step motors. It was necessary to design the multichannel stepper motors driver controlled via Ethernet. The driver is built on the basis of low-power CMOS 8-bit AVR RISC microcontroller and the MODBUS protocol. The 16 drivers integrated on a single PCB allow for controlling 16 RF (Radio Frequency) Phase Shifters for the proper adjustment of the waveguides to cavities coupling.

Fabrication and tests and RF control of the superconducting resonators of the Saclay heavy ion LINAC

International Nuclear Information System (INIS)

Cauvin, B.; Coret, M.; Fouan, J.P.; Girard, J.; Girma, J.L.; Leconte, P.; Lussignol, Y.; Moreau, R.; Passerieux, J.P.; Ramstein, G.; Wartski, L.

1987-01-01

Two types of niobium superconducting resonators used in the Saclay linac are discussed. The outer cylinder and RF ports are identical for the two designs, but internal structures are different: full wave helix with three gaps behavior; or half wave with two gaps behavior. All cavities (34 full wave, 16 half) were tested for field and mounted in the machine cryostats. Cavity fabrication and performance are summarized. Vibration tests and Rf control are described. It is argued that helix resonators can overcome problems due to vibration. The very low lock out time percentage measured in an acceleration test with 21 cavities supports this confidence

Beam physics design strategy for a high-current rf linac

Energy Technology Data Exchange (ETDEWEB)

Reiser, M. [Univ. of Maryland, College Park, MD (United States)

1995-10-01

The high average beam power of an rf linac system for transmutation of nuclear waste puts very stringent requirements on beam quality and beam control. Fractional beam losses along the accelerator must be kept at extremely low levels to assure {open_quotes}hands-on{close_quotes} maintenance. Hence, halo formation and large-amplitude tails in the particle distribution due to beam mismatch and equipartitioning effects must be avoided. This implies that the beam should ideally be in near-perfect thermal equilibrium from injection to full energy - in contrast to existing rf linacs in which the transverse temperature, T {sub {perpendicular}}, is higher than the longitudinal temperature, T{sub {parallel}}. The physics and parameter scaling for such a system will be reviewed using the results of recent work on high-intensity bunched beams. A design strategy for a high-current rf linac with equilibrated beam will be proposed.

A high-efficiency, low-noise power solution for a dual-channel GNSS RF receiver

International Nuclear Information System (INIS)

Shi Jian; Mo Taishan; Gan Yebing; Ma Chengyan; Ye Tianchun; Le Jianlian

2012-01-01

A high-efficiency low-noise power solution for a dual-channel GNSS RF receiver is presented. The power solution involves a DC—DC buck converter and a followed low-dropout regulator (LDO). The pulse-width-modulation (PWM) control method is adopted for better noise performance. An improved low-power high-frequency PWM control circuit is proposed, which halves the average quiescent current of the buck converter to 80 μA by periodically shutting down the OTA. The size of the output stage has also been optimized to achieve high efficiency under a light load condition. In addition, a novel soft-start circuit based on a current limiter has been implemented to avoid inrush current. Fabricated with commercial 180-nm CMOS technology, the DC—DC converter achieves a peak efficiency of 93.1% under a 2 MHz working frequency. The whole receiver consumes only 20.2 mA from a 3.3 V power supply and has a noise figure of 2.5 dB. (semiconductor integrated circuits)

Empirical Correlates of Low Scores on MMPI-2/MMPI-2-RF Restructured Clinical Scales in a Sample of University Students

Science.gov (United States)

Avdeyeva, Tatyana V.; Tellegen, Auke; Ben-Porath, Yossef S.

2012-01-01

In the present study, the authors explored the meaning of low scores on the MMPI-2/MMPI-2-RF Restructured Clinical (RC) scales. Using responses of a sample of university students (N = 811), the authors examined whether low (T less than 39), within-normal-limits (T = 39-64), and high (T greater than 65) score levels on the RC scales are…

Low temperature rf sputtering deposition of (Ba, Sr) TiO3 thin film with crystallization enhancement by rf power supplied to the substrate

International Nuclear Information System (INIS)

Yoshimaru, Masaki; Takehiro, Shinobu; Abe, Kazuhide; Onoda, Hiroshi

2005-01-01

The (Ba, Sr) TiO 3 thin film deposited by radio frequency (rf) sputtering requires a high deposition temperature near 500 deg. C to realize a high relative dielectric constant over of 300. For example, the film deposited at 330 deg. C contains an amorphous phase and shows a low relative dielectric constant of less than 100. We found that rf power supplied not only to the (Ba, Sr) TiO 3 sputtering target, but also to the substrate during the initial step of film deposition, enhanced the crystallization of the (Ba, Sr) TiO 3 film drastically and realized a high dielectric constant of the film even at low deposition temperatures near 300 deg. C. The 50-nm-thick film with only a 10 nm initial layer deposited with the substrate rf biasing is crystallized completely and shows a high relative dielectric constant of 380 at the deposition temperature of 330 deg. C. The (Ba, Sr) TiO 3 film deposited at higher temperatures (upwards of 400 deg. C) shows preferred orientation, while the film deposited at 330 deg. C with the 10 nm initial layer shows a preferred orientation on a -oriented ruthenium electrode. The unit cell of (Ba, Sr) TiO 3 (111) plane is similar to that of ruthenium (001) plane. We conclude that the rf power supplied to the substrate causes ion bombardments on the (Ba, Sr) TiO 3 film surface, which assists the quasiepitaxial growth of (Ba, Sr) TiO 3 film on the ruthenium electrode at low temperatures of less than 400 deg. C

Low temperature rf sputtering deposition of (Ba, Sr) TiO3 thin film with crystallization enhancement by rf power supplied to the substrate

Science.gov (United States)

Yoshimaru, Masaki; Takehiro, Shinobu; Abe, Kazuhide; Onoda, Hiroshi

2005-05-01

The (Ba, Sr) TiO3 thin film deposited by radio frequency (rf) sputtering requires a high deposition temperature near 500 °C to realize a high relative dielectric constant over of 300. For example, the film deposited at 330 °C contains an amorphous phase and shows a low relative dielectric constant of less than 100. We found that rf power supplied not only to the (Ba, Sr) TiO3 sputtering target, but also to the substrate during the initial step of film deposition, enhanced the crystallization of the (Ba, Sr) TiO3 film drastically and realized a high dielectric constant of the film even at low deposition temperatures near 300 °C. The 50-nm-thick film with only a 10 nm initial layer deposited with the substrate rf biasing is crystallized completely and shows a high relative dielectric constant of 380 at the deposition temperature of 330 °C. The (Ba, Sr) TiO3 film deposited at higher temperatures (upwards of 400 °C) shows preferred orientation, while the film deposited at 330 °C with the 10 nm initial layer shows a preferred orientation on a -oriented ruthenium electrode. The unit cell of (Ba, Sr) TiO3 (111) plane is similar to that of ruthenium (001) plane. We conclude that the rf power supplied to the substrate causes ion bombardments on the (Ba, Sr) TiO3 film surface, which assists the quasiepitaxial growth of (Ba, Sr) TiO3 film on the ruthenium electrode at low temperatures of less than 400 °C.

Development of a Solid State RF Amplifier in the kW Regime for Application with Low Beta Superconducting RF Cavities

CERN Document Server

Piel, Christian; Borisov, A; Kolesov, Sergej; Piel, Helmut

2005-01-01

Projects based on the use of low beta superconducting cavities for ions are under operation or development at several labs worldwide. Often these cavities are individually driven by RF power sources in the kW regime. For an ongoing project a modular 2 kW, 176 MHz unconditionally stable RF amplifier for CW and pulsed operation was designed, built, and tested. Extended thermal analysis was used to develop a water cooling system in order to optimize the performance of the power transistors and other thermally loaded components. The paper will outline the design concept of the amplifier and present first results on the test of the amplifier with a superconducting cavity.

Design of RF system for CYCIAE-230 superconducting cyclotron

Energy Technology Data Exchange (ETDEWEB)

Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Ji, Bin; Fu, Xiaoliang; Cao, Xuelong; Zhao, Zhenlu; Zhang, Tinajue

2017-05-11

The CYCIAE230 is a low-current, compact superconducting cyclotron designed for proton therapy. The Radio Frequency system consists of four RF cavities and applies second harmonic to accelerate beams. The driving power for the cavity system is estimated to be approximately 150 kW. The LLRF controller is a self-made device developed and tested at low power using a small-scale cavity model. In this paper, the resonator systems of an S.C. cyclotron in history are reviewed. Contrary to those RF systems, the cavities of the CYCIAE230 cyclotron connect two opposite dees. Two high-power RF windows are included in the system. Each window carries approximately 75 kW RF power from the driver to the cavities. Thus, the RF system for the CY-CIAE230 cyclotron is operated in driven push–pull mode. The two-way amplifier-coupler-cavity systems are operated with approximately the same amount of RF power but 180° out of phase compared with each other. The design, as well as the technical advantage and limitations of this operating mode, of the CYCIAE230 cyclotron RF system is analyzed.

Design of RF system for CYCIAE-230 superconducting cyclotron

Science.gov (United States)

Yin, Zhiguo; Ji, Bin; Fu, Xiaoliang; Cao, Xuelong; Zhao, Zhenlu; Zhang, Tinajue

2017-05-01

The CYCIAE230 is a low-current, compact superconducting cyclotron designed for proton therapy. The Radio Frequency system consists of four RF cavities and applies second harmonic to accelerate beams. The driving power for the cavity system is estimated to be approximately 150 kW. The LLRF controller is a self-made device developed and tested at low power using a small-scale cavity model. In this paper, the resonator systems of an S.C. cyclotron in history are reviewed. Contrary to those RF systems, the cavities of the CYCIAE230 cyclotron connect two opposite dees. Two high-power RF windows are included in the system. Each window carries approximately 75 kW RF power from the driver to the cavities. Thus, the RF system for the CY-CIAE230 cyclotron is operated in driven push-pull mode. The two-way amplifier-coupler-cavity systems are operated with approximately the same amount of RF power but 180° out of phase compared with each other. The design, as well as the technical advantage and limitations of this operating mode, of the CYCIAE230 cyclotron RF system is analyzed.

New Control Structure of the 200 MHz RF System in the CERN PS

CERN Document Server

Damerau, H; CERN. Geneva. AB Department

2008-01-01

The 200 MHz RF system is an essential tool for the preparation of high-intensity beams in the CERN PS. Presently, six RF cavities are operated to control the longitudinal bunch emittance and rebunching of the beam before the transfer to the SPS. Cavities are selected for the various processes with a dedicated hardware matrix, switching the individual timing pulses and voltage programs per cavity. However, the electronics used for the matrix hardware is obsolete and its reliability cannot be guaranteed due to a lack of spare modules and components. Instead of replacing the old hardware matrix by modern hardware, this note describes a new control structure for the 200MHz RF system so that no dedicated hardware will be required anymore. The implementation of the new control structure is based on two main concepts. Firstly, linked timing trees per blow-up or rebunching are used to handle all related timing and to store one row of the matrix. Secondly, as a reflection of the RF signal generation for the 200 MHz sy...

Tilt optimized flip uniformity (TOFU) RF pulse for uniform image contrast at low specific absorption rate levels in combination with a surface breast coil at 7 Tesla.

Science.gov (United States)

van Kalleveen, Irene M L; Boer, Vincent O; Luijten, Peter R; Klomp, Dennis W J

2015-08-01

Going to ultrahigh field MRI (e.g., 7 Tesla [T]), the nonuniformity of the B1+ field and the increased radiofrequency (RF) power deposition become challenging. While surface coils improve the power efficiency in B1+, its field remains nonuniform. In this work, an RF pulse was designed that uses the slab selection to compensate the inhomogeneous B1+ field of a surface coil without a substantial increase in specific absorption rate (SAR). A breast surface coil was used with a decaying B1+ field in the anterior-posterior direction of the human breast. Slab selective RF pulses were designed and compared with adiabatic and spokes RF pulses. Proof of principle was demonstrated with FFE and B1+ maps of the human breast. In vivo measurements obtained with the breast surface coil show that the tilt optimized flip uniformity (TOFU) RF pulses can improve the flip angle homogeneity by 31%, while the SAR will be lower compared with BIR-4 and spokes RF pulses. By applying TOFU RF pulses to the breast surface coil, we are able to compensate the inhomogeneous B1+ field, while keeping the SAR low. Therefore stronger T1 -weighting in FFE sequences can be obtained, while pulse durations can remain short, as shown in the human breast at 7T. © 2014 Wiley Periodicals, Inc.

Low Actuating Voltage Spring-Free RF MEMS SPDT Switch

Directory of Open Access Journals (Sweden)

Deepak Bansal

2016-01-01

Full Text Available RF MEMS devices are known to be superior to their solid state counterparts in terms of power consumption and electromagnetic response. Major limitations of MEMS devices are their low switching speed, high actuation voltage, larger size, and reliability. In the present paper, a see-saw single pole double throw (SPDT RF MEMS switch based on anchor-free mechanism is proposed which eliminates the above-mentioned disadvantages. The proposed switch has a switching time of 394 nsec with actuation voltage of 5 V. Size of the SPDT switch is reduced by utilizing a single series capacitive switch compared to conventional switches with capacitive and series combinations. Reliability of the switch is improved by adding floating metal and reducing stiction between the actuating bridge and transmission line. Insertion loss and isolation are better than −0.6 dB and −20 dB, respectively, for 1 GHz to 20 GHz applications.

SNS Superconducting RF cavity modeling-iterative learning control

CERN Document Server

Kwon, S I; Wang, Y M

2002-01-01

The Spallation Neutron Source (SNS) Superconducting RF (SRF) linear accelerator is operated with a pulsed beam. For the SRF control system to track the repetitive electromagnetic field reference trajectory, both feedback and feedforward controllers have been proposed. The feedback controller is utilized to guarantee the closed loop system stability and the feedforward controller is used to improve the tracking performance for the repetitive reference trajectory and to suppress repetitive disturbances. As the iteration number increases, the feedforward controller decreases the tracking error. Numerical simulations demonstrate that inclusion of the feedforward controller significantly improves the control system performance over its performance with just the feedback controller.

SNS Superconducting RF cavity modeling-iterative learning control

International Nuclear Information System (INIS)

Kwon, S.-I.; Regan, Amy; Wang, Y.-M.

2002-01-01

The Spallation Neutron Source (SNS) Superconducting RF (SRF) linear accelerator is operated with a pulsed beam. For the SRF control system to track the repetitive electromagnetic field reference trajectory, both feedback and feedforward controllers have been proposed. The feedback controller is utilized to guarantee the closed loop system stability and the feedforward controller is used to improve the tracking performance for the repetitive reference trajectory and to suppress repetitive disturbances. As the iteration number increases, the feedforward controller decreases the tracking error. Numerical simulations demonstrate that inclusion of the feedforward controller significantly improves the control system performance over its performance with just the feedback controller

Gas and plasma dynamics of RF discharge jet of low pressure in a vacuum chamber with flat electrodes and inside tube, influence of RF discharge on the steel surface parameters

Science.gov (United States)

Khristoliubova, V. I.; Kashapov, N. F.; Shaekhov, M. F.

2016-06-01

Researches results of the characteristics of the RF discharge jet of low pressure and the discharge influence on the surface modification of high speed and structural steels are introduced in the article. Gas dynamics, power and energy parameters of the RF low pressure discharge flow in the discharge chamber and the electrode gap are studied in the presence of the materials. Plasma flow rate, discharge power, the concentration of electrons, the density of RF power, the ion current density, and the energy of the ions bombarding the surface materials are considered for the definition of basic properties crucial for the process of surface modification of materials as they were put in the plasma jet. The influence of the workpiece and effect of products complex configuration on the RF discharge jet of low pressure is defined. The correlation of the input parameters of the plasma unit on the characteristics of the discharge is established.

APT LLRF control system functionality and architecture

International Nuclear Information System (INIS)

Regan, A.H.; Rohlev, A.S.; Ziomek, C.D.

1996-01-01

The low-level RF (LLRF) control system for the Accelerator Production of Tritium (APT) will perform various functions. Foremost is the feedback control of the accelerating fields within the cavity in order to maintain field stability within ± 1% amplitude and 1 degree phase. The feedback control system requires a phase-stable RF reference subsystem signal to correctly phase each cavity. Also, instead of a single klystron RF source for individual accelerating cavities, multiple klystrons will drive a string of resonantly coupled cavities, based on input from a single LLRF feedback control system. To achieve maximum source efficiency, we will be employing single fast feedback controls around individual klystrons such that the gain and phase characteristics of each will be 'identical'. In addition, the resonance condition of the cavities is monitored and maintained. To quickly respond to RF shutdowns, and hence rapid accelerating cavity cool-down, due to RF fault conditions, drive frequency agility in the main feedback control subsystem will also be incorporated. Top level block diagrams will be presented and described as they will first be developed and demonstrated on the Low Energy Demonstrator Accelerator (LEDA). (author)

Racetrack microtron rf system

International Nuclear Information System (INIS)

Tallerico, P.J.; Keffeler, D.R.

1985-01-01

The rf system for the National Bureau of Standards (NBS)/Los Alamos cw racetrack microtron is described. The low-power portion consists of five 75-W amplifers that drive two input ports in each of two chopper deflection cavities and one port in the prebuncher cavity. A single 500-kW klystron drives four separate 2380-MHz cavity sections: the two main accelerator sections, a capture section, and a preaccelerator section. The phases and amplitudes in all cavities are controlled by electronic or electromechanical controls. The 1-MW klystron power supply and crowbar system were purchased as a unit; several modifications are described that improve power-supply performance. The entire rf system has been tested and shipped to the NBS, and the chopper-buncher system has been operated with beam at the NBS. 5 refs., 2 figs

Novel Low Loss Wide-Band Multi-Port Integrated Circuit Technology for RF/Microwave Applications

Science.gov (United States)

Simons, Rainee N.; Goverdhanam, Kavita; Katehi, Linda P. B.; Burke, Thomas P. (Technical Monitor)

2001-01-01

In this paper, novel low loss, wide-band coplanar stripline technology for radio frequency (RF)/microwave integrated circuits is demonstrated on high resistivity silicon wafer. In particular, the fabrication process for the deposition of spin-on-glass (SOG) as a dielectric layer, the etching of microvias for the vertical interconnects, the design methodology for the multiport circuits and their measured/simulated characteristics are graphically illustrated. The study shows that circuits with very low loss, large bandwidth, and compact size are feasible using this technology. This multilayer planar technology has potential to significantly enhance RF/microwave IC performance when combined with semi-conductor devices and microelectromechanical systems (MEMS).

LIF-measurements on a low prassure RF-driven InBr lamp

NARCIS (Netherlands)

Mulders, H.C.J.; Stoffels, W.W.

2007-01-01

A laser induced fluorescence (LIF) experiment has been carried out on a low pressure, capacitively coupled RF driven. Ar discharge with InBr as an additive. The intention is to find the density of the different states of InBr and the metastable states in particular. We measured the density profile

Simulations of the BNL/SLAC/UCLA 1.6 cell emittance compensated photocathode RF gun low energy beam line

International Nuclear Information System (INIS)

Palmer, D.T.; Miller, R.H.; Winick, H.

1995-01-01

A dedicated low energy (2 to 10 MeV) experimental beam line is now under construction at Brookhaven National Laboratories Accelerator Test Facility (BNL/ATF) for photocathode RF gun testing and photoemission experiments. The design of the experimental line, using the 1.6 cell photocathode RF gun developed by the BNL/SLAC/UCLA RF gun collaboration is presented. Detailed beam dynamics simulations were performed for the 1.6 cell RF gun injector using a solenoidal emittance compensation technique. An experimental program for testing the 1.6 cell RF gun is presented. This program includes beam loading caused by dark current, higher order mode field measurements, integrated and slice emittance measurements using a pepper-pot and RF kicker cavity

An ultra-low-power RF transceiver for WBANs in medical applications

Energy Technology Data Exchange (ETDEWEB)

Zhang Qi; Wu Nanjian [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Kuang Xiaofei, E-mail: nanjian@semi.ac.cn [College of Electronic Information, Hangzhou Dianzi University, Hangzhou 310018 (China)

2011-06-15

A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks (WBANs) in medical applications is presented. The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs. The transceiver consists of a main receiver (RX) with an ultra-low-power free-running ring oscillator and a high speed main transmitter (TX) with fast lock-in PLL. A passive wake-up receiver (WuRx) for wake-up function with a high power conversion efficiency (PCE) CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power. The chip is implemented in a 0.18 {mu}m CMOS process. Its core area is 1.6 mm{sup 2}. The main RX achieves a sensitivity of -55 dBm at a 100 kbps OOK data rate while consuming just 210 {mu}A current from the 1 V power supply. The main TX achieves +3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is -15 dBm and the PCE is more than 25%. (semiconductor integrated circuits)

An ultra-low-power RF transceiver for WBANs in medical applications

International Nuclear Information System (INIS)

Zhang Qi; Wu Nanjian; Kuang Xiaofei

2011-01-01

A 2.4 GHz ultra-low-power RF transceiver with a 900 MHz auxiliary wake-up link for wireless body area networks (WBANs) in medical applications is presented. The RF transceiver with an asymmetric architecture is proposed to achieve high energy efficiency according to the asymmetric communication in WBANs. The transceiver consists of a main receiver (RX) with an ultra-low-power free-running ring oscillator and a high speed main transmitter (TX) with fast lock-in PLL. A passive wake-up receiver (WuRx) for wake-up function with a high power conversion efficiency (PCE) CMOS rectifier is designed to offer the sensor node the capability of work-on-demand with zero standby power. The chip is implemented in a 0.18 μm CMOS process. Its core area is 1.6 mm 2 . The main RX achieves a sensitivity of -55 dBm at a 100 kbps OOK data rate while consuming just 210 μA current from the 1 V power supply. The main TX achieves +3 dBm output power with a 4 Mbps/500 kbps/200 kbps data rate for OOK/4 FSK/2 FSK modulation and dissipates 3.25 mA/6.5 mA/6.5 mA current from a 1.8 V power supply. The minimum detectable RF input energy for the wake-up RX is -15 dBm and the PCE is more than 25%. (semiconductor integrated circuits)

Pulsed rf excited spectrometer having improved pulse width control

International Nuclear Information System (INIS)

1977-01-01

RF excitation for a spectrometer is obtained by pulse width modulating an RF carrier to produce the desired broadband RF exciting spectrum. The RF excitation includes a train of composite RF pulses, each composite pulse having a primary pulse portion of a first RF phase and a second pulse portion of a second RF phase opposite that of the first. In this manner, the finite rise and fall times of the primary pulse portion are compensated for by the corresponding rise and fall times of the secondary pulse portion. The primary pulse portion is lengthened by an amount equal to the secondary pulse portion so that the secondary pulse portion cancels the added primary pulse portion. In a spectrometer, the compensating second pulse component removes certain undesired side bands of the RF excitation caused by the finite rise and fall times of the applied RF pulses. The compensating second pulse component removes certain undesired side bands associated with each of the resonant lines of the excited resonance spectrum of the sample under analysis, particularly for wide band RF excitation

A differential low-voltage high gain current-mode integrated RF receiver front-end

Energy Technology Data Exchange (ETDEWEB)

Wang Chunhua; Ma Minglin; Sun Jingru; Du Sichun; Guo Xiaorong; He Haizhen, E-mail: wch1227164@sina.com [School of Information Science and Technology, Hunan University, Changsha 410082 (China)

2011-02-15

A differential low-voltage high gain current-mode integrated RF front end for an 802.11b WLAN is proposed. It contains a differential transconductance low noise amplifier (G{sub m}-LNA) and a differential current-mode down converted mixer. The single terminal of the G{sub m}-LNA contains just one MOS transistor, two capacitors and two inductors. The gate-source shunt capacitors, C{sub x1} and C{sub x2}, can not only reduce the effects of gate-source C{sub gs} on resonance frequency and input-matching impedance, but they also enable the gate inductance L{sub g1,2} to be selected at a very small value. The current-mode mixer is composed of four switched current mirrors. Adjusting the ratio of the drain channel sizes of the switched current mirrors can increase the gain of the mixer and accordingly increase the gain of RF receiver front-end. The RF front-end operates under 1 V supply voltage. The receiver RFIC was fabricated using a chartered 0.18 {mu}m CMOS process. The integrated RF receiver front-end has a measured power conversion gain of 17.48 dB and an input referred third-order intercept point (IIP3) of -7.02 dBm. The total noise figure is 4.5 dB and the power is only 14 mW by post-simulations. (semiconductor integrated circuits)

Phase loop bandwidth measurements on the advanced photon source 352 MHz rf systems

International Nuclear Information System (INIS)

Horan, D.; Nassiri, A.; Schwartz, C.

1997-01-01

Phase loop bandwidth tests were performed on the Advanced Photon Source storage ring 352-MHz rf systems. These measurements were made using the HP3563A Control Systems Analyzer, with the rf systems running at 30 kilowatts into each of the storage ring cavities, without stored beam. An electronic phase shifter was used to inject approximately 14 degrees of stimulated phase shift into the low-level rf system, which produced measureable response voltage in the feedback loops without upsetting normal rf system operation. With the PID (proportional-integral-differential) amplifier settings at the values used during accelerator operation, the measurement data revealed that the 3-dB response for the cavity sum and klystron power-phase loops is approximately 7 kHz and 45 kHz, respectively, with the cavities the primary bandwidth-limiting factor in the cavity-sum loop. Data were taken at various PID settings until the loops became unstable. Crosstalk between the two phase loops was measured

Modulator considerations for the SNS RF system

International Nuclear Information System (INIS)

Tallerico, P.J.; Reass, W.A.

1998-01-01

The Spallation Neutron Source (SNS) is an intense neutron source for neutron scattering experiments. The project is in the research stage, with construction funding beginning next year. The SNS is comprised of an ion source, a 1,000 MeV, H - linear accelerator, an accumulator ring, a neutron producing target, and experimental area to utilize the scattering of the neutrons. The linear accelerator is RF driven, and the peak beam current is 27 mA and the beam duty factor is 5.84%. The peak RF power required is 104 MW, and the H - beam pulse length is 0.97 ms at a 60 Hz repetition rate. The RF pulses must be about 0.1 ms longer than the beam pulses, due to the Q of the accelerating cavities, and the time required to establish control of the cavity fields. The modulators for the klystrons in this accelerator are discussed in this paper. The SNS is designed to be expandable, so the beam power can be doubled or even quadrupled in the future. One of the double-power options is to double the beam pulse length and duty factor. The authors are specifying the klystrons to operate in this twice-duty-factor mode, and the modulator also should be expandable to 2 ms pulses at 60 Hz. Due to the long pulse length and low RF frequency of 805 MHz, the klystron power is specified at 2.5 MW peak, and the RF system will have 56 klystrons at 805 MHz, and three 1.25 MW peak power klystrons at 402.5 MHz for the low energy portion of the accelerator. The low frequency modulators are conventional floating-deck modulation anode control systems

Operation of the APS rf gun

International Nuclear Information System (INIS)

Lewellen, J. W.

1998-01-01

The Advanced Photon Source (APS) has a thermionic-cathode rf gun system capable of providing beam to the APS linac. The gun system consists of a 1.6-cell thermionic-cathode rf gun, a fast kicker for beam current control, and an alpha magnet for bunch compression and injection into the APS linac line. This system is intended for use both as an injector for positron creation, and as a first beam source for the Low-Energy Undulator Test Line (LEUTL) project [1]. The first measured performance characteristics of the gun are presented.

Effects of RF low levels electromagnetic fields on Paramecium primaurelia

International Nuclear Information System (INIS)

Tofani, S.; Testa, B.; Agnesod, G.; Tartagbino, L.; Bonazzola, G.C.

1988-01-01

In the last years many studies have been performed to examine biological effects of prolonged exposure at electric field low levels. This great interest is linked to a specific interaction possibility, also related to the exposure length, between electromagnetic fields and biological systems without remarkable enhancement of organism's temperature. Hence the need to investigate in vitro the possible cellular regulation mechanisms involved in these interactions, varying physical exposure parameters

RF Phase Scan for Beam Energy Measurement of KOMAC DTL

Energy Technology Data Exchange (ETDEWEB)

Kim, Hansung; Kwon, Hyeokjung; Kim, Seonggu; Lee, Seokgeun; Cho, Yongsub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2016-10-15

The energy gain through the drift tube linac is a function of the synchronous phase, therefore, the output beam energy from DTL can be affected by the RF phase setting in low-level RF (LLRF) system. The DTL at Korea Multi-purpose Accelerator Complex (KOMAC) consists of 11 tanks and the RF phase setting in each tank should be matched for synchronous acceleration in successive tanks. That means a proper setting of RF phase in each DTL tank is critical for efficient and loss-free operation. The matching RF phase can be determined based on the output energy measurement from the DTL tank. The beam energy can be measured by several methods. For example, we can use a bending magnet to determine the beam energy because the higher momentum of beam means the less deflection angle in the fixed magnetic field. By measuring the range of proton beam through a material with known stopping power also can be utilized to determine the beam energy. We used a well-known time-of-flight method to determine the output beam energy from the DTL tank by measuring beam phase with a beam position monitor (BPM). Based on the energy measurement results, proper RF operating point could be obtained. We performed a RF phase scan to determine the output beam energy from KOMAC DTL by using a time-of-flight method and to set RF operating point precisely. The measured beam energy was compared with a beam dynamics simulation and showed a good agreement. RF phase setting is critical issue for the efficient operation of the proton accelerator, we have a plan to implement and integrate the RF phase measurement system into an accelerator control system for future need.

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

OpenAIRE

Zhuhao Gong; Yulong Zhang; Xin Guo; Zewen Liu

2018-01-01

A radio-frequency micro-electro-mechanical system (RF MEMS) wafer-level packaging (WLP) method using pre-patterned benzo-cyclo-butene (BCB) polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to gener...

Short range RF communication for jet engine control

Science.gov (United States)

Sexton, Daniel White (Inventor); Hershey, John Erik (Inventor)

2007-01-01

A method transmitting a message over at least one of a plurality of radio frequency (RF) channels of an RF communications network is provided. The method comprises the steps of detecting a presence of jamming pulses in the at least one of the plurality of RF channels. The characteristics of the jamming pulses in the at least one of the plurality of RF channels is determined wherein the determined characteristics define at least interstices between the jamming pulses. The message is transmitted over the at least one of the plurality of RF channels wherein the message is transmitted within the interstices of the jamming pulse determined from the step of determining characteristics of the jamming pulses.

APT LLRF control system functionality and architecture

International Nuclear Information System (INIS)

Regan, A.H.; Rohlev, A.S.; Ziomek, C.D.

1996-01-01

1% amplitude and l degree phase. The feedback control system requires a phase-stable RF reference subsystem signal to correctly phase each cavity. Also, instead of a single klystron RF source for individual accelerating cavities, multiple klystrons will drive a string of resonantly coupled cavities, based on input from a single LLRF feedback control system. To achieve maximum source efficiency, we will be employing single fast feedback controls around individual klystrons such that the gain and phase characteristics of each will be ''identical.'' In addition, resonance control is performed by providing a proper drive signal to structure cooling water valves in order to keep the cavity resonant during operation. To quickly respond to RF shutdowns, and hence rapid accelerating cavity cool- down, due to RF fault conditions, drive frequency agility in the main feedback control subsystem will also be incorporated. Top level block diagrams will be presented and described for each of the aforementioned subsystems as they will first be developed and demonstrated on the Low Energy Demonstrator Accelerator (LEDA) The low-level RF (LLRF) control system for the Accelerator Production of Tritium (APT) will perform various functions. Foremost is the feedback control of the accelerating fields within the cavity in order to maintain field stability within

Hearthfire design base for the high current low velocity rf linac

International Nuclear Information System (INIS)

Burke, R.J.; Khoe, T.K.; Kustom, R.L.; Martin, R.L.; Moretti, A.

1977-01-01

The particle beam parameters needed for inertial fusion can be achieved with conventional accelerator technology if heavy ion machines attain the level of performance of the most intense high energy proton machines. Many of the problems posed by this goal pertain to the low energy portions of the accelerator system. In particular, the implied particle current in the rf linac is 10 3 --10 4 times the values achieved with existing heavy ion machines. Much of this discrepancy is simply attributable to the great differences between the design considerations relevant to accelerators for fusion and those which have determined the performance of the existing machines. The basic concept chosen at Argonne National Laboratory is cavities containing single drift tubes mounted on lambda/4 supports. Such structures pose the least problem for the beam transport system, and one cavity is placed between adjacent quadrupole magnets. The average voltage gain of the first cells of the low velocity section is moderate; and, although probably acceptable and improved by the end of the 10 MV section, the low initial gain adds to the motivation provided by the transport problem to increase the preinjector voltage substantially above 750 kV

rf quadrupole linac: a new low-energy accelerator

International Nuclear Information System (INIS)

Hamm, R.W.; Crandall, K.R.; Fuller, C.W.

1980-01-01

A new concept in low-energy particle accelerators, the radio-frequency quadrupole (RFQ) linac, is currently being developed at the Los Alamos National Scientific Laboratory. In this new linear accelerating structure both the focusing and accelerating forces are produced by the rf fields. It can accept a high-current, low-velocity dc ion beam and bunch it with a high capture efficiency. The performance of this structure as a low-energy linear accelerator has been verified with the successful construction of a proton RFQ linac. This test structure has accelerated 38 mA of protons from 100 keV to 640 keV in 1.1 meters with a capture efficiency greater than 80%. In this paper a general description of the RFQ linac and an outline of the basic RFQ linac design procedure are presented in addition to the experimental results from the test accelerator. Finally, several applications of this new accelerator are discussed

The amplitude and phase control of the ALS Storage Ring RF System

International Nuclear Information System (INIS)

Lo, C.C.; Taylor, B.; Baptiste, K.

1995-03-01

A 500MHz, 300KW Klystron power amplifier provides RF power to the ALS Storage Ring. In order to accommodate the amplitude and phase changes during beam stacking and decay, which demand continuously varying power levels from the Klystron, four loops are used to keep the system operating properly, with two of those loops dedicated to keeping the two cavity tuners on tune. Description of the control loops and their performance data will be given. Using the modulation anode of the Klystron in the amplitude loop will be discussed

New Control Structure of the 10 MHz RF System in the CERN PS

CERN Document Server

Damerau, H

2013-01-01

The 10MHz cavities comprise the main RF system in the CERN PS and the only one that allows acceleration. In total 11 tunable cavities (10 operational and a hot spare, grouped into 3+1 tuning groups and up to presently 6 voltage program groups) are distributed all around the circumference of the PS ring. Next to the RF drive signal each of the cavities is controlled by a voltage program and timing pulses to open and close the relays to short-circuit the cavity gaps. These control signals are presently generated by a dedicated hardware matrix. It translates voltage functions and relay timing pulses per cavity group into functions and timings per cavity. However, due to its central position in the RF beam control system, the dedicated hardware matrix can cause significant downtime in case of a major hardware failure. Instead of upgrading the existing obsolete hardware, this note suggests a replacement by standard controls hardware and dedicated application software. Thanks to advanced software concepts like “M...

A low-frequency high-voltage rf-barrier-bunching system for high-intensity neutron source compressor rings

International Nuclear Information System (INIS)

Hardek, T.W.; Ziomek, C.; Rees, D.

1995-01-01

A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an rf-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in this case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured retrode amplifiers incorporating local rf feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with rf feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated

Cu Pillar Low Temperature Bonding and Interconnection Technology of for 3D RF Microsystem

Science.gov (United States)

Shi, G. X.; Qian, K. Q.; Huang, M.; Yu, Y. W.; Zhu, J.

2018-03-01

In this paper 3D interconnects technologies used Cu pillars are discussed with respect to RF microsystem. While 2.5D Si interposer and 3D packaging seem to rely to cu pillars for the coming years, RF microsystem used the heterogeneous chip such as GaAs integration with Si interposers should be at low temperature. The pillars were constituted by Cu (2 micron) -Ni (2 micron) -Cu (3 micron) -Sn (1 micron) multilayer metal and total height is 8 micron on the front-side of the wafer by using electroplating. The wafer backside Cu pillar is obtained by temporary bonding, thinning and silicon surface etching. The RF interposers are stacked by Cu-Sn eutectic bonding at 260 °C. Analyzed the reliability of different pillar bonding structure.

High titers of both rheumatoid factor and anti-CCP antibodies at baseline in patients with rheumatoid arthritis are associated with increased circulating baseline TNF level, low drug levels, and reduced clinical responses: a post hoc analysis of the RISING study.

Science.gov (United States)

Takeuchi, Tsutomu; Miyasaka, Nobuyuki; Inui, Takashi; Yano, Toshiro; Yoshinari, Toru; Abe, Tohru; Koike, Takao

2017-09-02

Although both rheumatoid factor (RF) and anticyclic citrullinated peptide antibodies (anti-CCP) are useful for diagnosing rheumatoid arthritis (RA), the impact of these autoantibodies on the efficacy of tumor necrosis factor (TNF) inhibitors has been controversial. The aim of this post hoc analysis of a randomized double-blind study (the RISING study) was to investigate the influences of RF and anti-CCP on the clinical response to infliximab in patients with RA. Methotrexate-refractory patients with RA received 3 mg/kg of infliximab from weeks 0 to 6 and then 3, 6, or 10 mg/kg every 8 weeks from weeks 14 to 46. In this post hoc analysis, patients were stratified into three classes on the basis of baseline RF/anti-CCP titers: "low/low-C" (RF < 55 IU/ml, anti-CCP < 42 U/ml), "high/high-C" (RF ≥ 160 IU/ml, anti-CCP ≥ 100 U/ml), and "middle-C" (neither low/low-C nor high/high-C). Baseline plasma TNF level, serum infliximab level, and disease activity were compared between the three classes. Baseline RF and anti-CCP titers showed significant correlations with baseline TNF and infliximab levels in weeks 2-14. Comparison of the three classes showed that baseline TNF level was lowest in the low/low-C group and highest in the high/high-C group (median 0.73 versus 1.15 pg/ml), that infliximab levels at week 14 were highest in the low/low-C group and lowest in the high/high-C group (median 1.0 versus 0.1 μg/ml), and that Disease Activity Score in 28 joints based on C-reactive protein at week 14 was lowest in the low/low-C group and highest in the high/high-C group (median 3.17 versus 3.82). A similar correlation was observed at week 54 in the 3 mg/kg dosing group, but not in the 6 or 10 mg/kg group. Significant decreases in both RF and anti-CCP were observed during infliximab treatment. RF/anti-CCP titers correlated with TNF level. This might explain the association of RF/anti-CCP with infliximab level and clinical response in patients with RA

Liquid Metal Droplet and Micro Corrugated Diaphragm RF-MEMS for reconfigurable RF filters

Science.gov (United States)

Irshad, Wasim

Widely Tunable RF Filters that are small, cost-effective and offer ultra low power consumption are extremely desirable. Indeed, such filters would allow drastic simplification of RF front-ends in countless applications from cell phones to satellites in space by replacing switched-array of static acoustic filters and YIG filters respectively. Switched array of acoustic filters are de facto means of channel selection in mobile applications such as cell phones. SAW and BAW filters satisfy most criteria needed by mobile applications such as low cost, size and power consumption. However, the trade-off is a significant loss of 3-4 dB in modern cell phone RF front-end. This leads to need for power-hungry amplifiers and short battery life. It is a necessary trade-off since there are no better alternatives. These devices are in mm scale and consume mW. YIG filters dominate applications where size or power is not a constraint but demand excellent RF performance like low loss and high tuning ratio. These devices are measured in inches and require several watts to operate. Clearly, a tunable RF filter technology that would combine the cost, size and power consumption benefits of acoustic filters with excellent RF performance of YIG filters would be extremely desirable and imminently useful. The objective of this dissertation is to develop such a technology based upon RF-MEMS Evanescent-mode cavity filter. Two highly novel RF-MEMS devices have been developed over the course of this PhD to address the unique MEMS needs of this technology. The first part of the dissertation is dedicated to introducing the fundamental concepts of tunable cavity resonators and filters. This includes the physics behind it, key performance metrics and what they depend on and requirements of the MEMS tuners. Initial gap control and MEMS attachment method are identified as potential hurdles towards achieving very high RF performance. Simple and elegant solutions to both these issues are discussed in

RF MEMS

Indian Academy of Sciences (India)

At the bare die level the insertion loss, return loss and the isolation ... ing and packaging of a silicon on glass based RF MEMS switch fabricated using DRIE. ..... follows the power law based on the asperity deformation model given by Pattona & ... Surface mount style RF packages (SMX series 580465) from Startedge Corp.

Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum

Science.gov (United States)

Brady, David; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Frank J.

2014-01-01

This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not

Performance of RF power and phase control on JT-60 LHRF heating system

International Nuclear Information System (INIS)

Fujii, T.; Ikeda, Y.; Imai, T.; Honda, M.; Kiyono, K.; Maebara, S.; Saigusa, M.; Sakamoto, K.; Sawahata, M.; Seki, M.

1987-01-01

The performance of RF power and phase control on the JT-60 LHRFD heating system are presented. The JT-60 LHRF heating system has three units of huge RF source with a total output of 24 MW, each unit consisting of eight amplifier chains. A high power klystron generating 1 MW for 10 s at 2 GHz is used in each chain. Automatic gain control is employed to regulate the output power not only against gain fluctuations in the chain but also against the unstable plasma load without any output circulator for the klystron

Measured performance of the GTA rf systems

International Nuclear Information System (INIS)

Denney, P.M.; Jachim, S.P.

1993-01-01

This paper describes the performance of the RF systems on the Ground Test Accelerator (GTA). The RF system architecture is briefly described. Among the RF performance results presented are RF field flatness and stability, amplitude and phase control resolution, and control system bandwidth and stability. The rejection by the RF systems of beam-induced disturbances, such as transients and noise, are analyzed. The observed responses are also compared to computer-based simulations of the RF systems for validation

Designing RF control subsystems using the VXIbus standard

International Nuclear Information System (INIS)

Stepp, J.D.; Vong, F.C.; Bridges, J.F.

1993-01-01

Various components are being designed to control the RF system of the 7-GeV Advanced Photon Source (APS). The associated control electronics (phase shifters, amplitude modulators, phase detectors, automatic tuning control, and local feedback control) are designed as modular cards with multiple channels for ease of replacement as well as for compact design. Various specifications of the VXIbus are listed and the method used to simplify the design of the control subsystem is shown. A commercial VXI interface board was used to speed the design cycle. Required manpower and actual task times are included. A discussion of the computer architecture and software development of the device drivers which allowed computer control from a VME processor located in a remote crate operating under the Experimental Physics and Industrial Controls Software (EPICS) program is also presented

Control of quality in spectrometry gamma of low level

CERN Document Server

Salazar, A

1997-01-01

Low level gamma spectrometry is a very precise technique to measure the concentration of nuclides present in different samples in Bq kg sup - sup 1. The quality control of the procedure and method used can be carried out by intercomparison exercises with world recognized institutions. During the last three years the Nuclear Physics Laboratory Of The University of Costa Rica (LAFNA) has been participating in the international quality assessment program (QAP) carried out by the Environmental Measurements Laboratory (EML), department of Energy, USA. The results show a very good agreement with the rest of the participant laboratories. This provides a very objective evaluation of the high precision of the methods used by LAFNA in low level spectroscopy measurements. (Author)

Control of quality in spectrometry gamma of low level

International Nuclear Information System (INIS)

Salazar, A.; Loria, G.

1997-01-01

Low level gamma spectrometry is a very precise technique to measure the concentration of nuclides present in different samples in Bq kg -1 . The quality control of the procedure and method used can be carried out by intercomparison exercises with world recognized institutions. During the last three years the Nuclear Physics Laboratory Of The University of Costa Rica (LAFNA) has been participating in the international quality assessment program (QAP) carried out by the Environmental Measurements Laboratory (EML), department of Energy, USA. The results show a very good agreement with the rest of the participant laboratories. This provides a very objective evaluation of the high precision of the methods used by LAFNA in low level spectroscopy measurements. (Author) [es

Microscopic investigation of RF surfaces of 3 GHz niobium accelerator cavities following RF processing

International Nuclear Information System (INIS)

Graber, J.; Barnes, P.; Flynn, T.; Kirchgessner, J.; Knobloch, J.; Moffat, D.; Muller, H.; Padamsee, H.; Sears, J.

1993-01-01

RF processing of Superconducting accelerating cavities is achieved through a change in the electron field emission (FE) characteristics of the RF surface. The authors have examined the RF surfaces of several single-cell 3 GHz cavities, following RF processing, in a Scanning Electron Microscope (SEM). The RF processing sessions included both High Peak Power (P ≤ 50 kW) pulsed processing, and low power (≤ 20 W) continuous wave processing. The experimental apparatus also included a thermometer array on the cavity outer wall, allowing temperature maps to characterize the emission before and after RF processing gains. Multiple sites have been located in cavities which showed improvements in cavity behavior due to RF processing. Several SEM-located sites can be correlated with changes in thermometer signals, indicating a direct relationship between the surface site and emission reduction due to RF processing. Information gained from the SEM investigations and thermometry are used to enhance the theoretical model of RF processing

Progress of the Moscow Meson Factory linac RF phase and amplitude control system

International Nuclear Information System (INIS)

Sharamentov, S.I.; Edachev, V.V.; Kvasha, A.I.; Belov, A.D.; Kuznetsov, V.V.

1992-01-01

The updated configuration of the MMF linac rf phase and amplitude control systems are presented. The structure of systems, controlling devices and specific feedback controller with Smith compensation and simulated feed-forward control loop are described. (Author) 2 refs., 5 figs

An analog RF gap voltage regulation system for the Advanced Photon Source storage ring

International Nuclear Information System (INIS)

Horan, D.

1999-01-01

An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control and permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands

Main results on the RF amplitude and phase regulation systems in operation at GANIL

International Nuclear Information System (INIS)

Joubert, A.; Ducoudret, B.; Labiche, J.C.; Loyant, J.M.

1984-06-01

The general features of the amplitude and phase regulations and their control systems are briefly reviewed. These feedback control systems are fully under the control of the main computer aided by dedicated CAMAC microprocessors for actions such as starting, parameters tuning or phase stability surveying. Numerous results obtained with spectrum analysis method give the actual RF purity and the residual modulation and crossmodulation noise level for all RF signals picked up in the RF resonators. A typical value for the noise immunity is 80 dB below the carrier at 100 Hz deviation. Another set of results gives the actual long term phase drift between resonators (< 0.2 RF degree within 6 hours). The stability of the RF phases is confirmed by on line beam phase measurements

Measurement of the Low Frequency Noise of MOSFETs under Large Signal RF Excitation

NARCIS (Netherlands)

van der Wel, A.P.; Klumperink, Eric A.M.; Nauta, Bram

2002-01-01

A measurement technique [1] is presented that allows measurement of MOSFET low frequency (LF) noise under large signal RF (Radio Frequency) excitation. Measurements indicate that MOSFETS exhibit a reduction in LF noise when they are cycled from inversion to accummulation and that this reduction does

RF feedback development for the PEP-II B Factory

Energy Technology Data Exchange (ETDEWEB)

Corredoura, P.; Sapozhnikov, L.; Tighe, R.

1994-06-01

In PEP-II heavy beam loading along with a relatively long revolution period combine to strongly drive lower coupled-bunch modes through interaction with the fundamental cavity mode. Feedback techniques can be applied to reduce the cavity impedance seen by the beam. Several RF feedback loops are planned to reduce the growth rates down to a level which can be damped by the relatively low power bunch-by-bunch longitudinal feedback system. This paper describes the RF feedback loops as well as hardware tests using a 500 kW klystron, analog and digital feedback loops, and a low power test cavity.

RF feedback development for the PEP-II B Factory

International Nuclear Information System (INIS)

Corredoura, P.; Sapozhnikov, L.; Tighe, R.

1994-06-01

In PEP-II heavy beam loading along with a relatively long revolution period combine to strongly drive lower coupled-bunch modes through interaction with the fundamental cavity mode. Feedback techniques can be applied to reduce the cavity impedance seen by the beam. Several RF feedback loops are planned to reduce the growth rates down to a level which can be damped by the relatively low power bunch-by-bunch longitudinal feedback system. This paper describes the RF feedback loops as well as hardware tests using a 500 kW klystron, analog and digital feedback loops, and a low power test cavity

Controllable Absorption and Dispersion Properties of an RF-driven Five-Level Atom in a Double-Band Photonic-Band-Gap Material

International Nuclear Information System (INIS)

Ding Chunling; Li Jiahua; Yang Xiaoxue

2011-01-01

The probe absorption-dispersion spectra of a radio-frequency (RF)-driven five-level atom embedded in a photonic crystal are investigated by considering the isotropic double-band photonic-band-gap (PBG) reservoir. In the model used, the two transitions are, respectively, coupled by the upper and lower bands in such a PBG material, thus leading to some curious phenomena. Numerical simulations are performed for the optical spectra. It is found that when one transition frequency is inside the band gap and the other is outside the gap, there emerge three peaks in the absorption spectra. However, for the case that two transition frequencies lie inside or outside the band gap, the spectra display four absorption profiles. Especially, there appear two sharp peaks in the spectra when both transition frequencies exist inside the band gap. The influences of the intensity and frequency of the RF-driven field on the absorptive and dispersive response are analyzed under different band-edge positions. It is found that a transparency window appears in the absorption spectra and is accompanied by a very steep variation of the dispersion profile by adjusting system parameters. These results show that the absorption-dispersion properties of the system depend strongly on the RF-induced quantum interference and the density of states (DOS) of the PBG reservoir. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

RF system modeling and controller design for the European XFEL

International Nuclear Information System (INIS)

Schmidt, Christian

2011-06-01

The European XFEL is being constructed at the Deutsche Elektronen Synchrotron DESY to generate intense, ultrashort pulses of highly coherent and monochromatic X-Rays for material science research. X-ray flashes are generated by accelerating electron bunches within superconducting cavities with radio frequency (RF) fields to energies up to 17.5 GeV. The digital control of these fields requires extremely high quality in order to achieve the physical processes of photon generation. DESY offers with FLASH a pilot test facility, allowing to test and develop most necessary components, even before the XFEL is conducted. Current field control is based on a proportional feedback controller in addition to a constant feedforward drive, which do not meet the high requirements of the XFEL. This thesis shows that a model based controller design can achieve the necessary field regulation requirements. A linear, time invariant ''black box model'' is estimated, which characterizes the essential dynamic behavior. This model is not based on physical assumptions, but describes exclusively the transfer behavior of the plant. The acceleration modules are operated in a pulsed mode, in which the RF field must be kept constant for a finite period. The character of the disturbances and variations from pulse-to-pulse, together with the properties of the system, require a combination of controlled feedforward drive and feedback. Generally unpredictable, low frequency pulse-to-pulse variations are suppressed by the feedback controller. The structural design of the complex multivariable feedback controller is given, which constrains the model based design approach to assign the controller parameters only. Estimation of the parameters, which can not be tuned manually, is done by the method of H loop shaping which is often applied in modern control theory. However, disturbances within a pulse are in a high frequency range concerning the short pulse duration. They are not sufficiently suppressed

RF power absorption by plasma of low pressure low power inductive discharge located in the external magnetic field

Science.gov (United States)

Kralkina, E. A.; Rukhadze, A. A.; Nekliudova, P. A.; Pavlov, V. B.; Petrov, A. K.; Vavilin, K. V.

2018-03-01

Present paper is aimed to reveal experimentally and theoretically the influence of magnetic field strength, antenna shape, pressure, operating frequency and geometrical size of plasma sources on the ability of plasma to absorb the RF power characterized by the equivalent plasma resistance for the case of low pressure RF inductive discharge located in the external magnetic field. The distinguishing feature of the present paper is the consideration of the antennas that generate not only current but charge on the external surface of plasma sources. It is shown that in the limited plasma source two linked waves can be excited. In case of antennas generating only azimuthal current the waves can be attributed as helicon and TG waves. In the case of an antenna with the longitudinal current there is a surface charge on the side surface of the plasma source, which gives rise to a significant increase of the longitudinal and radial components of the RF electric field as compared with the case of the azimuthal antenna current.

Barrier rf systems in synchrotrons

International Nuclear Information System (INIS)

Bhat, Chandra M.

2004-01-01

Recently, many interesting applications of the barrier RF system in hadron synchrotrons have been realized. A remarkable example of this is the development of longitudinal momentum mining and implementation at the Fermilab Recycler for extraction of low emittance pbars for the Tevatron shots. At Fermilab, we have barrier RF systems in four different rings. In the case of Recycler Ring, all of the rf manipulations are carried out using a barrier RF system. Here, the author reviews various uses of barrier rf systems in particle accelerators including some new schemes for producing intense proton beam and possible new applications

Direct RF modulation transmitter, sampling clock frequency setting method for direct RF modulation transmitter

NARCIS (Netherlands)

Fukuda, Shuichi; Nauta, Bram

2013-01-01

PROBLEM TO BE SOLVED: To provide a direct RF modulation transmitter capable of satisfying a radiation level regulation even without providing a SAW filter. SOLUTION: A direct RF modulation transmitter includes: digital/RF converters 105, 106 to which an I digital baseband signal, a Q digital

Direct RF modulation transmitter, sampling clock frequency setting method for direct RF modulation transmitter

NARCIS (Netherlands)

Fukuda, Shuichi; Nauta, Bram

2014-01-01

PROBLEM TO BE SOLVED: To provide a direct RF modulation transmitter capable of satisfying a radiation level regulation even without providing a SAW filter. SOLUTION: A direct RF modulation transmitter includes: digital/RF converters 105, 106 to which an I digital baseband signal, a Q digital

The experience with JET's combined dc/Rf glow discharge cleaning (GDC) system

International Nuclear Information System (INIS)

Pearce, R.J.H.; Andrew, P.; Bryan, S.

1996-01-01

The JET Tokamak was fitted with four new electrodes of novel design, each powered from individual computer controlled dc and RF supplies. Details of enhancements and problems from 15 months experience with the system are outlined. Experiments were performed to assess the effect of RF on the glow discharge characteristics, and to establish stable glow at low pressure and high voltage. JET combined RF/dc glow discharge cleaning (GDC) had no significant advantages over pure dc GDC, provided highly stable dc current control was obtained. In fact, the mechanically weak electrode inductor spiral required to allow RF posed a distinct disadvantage. The electrodes were converted to simple plates, following damage caused by halo currents during Tokamak plasma disruptions. The performance of these electrodes was assessed. Future developments in the JET GDC system are outlined. (Author)

RF power source for the compact linear collider test facility (CTF3)

CERN Document Server

McMonagle, G; Brown, Peter; Carron, G; Hanni, R; Mourier, J; Rossat, G; Syratchev, I V; Tanner, L; Thorndahl, L

2004-01-01

The CERN CTF3 facility will test and demonstrate many vital components of CLIC (Compact Linear Collider). This paper describes the pulsed RF power source at 2998.55 MHz for the drive-beam accelerator (DBA), which produces a beam with an energy of 150 MeV and a current of 3.5 Amps. Where possible, existing equipment from the LEP preinjector, especially the modulators and klystrons, is being used and upgraded to achieve this goal. A high power RF pulse compression system is used at the output of each klystron, which requires sophisticated RF phase programming on the low level side to achieve the required RF pulse. In addition to the 3 GHz system two pulsed RF sources operating at 1.5 GHz are being built. The first is a wide-band, low power, travelling wave tube (TWT) for the subharmonic buncher (SHB) system that produces a train of "phase coded" subpulses as part of the injector scheme. The second is a high power narrow band system to produce 20 MW RF power to the 1.5 GHz RF deflectors in the delay loop situate...

Gallium arsenide digital integrated circuits for controlling SLAC CW-RF systems

International Nuclear Information System (INIS)

Ronan, M.T.; Lee, K.L.; Corredoura, P.; Judkins, J.G.

1989-01-01

In order to fill the PEP and SPEAR storage rings with beams from the SLC linac and damping rings, precise control of the linac subharmonic buncher and the damping ring RF is required. Recently several companies have developed resettable GaAs master/slave D-type flip-flops which are capable of operating at frequencies of 3 GHz and higher. Using these digital devices as frequency dividers, one can phase shift the SLAC CW-RF systems to optimize the timing for filling the storage rings. The authors have evaluated the performance of integrated circuits from two vendors for our particular application. Using microstrip circuit techniques, they have built and operated in the accelerator several chassis to synchronize a reset signal from the storage rings to the SLAC 2.856 GHz RF and to phase shift divide-by-four and divide-by-sixteen frequency dividers to the nearest 350 psec bucket required for filling

Gallium arsenide digital integrated circuits for controlling SLAC CW-RF systems

International Nuclear Information System (INIS)

Ronan, M.T.; Lee, K.L.; Corredoura, P.; Judkins, J.G.

1988-10-01

In order to fill the PEP and SPEAR storage rings with beams from the SLC linac and damping rings, precise control of the linac subharmonic buncher and the damping ring RF is required. Recently several companies have developed resettable GaAs master/slave D-type flip-flops which are capable of operating at frequencies of 3 GHz and higher. Using these digital devices as frequency dividers, one can phase shift the SLAC CW-RF systems to optimize the timing for filling the storage rings. We have evaluated the performance of integrated circuits from two vendors for our particular application. Using microstrip circuit techniques, we have built and operated in the accelerator several chassis to synchronize a reset signal from the storage rings to the SLAC 2.856 GHz RF and to phase shift divide-by-four and divide-by-sixteen frequency dividers to the nearest 350 psec bucket required for filling. 4 refs., 4 figs., 2 tabs

RF Power Requirements for PEFP SRF Cavity Test

International Nuclear Information System (INIS)

Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub

2011-01-01

For the future extension of the PEFP (Proton Engineering Frontier Project) Proton linac, preliminary study on the SRF (superconducting radio-frequency) cavity is going on including a five-cell prototype cavity development to confirm the design and fabrication procedures and to check the RF and mechanical properties of a low-beta elliptical cavity. The main parameters of the cavity are like followings. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m (1.21 Kilp.) - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Stiffening structure: Double ring - Effective length: 0.45 m For the test of the cavity at low temperature of 4.2 K, many subsystems are required such as a cryogenic system, RF system, vacuum system and radiation shielding. RF power required to generate accelerating field inside cavity depends on the RF coupling parameters of the power coupler and quality factor of the SRF cavity and the quality factor itself is affected by several factors such as operating temperature, external magnetic field level and surface condition. Therefore, these factors should be considered to estimate the required RF power for the SRF cavity test

Phase calibration strategies for synchrotron RF signals

Energy Technology Data Exchange (ETDEWEB)

Andreev, Aleksandr [TEMF, Technische Universitaet Darmstadt (Germany); Klingbeil, Harald [TEMF, Technische Universitaet Darmstadt (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Lens, Dieter [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)

2016-07-01

For the FAIR facility that is currently under construction, the beam quality requirements impose several demands on the low-level RF (LLRF) systems. For example the phase error of the gap voltage of a specific RF cavity must be less than 1 . The RF reference signals for the FAIR synchrotron RF cavity systems are generated by direct digital synthesis modules (DDS) mounted in one crate called Group-DDS. In order to allow performing various multi-harmonic operations, each DDS unit operates at a certain mode defined by the harmonic number that can be changed during the operation. Since the DDS modules generate reference RF signals for different LLRF systems, the precise calibration of units to compensate the different phase response is of importance. The currently used calibration procedure is done with a fixed harmonic number for each module and uses the DDS module configured to the highest harmonic number as a reference. If the harmonic number of the DDS module is changed, one then has to repeat the calibration for the new values. Therefore, a new calibration method with respect to the absolute phases of DDS modules is under development and will be presented.

Control of hydrocarbon radicals and film deposition by using an RF Whistler wave discharge

International Nuclear Information System (INIS)

Mieno, Tetsu; Shoji, Tatsuo; Kadota, Kiyoshi.

1991-10-01

Production of hydrocarbon radicals is controlled by using an RF Whistler wave discharge in a low pressure region (∼0.1 Pa). Plasma density of 10 10 - 10 13 cm -3 , electron temperature of 2-20 eV is obtained for the discharge of admixture of Ar and small content of source gases (CH 4 , C 2 H 2 , CO). Spectroscopic measurement indicates that densities of CH and H radicals and deposition rate of amorphous carbon:H film increase with electron density, electron temperature and source gas pressure. The etching effect of H atoms influences on the deposition rate and a high deposition rate (90 μm/hr for CO/Ar discharge) is obtained even in a low neutral pressure discharge. (author)

Reliability review of the LHC collimators low level control system

International Nuclear Information System (INIS)

Masi, A.; Donze, M.; Losito, R.

2011-01-01

The LHC collimators' low level control system is responsible for the positioning, with an accuracy of a few um, of more than 500 motor axes located around the entire LHC tunnel and synchronized at us level,The collimators' axes position is verified in Real Time, monitoring at 100 Hz more than 700 LVDT positioning sensors. Apart from the challenging requirements of timing and positioning accuracy, the system is characterized by a high level of reliability since the collimators have the crucial function of machine protection. In this paper we focus on the architectural and technical choices adopted to guarantee the level of reliability required by the application. We also present the tools and solutions developed to manage this huge control system making the support easier and faster for its operation. (authors)

Analysis and software development for controlling RF signal generator proton cyclotron Decy-13 using DDS Technique

International Nuclear Information System (INIS)

Prajitno

2012-01-01

Analysis and manufacture of computer programs for controlling the signal generator Radio Frequency (RF) proton cyclotron Decy-13 have been done. Signal generator uses a technique Direct Digital Synthesiser (DDS) which settings must be done with software. Signal generator consists of electronic modules which are: DDS, micro controller ATmega16, amplifier RF.dan ± 12 Vdc power supply. Function of the programs that have been made is to set the DDS module, namely: output frequency, step frequency and phase settings and displays the operating parameters of the DDS and the RF amplifier on the monitor screen. Computer programs created with Visual Basic and has been tested to control the RF signal generator to send data serially to the module ATmega16 and receives data to be displayed on the monitor screen. Testing sending and receiving data is done with a baudrate of 1200 bps to 19200 bps with perfect results. Computer programs that have been made equipped with a Human Machine Interface to provide values parameter input on the DDS operations. (author)

RF Energy Compressor

International Nuclear Information System (INIS)

Farkas, Z.D.

1980-02-01

The RF Energy Compressor, REC described here, transforms cw rf into periodic pulses using an energy storage cavity, ESC, whose charging is controlled by 180 0 bi-phase modulation, PSK, and external Q switching, βs. Compression efficiency, C/sub e/, of 100% can be approached at any compression factor C/sub f/

Development of an Automatic Frequency Control (AFC) System for RF Electron Linear Accelerators

International Nuclear Information System (INIS)

Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Joo, Youngwoo; Lee, Soo Min; Lee, Byung Cheol; Cha, Hyungki; Park, Hyung Dal; Lee, Seung Hyun

2015-01-01

In this paper, the design, fabrication, and RF power test of the AFC system for the X-band linac are presented. The main function of the AFC system is automatically matching of the resonance frequency of the accelerating structure and the RF frequency of the magnetron. For the frequency tuning, a fine tuning of 10 kHz is possible by rotating the tuning shaft with a rotation of 0.72 degree per pulse. Therefore, the frequency deviation is about 0.01%, and almost full RF power (2.1 MW) transmission was obtained because the reflected power is minimized. The Radiation Equipment Research Division of the Korea Atomic Energy Research Institute has been developing and upgrading a medical/industrial X-band RF electron linear accelerators. The medical compact RF electron linear accelerator consists of an electron gun, an acceleration tube (accelerating structure), two solenoid magnets, two steering magnets, a magnetron, modulator, an automatic frequency control (AFC) system, and an X-ray generating target. The accelerating structure of the component is composed of oxygen-free high-conductivity copper (OFHC). Therefore, the volume of the structure, hence, its resonance frequency can easily be changeable if the ambient temperature and pressure are changed. If the RF frequency of the 9300 MHz magnetron and the resonance frequency of accelerating structure are not matched, performance of the structure can be degraded. An AFC system is automatically matched with the RF frequency of the magnetron and resonance frequency of the accelerating structure, which obtained a high output power and reliable accelerator operation

Development of an Automatic Frequency Control (AFC) System for RF Electron Linear Accelerators

Energy Technology Data Exchange (ETDEWEB)

Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Joo, Youngwoo; Lee, Soo Min; Lee, Byung Cheol; Cha, Hyungki [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Hyung Dal [Radiation Technology eXcellence, Daejeon (Korea, Republic of); Lee, Seung Hyun [Sungkyunkwan University, Suwon (Korea, Republic of)

2015-10-15

In this paper, the design, fabrication, and RF power test of the AFC system for the X-band linac are presented. The main function of the AFC system is automatically matching of the resonance frequency of the accelerating structure and the RF frequency of the magnetron. For the frequency tuning, a fine tuning of 10 kHz is possible by rotating the tuning shaft with a rotation of 0.72 degree per pulse. Therefore, the frequency deviation is about 0.01%, and almost full RF power (2.1 MW) transmission was obtained because the reflected power is minimized. The Radiation Equipment Research Division of the Korea Atomic Energy Research Institute has been developing and upgrading a medical/industrial X-band RF electron linear accelerators. The medical compact RF electron linear accelerator consists of an electron gun, an acceleration tube (accelerating structure), two solenoid magnets, two steering magnets, a magnetron, modulator, an automatic frequency control (AFC) system, and an X-ray generating target. The accelerating structure of the component is composed of oxygen-free high-conductivity copper (OFHC). Therefore, the volume of the structure, hence, its resonance frequency can easily be changeable if the ambient temperature and pressure are changed. If the RF frequency of the 9300 MHz magnetron and the resonance frequency of accelerating structure are not matched, performance of the structure can be degraded. An AFC system is automatically matched with the RF frequency of the magnetron and resonance frequency of the accelerating structure, which obtained a high output power and reliable accelerator operation.

Synchronization of RF fields of Indus 2 RF cavities for proper injection and acceleration of beam

International Nuclear Information System (INIS)

Tiwari, Nitesh; Bagduwal, Pritam S.; Lad, M.; Hannurkar, P.R.

2009-01-01

Indus-2 is a synchrotron light source with designed parameters of 2.5 GeV, 300 mA beam current. Four RF cavities fed from four RF power stations have been used for beam acceleration from 550 MeV to 2.5 GeV and synchrotron loss compensation. Particle should reach the RF cavity at the proper phase for proper acceptance of the beam in ring. At injection if the phase is not proper the acceptance efficiency reduces and the maximum stored current in the ring also gets limited. Equal contribution from four cavities at every value of current and energy level is very important. Improper phase will cause the imbalance of the power among different station hence will limit maximum stored current and reduce life time of the stored beam. Phase optimization was done in two-step, first at injection to have better injection rate and the stations were operated at the sufficient power for control loops to operate. Then at 2 GeV and 2.5 GeV energy so that beam extracts equal power from all four RF stations. Phase synchronization of all four cavities from injection to 2.5 GeV has already been done at 50 mA stored beam current. If phases of RF fields inside four RF cavities is not proper then beam will not see the total RF voltage as summation of all four cavity gap voltages, hence it is a very important parameter to be optimized and maintained during operation. (author)

Investigation of Inonotus obliquus (Pers. Pil. Extracts and Melanins after RF-plasma Treatment of Raw Material

Directory of Open Access Journals (Sweden)

O.Yu. Kuznetsova

2016-03-01

Full Text Available High-frequency capacitive discharge (RF plasma at low pressure was used as preliminary stage for the intensification of extraction from natural medicinal raw material. RF-plasma treatment was carried out in two modes differed by the nature of plasma-forming gas. Chaga (Inonotus obliquus (Pers. Pil. known as the birch mushroom was selected as a perspective source of raw material. Extraction was carried out in two ways – remaceration and maceration. The analy-sis of chaga extracts and melanins was performed using traditional techniques including determination of physical and chemical, antioxidant and spectral characteristics. The obtained extracts and melanins were compared to the control samples and literature data. RF-plasma treatment of medicinal raw material increased the yield of extractive substances, in particular of the main active component of chaga – melanin. The antioxidant activity of chaga extracts grew, while for melanins it remained at the level similar to that of control samples. The IR spectral characteristics of the studied chaga melanins are similar and agree well with the literature data. Insignificant deviations in the position and intensity of absorption strips were observed for the samples after RF treatment. IR spectra of the studied chaga melanins are similar to those for mushroom melanins, thereby confirming the similarity in their nature. RF-plasma treatment of chaga medicinal raw materials allows to modify them partially. The structural and mechanical properties of melanins modified by RF plasma remain the same.

Digital control of the superconducting cavities for the LEP energy upgrade

International Nuclear Information System (INIS)

Gavallari, G.; Ciapala, E.

1992-01-01

The superconducting (SC) cavities for the LEP200 energy upgrade will be installed in units of 16 as for the present copper cavity system. Similar equipment will be used for RF power generation and distribution, for the low-level RF system and for digital control. The SC cavities and their associated equipment however require different interface hardware and new control software. To simplify routine operation control of the SC cavity units is made to resemble as closely as possible that of the existing units. Specific controls for the SC cavities at the equipment level, the facilities available and the integration of the SC cavity units into the LEP RF control system are described. (author)

Rare Variants in Genes Encoding MuRF1 and MuRF2 Are Modifiers of Hypertrophic Cardiomyopathy

Directory of Open Access Journals (Sweden)

Ming Su

2014-05-01

Full Text Available Modifier genes contribute to the diverse clinical manifestations of hypertrophic cardiomyopathy (HCM, but are still largely unknown. Muscle ring finger (MuRF proteins are a class of muscle-specific ubiquitin E3-ligases that appear to modulate cardiac mass and function by regulating the ubiquitin-proteasome system. In this study we screened all the three members of the MuRF family, MuRF1, MuRF2 and MuRF3, in 594 unrelated HCM patients and 307 healthy controls by targeted resequencing. Identified rare variants were confirmed by capillary Sanger sequencing. The prevalence of rare variants in both MuRF1 and MuRF2 in HCM patients was higher than that in control subjects (MuRF1 13/594 (2.2% vs. 1/307 (0.3%, p = 0.04; MuRF2 22/594 (3.7% vs. 2/307 (0.7%; p = 0.007. Patients with rare variants in MuRF1 or MuRF2 were younger (p = 0.04 and had greater maximum left ventricular wall thickness (p = 0.006 than those without such variants. Mutations in genes encoding sarcomere proteins were present in 19 (55.9% of the 34 HCM patients with rare variants in MuRF1 and MuRF2. These data strongly supported that rare variants in MuRF1 and MuRF2 are associated with higher penetrance and more severe clinical manifestations of HCM. The findings suggest that dysregulation of the ubiquitin-proteasome system contributes to the pathogenesis of HCM.

High power RF window deposition apparatus, method, and device

Science.gov (United States)

Ives, Lawrence R.; Lucovsky, Gerald; Zeller, Daniel

2017-07-04

A process for forming a coating for an RF window which has improved secondary electron emission and reduced multipactor for high power RF waveguides is formed from a substrate with low loss tangent and desirable mechanical characteristics. The substrate has an RPAO deposition layer applied which oxygenates the surface of the substrate to remove carbon impurities, thereafter has an RPAN deposition layer applied to nitrogen activate the surface of the substrate, after which a TiN deposition layer is applied using Titanium tert-butoxide. The TiN deposition layer is capped with a final RPAN deposition layer of nitridation to reduce the bound oxygen in the TiN deposition layer. The resulting RF window has greatly improved titanium layer adhesion, reduced multipactor, and is able to withstand greater RF power levels than provided by the prior art.

Outage Performance of Hybrid FSO/RF System with Low-Complexity Power Adaptation

KAUST Repository

Rakia, Tamer

2016-02-26

Hybrid free-space optical (FSO) / radio-frequency (RF) systems have emerged as a promising solution for high data- rate wireless communication systems. We consider truncated channel inversion based power adaptation strategy for coherent and non- coherent hybrid FSO/RF systems, employing an adaptive combining scheme. Specifically, we activate the RF link along with the FSO link when FSO link quality is unacceptable, and adaptively set RF transmission power to ensure constant combined signal-to-noise ratio at receiver terminal. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are derived. Numerical examples show that, the hybrid FSO/RF systems with power adaptation achieve considerable outage performance improvement over conventional hybrid FSO/RF systems without power adaptation. © 2015 IEEE.

Regulatory control of low level radiation exposure in Tanzania

International Nuclear Information System (INIS)

Nyanda, A.M.; Muhogora, W.E.

1997-01-01

In Tanzania, the radiation protection law was issued in 1983. Under this law, the National Radiation Commission is responsible for safe uses of ionizing radiation. The regulatory control of the resulting doses from the uses of radiation sources in medicine, industry, research and teaching is presented. The system of control reflects the existing interactions between the National Radiation Commission and users through the established radiation protection infrastructure. From the national dose registry data, it is found that the highest annual individual doses over 10 years ago, came from less than 5% of total monitored workers and were in the range 10 - 15 mSv y -1 . The experienced radiation levels in uncontrolled areas of potential workplaces is less than 1 μSv h -1 . The possibility for associating such low dose levels to the effectiveness of the existing regulatory dose control framework is discussed. Despite of this achievement, the need to improve further the radiation protection and safety programs is found necessary. (author)

A leading-edge hardware family for diagnostics applications and low-level RF in CERN's ELENA ring

CERN Document Server

Angoletta, M E; Jaussi, M; Leiononen, P; Levens, T E; Molendijk, J C; Sanchez-Quesada, J; Simonin, J

2013-01-01

The CERN Extra Low ENergy Antiproton (ELENA) Ring is a new synchrotron that will be commissioned in 2016 to further decelerate the antiprotons transferred from the CERN’s Antiproton Decelerator (AD). The requirements for the acquisition and treatment of signals for longitudinal diagnostics are very demanding, owing to the revolution frequency swing as well as to the digital signal processing required. The requirements for the Low-Level Radio-Frequency (LLRF) system are very demanding as well, especially in terms of revolution frequency swing, dynamic range and low noise required by the cavity voltage control and digital signal processing to be performed. Both sets of requirements will be satisfied by using a leading-edge hardware family, developed to cover the LLRF needs of all synchrotrons in the Meyrin site; it will be first deployed in 2014 in the CERN’s PSB and in the medical machine MedAustron. This paper gives an overview of the main building blocks of the hardware family and of th...

Design and results of the radio frequency quadrupole RF system at the Superconducting Super Collider Laboratory

International Nuclear Information System (INIS)

Grippe, J.; Marsden, E.; Marrufo, O.; Regan, A.; Rees, D.; Ziomek, C.

1993-05-01

The Superconducting Super Collider Laboratory (SSCL) and the Los Alamos National Laboratory (LANL) entered into a joint venture to design and develop a 600 kW amplifier and its low-level controls for use in the Radio-Frequency Quadrupole (RFQ) accelerating cavity of the SSC. The design and development work has been completed. After being tested separately, the high power amplifier and low level RF control system were integrated and tested on a test cavity. Results of that tests are given. Tests were then carried out on the actual RFQ with and without the presence of the accelerated beam. Results of these tests are also given, along with the phase and amplitude information

Performance test of lower hybrid waveguide under long/high-RF power transmission

International Nuclear Information System (INIS)

Seki, Masami; Obara, Kenjiro; Maebara, Sunao

1996-06-01

Performance tests of a module for lower hybrid waveguides were carried out at the CEA Cadarache RF Test Facility. For the experiments the test module was fabricated by JAERI, the transmission line of the test bed was modified and the connection waveguides were manufactured by CEA. As the results, the thermal treatment by baking at a higher temperature was the most effective for reducing outgassing during injection of high RF power. The outgassing strongly depended on the temperature of the test module, but was independent to initial temperature. The RF injection reduced outgassing. The outgassing rate decreased to a low level of 10 -6 -10 -5 Pa m 3 /sec m 2 (10 -9 -10 -8 Torr 1/sec cm 2 ) at 400degC after 450degC-baking. The gas injection did not affect outgassing before and during RF injection. The baking under H 2 or D 2 gas atmosphere were not so effective for reducing outgassing rate. The outgassing rate did not depend on input RF power densities. The temperature in central part of the test module saturated to be ∼100degC by using of water cooling at a power level of 150 MW/m 2 RF injection, and a neutral gas pressure decreased gradually. In the water cooling case, the outgassing rate was very low less than 10 -7 Pa m 3 /sec m 2 (10 -10 Torr 1/sec cm 2 ). The steady state RF injection was demonstrated with water cooling. (author)

RF-Based Accelerators for HEDP Research

CERN Document Server

Staples, John W; Keller, Roderich; Ostroumov, Peter; Sessler, Andrew M

2005-01-01

Accelerator-driven High-Energy Density Physics experiments require typically 1 nanosecond, 1 microcoulomb pulses of mass 20 ions accelerated to several MeV to produce eV-level excitations in thin targets, the "warm dense matter" regime. Traditionally the province of induction linacs, RF-based acceleration may be a viable alternative with recent breakthroughs in accelerating structures and high-field superconducting solenoids. A reference design for an RF-based accelerator for HEDP research is presented using 15 T solenoids and multiple-gap RF structures configured with either multiple parallel beams (combined at the target) or a single beam and a small stacking ring that accumulates 1 microcoulomb of charge. In either case, the beam is ballistically compressed with an induction linac core providing the necessary energy sweep and injected into a plasma-neutralized drift compression channel resulting in a 1 mm radius beam spot 1 nanosecond long at a thin foil or low-density target.

RF gun using laser-triggered photocathode

International Nuclear Information System (INIS)

Akiyama, H.; Otake, Y.; Naito, T.; Takeuchi, Y.; Yoshioka, M.

1992-01-01

An RF gun using laser-triggered photocathode has many advantages as an injector of the linear colliders since it can generate a low emittance and high current pulsed beam. The experimental facility for the RF gun, such as an RF system, a laser system and a photocathode have been fabricated to study the fundamental characteristics. The dynamics of the RF gun has also studied by the 1D sheet beam model. (author)

RF system modeling and controller design for the European XFEL

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Christian

2011-06-15

The European XFEL is being constructed at the Deutsche Elektronen Synchrotron DESY to generate intense, ultrashort pulses of highly coherent and monochromatic X-Rays for material science research. X-ray flashes are generated by accelerating electron bunches within superconducting cavities with radio frequency (RF) fields to energies up to 17.5 GeV. The digital control of these fields requires extremely high quality in order to achieve the physical processes of photon generation. DESY offers with FLASH a pilot test facility, allowing to test and develop most necessary components, even before the XFEL is conducted. Current field control is based on a proportional feedback controller in addition to a constant feedforward drive, which do not meet the high requirements of the XFEL. This thesis shows that a model based controller design can achieve the necessary field regulation requirements. A linear, time invariant ''black box model'' is estimated, which characterizes the essential dynamic behavior. This model is not based on physical assumptions, but describes exclusively the transfer behavior of the plant. The acceleration modules are operated in a pulsed mode, in which the RF field must be kept constant for a finite period. The character of the disturbances and variations from pulse-to-pulse, together with the properties of the system, require a combination of controlled feedforward drive and feedback. Generally unpredictable, low frequency pulse-to-pulse variations are suppressed by the feedback controller. The structural design of the complex multivariable feedback controller is given, which constrains the model based design approach to assign the controller parameters only. Estimation of the parameters, which can not be tuned manually, is done by the method of H{sub {infinity}} loop shaping which is often applied in modern control theory. However, disturbances within a pulse are in a high frequency range concerning the short pulse duration

R and D of control system of compact self-bunching RF gun test facility

International Nuclear Information System (INIS)

Pang Jian; Pei Yuanji; Huang Guirong; Wang Jinxiang

2010-01-01

An experimental device was recently constructed for testing the beam characteristics of a compact self-bunching RF gun at the National Synchrotron Radiation Laboratory. It designs an independent monitor and control system for the experimental device so as not to disturb the operation of 200MeV LINAC. According to the three-level architecture of a general control scheme, the proposed system consists of circuits that execute kernel control, photosignal emission/reception, and switch values input/output, respectively. It performs timing control, device status monitoring as well as interlock protection, and it can be remotely operated with the assistance of PC software. Testing results show that our system achieves the specified performance and meets the requirement of experimental device stably and reliably. Our proposed system can also be applied to control other small-scale accelerators. (authors)

Research and Development for an Alternative RF Source Using Magnetrons in CEBAF

Science.gov (United States)

Jacobs, Andrew

2016-09-01

At Jefferson Lab, klystrons are currently used as a radiofrequency (RF) power source for the 1497 MHz Continuous Electron Beam Accelerator Facility (CEBAF) Continuous Wave (CW) system. A drop-in replacement for the klystrons in the form of a system of magnetrons is being developed. The klystron DC-RF efficiency at CEBAF is 35-51% while the estimated magnetron efficiency is 80-90%. Thus, the introduction of magnetrons to CEBAF will have enormous benefits in terms of electrical power saving. The primary focus of this project was to characterize a magnetron's frequency pushing and pulling curves at 2.45 GHz with stub tuner and anode current adjustments so that a Low Level RF controller for a new 1.497 GHz magnetron can be built. A Virtual Instrument was created in LabVIEW, and data was taken. The resulting data allowed for the creation of many constant lines of frequency and output power. Additionally, the results provided a characterization of magnetron oven temperature drift over the operation time and the relationship between anode current and frequency. Using these results, the control model of different variables and their feedback or feedforward that affect the frequency pushing and pulling of the magnetron is better developed. Department of Energy, Science Undergraduate Laboratory Internships, and Jefferson Lab.

A digital signal processor based rf control system for the TRIUMF ISAC RFQ prototype

International Nuclear Information System (INIS)

Fong, K.; Fang, S.; Laverty, M.

1996-01-01

A stand alone digital signal processor is used to control the RFQ prototype in the TRIUMF ISAC development program. The advantage of a digital control system over the traditional analogue system is that it offers the higher degree of flexibility necessary for a development system. For this application the system is designed to have the outward appearance of an analogue system, and uses dials, knobs, and switches as the operator interface. The digital signal processor is used as a feedback controller during CW rf operation, with the feedback gain parameters continually adjustable. It is also able to perform the same regulation during pulsed operation, with additional feedforward compensation for initial pulse on duration. Using a low cost analogue-to-digital converter with a sample rate of 100 kHz, a regulation bandwidth of 10 kHz is achieved. (author)

LEDA LLRF control system characterization

International Nuclear Information System (INIS)

Regan, A.H.; Balleyguier, P.; Ziomek, C.D.

1998-01-01

The Low Energy Demonstration Accelerator (LEDA) for the Accelerator for the Production of Tritium (APT) project will be built at Los Alamos National Laboratory. The low-level RF (LLRF) control system portion of this accelerator must perform many functions, of which the primary one is controlling the RF fields in the accelerating cavities. Plans have been made to provide for on-line characterization of the LLRF control system and the complete RF system through use of stimulus and response buffers, and a digital signal processor built into the field control system electronics. The purpose of this circuitry is to characterize the behavior of the entire RF system (klystron, waveguides, high power splitters, accelerator cavity, etc.). This characterization feature can be used to measure the performance of the closed loop system with respect to the open loop system, to provide an automated way to set loop parameters, to determine the cavity Q-curve, and to detect any abnormal behavior in the RF chain. The types of measurements include frequency and time-domain responses to given perturbations, amplitude modulations, etc. This paper will discuss types of algorithms that can be implemented and present a description and block diagram of the electronics to be used

Phase synchronization of multiple klystrons in RF system

International Nuclear Information System (INIS)

Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

1998-01-01

The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of the Acceleration Production of Tritium (APT) accelerator. The first LEDA RF system includes three, 1.2 MW, 350 MHz, continuous wave, klystrons driving a radio frequency quadrupole (RFQ). A phase control loop is necessary for each individual klystron in order to guarantee the phase matching of these klystrons. To meet this objective, they propose adaptive PI controllers which are based on simple adaptive control. These controllers guarantee not only phase matching but also amplitude matching

An amplitude and phase control system for the TFTR rf heating sources

International Nuclear Information System (INIS)

Cutsogeorge, G.

1989-04-01

Feedback loops that control the amplitude and phase of the rf heating sources on TFTR are described. The method for providing arc protection is also discussed. Block diagrams and Bode plots are included. 6 figs

An RF driven H- source and a low energy beam injection system for RFQ operation

International Nuclear Information System (INIS)

Leung, K.N.; Bachman, D.A.; Chan, C.F.; McDonald, D.S.

1992-01-01

An RF driven H - source has been developed at LBL for use in the Superconducting Super Collider (SSC). To date, an H - current of ∼40 mA can be obtained from a 5.6-cm-diam aperture with the source operated at a pressure of about 12 m Torr and 50 kW of RF power. In order to match the accelerated H - beam into the SSC RFQ, a low-energy H - injection system has been designed. This injector produces an outgoing H - beam free of electron contamination, with small radius, large convergent angle and small projectional emittance

The RF Design of an HOM Polarized RF Gun for the ILC

International Nuclear Information System (INIS)

Wang, J.W.; Clendenin, J.E.; Colby, E.R.; Miller, R.A.; Lewellen, J.W.

2006-01-01

The ILC requires a polarized electron beam. While a highly polarized beam can be produced by a GaAs-type cathode in a DC gun of the type currently in use at SLAC, JLAB and elsewhere, the ILC injector system can be simplified and made more efficient if a GaAs-type cathode can be combined with a low emittance RF gun. Since this type of cathode is known to be extremely sensitive to vacuum contamination including back bombardment by electrons and ions, any successful polarized RF gun must have a significantly improved operating vacuum compared to existing RF guns. We present a new RF design for an L-Band normal conducting (NC) RF gun for the ILC polarized electron source. This design incorporates a higher order mode (HOM) structure, whose chief virtue in this application is an improved conductance for vacuum pumping on the cathode. Computer simulation models have been used to optimize the RF parameters with two principal goals: first to minimize the required RF power; second to reduce the peak surface field relative to the field at the cathode in order to suppress field emitted electron bombardment. The beam properties have been simulated initially using PARMELA. Vacuum and other practical issues for implementing this design are discussed

Binary rf pulse compression experiment at SLAC

International Nuclear Information System (INIS)

Lavine, T.L.; Spalek, G.; Farkas, Z.D.; Menegat, A.; Miller, R.H.; Nantista, C.; Wilson, P.B.

1990-06-01

Using rf pulse compression it will be possible to boost the 50- to 100-MW output expected from high-power microwave tubes operating in the 10- to 20-GHz frequency range, to the 300- to 1000-MW level required by the next generation of high-gradient linacs for linear for linear colliders. A high-power X-band three-stage binary rf pulse compressor has been implemented and operated at the Stanford Linear Accelerator Center (SLAC). In each of three successive stages, the rf pulse-length is compressed by half, and the peak power is approximately doubled. The experimental results presented here have been obtained at low-power (1-kW) and high-power (15-MW) input levels in initial testing with a TWT and a klystron. Rf pulses initially 770 nsec long have been compressed to 60 nsec. Peak power gains of 1.8 per stage, and 5.5 for three stages, have been measured. This corresponds to a peak power compression efficiency of about 90% per stage, or about 70% for three stages, consistent with the individual component losses. The principle of operation of a binary pulse compressor (BPC) is described in detail elsewhere. We recently have implemented and operated at SLAC a high-power (high-vacuum) three-stage X-band BPC. First results from the high-power three-stage BPC experiment are reported here

Rf power sources

International Nuclear Information System (INIS)

Allen, M.A.

1988-01-01

In this paper, the author reports on RF power sources for accelerator applications. The approach will be with particular customers in mind. These customers are high energy physicists who use accelerators as experimental tools in the study of the nucleus of the atom, and synchrotron light sources derived from electron or positron storage rings. The author pays close attention to electron- positron linear accelerators since the RF sources have always defined what is possible to achieve with these accelerators. Circular machines, cyclotrons, synchrotrons, etc. have usually not been limited by the RF power available and the machine builders have usually had their RF power source requirements met off the shelf. The main challenge for the RF scientist has been then in the areas of controls. An interesting example of this is in the Conceptual Design Report of the Superconducting Super Collider (SSC) where the RF system is described in six pages of text in a 700-page report. Also, the cost of that RF system is about one-third of a percent of the project's total cost. The RF system is well within the state of the art and no new power sources need to be developed. All the intellectual effort of the system designer would be devoted to the feedback systems necessary to stabilize beams during storage and acceleration, with the main engineering challenges (and costs) being in the superconducting magnet lattice

Performance test of lower hybrid waveguide under long/high-RF power transmission

Energy Technology Data Exchange (ETDEWEB)

Seki, Masami; Obara, Kenjiro; Maebara, Sunao [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; and others

1996-06-01

Performance tests of a module for lower hybrid waveguides were carried out at the CEA Cadarache RF Test Facility. For the experiments the test module was fabricated by JAERI, the transmission line of the test bed was modified and the connection waveguides were manufactured by CEA. As the results, the thermal treatment by baking at a higher temperature was the most effective for reducing outgassing during injection of high RF power. The outgassing strongly depended on the temperature of the test module, but was independent to initial temperature. The RF injection reduced outgassing. The outgassing rate decreased to a low level of 10{sup -6}-10{sup -5} Pa m{sup 3}/sec m{sup 2} (10{sup -9}-10{sup -8} Torr 1/sec cm{sup 2}) at 400degC after 450degC-baking. The gas injection did not affect outgassing before and during RF injection. The baking under H{sub 2} or D{sub 2} gas atmosphere were not so effective for reducing outgassing rate. The outgassing rate did not depend on input RF power densities. The temperature in central part of the test module saturated to be {approx}100degC by using of water cooling at a power level of 150 MW/m{sup 2} RF injection, and a neutral gas pressure decreased gradually. In the water cooling case, the outgassing rate was very low less than 10{sup -7} Pa m{sup 3}/sec m{sup 2} (10{sup -10} Torr 1/sec cm{sup 2}). The steady state RF injection was demonstrated with water cooling. (author).

RF Energy Harvesting Peel-and-Stick Sensors

Energy Technology Data Exchange (ETDEWEB)

Lalau-Keraly, Christopher [PARC; Schwartz, David; Daniel, George; Lee, Joseph

2017-08-29

PARC, a Xerox Company, is developing a low-cost system of peel-and-stick wireless sensors that will enable widespread building environment sensor deployment with the potential to deliver up to 30% energy savings. The system is embodied by a set of RF hubs that provide power to the automatically located sensor nodes, and relays data wirelessly to the building management system (BMS). The sensor nodes are flexible electronic labels powered by rectified RF energy transmitted by a RF hub and can contain multiple printed and conventional sensors. The system design overcomes limitations in wireless sensors related to power delivery, lifetime, and cost by eliminating batteries and photovoltaic devices. The sensor localization is performed automatically by the inclusion of a programmable multidirectional antenna array in the RF hub. Comparison of signal strengths when the RF beam is swept allows for sensor localization, further reducing installation effort and enabling automatic recommissioning of sensors that have been relocated, overcoming a significant challenge in building operations. PARC has already demonstrated wireless power and temperature data transmission up to a distance of 20m with a duty cycle less than a minute between measurements, using power levels well within the FCC regulation limits in the 902-928 MHz ISM band. The sensor’s RF energy harvesting antenna dimensions was less than 5cmx9cm, demonstrating the possibility of small form factor for the sensor nodes.

Lifespan studies on different strains of mice exposed chronically to low levels of whole body gamma irradiation

International Nuclear Information System (INIS)

Fox, L.A.; Klein, A.K.; Cain, G.R.; Rosenblatt, L.S.

1982-01-01

Several strains of mice, chosen for their predisposition to immunohematological disorders, were exposed to low levels of 60 irradiation continuously for four weeks. All individuals were subsequently followed throughout their lifetimes. W/W/sup v/ mice, which are tyically subject to a stem cell deficiency, had a lower cumulative survival rate for the irradiated group than for the unirradiated controls. Irradiated RF/sub j/ mice had a dramatically lower cumulative survival rate than their unirradiated controls. Conversely, BXSB mice, which have a lumphoproliferative autoimmune disorder, had a higher cumulative survival rate after chronic irradiation than did unirradiated BXSBs. Irradiation had no effect upon the survival rate curves of the NZB strain, the murine model for Lupus Erythematosus

Onset of chaos and dc current-voltage characteristics of rf-driven Josephson junctions in the low-frequency regime

International Nuclear Information System (INIS)

Chi, C.C.; Vanneste, C.

1990-01-01

A comprehensive picture of the dc current-voltage (I-V) characteristics of rf-driven Josephson junctions in the low-frequency regime is presented. The boundary of the low-frequency regime is roughly defined by the junction characteristic frequency for overdamped junctions, and by the inverse of the junction damping time for underdamped junctions. An adiabatic model valid for the low-frequency regime is used to describe the overall shapes of the I-V curves, which is in good agreement with both the numerical simulations and the experimental results. For underdamped junctions, the Shapiro steps are the prominent features on the I-V curves if the rf frequency is sufficiently below the boundary. As the rf frequency is increased towards the boundary, large negatively-going tails on top of the Shapiro steps are observed both experimentally and numerically. Numerical simulations using the resistively- and capacitively-shunted-junction model (RCSJ model) reveal that the negatively-going tail is a signature of the low-frequency boundary of the junction chaotic regime. With use of the adiabatic model and the existence of plasma oscillations for underdamped junctions, the onset of chaos and its effect on the Shapiro steps can be fully explained. The high-frequency limit of the adiabatic model and the chaotic behavior of the Josephson junctions beyond the low-frequency regime are also briefly discussed

A divide-down RF source generation system for the Advanced Photon Source

International Nuclear Information System (INIS)

Horan, D.; Lenkszus, F.; Laird, R.

1997-01-01

A divide-down rf source system has been designed and built at Argonne National Laboratory to provide harmonically-related and phase-locked rf source signals between the APS 352-MHz storage ring and booster synchrotron rf systems and the 9.77-MHz and 117-MHz positron accumulator ring rf systems. The design provides rapid switching capability back to individual rf synthesizers for each one. The system also contains a digital bucket phase shifter for injection bucket selection. Input 352-MHz rf from a master synthesizer is supplied to a VXI-based ECL divider board which produces 117-MHz and 9.77-MHz square-wave outputs. These outputs are passed through low-pass filters to produce pure signals at the required fundamental frequencies. These signals, plus signals at the same frequencies from independent synthesizers, are fed to an interface chassis where source selection is made via local/remote control of coaxial relays. This chassis also produces buffered outputs at each frequency for monitoring and synchronization of ancillary equipment

Upgraded phase control system for superconducting low-velocity accelerating structures

International Nuclear Information System (INIS)

Added, N.

1992-01-01

Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the Rf cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This paper discusses recent upgrades to the ATLAS fast tuner which can now provide as much as 30 KVA of reactive tuning capability with a real RF power loss of less than 300 watts. The design was guided by numerical modeling of all elements of the device. Also discussed is the RF coupler which can couple 30 KW from 77 K tuner to a 42 K resonant cavity with less than 2 W of RF loss into 4.2 K

Upgraded phase control system for superconducting low-velocity accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Added, N. (Sao Paulo Univ., SP (Brazil). Dept. de Fisica Nuclear); Clifft, B.E.; Shepard, K.W. (Argonne National Lab., IL (United States))

1992-01-01

Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the Rf cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This paper discusses recent upgrades to the ATLAS fast tuner which can now provide as much as 30 KVA of reactive tuning capability with a real RF power loss of less than 300 watts. The design was guided by numerical modeling of all elements of the device. Also discussed is the RF coupler which can couple 30 KW from 77 K tuner to a 42 K resonant cavity with less than 2 W of RF loss into 4.2 K.

Upgraded phase control system for superconducting low-velocity accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Added, N. [Sao Paulo Univ., SP (Brazil). Dept. de Fisica Nuclear; Clifft, B.E.; Shepard, K.W. [Argonne National Lab., IL (United States)

1992-09-01

Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the Rf cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This paper discusses recent upgrades to the ATLAS fast tuner which can now provide as much as 30 KVA of reactive tuning capability with a real RF power loss of less than 300 watts. The design was guided by numerical modeling of all elements of the device. Also discussed is the RF coupler which can couple 30 KW from 77 K tuner to a 42 K resonant cavity with less than 2 W of RF loss into 4.2 K.

New high power 200 MHz RF system for the LANSCE drift tube linac

International Nuclear Information System (INIS)

Lyles, J.; Friedrichs, C.; Lynch, M.

1998-01-01

The Los Alamos Neutron Science Center (LANSCE) linac provides an 800 MeV direct H + proton beam, and injects H - to the upgraded proton storage ring for charge accumulation for the Short Pulse Spallation Source. Accelerating these interlaced beams requires high average power from the 201.25 MHz drift tube linac (DTL) RF system. Three power amplifiers have operated at up to three Megawatts with 12% duty factor. The total number of electron power tubes in the RF amplifiers and their modulators has been reduced from fifty-two to twenty-four. The plant continues to utilize the original design of a tetrode driving a super power triode. Further increases in the linac duty factor are limited, in part, by the maximum dissipation ratings of the triodes. A description of the system modifications proposed to overcome these limitations includes new power amplifiers using low-level RF modulation for tank field control. The first high power Diacrode reg-sign is being delivered and a new amplifier cavity is being designed. With only eight power tubes, the new system will deliver both peak power and high duty factor, with lower mains power and cooling requirements. The remaining components needed for the new RF system will be discussed

Dead beat filling and feedforward rf control for the spallation neutron source SNQ

International Nuclear Information System (INIS)

Schulze, D.

1982-01-01

For the 1.1 GeV-100 mA Spallation Neutron Source SNQ operation costs and beam losses ask for the possible potential of rf control improvements. Two novel methods are investigated. First, in order to increase the overall rf efficiency, the cavity field is built up as fast as possible in the open loop state of feedback control and in detuned position of the cavity in such a manner that the cavity with beam is matched to the generator. It is shown that this requires the simulataneous application of a generator amplitude and a generator phase step. Secondly, a feedforward control system is proposed, which reduces the amplitude and phase control error caused by an arbitrary beam transient into the limits of +-0.1% and +-0.1 0 and maintains these error limits also in the presence of parameter drift. This is done by an adaptive parameter adjustment procedure using a digital model of the control system. The system structure and a promising digital simulation are discussed

Low-level alcohol consumption during adolescence and its impact on cognitive control development.

Science.gov (United States)

Jurk, Sarah; Mennigen, Eva; Goschke, Thomas; Smolka, Michael N

2018-01-01

Adolescence is a critical period for maturation of cognitive control and most adolescents start experimenting with alcohol around that time. On the one hand, recent studies indicate that low control abilities predict future problematic alcohol use. On the other hand, binge drinking during young adulthood can (further) impair cognitive control. However, so far no study examined the effects of low-level alcohol use during adolescence. In the present longitudinal fMRI study, we therefore investigated the development of cognitive control in a community-based sample of 92 adolescents at ages 14, 16 and 18. Two different cognitive control functions, i.e. inhibition of pre-potent responses (operationalized by incongruence effects) and switching between different task sets, were measured within one task. Alcohol use in our sample was low (mean: 54 g/week at age 18). The study revealed that neither behavioural nor neural measures of cognitive control function at age 14 predicted alcohol use at age 18 but confirmed established predictors such as gender and personality. As expected, from age 14 to 18, cognitive control abilities were improving (decreased reaction times and/or errors), and activation of cognitive control networks (dorsal anterior cingulate cortex and pre-supplementary motor area) during incongruent trials increased. Unexpectedly, higher alcohol consumption during adolescence was associated with a more pronounced increase in cognitive performance and a smaller increase of neural activation when incongruent trials afforded inhibitory control. We conclude that low-level alcohol use during adolescence does not severely impair ongoing maturation of cognitive control abilities and networks. © 2016 Society for the Study of Addiction.

The Bohm criterion for rf discharges

International Nuclear Information System (INIS)

Meijer, P.M.; Goedheer, W.J.

1991-01-01

The well-known dc Bohm criterion is extended to rf discharges. Both low- (ω rf much-lt ω pi ) and high-(ω pi much-lt ω rf ) frequency regimes are considered. For low frequencies, the dc Bohm criterion holds. This criterion states that the initial energy of the ions entering the sheath must exceed a limit in order to obtain a stable sheath. For high frequencies, a modified limit is derived, which is somewhat lower than that of the dc Bohm criterion. The resulting ion current density in a high-frequency sheath is only a few percent lower than that for the dc case

RF slice profile effects in magnetic resonance fingerprinting.

Science.gov (United States)

Hong, Taehwa; Han, Dongyeob; Kim, Min-Oh; Kim, Dong-Hyun

2017-09-01

The radio frequency (RF) slice profile effects on T1 and T2 estimation in magnetic resonance fingerprinting (MRF) are investigated with respect to time-bandwidth product (TBW), flip angle (FA) level and field inhomogeneities. Signal evolutions are generated incorporating the non-ideal slice selective excitation process using Bloch simulation and matched to the original dictionary with and without the non-ideal slice profile taken into account. For validation, phantom and in vivo experiments are performed at 3T. Both simulations and experiments results show that T1 and T2 error from non-ideal slice profile increases with increasing FA level, off-resonance, and low TBW values. Therefore, RF slice profile effects should be compensated for accurate determination of the MR parameters. Copyright © 2017 Elsevier Inc. All rights reserved.

Development of L-band pillbox RF window

International Nuclear Information System (INIS)

Takeuchi, Y.; Fukuda, S.; Hisamatsu, H.; Saito, Y.; Takahashi, A.

1994-01-01

A pillbox RF output window was developed for the L-band pulsed klystron for the Japanese Hadron Project (JHP) 1-GeV proton linac. The window was designed to withstand a peak RF power of 6 MW, where the pulse width is 600 μsec and the repetition rate is 50 Hz. A high power model was fabricated using an alumina ceramic which has a low loss tangent of 2.5x10 -5 . A high power test was successfully performed up to a 113 kW RF average power with a 4 MW peak power, a 565 μsec pulse width and a 50 Hz repetition rate. By extrapolating the data of this high power test, the temperature rise of the ceramic is estimated low enough at the full RF power of 6 MW. Thus this RF window is expected to satisfy the specifications of the L-band Klystron. (author)

AN ALTERNATIVE APPROACH TO LOW FREQUENCY RF ACCELERATORS AND POWER SOURCES

International Nuclear Information System (INIS)

ZHAO, Y.

2001-01-01

The Muon Collider and Neutrino Factory projects require low frequency rf cavities because the size and emittance of the muon beam is much larger than is usual for electron or proton beams. The range of 30 MHz to 200 MHz is of special interest. However, the size of an accelerator with low frequency will be impractically large if it is simply scaled up from usual designs. In addition, to get very high peak power in this range is difficult. Presented in this paper is an alternative structure that employs a quasi-lumped inductance that can significantly reduce the transverse size while keeping high gradient. Also addressed is a power compression scheme with a thyratron. This gives a possible solution to provide very high peak power

Electron Beam Energy Compensation by Controlling RF Pulse Shape

CERN Document Server

Kii, T; Kusukame, K; Masuda, K; Nakai, Y; Ohgaki, H; Yamazaki, T; Yoshikawa, K; Zen, H

2005-01-01

We have studied on improvement of electron beam macropulse properties from a thermionic RF gun. Though a thermionic RF gun has many salient features, there is a serious problem that back-bombardment effect worsens quality of the beam. To reduce beam energy degradation by this effect, we tried to feed non-flat RF power into the gun. As a result, we successfully obtained about 1.5 times longer macropulse and two times larger total charge per macropulse. On the other hand, we calculated transient evolution of RF power considering non-constant beam loading. The beam loading is evaluated from time evolution of cathode temperature, by use of one dimensional heat conduction model and electron trajectories' calculations by a particle simulation code. Then we found good agreement between the experimental and calculation results. Furthermore, with the same way, we studied the electron beam output dependence on the cathode radius.

Reducing Energy Degradation Due to Back-bombardment Effect with Modulated RF Input in S-band Thermionic RF Gun

Science.gov (United States)

Kii, Toshiteru; Nakai, Yoko; Fukui, Toshio; Zen, Heishun; Kusukame, Kohichi; Okawachi, Norihito; Nakano, Masatsugu; Masuda, Kai; Ohgaki, Hideaki; Yoshikawa, Kiyoshi; Yamazaki, Tetsuo

2007-01-01

Energy degradation due to back-bombardment effect is quite serious to produce high-brightness electron beam with long macro-pulse with thermionic rf gun. To avoid the back-bombardment problem, a laser photo cathode is used at many FEL facilities, but usually it costs high and not easy to operate. Thus we have studied long pulse operation of the rf gun with thermionic cathode, which is inexpensive and easy to operate compared to the photocathode rf gun. In this work, to reduce the energy degradation, we controlled input rf power amplitude by controlling pulse forming network of the power modulator for klystron. We have successfully increased the pulse duration up to 4 μs by increasing the rf power from 7.8 MW to 8.5 MW during the macro pulse.

Profile Control by Biased Electrodes in Large Diameter RF Produced Pl asma

Science.gov (United States)

Shinohara, Shunjiro; Matsuoka, Norikazu; Yoshinaka, Toshiro

1998-10-01

Control of the plasma profile has been carried out, using the voltage biasing method in the large diameter (45 cm) RF (radio frequency) produced plasma in the presence of the uniform magnetic field (less than 1200 G). Under the low filling pressure condition of 0.16 mTorr, changing the biasing voltages to the three individual end plates with concentric circular ring shapes, the radial electron density (about 10^10 cm-3) profile could be changed from the hollow to the peaked one. On the contrary, the nearly flat electron temperature (several eV) profile did not change appreciably. The azimuthal rotation velocity measured by the Mach probe, i.e. directional probe, showed the different radial profiles (but nearly uniform along the axis) depending on the biasing voltage. This velocity became slower with the low magnetic field (less than 200 G) or in the higher pressure regime up to 20 mTorr with the higher electron density. The experimental results by other biasing methods will also be presented.

Upgraded phase control system for superconducting low-velocity accelerating structures

Energy Technology Data Exchange (ETDEWEB)

Added, N [Sao Paulo Univ., SP (Brazil); Clifft, B E; Shepard, K W [Argonne National Lab., IL (United States)

1992-11-01

Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the RF cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This paper discusses recent upgrades to the ATLAS fast tuner which can now provide as much as 30 KVA of reactive tuning capability with a real RF power loss of less than 300 watts. The design was guided by numerical modeling of all elements of the device. Also discussed is the RF coupler which can couple 30 KW from 77 K tuner to a 4.2 K resonant cavity with less than 2 W of RF loss into 4.2 K. (Author) 6 refs., 2 figs.

Upgraded phase control system for superconducting low-velocity accelerating structures

International Nuclear Information System (INIS)

Added, N.; Clifft, B.E.; Shepard, K.W.

1992-01-01

Microphonic-induced fluctuations in the RF eigenfrequency of superconducting (SC) slow-wave structures must be compensated by a fast-tuning system in order to control the RF phase. The tuning system must handle a reactive power proportional to the product of the frequency range and the RF energy content of the RF cavity. The fast tuner for the SC resonators in the ATLAS heavy-ion linac is a voltage-controlled reactance based on an array of PIN diodes operating immersed in liquid nitrogen. This paper discusses recent upgrades to the ATLAS fast tuner which can now provide as much as 30 KVA of reactive tuning capability with a real RF power loss of less than 300 watts. The design was guided by numerical modeling of all elements of the device. Also discussed is the RF coupler which can couple 30 KW from 77 K tuner to a 4.2 K resonant cavity with less than 2 W of RF loss into 4.2 K. (Author) 6 refs., 2 figs

Indoor Wireless RF Energy Transfer for Powering Wireless Sensors

Directory of Open Access Journals (Sweden)

H. Visser

2012-12-01

Full Text Available For powering wireless sensors in buildings, rechargeable batteries may be used. These batteries will be recharged remotely by dedicated RF sources. Far-field RF energy transport is known to suffer from path loss and therefore the RF power available on the rectifying antenna or rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency of the rectenna will also be very low. By optimizing not only the subsystems of a rectenna but also taking the propagation channel into account and using the channel information for adapting the transmit antenna radiation pattern, the RF energy transport efficiency will be improved. The rectenna optimization, channel modeling and design of a transmit antenna are discussed.

Design and manufacture of the RF power supply and RF transmission line for SANAEM project Prometheus

Science.gov (United States)

Turemen, G.; Ogur, S.; Ahiska, F.; Yasatekin, B.; Cicek, E.; Ozbey, A.; Kilic, I.; Unel, G.; Alacakir, A.

2017-08-01

A 1-5 MeV proton beamline is being built by the Turkish Atomic Energy Authority in collaboration with a number of graduate students from different universities. The primary goal of the project, is to acquire the design ability and manufacturing capability of all the components locally. SPP will be an accelerator and beam diagnostics test facility and it will also serve the detector development community with its low beam current. This paper discusses the design and construction of the RF power supply and the RF transmission line components such as its waveguide converters and its circulator. Additionally low and high power RF test results are presented to compare the performances of the locally produced components to the commercially available ones.

Emittance control and RF bunch compression in the NSRRC photoinjector

International Nuclear Information System (INIS)

Lau, W.K.; Hung, S.B.; Lee, A.P.; Chou, C.S.; Huang, N.Y.

2011-01-01

The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

Radiofrequency radiation exposure from RF-generating plant

International Nuclear Information System (INIS)

Wright, J.M.; Bell, K.M.

2000-01-01

As part of an intervention to assist industry improve the control of risks associated with the use of RF-generating plant, exposure to radiofrequency radiation (RFR) was assessed in 30 workplaces. Information about the workplace, work practices and knowledge about RFR and its control was also collected. The study found that: 1. For 72% of operators and 35% of bystanders, the spatially averaged exposure exceeded the exposure limits. These figures approximately halved when the duty cycle was applied; 2. Assessment of RFR levels was not common; 3. Task rotation was used to limit exposure of operators; 4. Access was not controlled to areas where RFR sources were used; 5. There was lack of knowledge about RF shielding practices in industry; 6. Nearly 50% of workplaces did not maintain the plant regularly; and 7. There had been no health surveillance on any plant operators in any of the workplaces in the study. Copyright (2000) Australasian Radiation Protection Society Inc

Operating experience with the new TRIUMF RF control system

International Nuclear Information System (INIS)

Fong, K.; Laverty, M.; Fang, S.

1995-06-01

The 23 MHz rf control of the TRIUMF cyclotron has been replaced by a new VXI control system based on digital signal processing. It provides amplitude and phase regulation of the cyclotron dee voltage, as well as other functions such as power-up sequencing, spark and high VSWR protection. Modularity of the hardware is achieved by the VXI architecture, and in the software by Object Oriented Programming. It is expected that this will result in a considerably longer MTBF, and shorter fault diagnosis and repair times, than the equipment it replaces. The new system has now been in operation for over two months. The results of commissioning, testing, and early operating experience are presented. (author). 4 refs., 5 figs

Discussion of high brightness rf linear accelerators

International Nuclear Information System (INIS)

Jameson, R.A.

1987-01-01

The fundamental aspects of high-brightness rf linacs are outlined, showing the breadth and complexity of the technology and indicating that synergism with advancements in other areas is important. Areas of technology reviewed include ion sources, injectors, rf accelerator structures, beam dynamics, rf power, and automatic control

First results on nitriding aluminium alloys in a low-pressure RF plasma

International Nuclear Information System (INIS)

Fewell, M.P.; Priest, J.M.; Collins, G.A.; Short, K.T.

2000-01-01

Full text: Aluminium alloys are now well established as materials of choice for many commercial applications, especially where strength-to-weight ratio is a critical parameter. However, their more widespread use is inhibited by their low surface hardness. For steels, similar problems can be overcome by nitriding. The nitrogen-rich surface layer has high hardness and load-bearing capacity, and is very well bonded to the substrate. The development of a similar surface-treatment process for aluminium alloys is clearly a desirable goal. It is therefore not surprising that many research groups worldwide have attempted to nitride aluminium. Much of this work studied pure aluminium, a material of no interest for structural applications. Previous investigations into nitriding aluminium alloys' had indifferent results. However, they have served to identify the key issues, which are the importance of a pre-cleaning steps to remove the surface oxide, of impurity control during the nitriding and the desirability of using as low a process temperature as possible. In all of these areas, our process using a low-pressure RF plasma is likely to be competitive. In view of this, we have undertaken a comparative study of a range of commercially available aluminium alloys. All treatments were carried out in the hot-wall nitriding reactor at ANSTO. The samples consist of disks 25mm in diameter and ∼3mm thick which were polished and ultrasonically cleaned in alcohol prior to treatment. The samples were stored in air at all times except when in the nitriding reactor. In a series of treatments, the treatment time was varied in the range 1-16 h and the temperature in the range 350-500 deg C. All treatments were preceeded by a plasma cleaning step in a H 2 /50%Ar mixture for a duration of 1.5-2.0 h while the reactor reached processing temperature. The treatments all used pure N 2 at a pressure of 0.4Pa and a nitrogen flow rate of 12μmol s -1 , with 245W of rf power at 13.56MHz applied to

1 ms pulse beam generation and acceleration by photo-cathode RF gun

International Nuclear Information System (INIS)

Watanabe, Ken; Hayano, Hitoshi; Urakawa, Jyunji

2012-01-01

We report successful generation of 1 ms long pulse and multi-bunch electron beam by a normal conducting photo-cathode RF gun at KEK-STF (Superconducting accelerator Test Facility). The 1 ms long Pulse beam generated by the RF gun is delivered to the injection line to examine stable acceleration and precise RF control. The 1 ms pulse beam is also used to demonstrate high brightness X-ray generation by inverse laser Compton scattering which will be also carried out at STF, supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. Performing high power RF process and ethanol rinse to the cavity, a stable operation of the cavity up to 4.0 MW RF input power with ∼1 ms pulse length was achieved by keeping even low dark current. The beam generation test has been started since February 2012, 1 ms pulse was generated in March 2012. We explain about the STF injector and report the basic property of this 1 ms beam generation. (author)

Electron dynamics in RF sources with a laser controlled emission

CERN Document Server

Khodak, I V; Metrochenko, V V

2001-01-01

Photoemission radiofrequency (RF) electron sources are sources of electron beams with extremely high brightness. Beam bunching processes in such devices are well studied in case when laser pulse duration is much lower of rf oscillation period.At the same time photoemission RF guns have some merits when operating in 'long-pulse' mode. In this case the laser pulse duration is much higher of rf oscillation period but much lower of rise time of oscillations in a gun cavity. Beam parameters at the gun output are compared for photoemission and thermoemission cathode applications. The paper presents results of a beam dynamics simulation in such guns with different resonance structures. Questions connected with defining of the current pulse peak value that can be obtained in such guns are discussed.

Wafer-Level Packaging Method for RF MEMS Applications Using Pre-Patterned BCB Polymer

Directory of Open Access Journals (Sweden)

Zhuhao Gong

2018-02-01

Full Text Available A radio-frequency micro-electro-mechanical system (RF MEMS wafer-level packaging (WLP method using pre-patterned benzo-cyclo-butene (BCB polymers with a high-resistivity silicon cap is proposed to achieve high bonding quality and excellent RF performance. In this process, the BCB polymer was pre-defined to form the sealing ring and bonding layer by the spin-coating and patterning of photosensitive BCB before the cavity formation. During anisotropic wet etching of the silicon wafer to generate the housing cavity, the BCB sealing ring was protected by a sputtered Cr/Au (chromium/gold layer. The average measured thickness of the BCB layer was 5.9 μm. In contrast to the conventional methods of spin-coating BCB after fabricating cavities, the pre-patterned BCB method presented BCB bonding layers with better quality on severe topography surfaces in terms of increased uniformity of thickness and better surface flatness. The observation of the bonded layer showed that no void or gap formed on the protruding coplanar waveguide (CPW lines. A shear strength test was experimentally implemented as a function of the BCB widths in the range of 100–400 μm. The average shear strength of the packaged device was higher than 21.58 MPa. A RF MEMS switch was successfully packaged using this process with a negligible impact on the microwave characteristics and a significant improvement in the lifetime from below 10 million to over 1 billion. The measured insertion loss of the packaged RF MEMS switch was 0.779 dB and the insertion loss deterioration caused by the package structure was less than 0.2 dB at 30 GHz.

RF Coupler Design for the TRIUMF ISAC-II Superconducting Quarter Wave Resonator

CERN Document Server

Poirier, R L; Harmer, P; Laxdal, R E; Mitra, A K; Sekatchev, I; Waraich, B; Zvyagintsev, V

2004-01-01

An RF Coupler for the ISAC-II medium beta (β=0.058 and 0.071) superconducting quarter wave resonators was designed and tested at TRIUMF. The main goal of this development was to achieve stable operation of superconducting cavities at high acceleration gradients and low thermal load to the helium refrigeration system. The cavities will operate at 6 MV/m acceleration gradient in overcoupled mode at a forward power 200 W at 106 MHz. The overcoupling provides ±20 Hz cavity bandwidth, which improves the stability of the RF control system for fast helium pressure fluctuations, microphonics and environmental noise. Choice of materials, cooling with liquid nitrogen, aluminum nitride RF window and thermal shields insure a small thermal load on the helium refrigeration system by the Coupler. An RF finger contact which causedμdust in the coupler housing was eliminated without any degradation of the coupler performance. RF and thermal calculations, design and test results on the coupler are p...

Overview and status of RF systems for the SSC Linac

International Nuclear Information System (INIS)

Mynk, J.; Grippe, J.; Cutler, R.I.; Rodriguez, R.

1993-05-01

The Superconducting Super Collider (SSC) Linear Accelerator (Linac) produces a 600-MeV, 35-μs, H-beam at a 10-Hz repetition rate. The beam is accelerated by a series of RF cavities. These consist of a Radio Frequency Quadrupole (RFQ), two bunchers, and four Drift Tube Linac (DTL) tanks at 427.617 MHz, and two bunchers, nine side-coupled Linac modules, and an energy compressor at 1282.851 MHz. The RFQ amplifier and the low-frequency buncher cavity amplifiers use gridded tubes, while the other cavities use klystron amplifier systems. The RF control system consists of a reference line and cavity feedback and feedforward loops for each amplifier. The RF amplifier system for each of these accelerator cavities is described, and the current status of each system is presented

Adaptive RF front-ends for hand-held applications

CERN Document Server

van Bezooijen, Andre; van Roermund, Arthur

2010-01-01

The RF front-end - antenna combination is a vital part of a mobile phone because its performance is very relevant to the link quality between hand-set and cellular network base-stations. The RF front-end performance suffers from changes in operating environment, like hand-effects, that are often unpredictable. ""Adaptive RF Front-Ends for Hand-Held Applications"" presents an analysis on the impact of fluctuating environmental parameters. In order to overcome undesired behavior two different adaptive control methods are treated that make RF frond-ends more resilient: adaptive impedance control,

Design, development and operational experience of radio frequency (RF) power systems/technologies for LEHIPA and 400 keV RFQ

International Nuclear Information System (INIS)

Pande, Manjiri; Shrotriya, Sandip; Patel, Niranjan

2015-01-01

The important technology development for ion accelerators of 'accelerator driven sub critical reactor system (ADS) is being done under the program of Department of Atomic Energy (DAE). In BARC (BARC) of DAE, technology development of 400 keV radio frequency quadrupole (RFQ) accelerator is done and a 20 MeV - low energy high intensity proton accelerator (LEHIPA) is under development. A 400 KeV deuteron RFQ accelerator is already developed at BARC and its 60 kW radio frequency (RF) power system required for beam acceleration has been designed, developed and tested both in CW mode and in pulse mode for full power of 60 leW. It has been successfully integrated with RFQ via 6-1/8'', 50 ohm RF transmission line, to accelerate proton beam up to 200 KeV energy and deuteron beam to 400 KeV energy. LEHIPA requires about 3 MW of RF power for its operation. So, three 1 MW, 352 MHz RF systems based on klystron will be developed for RFQ and two DTLs. The klystron based RF system for 3 MeV RFQ is under commissioning. Its various subsystems like energy less and insulated gate bipolar transistor (IGBT) based high voltage and low voltage bias supplies, a critical and fast protection and control system - handling various types of field signals, fast acting hard wired instrumentation circuits for critical signals, 100 kV crowbar with its circuits, pulsing circuits and RF circuits have been successfully designed, developed and integrated with klystron. Latest technology development of solid state RF amplifiers at 325 MHz and 350 MHz for normal and super conducting accelerators has attained a certain power level. This paper will discuss all these high power RF systems in detail. (author)

Rf Station For Ion Beam Staking In Hirfl-csr

CERN Document Server

Arbuzov, V S; Bushuev, A A; Dranichnikov, A N; Gorniker, E I; Kendjebulatov, E K; Kondakov, A A; Kondaurov, M; Kruchkov, Ya G; Krutikhin, S A; Kurkin, G Ya; Mironenko, L A; Motygin, S V; Osipov, V N; Petrov, V M; Pilan, Andrey M; Popov, A M; Rashenko, V V; Selivanov, A N; Shteinke, A R; Vajenin, N F

2004-01-01

BINP has developed and produced the RF station for Institute of Modern Physics (IMP), Lanzhou, China, for multipurpose accelerator complex with electron cooling. The RF station will be used for accumulation of ion beams in the main ring of the system. It was successfully tested in IMP and installed into the main accelerator ring of the complex. The RF station includes accelerating RF cavity and RF power generator with power supplies. The station works within frequency range 6.0 - 14.0 MHz, maximum voltage across the accelerating gap of the RF cavity - 20 kV. In the RF cavity the 200 VNP ferrite is utilized. A residual gas pressure in vacuum chamber does not exceed 2,5E-11 mbar. Maximum output power of the RF generator 25 kW. The data acquisition and control of the RF station is based on COMPACT - PCI bus and provides all functions of monitoring and control.

Peel-and-Stick Sensors Powered by Directed RF Energy

Energy Technology Data Exchange (ETDEWEB)

Lalau-Keraly, Christopher; Daniel, George; Lee, Joseph; Schwartz, David

2017-08-30

PARC, a Xerox Company, is developing a low-cost system of peel-and-stick wireless sensors that will enable widespread building environment sensor deployment with the potential to deliver up to 30% energy savings. The system is embodied by a set of RF hubs that provide power to automatically located sensor nodes, and relay data wirelessly to the building management system (BMS). The sensor nodes are flexible electronic labels powered by rectified RF energy transmitted by an RF hub and can contain multiple printed and conventional sensors. The system design overcomes limitations in wireless sensors related to power delivery, lifetime, and cost by eliminating batteries and photovoltaic devices. Sensor localization is performed automatically by the inclusion of a programmable multidirectional antenna array in the RF hub. Comparison of signal strengths while the RF beam is swept allows for sensor localization, reducing installation effort and enabling automatic recommissioning of sensors that have been relocated, overcoming a significant challenge in building operations. PARC has already demonstrated wireless power and temperature data transmission up to a distance of 20m with less than one minute between measurements, using power levels well within the FCC regulation limits in the 902-928 MHz ISM band. The sensor’s RF energy harvesting antenna achieves high performance with dimensions below 5cm x 9cm

Microprocessor-based control for independently-phased RF linac cavities

International Nuclear Information System (INIS)

Dawson, J.W.

1979-01-01

A microprocessor based system has been built to control the RF amplifiers associated with independently phased linac cavities. The system has an 8080A at each amplifier station, together with associated ROM, RAM, I/O, etc. At a central NOVA 3 computer an additional 8080A system is incorporated in the interface to the NOVA I/O bus. The NOVA interface is connected by a bus of eighteen twisted pairs to each amplifier station, providing bilateral transmission between each station and the NOVA. The system architecture, bus protocol, and operating characteristics are described

Testing of super conducting low-beta 704 Mhz cavities at 50 Hz pulse repetition rate in view of SPL- first results

CERN Document Server

Höfle, W; Lollierou, J; Valuch, D; Chel, S; Devanz, G; Desmons, M; Piquet, O; Paparella, R; Pierini, P

2010-01-01

In the framework of the preparatory phase for the luminosity upgrade of the LHC (SLHC-PP ) it is foreseen to characterize two superconducting RF cavities and demonstrate compliance of the required SPL field stability in amplitude and phase using a prototype LLRF system. We report on the preparation for testing of two superconducting low-beta cavities at 50 Hz pulse repetition rate including the setting-up of the low level RF control system to evaluate the performance of the piezo-tuning system and cavity field stability in amplitude and phase. Results from tests with 50 Hz pulse repetition rate are presented. Simulations of the RF system will be used to predict the necessary specifications for power and bandwidth to control the cavity field and derive specifications for the RF system and its control. Exemplary results of the simulation are presented.

Neoclassical effects on RF current drive in tokamaks

International Nuclear Information System (INIS)

Yoshioka, K.; Antonsen, T.M. Jr.

1986-01-01

Neoclassical effects on RF current drive which arise because of the inhomogeneity of the magnetic field in tokamak devices are analysed. A bounce averaged 2-D Fokker-Planck equation is derived from the drift kinetic equation and is solved numerically. The model features current drive due to a strong RF wave field. The efficiency of current drive by electron cyclotron waves is significantly reduced when the waves are absorbed at the low magnetic field side of a given flux surface, whereas the efficiency remains at the same level as in the homogeneous ideal plasma when the waves are absorbed at the high field side. The efficiency of current drive by fast waves (compressional Alfven waves) with low phase velocity (vsub(parallel)/vsub(th)<1) is significantly degraded by neoclassical effects, no matter where the wave is absorbed, and the applicability of this wave seems, therefore, to be doubtful. (author)

PEP-II RF System Operation and Performance

International Nuclear Information System (INIS)

McIntosh, P.

2005-01-01

The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured. The Low Energy Ring (LER) and High Energy Ring (HER) RF systems have operated now on PEP-II since July 1998 and have assisted in breaking all design luminosity records back in June 2001. Luminosity on PEP-II has steadily increased since then as a consequence of larger e+ and e- beam currents being accumulated. This has meant that the RF systems have inevitably been driven harder, not only to achieve these higher stored beam currents, but also to reliably keep the beams circulating whilst at the same time minimizing the number of aborts due to RF system faults. This paper details the current PEP-II RF system configurations for both rings, as well as future upgrade plans spanning the next 3-5 years. Limitations of the current RF system configurations are presented, highlighting improvement projects which will target specific areas within the RF systems to ensure that adequate operating overheads are maintained and reliable operation is assured

A study on water level control of PWR steam generator at low power and the self-tuning of its fuzzy controller

International Nuclear Information System (INIS)

Na, N.; Kwon, K.; Ham, C.; Bien, Z.

1994-01-01

The water level control system of a steam generator in a pressurized water reactor and its control problems during the operation at low power is analysed. In particular, a strategy for a water level control system, which is based on the use of a fuzzy logic controller, is proposed. The control strategy includes dynamic tuning for the large transient. The fuzzy variable of the flow rate during the power operation is obtained from the bypass valve opening and not from the incorrect measured signal at the low flow rate. The practical self-tuning algorithm is based on the optimal control performance

Kinetics of lymphohematopoiesis and leukemia induction in chronically whole-body irradiated RF/J mice

International Nuclear Information System (INIS)

Cain, G.R.; Stitzel, K.A.; Fox, L.A.; Klein, A.K.; Dyck, J.A.; Shimizu, J.A.; Rosenblatt, L.S.

1982-01-01

Lymphohematopoietic progenitor cell populations (bone marrow CFU-GM, splenic CFU-BL) were quantitated in unirradiated and in chronically irradiated (17.5 R/day for 4 weeks) RF/J mice and control CAF 1 mice. RF/J mice were found capable of making substantial numbers of bone marrow CFU-GM but less so than the control strain CAF 1 . Significant strain differences were also seen in ability to form splinic B lymphocyte progenitor cells (CFU-BL). Unirradiated and irradiated RF mice produced over three times as many CFU-BL as CAF 1 mice. Throughout the period of protracted irradiation, followed by a twelve week recovery period, CFU-BL and CFU-GM were depressed less in the RF strain than the CAF 1 strain. This was due to an overcompensatory regenerative response which surpassed homostatic baseline levels. Despite strain and strain x dose differences in CFU-BL and CFU-GM, no significant strain x dose relationships were seen in circulati leukocyte counts. The increased susceptibility of RF mice to radiation-induced leukemia may be related to either inherent depressed regulatory control or the persistence of progenitor cell compartments. An apparent increased cell turnover rate in both CFU-BL and CFU-GM in RF mice following radiation damage may likewise play a contributory role

RF applications in digital signal processing

CERN Document Server

Schilcher, T

2008-01-01

Ever higher demands for stability, accuracy, reproducibility, and monitoring capability are being placed on Low-Level Radio Frequency (LLRF) systems of particle accelerators. Meanwhile, continuing rapid advances in digital signal processing technology are being exploited to meet these demands, thus leading to development of digital LLRF systems. The rst part of this course will begin by focusing on some of the important building-blocks of RF signal processing including mixer theory and down-conversion, I/Q (amplitude and phase) detection, digital down-conversion (DDC) and decimation, concluding with a survey of I/Q modulators. The second part of the course will introduce basic concepts of feedback systems, including examples of digital cavity eld and phase control, followed by radial loop architectures. Adaptive feed-forward systems used for the suppression of repetitive beam disturbances will be examined. Finally, applications and principles of system identi cation approaches will be summarized.

Developments on the RF system for the Fusion Materials Irradiation Test Facility accelerator

International Nuclear Information System (INIS)

Fazio, M.V.; Johnson, H.P.; Riggin, D.M.

1979-01-01

The rf system for the Fusion Materials Irradiation Test (FMIT) accelerator is currently in the design phase at the Los Alamos Scientific Laboratory (LASL). The 35-MeV, 100-mA deuteron beam will require approximately 6 MW of rf power at 80 MHz. The EIMAC 8973 power tetrode, capable of a 600-kW cw output, has been chosen as the final amplifier tube for each of 15 amplifier chains. The final power stage of each chain is designed to perform as a linear Class B amplifier. Each low-power rf system (less than or equal to 100W) is to be phase, amplitude, and frequency controlled to provide a drive signal for each high-power amplifier. Beam dynamics for particle acceleration and for minimal beam spill require each rf amplifier output to be phase controlled to +-1 0 . The amplitude of the accelerating field must be held to +-1%. A varactor-tuned electronic phase shifter and a linear phase detector are under development for use in this system. To complement hardware development, analog computer simulations are being performed to optimize the closed-loop control characteristics of the system

RF control studies for moderate beamtime coupling between SRF cavities

International Nuclear Information System (INIS)

Doolittle, L.R.; Wang, D.X.

1998-01-01

When an SRF accelerator is designed, there is motivation to move the cavities close together on the beamline. Assuming the beamline apertures are not shrunk as well, this compaction (which will increase the overall accelerating gradient and/or lower the dynamic cryogenic heat load) increases the inter-cavity coupling. Within certain limits, the control system can compensate for this coupling by retuning each of the cavities. This paper describes constraints on the RF system, tuners, couplers, and control systems that are required to provide stable operation of cavities in the presence of inter-cavity coupling that exceeds the loaded bandwidth of an individual cavity

Construing Morality at High versus Low Levels Induces Better Self-control, Leading to Moral Acts

Directory of Open Access Journals (Sweden)

Chia-Chun Wu

2017-06-01

Full Text Available Human morality entails a typical self-control dilemma in which one must conform to moral rules or socially desirable norms while exerting control over amoral, selfish impulses. Extant research regarding the connection between self-control and level of construal suggest that, compared with a low-level, concrete construal (highlighting means and resources, e.g., answering ‘how’ questions, a high-level, abstract construal (highlighting central goals, e.g., answering ‘why’ questions promotes self-control. Hence, construing morality at higher levels rather than lower levels should engender greater self-control and, it follows, promote a tendency to perform moral acts. We conducted two experiments to show that answering “why” (high-level construal vs. “how” (low-level construal questions regarding morality was associated with a situational state of greater self-control, as indexed by less Stroop interference in the Stroop color-naming task (Experiments 1 and 2. Participants exposed to “why” questions regarding morality displayed a greater inclination for volunteerism (Experiment 1, showed a lower tendency toward selfishness in a dictator game (Experiment 2, and were more likely to return undeserved money (Experiment 2 compared with participants exposed to “how” questions regarding morality. In both experiments, self-control mediated the effect of a high-level construal of morality on dependent measures. The current research constitutes a new approach to promoting prosociality and moral education. Reminding people to think abstractly about human morality may help them to generate better control over the temptation to benefit from unethical acts and make it more likely that they will act morally.

Construing Morality at High versus Low Levels Induces Better Self-control, Leading to Moral Acts.

Science.gov (United States)

Wu, Chia-Chun; Wu, Wen-Hsiung; Chiou, Wen-Bin

2017-01-01

Human morality entails a typical self-control dilemma in which one must conform to moral rules or socially desirable norms while exerting control over amoral, selfish impulses. Extant research regarding the connection between self-control and level of construal suggest that, compared with a low-level, concrete construal (highlighting means and resources, e.g., answering 'how' questions), a high-level, abstract construal (highlighting central goals, e.g., answering 'why' questions) promotes self-control. Hence, construing morality at higher levels rather than lower levels should engender greater self-control and, it follows, promote a tendency to perform moral acts. We conducted two experiments to show that answering "why" (high-level construal) vs. "how" (low-level construal) questions regarding morality was associated with a situational state of greater self-control, as indexed by less Stroop interference in the Stroop color-naming task (Experiments 1 and 2). Participants exposed to "why" questions regarding morality displayed a greater inclination for volunteerism (Experiment 1), showed a lower tendency toward selfishness in a dictator game (Experiment 2), and were more likely to return undeserved money (Experiment 2) compared with participants exposed to "how" questions regarding morality. In both experiments, self-control mediated the effect of a high-level construal of morality on dependent measures. The current research constitutes a new approach to promoting prosociality and moral education. Reminding people to think abstractly about human morality may help them to generate better control over the temptation to benefit from unethical acts and make it more likely that they will act morally.

Survey of European Community efforts in RF heating

International Nuclear Information System (INIS)

Consoli, T.

1981-01-01

The present paper briefly reviews the efforts made over the last 10 years, with particular emphasis on the period from 1978 to 1980. The RF heating experiments within EC are presented: low frequency heating; heating at medium frequencies (ICRH); RF heating at low hybrid frequency; heating at the ECR frequency. The plan of Tore-Supra is given

Superconducting RF for energy-recovery linacs

International Nuclear Information System (INIS)

Liepe, M.; Knobloch, J.

2006-01-01

Since superconducting RF for particle accelerators made its first appearance in the 1970s, it has found highly successful application in a variety of machines. Recent progress in this technology has made so-called Energy-Recovery Linacs (ERLs)-originally proposed in 1965-feasible, and interest in this type of machine has increased enormously. A superconducting linac is the driving heart of ERLs, and emittance preservation and cost efficiency is of utmost importance. The resulting challenges for the superconducting cavity technology and RF field control are manifold. In March 2005 the first international workshop on ERLs was held at Newport News, VA, to explore the potential of ERLs and to discuss machine-physics and technology challenges and their solutions. This paper reviews the state-of-the-art in superconducting RF and RF control for ERLs, and summarizes the discussions of the SRF working group on this technology during the ERL2005 workshop

Use of Ethernet and TCP/IP socket communications library routines for data acquisition and control in the LEP RF system

International Nuclear Information System (INIS)

Ciapala, E.; Collier, P.; Lienard, P.

1991-01-01

A general move is being made at CERN towards the direct connection of intelligent equipment and device controllers to the control room consoles by the use of local Ethernet segments bridged to the main Token Ring networks. Communications is based on standard TCP/IP protocols which allows immediate use of standard software packages. The Data Managers which control the LEP RF accelerating units and transverse feedback systems have recently been connected. The implementation of Ethernet and TCP/IP socket communications routines for RF data acquisition and control is described. The adaptation of almost all of the existing software for RF system control, data acquisition and diagnostics to make use of this means of communication has proved straightforward. Furthermore the transparent transfer of data in the form of 'C' structures from the Data Managers to the control center workstations and other computers has considerably simplified the software required for remote surveillance and data logging with a corresponding increase in speed and reliability

ISR RF cavities

CERN Multimedia

1983-01-01

In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

High power RF systems for LEHIPA of ADS

International Nuclear Information System (INIS)

Pande, Manjiri; Shrotriya, Sandip; Sharma, Sonal; Rao, B.V.R.; Mishra, J.K.; Patel, Niranjan; Gupta, S.K.

2011-01-01

Worldwide accelerator driven sub-critical system (ADS) has generated a huge interest for various reasons. In India, as a part of accelerator driven sub-critical system (ADS) program, a normal conducting, low energy high intensity proton accelerator (LEHIPA) of energy 20 MeV and beam current of 30 mA is being developed in Bhabha Atomic Research Centre (BARC). LEHIPA comprises of Electron Cyclotron Resonance (ECR) ion source (50 KeV), Radio Frequency Quadrupole (RFQ) accelerator (3 MeV) and Drift tube Linac (DTL) 1 and 2 (10 MeV and 20 MeV respectively). As per the accelerator physics design, RFQ requires nearly 530 kW RF power while each of DTL need 900 kW. Each accelerating cavity will be driven by a one- megawatt (CW) klystron based high power RF (HPRF) system at 352.21 MHz. Three such RF systems will be developed. The RF system has been designed around five cavity klystron tube TH2089F (Thales make) capable of delivering 1 MW continuous wave power at 352.21 MHz. The klystron has a gain of 40 dB and efficiency around 62 %. Each of the RF system comprises of a low power solid state driver (∼ 100 W), klystron tube, harmonic filter, directional coupler, Y-junction circulator (AFT make), RF load and WR2300 wave guide based RF transmission line each of 1 MW capacity. It also includes other subsystems like bias supplies (high voltage (HV) and low voltage (LV)), HV interface system, interlock and protection circuits, dedicated low conductivity water-cooling, pulsing circuitry/mechanisms etc. WR 2300 based RF transmission line transmits and feeds the RE power from klystron source to respective accelerating cavity. This transmission line starts from second port of the circulator and consists of straight sections, full height to half height transition, magic Tee, termination load at the centre of magic tee, half height sections, directional couplers and RE windows. For X-ray shielding, klystron will be housed in a lead (3 mm) based shielded cage. This system set up has a

RF-plasma interactions in the antenna near fields

Energy Technology Data Exchange (ETDEWEB)

Colestock, P.; Greene, G.J.; Hosea, J.C.; Phillips, C.K.; Stevens, J.E.; Ono, M.; Wilson, J.R. (Princeton Univ., NJ (USA). Plasma Physics Lab.); D' Ippolito, D.A.; Myra, J.R. (Lodestar Research Corp., Boulder, CO (USA)); Lehrman, I.S. (Grumman Aerospace Corp., Bethpage, NY (USA))

1990-04-01

An assessment is made of the various linear and nonlinear mechanisms that are likely to play a role in the near-field of Faraday shielded inductive antennas commonly used in ICRF heating experiments. A number of low-level, but potentially important, RF loss mechanisms have been proposed as candidates to explain the observed surface phenomena and impurity production associated with ICRF. These range from edge heating via linear processes, such as surface wave or Bernstein wave generation to a variety of nonlinear phenomena including parametric decay and RF-driven sheath effects. The various proposed mechanisms will be examined in this work in terms of the available experimental data and an evaluation will be made of the scaling of these phenomena to higher density and temperature plasmas. (orig.).

RF system considerations for large high-duty-factor linacs

International Nuclear Information System (INIS)

Lynch, M.T.; Ziomek, C.D.; Tallerico, P.J.; Regan, A.H.; Eaton, L.; Lawrence, G.

1994-01-01

RF systems are often a major cost item for linacs, but this is especially true for large high-duty-factor linacs (up to and including CW) such as the Accelerator for Production of Tritium (APT) or the Accelerator for Transmutation of nuclear Waste (ATW). In addition, the high energy and high average beam current of these machines (approximately 1 GeV, 100--200 mA) leads to a need for excellent control of the accelerating fields in order to minimize the possibility of beam loss in the accelerator and the resulting activation. This paper will address the key considerations and limitations in the design of the RF system. These considerations impact the design of both the high power RF components and the RF controls. As might be expected, the two concerns sometimes lead to conflicting design requirements. For example minimum RF operating costs lead to a desire for operation near saturation of the high power RF generators in order to maximize the operating efficiency. Optimal control of the RF fields leads to a desire for maximum overdrive capability in those same generators in order to respond quickly to disturbances of the accelerator fields

RF properties of high-T/sub c/ superconductors

International Nuclear Information System (INIS)

Bohn, C.L.; Delayen, J.R.; Dos Santos, D.I.; Lanagan, M.T.; Shepard, K.W.

1988-01-01

We have investigated the rf properties of high-T/sub c/ superconductors over a wide range of temperature, frequency, and rf field amplitude. We have tested both bulk polycrystalline samples and thick films on silver substrates. At 150 MHz and 4.2 K, we have measured a surface resistance of 18 μ/sup /OMEGA// at low rf field and 3.6 m/sup /OMEGA// at an rf field of 270 gauss. All samples showed a strong dependence of the surface resistance on rf field; however, no breakdown of the superconducting state has been observed up to the highest field achieved (320 gauss). 9 refs., 4 figs., 1 tab

High power rf component testing for the NLC

International Nuclear Information System (INIS)

Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.

1998-09-01

In the Next Linear Collider (NLC), the high power rf components must be capable of handling peak rf power levels in excess of 600 MW. In the current view of the NLC, even the rectangular waveguide components must transmit at least 300 MW rf power. At this power level, peak rf fields can greatly exceed 100 MV/m. The authors present recent results of high power tests performed at the Accelerator Structure Test Area (ASTA) at SLAC. These tests are designed to investigate the rf breakdown limits of several new components potentially useful for the NLC. In particular, the authors tested a new TE 01 --TE 10 circular to rectangular wrap-around mode converter, a modified (internal fin) Magic Tee hybrid, and an upgraded flower petal mode converter

An RF-to-DC energy harvester for co-integration in a low-power 2.4 GHz transceiver frontend

NARCIS (Netherlands)

Masuch, J.; Delgado-Restituto, M.; Milosevic, D.; Baltus, P.G.M.

2012-01-01

A 2.4 GHz energy harvester for co-integration into a low-power transceiver (TRx) operating at the same frequency is presented. An RF switch decouples the harvester from the TRx and keeps the performance degradation of the TRx low, i.e. 0.2 dB reduced output power in Tx-mode and 0.4 dB reduced

A Long-Distance RF-Powered Sensor Node with Adaptive Power Management for IoT Applications.

Science.gov (United States)

Pizzotti, Matteo; Perilli, Luca; Del Prete, Massimo; Fabbri, Davide; Canegallo, Roberto; Dini, Michele; Masotti, Diego; Costanzo, Alessandra; Franchi Scarselli, Eleonora; Romani, Aldo

2017-07-28

We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to -17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc.) are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna) and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT). A nonlinear/electromagnetic co-design procedure is adopted to design the rectenna, which is optimized to operate at ultra-low power levels. An ultra-low power microcontroller controls on-board sensors and wireless protocol, to adapt the power consumption to the available detected power by changing wake-up policies. As a result, adaptive behavior can be observed in the designed platform, to the extent that the transmission data rate is dynamically determined by RF power. Among the novel features of the system, we highlight the use of nano-power energy harvesting, the implementation of specific hardware/software wake-up policies, optimized algorithms for best sampling rate implementation, and adaptive behavior by the node based on the power received.

A Long-Distance RF-Powered Sensor Node with Adaptive Power Management for IoT Applications

Directory of Open Access Journals (Sweden)

Matteo Pizzotti

2017-07-01

Full Text Available We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to −17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc. are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT. A nonlinear/electromagnetic co-design procedure is adopted to design the rectenna, which is optimized to operate at ultra-low power levels. An ultra-low power microcontroller controls on-board sensors and wireless protocol, to adapt the power consumption to the available detected power by changing wake-up policies. As a result, adaptive behavior can be observed in the designed platform, to the extent that the transmission data rate is dynamically determined by RF power. Among the novel features of the system, we highlight the use of nano-power energy harvesting, the implementation of specific hardware/software wake-up policies, optimized algorithms for best sampling rate implementation, and adaptive behavior by the node based on the power received.

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

Science.gov (United States)

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

2017-05-01

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

Energy Technology Data Exchange (ETDEWEB)

Cha, Sungsu, E-mail: sscha@kaeri.re.kr [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Kim, Yujong; Lee, Byung Cheol [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Park, Hyung Dal [Radiation Technology eXcellence(RTX), Daejeon 34025 (Korea, Republic of); Lee, Seung Hyun [Department of Energy Science, Sungkyunkwan University(SKKU), Suwon 16419 (Korea, Republic of); Buaphad, Pikad [Nuclear Data Center, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057 (Korea, Republic of); Radiation Technology eXcellence(RTX), Daejeon 34025 (Korea, Republic of); Accelerator and Nuclear Fusion Physical Engineering, University of Science and Technology(UST), Daejeon 34113 (Korea, Republic of)

2017-05-21

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

International Nuclear Information System (INIS)

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

2017-01-01

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per

ORIC RF system: preparation for HHIRF

International Nuclear Information System (INIS)

Mosko, S.W.; Rylander, J.D.; Schulze, G.K.

1977-01-01

The integration of the Oak Ridge Isochronous Cyclotron (ORIC) into the Holifield Heavy Ion Research Facility (HHIRF) requires several rf system modifications to permit injection of ion beams from the 25 MV tandem electrostatic accelerator into ORIC. A new dee eliminates structural interference with the injected beam path and provides an opportunity to improve the mechanical stability of the resonator and to reduce rf voltage gradients in areas susceptible to sparking. Space for structural improvements is realized by reducing the ion beam aperture from 4.8 cm to 2.4 cm. The complexity of the original ORIC rf power system was substantially reduced. A new broadband solid state driver amplifier between the frequency synthesizer and the main power amplifier eliminates most circuit tuning and permits the use of a new simplified dee rf voltage regulator loop. Most of the remaining instrumentation and control circuitry is TTL compatible and will eventually tie to the ORIC computer control system through a CAMAC interface

On active disturbance rejection based control design for superconducting RF cavities

Energy Technology Data Exchange (ETDEWEB)

Vincent, John; Morris, Dan; Usher, Nathan [National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, East Lansing, MI 48824-1321 (United States); Gao, Zhiqiang, E-mail: z.gao@csuohio.edu [Center for Advanced Control Technologies, Fenn College of Engineering, Cleveland State University, Cleveland, OH 44115-2214 (United States); Zhao Shen; Nicoletti, Achille; Zheng Qinling [Center for Advanced Control Technologies, Fenn College of Engineering, Cleveland State University, Cleveland, OH 44115-2214 (United States)

2011-07-01

Superconducting RF (SRF) cavities are key components of modern linear particle accelerators. The National Superconducting Cyclotron Laboratory (NSCL) is building a 3 MeV/u re-accelerator (ReA3) using SRF cavities. Lightly loaded SRF cavities have very small bandwidths (high Q) making them very sensitive to mechanical perturbations whether external or self-induced. Additionally, some cavity types exhibit mechanical responses to perturbations that lead to high-order non-stationary transfer functions resulting in very complex control problems. A control system that can adapt to the changing perturbing conditions and transfer functions of these systems would be ideal. This paper describes the application of a control technique known as 'Active Disturbance Rejection Control' (ARDC) to this problem.

The duration of the institutional controls on the low and intermediate level waste repositories

International Nuclear Information System (INIS)

Yang Jie; Li Yang; Liu Yafang; Lian Bing; Zhao Yangjun; Chen Hailong; Gu Zhijie

2014-01-01

Appropriate institutional controls are put in place prior to repository closure. Such controls can guarantee the long term safety of the repository. Today there is no clear standard on how to determine the institutional control period. This paper tries to give possible factors and activities of the institutional controls on the low and intermediate level waste repositories, and makes some suggestions on the institutional controls in our country. (authors)

Alternative RF coupling configurations for H− ion sources

International Nuclear Information System (INIS)

Briefi, S.; Fantz, U.; Gutmann, P.

2015-01-01

RF heated sources for negative hydrogen ions both for fusion and accelerators require very high RF powers in order to achieve the required H − current what poses high demands on the RF generators and the RF circuit. Therefore it is highly desirable to improve the RF efficiency of the sources. This could be achieved by applying different RF coupling concepts than the currently used inductive coupling via a helical antenna, namely Helicon coupling or coupling via a planar ICP antenna enhanced with ferrites. In order to investigate the feasibility of these concepts, two small laboratory experiments have been set up. The PlanICE experiment, where the enhanced inductive coupling is going to be investigated, is currently under assembly. At the CHARLIE experiment systematic measurements concerning Helicon coupling in hydrogen and deuterium are carried out. The investigations show that a prominent feature of Helicon discharges occurs: the so-called low-field peak. This is a local improvement of the coupling efficiency at a magnetic field strength of a few mT which results in an increased electron density and dissociation degree. The full Helicon mode has not been achieved yet due to the limited available RF power and magnetic field strength but it might be sufficient for the application of the coupling concept to ion sources to operate the discharge in the low-field-peak region

RF tuning system for superconducting cyclotron at VECC

International Nuclear Information System (INIS)

Mandal, Aditya; Som, S.; Pal, Saikat; Seth, S.; Mukherjee, A.K.; Gangopadhyay, P.; Prasad, J.S.; Raj, P.R.; Manna, S.K.; Banerjee, M.; Krishnaiah, K.V.; Maskawade, S.; Saha, M.S.; Biswas, S.; Panda, Umashakar

2009-01-01

The RF system of Superconducting cyclotron at VECC has operational frequency 9-27 MHz. It has three numbers of tunable rf amplifier cavities as well as six numbers of tunable Main resonant cavities. RF tuning system takes care of movement of nine stepper motor based sliding short movement and hydraulic driven three coupling capacitors and three trimmer capacitors. The PC-based stepper motor controlled sliding short movement system has positional accuracy of around 20 micron and PC-based hydraulically driven couplers and trimmers system has 10 micron positional accuracy. The RF power is capacitively coupled to the dee (accelerating electrode) of the main resonant cavity through Coupler (Coupling capacitor). The coupling capacitor is used to match the impedance of the main resonant cavity to the 50 Ohm output impedance of final RF power amplifier. Trimmer capacitor operates in closed loop for the adjustment of cavity phase variation arising due to temperature variation and beam loading of the cavity. Coupler can travel 100 mm. and trimmer has 20 mm. travels. A PLC based PID control system has been developed for positional control of the coupler and trimmer. One position control mode of trimmer is same as coupling capacitor and another is velocity control mode. Velocity control mode operates in close-loop. The positional data of different frequencies of nine stepper motors and three coupling capacitors are stored in a database. (author)

Concept Study of Radio Frequency (RF Plasma Thruster for Space Propulsion

Directory of Open Access Journals (Sweden)

Anna-Maria Theodora ANDREESCU

2016-12-01

Full Text Available Electric thrusters are capable of accelerating ions to speeds that are impossible to reach using chemical reaction. Recent advances in plasma-based concepts have led to the identification of electromagnetic (RF generation and acceleration systems as able to provide not only continuous thrust, but also highly controllable and wide-range exhaust velocities. For Future Space Propulsion there is a pressing need for low pressure, high mass flow rate and controlled ion energies. This paper explores the potential of using RF heated plasmas for space propulsion in order to mitigate the electric propulsion problems caused by erosion and gain flexibility in plasma manipulation. The main key components of RF thruster architecture are: a feeding system able to provide the required neutral gas flow, plasma source chamber, antenna/electrodes wrapped around the discharge tube and optimized electromagnetic field coils for plasma confinement. A preliminary analysis of system performance (thrust, specific impulse, efficiency is performed along with future plans of Space Propulsion based on this new concept of plasma mechanism.

Minnesota multiphasic personality inventory-2 restructured form (MMPI-2-RF) scale score differences in bariatric surgery candidates diagnosed with binge eating disorder versus BMI-matched controls.

Science.gov (United States)

Marek, Ryan J; Ben-Porath, Yossef S; Ashton, Kathleen; Heinberg, Leslie J

2014-04-01

Binge Eating Disorder (BED) is among the most common psychiatric disorders in bariatric surgery candidates. The Minnesota Multiphasic Personality Inventory-2 Restructured Form (MMPI-2-RF) is a broadband, psychological test that includes measures of emotional and behavioral dysfunction, which have been associated with BED behaviors in bariatric surgery candidates; however these studies have lacked appropriate controls. In the current study, we compared MMPI-2-RF scale scores of bariatric surgery patients diagnosed with BED (BED+) with BMI-matched controls without BED (BED-). Three-hundred and seven BED+ participants (72.64% female and 67.87% Caucasian; mean BMI of 51.36 kg/m(2) [SD = 11.94]) were drawn from a large, database (N = 1304). Three-hundred and seven BED- participants were matched on BMI and demographics (72.64% female, 68.63% Caucasian, and mean BMI of 51.30 kg/m(2) [SD = 11.70]). The BED+ group scored significantly higher on measures of Demoralization, Low Positive Emotions, and Dysfunctional Negative Emotions and scored lower on measures of Antisocial Behaviors, reflecting behavioral constraint. Optimal T-Score cutoffs were below the traditional 65 T score for several MMPI-2-RF scales. MMPI-2-RF externalizing measures also added incrementally to differentiating between the groups beyond the Binge Eating Scale (BES). BED+ individuals produced greater elevations on a number of MMPI-2-RF internalizing scales and externalizing scales. Use of the test in conjunction with a clinical interview and other self-report data can further aid the clinician in guiding patients to appropriate treatment to optimize outcome. Copyright © 2013 Wiley Periodicals, Inc.

Influence of Secondary Hyperparathyroidism Induced by Low Dietary Calcium, Vitamin D Deficiency, and Renal Failure on Circulating Rat PTH Molecular Forms.

Science.gov (United States)

D'Amour, Pierre; Rousseau, Louise; Hornyak, Stephen; Yang, Zan; Cantor, Tom

2011-01-01

Rats(r) with secondary hyperparathyroidism were studied to define the relationship between vitamin D metabolites and rPTH levels measured by 3 different rat ELISAs. Controls and renal failure (RF) rats were on a normal diet, while 2 groups on a low-calcium (-Ca) or a vitamin D-deficient (-D) diet. RF was induced surgically. Mild RF rats had normal calcium and 25(OH)D but reduced 1,25(OH)(2)D levels (P < .001) with a 2.5-fold increased in rPTH (P < .001). Severe RF rats and those on a -Ca or -D diet had reduced calcium (P < .01) and 25(OH)D levels (P < .05), with rPTH increased by 2 (-Ca diet; P < .05), 4 (-D diet; P < .001), and 20-folds (RF; P < .001) while 1,25(OH)(2)D was high (-Ca diet: P < .001) or low (-D diet, RF: P < .001). 25(OH)D and 1,25(OH)(2)D were positively and negatively related on the -Ca and -D diets, respectively. rPTH molecular forms behaved as expected in RF and on -Ca diet, but not on -D diet with more C-rPTH fragments when less were expected. This may be related to the short-time course of this study compared to prior studies.

Status of 174 MHz RF system for BEP

International Nuclear Information System (INIS)

Biryuchevsky, Yu.A.; Gorniker, E.I.; Kendjebulatov, E.K.; Krutikhin, S.A.; Kurkin, G.Ya.; Petrov, V.M.; Pilan, A.M.

2012-01-01

The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system.

Application of quasi-optical approach to construct RF power supply for TeV linear colliders

International Nuclear Information System (INIS)

Saldin, E.L.; Sarantsev, V.P.; Schneidmiller, E.A.; Ulyanov, Yu.N.; Yurkov, M.V.

1995-01-01

An idea to use a quasi-optical approach for constructing an RF power supply for TeV linear e + e - colliders is developed. The RF source of the proposed scheme is composed of a large number of low-power RF amplifiers commutated by quasi-optical elements. The RF power of this source is transmitted to the accelerating structure of the collider by means of quasi-optical waveguides and mirrors. Such an approach enables one not only to decrease the required peak RF power by several orders of magnitude with respect to the traditional approach based on standard klystron technique, but also to achieve the required level of reliability, as it is based on well-developed technology of serial microwave devices. To illustrate the proposed scheme, a conceptual project of 2x500 GeV X-band collider is considered. Accelerating structure of the collider is of the standard travelling wave type and the RF source is assumed to be composed of 0.7 MW klystrons. All equipment of such a collider is placed in a tunnel of 12x6 m 2 cross section. It is shown that such a collider may be constructed at the present level of accelerator technique. ((orig.))

Impact of device engineering on analog/RF performances of tunnel field effect transistors

Science.gov (United States)

Vijayvargiya, V.; Reniwal, B. S.; Singh, P.; Vishvakarma, S. K.

2017-06-01

The tunnel field effect transistor (TFET) and its analog/RF performance is being aggressively studied at device architecture level for low power SoC design. Therefore, in this paper we have investigated the influence of the gate-drain underlap (UL) and different dielectric materials for the spacer and gate oxide on DG-TFET (double gate TFET) and its analog/RF performance for low power applications. Here, it is found that the drive current behavior in DG-TFET with a UL feature while implementing dielectric material for the spacer is different in comparison to that of DG-FET. Further, hetero gate dielectric-based DG-TFET (HGDG-TFET) is more resistive against drain-induced barrier lowering (DIBL) as compared to DG-TFET with high-k (HK) gate dielectric. Along with that, as compared to DG-FET, this paper also analyses the attributes of UL and dielectric material on analog/RF performance of DG-TFET in terms of transconductance (gm ), transconductance generation factor (TGF), capacitance, intrinsic resistance (Rdcr), cut-off frequency (F T), and maximum oscillation frequency (F max). The LK spacer-based HGDG-TFET with a gate-drain UL has the potential to improve the RF performance of device.

Design of a low-power 433/915-MHz RF front-end with a current-reuse common-gate LNA

International Nuclear Information System (INIS)

Jing Yiou; Lu Huaxiang

2013-01-01

This paper presents a wideband RF front-end with novel current-reuse wide band low noise amplifier (LNA), current-reuse V—I converter, active double balanced mixer and transimpedance amplifier for short range device (SRD) applications. With the proposed current-reuse LNA, the DC consumption of the front-end reduces considerably while maintaining sufficient performance needed by SRD devices. The RF front-end was fabricated in 0.18 μm RFCMOS process and occupies a silicon area of just 0.11 mm 2 . Operating in 433 MHz band, the measurement results show the RF front-end achieves a conversion gain of 29.7 dB, a double side band noise figure of 9.7 dB, an input referenced third intercept point of −24.9 dBm with only 1.44 mA power consumption from 1.8 V supply. Compared to other reported front-ends, it has an advantage in power consumption. (semiconductor integrated circuits)

Normal Conducting RF Cavity for MICE

International Nuclear Information System (INIS)

Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.

2010-01-01

Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.

Beyond the Interconnections: Split Manufacturing in RF Designs

Directory of Open Access Journals (Sweden)

Yu Bi

2015-08-01

Full Text Available With the globalization of the integrated circuit (IC design flow of chip fabrication, intellectual property (IP piracy is becoming the main security threat. While most of the protection methods are dedicated for digital circuits, we are trying to protect radio-frequency (RF designs. For the first time, we applied the split manufacturing method in RF circuit protection. Three different implementation cases are introduced for security and design overhead tradeoffs, i.e., the removal of the top metal layer, the removal of the top two metal layers and the design obfuscation dedicated to RF circuits. We also developed a quantitative security evaluation method to measure the protection level of RF designs under split manufacturing. Finally, a simple Class AB power amplifier and a more sophisticated Class E power amplifier are used for the demonstration through which we prove that: (1 the removal of top metal layer or the top two metal layers can provide high-level protection for RF circuits with a lower request to domestic foundries; (2 the design obfuscation method provides the highest level of circuit protection, though at the cost of design overhead; and (3 split manufacturing may be more suitable for RF designs than for digital circuits, and it can effectively reduce IP piracy in untrusted off-shore foundries.

Modification of the surface properties of glass-ceramic materials at low-pressure RF plasma stream

Science.gov (United States)

Tovstopyat, Alexander; Gafarov, Ildar; Galeev, Vadim; Azarova, Valentina; Golyaeva, Anastasia

2018-05-01

The surface roughness has a huge effect on the mechanical, optical, and electronic properties of materials. In modern optical systems, the specifications for the surface accuracy and smoothness of substrates are becoming even more stringent. Commercially available pre-polished glass-ceramic substrates were treated with the radio frequency (RF) inductively coupled (13.56 MHz) low-pressure plasma to clean the surface of the samples and decrease the roughness. Optical emission spectroscopy was used to investigate the plasma stream parameters and phase-shifted interferometry to investigate the surface of the specimen. In this work, the dependence of RF inductively coupled plasma on macroscopic parameters was investigated with the focus on improving the surfaces. The ion energy, sputtering rate, and homogeneity were investigated. The improvements of the glass-ceramic surfaces from 2.6 to 2.2 Å root mean square by removing the "waste" after the previous operations had been achieved.

Land and Undersea Field Testing of Very Low Frequency RF Antennas and Loop Transceivers

Science.gov (United States)

2017-12-01

report presents experiments and findings for VLF RF communications using both commercial off-the-shelf (COTS) transceivers acquired from vendor...RF) communication in the ocean environment. This report presents experiments and findings for VLF RF communications using both commercial off the...work described in this report was performed for the Office of Naval Research (ONR) Forward Deployed Energy and Communications Outpost (FDECO) Innovative

IR-RF dating of sand-sized K-feldspar extracts: A test of accuracy

International Nuclear Information System (INIS)

Buylaert, J.-P.; Jain, M.; Murray, A.S.; Thomsen, K.J.; Lapp, T.

2012-01-01

In this paper we use a recently developed radioluminescence (RL) attachment to the Risø TL/OSL reader to test the InfraRed-RadioFluorescence (IR-RF) dating method applied to K-feldspar rich extracts from our known-age archive samples. We present experiments to characterise the instrument performance and to test the reproducibility of IR-RF measurements. These experiments illustrate the high sensitivity and dose rate of our RL system, the negligible influence of the turntable movement on IR-RF signals and the effectiveness of the built in 395 nm LED at bleaching IR-RF signals. We measure IR-RF ages on a set of samples with independent age control using a robust analytical method, which is able to detect any possible sensitivity change. Our IR-RF ages do not agree well with the independent age control; the ages of the younger samples (20–45 ka) are significantly over-estimated while the ages of the older samples (∼130 ka) are significantly under-estimated. Experiments are undertaken to investigate this disagreement and our results indicate that they can most likely be explained by 1) the difficulty of defining the correct bleaching level prior to regeneration measurements, 2) signal instability, 3) sensitivity changes between the additive dose and regenerative dose measurements, or a combination of these three factors.

Pregnant women models analyzed for RF exposure and temperature increase in 3T RF shimmed birdcages.

Science.gov (United States)

Murbach, Manuel; Neufeld, Esra; Samaras, Theodoros; Córcoles, Juan; Robb, Fraser J; Kainz, Wolfgang; Kuster, Niels

2017-05-01

MRI is increasingly used to scan pregnant patients. We investigated the effect of 3 Tesla (T) two-port radiofrequency (RF) shimming in anatomical pregnant women models. RF shimming improves B 1 + uniformity, but may at the same time significantly alter the induced current distribution and result in large changes in both the level and location of the absorbed RF energy. In this study, we evaluated the electrothermal exposure of pregnant women in the third, seventh, and ninth month of gestation at various imaging landmarks in RF body coils, including modes with RF shimming. Although RF shimmed configurations may lower the local RF exposure for the mother, they can increase the thermal load on the fetus. In worst-case configurations, whole-body exposure and local peak temperatures-up to 40.8°C-are equal in fetus and mother. Two-port RF shimming can significantly increase the fetal exposure in pregnant women, requiring further research to derive a very robust safety management. For the time being, restriction to the CP mode, which reduces fetal SAR exposure compared with linear-horizontal polarization modes, may be advisable. Results from this study do not support scanning pregnant patients above the normal operating mode. Magn Reson Med 77:2048-2056, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Intelligent RF-Based Gesture Input Devices Implemented Using e-Textiles

Directory of Open Access Journals (Sweden)

Dana Hughes

2017-01-01

Full Text Available We present an radio-frequency (RF-based approach to gesture detection and recognition, using e-textile versions of common transmission lines used in microwave circuits. This approach allows for easy fabrication of input swatches that can detect a continuum of finger positions and similarly basic gestures, using a single measurement line. We demonstrate that the swatches can perform gesture detection when under thin layers of cloth or when weatherproofed, providing a high level of versatility not present with other types of approaches. Additionally, using small convolutional neural networks, low-level gestures can be identified with a high level of accuracy using a small, inexpensive microcontroller, allowing for an intelligent fabric that reports only gestures of interest, rather than a simple sensor requiring constant surveillance from an external computing device. The resulting e-textile smart composite has applications in controlling wearable devices by providing a simple, eyes-free mechanism to input simple gestures.

The LEP RF Trip and Beam Loss Diagnostics System

CERN Document Server

Arnaudon, L; Beetham, G; Ciapala, Edmond; Juillard, J C; Olsen, R

2002-01-01

During the last years of operation the number of operationally independent RF stations distributed around LEP reached a total of 40. A serious difficulty when running at high energy and high beam intensities was to establish cause and effect in beam loss situations, where the trip of any single RF station would result in beam loss, rapidly producing further multiple RF station trips. For the last year of operation a fast post-mortem diagnostics system was developed to allow precise time-stamping of RF unit trips and beam intensity changes. The system was based on eight local DSP controlled fast acquisition and event recording units, one in each RF sector, connected to critical RF control signals and fast beam intensity monitors and synchronised by GPS. The acquisition units were armed and synchronised at the start of each fill. At the end of the fill the local time-stamped RF trip and beam intensity change history tables were recovered, events ordered and the results stored in a database for subsequent analys...

Reliability impact of RF tube technology for the NPB

International Nuclear Information System (INIS)

Bueck, J.C.

1989-01-01

Two reliability options, redundancy and operating margin, are examined to determine their effect on power system configurations using RF tube technology (klystron and klystrode) powered Neutral Particle Beam weapons. Redundance is addressed by providing an additional identical RF tube to the tubes required to power an accelerator RF element (DTL section, RFQ, or CCL). RF elements do not share RF power with other RF elements. Operating margin provides increased reliability by sizing the RF tubes such that tube operating levels may be increased compensate for the loss of a tube. It is shown that power system mass is affected by the choice of reliability measures, that higher power tubes coupled with higher power RF elements may mitigate mass increases, and that redundancy appears preferable to operating margin as a method of improving RF system reliability

RF electrodynamics in small particles of oxides - a review

CSIR Research Space (South Africa)

Srinivasu, VV

2008-01-01

Full Text Available RF electrodynamics, particularly, the low field rf absorption in small superconducting and manganite particles is reviewed and compared with their respective bulk counterparts. Experimental and theoretical aspects of the small particle...

Technology development of solid state rf systems at 350 MHz and 325 MHz for RF accelerator

International Nuclear Information System (INIS)

Rama Rao, B.V.; Mishra, J.K.; Pande, Manjiri; Gupta, S.K.

2011-01-01

For decades vacuum tubes and klystrons have been used in high power application such as RF accelerators and broadcast transmitters. However, now, the solid-state technology can give power output in kilowatt regime. Higher RF power output can be achieved by combining several solid-state power amplifier modules using power combiners. This technology presents several advantages over traditional RF amplifiers, such as simpler start-up procedure, high modularity, high redundancy and flexibility, elimination of high voltage supplies and high power circulators, low operational cost, online maintenance without shut down of RF power station and no warm up time. In BARC, solid state amplifier technology development is being done both at 350 MHz and 325 MHz using RF transistors such as 1 kW LDMOS and 350 Watt VDMOS. Topology of input and output matching network in RF modules developed, consist of two L type matching sections with each section having a combination of series micro-strip line and parallel capacitor. The design is of equal Q for both the sections and of 25 ohm characteristics impedance of micro strip lines. Based on this, lengths of micro strips lines and values of shunt capacitors have been calculated. The calculated and simulated values of network elements have been compared. Similarly power combiners have been designed and developed based on Wilkinson techniques without internal resistors and using coaxial technology. This paper presents design and development of RF power amplifier modules, associated power combiner technologies and then integrated RF power amplifier. (author)

Control and RF-transmission in the ECW system on TEXTOR-94

International Nuclear Information System (INIS)

Dobbe, N.J.; Sterk, A.B.; Kruisbergen, R.P.J.J.M.; Kruyt, O.G.; Bestebreurtje, M.E.; Prins, P.R.; Hoekzema, J.A.; Grift, A.F. van der; Elzendoorn, B.S.Q.

2001-01-01

A real-time and multitasking control system has been developed for the new ECW system on the TEXTOR tokamak. It allows the system to be remotely controlled by client/server application. A quasi-optical transmission line has been installed which uses confocal mirrors and can be used for different frequencies (>100 GHz). It is suitable for transmission of up to two RF beams from different sources to the plasma. The launcher is mounted in a main horizontal port and injects a focused beam with a spot size of 2 cm (at 110 GHz) near the plasma axis. The launcher is steerable independently in the toroidal and poloidal directions

Control and RF-transmission in the ECW system on TEXTOR-94

Energy Technology Data Exchange (ETDEWEB)

Dobbe, N.J.; Sterk, A.B. E-mail: sterk@rijnh.nl; Kruisbergen, R.P.J.J.M.; Kruyt, O.G.; Bestebreurtje, M.E.; Prins, P.R.; Hoekzema, J.A.; Grift, A.F. van der; Elzendoorn, B.S.Q

2001-10-01

A real-time and multitasking control system has been developed for the new ECW system on the TEXTOR tokamak. It allows the system to be remotely controlled by client/server application. A quasi-optical transmission line has been installed which uses confocal mirrors and can be used for different frequencies (>100 GHz). It is suitable for transmission of up to two RF beams from different sources to the plasma. The launcher is mounted in a main horizontal port and injects a focused beam with a spot size of 2 cm (at 110 GHz) near the plasma axis. The launcher is steerable independently in the toroidal and poloidal directions.

COMPARISON OF RF CAVITY TRANSPORT MODELS FOR BBU SIMULATIONS

Energy Technology Data Exchange (ETDEWEB)

Ilkyoung Shin,Byung Yunn,Todd Satogata,Shahid Ahmed

2011-03-01

The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.

Comparison Of RF Cavity Transport Models For BBU Simulations

International Nuclear Information System (INIS)

Shin, Ilkyoung; Yunn, Byung; Satogata, Todd; Ahmed, Shahid

2011-01-01

The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will improve BBU simulation results to be more matched with analytic calculations and experimental results.

Optimizing RF energy transport : channel modelling and transmit antenna and rectenna design

NARCIS (Netherlands)

Visser, H.J.

2012-01-01

For powering wireless sensors in buildings rechargeable batteries may be used, being charged remotely by dedicated RF sources. RF energy transport suffers from path loss and therefore the RF power available on a rectenna will be very low. As a consequence, the RF-to-DC conversion efficiency will

RF extraction issues in the relativistic klystron amplifiers

Science.gov (United States)

Serlin, Victor; Friedman, Moshe; Lampe, Martin; Hubbard, Richard F.

1994-05-01

Relativistic klystron amplifiers (RKAs) were successfully operated at NRL in several frequency regimes and power levels. In particular, an L-band RKA was optimized for high- power rf extraction into the atmosphere and an S-band RKA was operated, both in a two-beam and a single-beam configuration. At L-band the rf extraction at maximum power levels (>= 15 GW) was hindered by pulse shortening and poor repeatability. Preliminary investigation showed electron emission in the radiating horn, due to very high voltages associated with the multi-gigawatt rf power levels. This electron current constituted an electric load in parallel with the radiating antenna, and precipitated the rf pulse collapse. At S-band the peak extracted power reached 1.7 GW with power efficiency approximately 50%. However, pulse shortening limited the duration to approximately 50 nanoseconds. The new triaxial RKA promises to solve many of the existing problems.

Low level control of metal belt CVT considering shift dynamics and ratio valve on-off characteristics

International Nuclear Information System (INIS)

Kim, Tal Chol; Kim, Hyun Soo

2000-01-01

In this paper, low level control algorithms of a metal belt CVT are suggested. A feedforward PID control algorithm is adopted for line pressure based on a steady state relationship between the input duty and the line pressure. Experimental results show that feedforward PID control of the line pressure guarantees a fast response while reducing the pressure undershoot which may result in belt slip. For ratio control, a fuzzy logic is suggested by considering the CVT shift dynamics and on-off characteristics of the ratio control valve. It is found from experimental results that a desired speed ratio can be achieved at steady state in spite of the fluctuating primary pressure. It is expected that the low level control algorithms for the line pressure and speed ratio suggested in this study can be implemented in a prototype CVT

Status of RF superconductivity at Argonne

International Nuclear Information System (INIS)

Shepard, K.W.

1990-01-01

Development of a superconducting slow-wave structures began at Argonne National Laboratory (ANL) in 1971, and led to the first superconducting heavy-ion linac (ATLAS - the Argonne Tandem-Linac Accelerator System). The Physics Division at ANL has continued to develop superconducting RF technology for accelerating heavy-ions, with the result that the linac has been in an almost continuous process of upgrade and expansion. In 1987, the Engineering Physics Division at ANL began developing of superconducting RF components for the acceleration of high-brightness proton and deuterium beams. The two divisions collaborate in work on several applications of RF superconductivity, and also in work to develop the technology generally. The present report briefly describes major features of the superconducting heavy-ion linac (very-low-velocity superconducting linac, positive ion injector), proton accelerating structures (superconducting resonant cavities for acceleration of high-current proton and deuteron beams, RF properties of oxide superconductors), and future work. Both divisions expect to continue a variety of studies, frequently in collaboration, to advance the basic technology of RF superconductivity. (N.K.)

Investigation of MIM Diodes for RF Applications

KAUST Repository

Khan, Adnan

2015-05-01

Metal Insulator Metal (MIM) diodes that work on fast mechanism of tunneling have been used in a number of very high frequency applications such as (Infra-Red) IR detectors and optical Rectennas for energy harvesting. Their ability to operate under zero bias condition as well as the possibility of realizing them through printing makes them attractive for (Radio Frequency) RF applications. However, MIM diodes have not been explored much for RF applications. One reason preventing their widespread RF use is the requirement of a very thin oxide layer essential for the tunneling operation that requires sophisticated nano-fabrication processes. Another issue is that the reliability and stable performance of MIM diodes is highly dependent on the surface roughness of the metallic electrodes. Finally, comprehensive RF characterization has not been performed for MIM diodes reported in the literature, particularly from the perspective of their integration with antennas as well as their rectification abilities. In this thesis, various metal deposition methods such as sputtering, electron beam evaporation, and Atomic Layer Deposition (ALD) are compared in pursuit of achieving low surface roughness. It is worth mentioning here that MIM diodes realized through ALD method have been presented for the first time in this thesis. Amorphous metal alloy have also been investigated in terms of their low surface roughness. Zinc-oxide has been investigated for its suitability as a thin dielectric layer for MIM diodes. Finally, comprehensive RF characterization of MIM diodes has been performed in two ways: 1) by standard S-parameter methods, and 2) by investigating their rectification ability under zero bias operation. It is concluded from the Atomic Force Microscopy (AFM) imaging that surface roughness as low as sub 1 nm can be achieved reliably from crystalline metals such as copper and platinum. This value is comparable to surface roughness achieved from amorphous alloys, which are non

DESIGN OF A DC/RF PHOTOELECTRON GUN

International Nuclear Information System (INIS)

YU, D.; NEWSHAM, Y.; SMIRONOV, A.; YU, J.; SMEDLEY, J.; SRINIVASAN RAU, T.; LEWELLEN, J.; ZHOLENTS, A.

2003-01-01

An integrated dc/rf photoelectron gun produces a low-emittance beam by first rapidly accelerating electrons at a high gradient during a short (∼1 ns), high-voltage pulse, and then injecting the electrons into an rf cavity for subsequent acceleration. Simulations show that significant improvement of the emittance appears when a high field (∼ 0.5-1 GV/m) is applied to the cathode surface. An adjustable dc gap ((le) 1 mm) which can be integrated with an rf cavity is designed for initial testing at the Injector Test Stand at Argonne National Laboratory using an existing 70-kV pulse generator. Plans for additional experiments of an integrated dc/rf gun with a 250-kV pulse generator are being made

Electron beam and rf characterization of a low-emittance X-band photoinjector

Directory of Open Access Journals (Sweden)

D. J. Gibson

2001-09-01

Full Text Available Detailed experimental studies of the first operation of an X-band (8.547 GHz rf photoinjector are reported. The rf characteristics of the device are first described, as well as the tuning technique used to ensure operation of the 11/2-cell rf gun in the balanced π-mode. The characterization of the photoelectron beam produced by the rf gun includes: measurements of the bunch charge as a function of the laser injection phase, yielding information about the quantum efficiency of the Cu photocathode ( 2×10^{-5} for a surface field of 100 MV/m; measurements of the beam energy (1.5–2 MeV and relative energy spread ( Δγ/γ_{0}=1.8±0.2% using a magnetic spectrometer; measurements of the beam 90% normalized emittance, which is found to be ɛ_{n}=1.65π mm mrad for a charge of 25 pC; and measurements of the bunch duration ( <2 ps. Coherent synchrotron radiation experiments at Ku-band and Ka-band confirm the extremely short duration of the photoelectron bunch and a peak power scaling quadratically with the bunch charge.

Design, fabrication and low power RF testing of a prototype beta=1, 1050 MHz cavity developed for electron linac

International Nuclear Information System (INIS)

Sarkar, S.; Mondal, J.; Mittal, K.C.

2013-01-01

A single cell 1050 MHz β = 1 elliptical cavity has been designed for possible use in High energy electron accelerator. A prototype Aluminium cavity has been fabricated by die punch method and low power testing of the cavity has been carried out by using VNA. The fundamental mode frequency of the prototype cavity is found out to be 1051.38 MHz and Q (loaded) and Q0 values corresponding to 2 modes are 8439 and 10013 respectively. Cell to cell coupling coefficient is 1.82 % from measurement which matches with the designed value (1.84%). The higher order mode frequencies are also measured and electric field of the cavity is confirmed by bead pull method. Low power RF measurements on the prototype cavity indicate that the critical RF parameters (Qo, f, Kc etc) for the cavity are consistent with the designed value. (author)

A low-jitter RF PLL frequency synthesizer with high-speed mixed-signal down-scaling circuits

International Nuclear Information System (INIS)

Tang Lu; Wang Zhigong; Xue Hong; He Xiaohu; Xu Yong; Sun Ling

2010-01-01

A low-jitter RF phase locked loop (PLL) frequency synthesizer with high-speed mixed-signal down-scaling circuits is proposed. Several techniques are proposed to reduce the design complexity and improve the performance of the mixed-signal down-scaling circuit in the PLL. An improved D-latch is proposed to increase the speed and the driving capability of the DMP in the down-scaling circuit. Through integrating the D-latch with 'OR' logic for dual-modulus operation, the delays associated with both the 'OR' and D-flip-flop (DFF) operations are reduced, and the complexity of the circuit is also decreased. The programmable frequency divider of the down-scaling circuit is realized in a new method based on deep submicron CMOS technology standard cells and a more accurate wire-load model. The charge pump in the PLL is also realized with a novel architecture to improve the current matching characteristic so as to reduce the jitter of the system. The proposed RF PLL frequency synthesizer is realized with a TSMC 0.18-μm CMOS process. The measured phase noise of the PLL frequency synthesizer output at 100 kHz offset from the center frequency is only -101.52 dBc/Hz. The circuit exhibits a low RMS jitter of 3.3 ps. The power consumption of the PLL frequency synthesizer is also as low as 36 mW at a 1.8 V power supply. (semiconductor integrated circuits)

Implications of ITER requirements on R and D of RF heating and current drive systems

International Nuclear Information System (INIS)

Bosia, G.

2002-01-01

A strategic, rather than auxiliary role is assigned to H and CD systems in ITER-FEAT, as all operation phases are driven and controlled by heating and current drive (H and CD) systems. RF systems (Electron Cyclotron, Ion Cyclotron and Lower Hybrid), planned to contribute for ∼60% of ITER auxiliary power (72 MW), still require different level of pre-industrial technology development to operate in ITER at the required level of efficiency and religiosite. In this paper, RF H and CD systems technical and operational issues are reviewed and future R and D actions at CEA-Cadarache discussed, with the aim of providing a demonstration of all RF H and CD systems, within the current ITER construction time scale. The need and the economical advantage of an early on- and off- plasma design validation program for ITER-like RF devices (such as launcher and/or power sources), is also discussed with the aim of identifying and resolving operational issues. (author)

Multi-Channel RF System for MRI-Guided Transurethral Ultrasound Thermal Therapy

Science.gov (United States)

Yak, Nicolas; Asselin, Matthew; Chopra, Rajiv; Bronskill, Michael

2009-04-01

MRI-guided transurethral ultrasound thermal therapy is an approach to treating localized prostate cancer which targets precise deposition of thermal energy within a confined region of the gland. This treatment requires a system incorporating a heating applicator with multiple planar ultrasound transducers and associated RF electronics to control individual elements independently in order to achieve accurate 3D treatment. We report the design, construction, and characterization of a prototype multi-channel system capable of controlling 16 independent RF signals for a 16-element heating applicator. The main components are a control computer, microcontroller, and a 16-channel signal generator with 16 amplifiers, each incorporating a low-pass filter and transmitted/reflected power detection circuit. Each channel can deliver from 0.5 to 10 W of electrical power and good linearity from 3 to 12 MHz. Harmonic RF signals near the Larmor frequency of a 1.5 T MRI were measured to be below -30 dBm and heating experiments within the 1.5 T MR system showed no significant decrease in SNR of the temperature images. The frequency and power for all 16 channels could be changed in less than 250 ms, which was sufficiently rapid for proper performance of the control algorithms. A common backplane design was chosen which enabled an inexpensive, modular approach for each channel resulting in an overall system with minimal footprint.

A design and performance analysis tool for superconducting RF systems

International Nuclear Information System (INIS)

Schilcher, T.; Simrock, S.N.; Merminga, L.; Wang, D.X.

1997-01-01

Superconducting rf systems are usually operated with continuous rf power or with rf pulse lengths exceeding 1 ms to maximize the overall wall plug power efficiency. Typical examples are CEBAF at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) and the TESLA Test Facility at DESY. The long pulses allow for effective application of feedback to stabilize the accelerating field in presence of microphonics, Lorentz force detuning, and fluctuations of the beam current. In this paper the authors describe a set of tools to be used with MATLAB and SIMULINK, which allow to analyze the quality of field regulation for a given design. The tools include models for the cavities, the rf power source, the beam, sources of field perturbations, and the rf feedback system. The rf control relevant electrical and mechanical characteristics of the cavity are described in form of time-varying state space models. The power source is modeled as a current generator and includes saturation characteristics and noise.An arbitrary time structure can be imposed on the beam current to reflect a macro-pulse structure and bunch charge fluctuations. For rf feedback several schemes can be selected: Traditional amplitude and phase control as well as I/Q control. The choices for the feedback controller include analog or digital approaches and various choices of frequency response. Feed forward can be added to further suppress repetitive errors. The results of a performance analysis of the CEBAF and the TESLA Linac rf system using these tools are presented

The Low-Level Control System for the CERN PS Multi-Turn Extraction Kickers

CERN Document Server

Schipper, J; Boucly, C; Carlier, E; Fowler, T; Gaudillet, H; Noulibos, R; Sermeus, L

2010-01-01

To reduce the beam losses when preparing high intensity proton beam for the CERN Neutrino to Gran Sasso (CNGS) facility, a new Multi-Turn extraction (MTE) scheme has been implemented in the PS, to replace the present Continuous Transfer (CT) to the SPS. Industrial off-the-shelf components have been used for the low-level part of the MTE kicker control system. National Instruments PXI systems are used to control the high voltage pulse generators and a SIEMENS programmable logic controller (PLC) handles the centralised oil cooling and gas insulation sub-systems

Cost-effective hybrid RF/FSO backhaul solution for next generation wireless systems

KAUST Repository

Dahrouj, Hayssam

2015-10-28

The rapid pace of demand for mobile data services and the limited supply of capacity in the current wireless access networks infrastructure are leading network operators to increase the density of base station deployments to improve network performance. This densification, made possible by small-cell deployment, also brings a novel set of challenges, specifically related to the cost of ownership, in which backhaul is of primary concern. This article proposes a cost-effective hybrid RF/free-space optical (FSO) solution to combine the advantages of RF backhauls (low cost, NLOS applications) and FSO backhauls (high-rate, low latency). To first illustrate the cost advantages of the RF backhaul solution, the first part of this article presents a business case of NLOS wireless RF backhaul, which has a low cost of ownership as compared to other backhaul candidates. RF backhaul, however, is limited by latency problems. On the other side, an FSO solution, which offers better latency and higher data rate than RF backhauls, remains sensitive to weather and nature conditions (e.g., rain, fog). To combine RF and FSO advantages, the second part of this article proposes a lowcost hybrid RF/FSO solution, wherein base stations are connected to each other using either optical fiber or hybrid RF/FSO links. This part addresses the problem of minimizing the cost of backhaul planning under reliability, connectivity, and data rate constraints, and proposes choosing the appropriate cost-effective backhaul connection between BSs (i.e., either OF or hybrid RF/FSO) using graph theory techniques.

Smoking, low formal level of education, alcohol consumption, and the risk of rheumatoid arthritis.

Science.gov (United States)

Bergström, U; Jacobsson, L T H; Nilsson, J Å; Wirfält, E; Turesson, C

2013-01-01

Suggested predictors of rheumatoid arthritis (RA) include environmental exposure, such as smoking. Our purpose was to investigate potential predictors of RA in a nested case-control study based on a prospective cohort. Between 1991 and 1996, 30,447 persons were included in the Malmö Diet and Cancer Study (MDCS). Individuals who developed RA after inclusion up to 31 December 2004 were identified by linking the database to different registers. Four controls were selected for every case. Data on lifestyle factors were collected in the MDCS. We identified 172 incident cases of RA [36 men/136 women, mean age at diagnosis 63 years, 69% rheumatoid factor (RF) positive, median time from inclusion to diagnosis 5 (range 1-13) years]. In bivariate analyses, baseline smoking [odds ratio (OR) 2.02, 95% confidence interval (CI) 1.31-3.12] and a low level of formal education (i.e. ≤ 8 years; OR 2.42, 95% CI 1.18-4.93 vs. University degree) predicted subsequent development of RA. Infrequent baseline alcohol consumption was a predictor of RA (OR 3.47, 95% CI 1.91-6.30) compared to recent use (within the past month), and individuals with moderate baseline alcohol consumption (3.5-15.2 g/day vs. education. Smoking and a low level of formal education were found to be independent predictors of RA. Moderate alcohol consumption may also be associated with a reduced risk.

Radiofrequency (RF) radiation measurement for diathermy machine

International Nuclear Information System (INIS)

Rozaimah Abdul Rahim; Roha Tukimin; Mohd Amirul Nizam; Ahmad Fadzli; Mohd Azizi

2010-01-01

Full-text: Diathermy machine is one of medical device that use widely in hospital and clinic. During the diathermy treatment, high radiofrequency (RF) currents (shortwave and microwave) are used to heat deep muscular tissues through electromagnetic energy to body tissues. The heat increases blood flow, relieve pain and speeding up recovery. The stray RF radiation from the machine can exposes to unintended tissue of the patient, to the operator (physical therapist) and also can cause electromagnetic interference (EMI) effect to medical devices around the machine. The main objective of this study is to establish a database of the RF radiation exposure levels experienced by the operator and patient during the treatments. RF radiation (electric and magnetic field) produced by the diathermy machines were measured using special RF survey meters. The finding of this study confirms that radiation levels on the surface and near the applicator of the diathermy machine much more elevated due to the much closer distance to the source and they exceeding the occupational and general public exposure limit. The results also shows the field strengths drop very significantly when the distance of measurement increase. (author)

A development and integration analysis of commercial and in-house control subsystems

International Nuclear Information System (INIS)

Moore, D.M.; Dalesio, L.R.

1998-01-01

The acquisition and integration of commercial automation and control subsystems in physics research is becoming more common. It is presumed these systems present lower risk and less cost. This paper studies four subsystems used in the Accelerator Production of Tritium (APT) Low Energy Demonstration Accelerator (LEDA) at the Los Alamos National Laboratory (LANL). The radio frequency quadrupole (RFQ) resonance-control cooling subsystem (RCCS), the high-power RF subsystem and the RFQ vacuum subsystem were outsourced; the low-level RF (LLRF) subsystem was developed in-house. Based on the authors experience a careful evaluation of the costs and risks in acquisition, implementation, integration, and maintenance associated with these approaches is given

Conventional RF system design

International Nuclear Information System (INIS)

Puglisi, M.

1994-01-01

The design of a conventional RF system is always complex and must fit the needs of the particular machine for which it is planned. It follows that many different design criteria should be considered and analyzed, thus exceeding the narrow limits of a lecture. For this reason only the fundamental components of an RF system, including the generators, are considered in this short seminar. The most common formulas are simply presented in the text, while their derivations are shown in the appendices to facilitate, if desired, a more advanced level of understanding. (orig.)

A New RF System for the CEBAF Normal Conducting Cavities

International Nuclear Information System (INIS)

Curt Hovater; Hai Dong; Alicia Hofler; George Lahti; John Musson; Tomasz Plawski

2004-01-01

The CEBAF Accelerator at Jefferson Lab is a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. CEBAF also has numerous normal conducting cavities for beam conditioning in the injector and for RF extraction to the experimental halls. The RF systems that presently control these cavities are becoming expensive to maintain, therefore a replacement RF control system is now being developed. For the new RF system, cavity field control is maintained digitally using an FPGA which contains the feedback algorithm. The system incorporates digital down conversion, using quadrature under-sampling at an IF frequency of 70 MHz. The VXI bus-crate was chosen as the operating platform because of its excellent RFI/EMI properties and its compatibility with the EPICS control system. The normal conducting cavities operate at both the 1497 MHz accelerating frequency and the sub-harmonic frequency of 499 MHz. To accommodate this, the ne w design will use different receiver-transmitter daughter cards for each frequency. This paper discusses the development of the new RF system and reports on initial results

RF Loads for Energy Recovery

CERN Document Server

Federmann, S; Caspers, F

2012-01-01

Different conceptional designs for RF high power loads are presented. One concept implies the use of solid state rectifier modules for direct RF to DC conversion with efficiencies beyond 80%. In addition, robust metallic low-Q resonant structures, capable of operating at high temperatures (>150 ◦C) are discussed. Another design deals with a very high temperature (up to 800 ◦C) air cooled load using a ceramic foam block inside a metal enclosure. This porous ceramic block is the microwave absorber and is not brazed to the metallic enclosure.

Extended RF shimming: Sequence-level parallel transmission optimization applied to steady-state free precession MRI of the heart.

Science.gov (United States)

Beqiri, Arian; Price, Anthony N; Padormo, Francesco; Hajnal, Joseph V; Malik, Shaihan J

2017-06-01

Cardiac magnetic resonance imaging (MRI) at high field presents challenges because of the high specific absorption rate and significant transmit field (B 1 + ) inhomogeneities. Parallel transmission MRI offers the ability to correct for both issues at the level of individual radiofrequency (RF) pulses, but must operate within strict hardware and safety constraints. The constraints are themselves affected by sequence parameters, such as the RF pulse duration and TR, meaning that an overall optimal operating point exists for a given sequence. This work seeks to obtain optimal performance by performing a 'sequence-level' optimization in which pulse sequence parameters are included as part of an RF shimming calculation. The method is applied to balanced steady-state free precession cardiac MRI with the objective of minimizing TR, hence reducing the imaging duration. Results are demonstrated using an eight-channel parallel transmit system operating at 3 T, with an in vivo study carried out on seven male subjects of varying body mass index (BMI). Compared with single-channel operation, a mean-squared-error shimming approach leads to reduced imaging durations of 32 ± 3% with simultaneous improvement in flip angle homogeneity of 32 ± 8% within the myocardium. © 2017 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

The RF system for the Accelerator Production of Tritium (APT) Low Energy Demonstration Accelerator (LEDA) at Los Alamos

International Nuclear Information System (INIS)

Lynch, M.T.; Rees, D.; Tallerico, P.; Regan, A.

1996-01-01

To develop and demonstrate the crucial front end of the APT accelerator and some of the critical components for APT, Los Alamos is building a CW proton accelerator (LEDA) to provide 100 mA at up to 40 MeV. LEDA will be installed where the SDI-sponsored Ground Test Accelerator was located. The first accelerating structure for LEDA is a 7-MeV RFQ operating at 350 MHz, followed by several stages of a coupled-cavity Drift Tube Linac (CCDTL) operating at 700 MHz. The first stage of LEDA will go to 12 MeV. Higher energies, up to 40 MeV, come later in the program. Three 1.2-MW CW RF systems will be used to power the RFQ. This paper describes the RF systems being assembled for LEDA, including the 350 and 700-MHz klystrons, the High Voltage Power Supplies, transmitters, RF transport, window/coupler assemblies, and controls. Some of the limitations imposed by the schedule and the building itself are addressed

Design of the New Wideband RF System for the CERN PS Booster

CERN Document Server

Paoluzzi, Mauro; Angoletta, Maria Elena; Arnaudon, Luca; Energico, Salvatore; Findlay, Alan; Haase, Matthias; Jaussi, Michael; Jones, Anthony; Landré, David; Molendijk, John; Quartullo, Danilo; Shaposhnikova, Elena

2016-01-01

For the renovation and upgrade of the CERN PS Booster (PSB) RF systems a development project was launched in 2012. The design, based on a new approach, aimed at replacing the existing tuned, narrowband RF systems with wideband, modular, solid-state driven units. A wide range of issues had to be addressed spanning from RF power production, radiation hardness of solid-state devices, active cancellation of beam-induced voltages, dedicated low-level electronics allowing multi-harmonic operation and beam stability. Following a three-year prototyping and testing campaign and two international reviews, the project endorsement came at the end of year 2015. It foresees the complete removal of present h1, h2 and h10 systems and the deployment of a new one covering all the frequency ranges from 1 MHz to 18 MHz. The four PSB rings will be equipped with 144 identical acceleration cells providing 24 kV total RF voltage per ring. This paper describes the design concepts, the retained solutions, the expected performances and...

LEDA RF distribution system design and component test results

International Nuclear Information System (INIS)

Roybal, W.T.; Rees, D.E.; Borchert, H.L.; McCarthy, M.; Toole, L.

1998-01-01

The 350 MHz and 700 MHz RF distribution systems for the Low Energy Demonstration Accelerator (LEDA) have been designed and are currently being installed at Los Alamos National Laboratory. Since 350 MHz is a familiar frequency used at other accelerator facilities, most of the major high-power components were available. The 700 MHz, 1.0 MW, CW RF delivery system designed for LEDA is a new development. Therefore, high-power circulators, waterloads, phase shifters, switches, and harmonic filters had to be designed and built for this applications. The final Accelerator Production of Tritium (APT) RF distribution systems design will be based on much of the same technology as the LEDA systems and will have many of the RF components tested for LEDA incorporated into the design. Low power and high-power tests performed on various components of these LEDA systems and their results are presented here

Printable Materials for the Realization of High Performance RF Components: Challenges and Opportunities

Directory of Open Access Journals (Sweden)

Eva S. Rosker

2018-01-01

Full Text Available Printing methods such as additive manufacturing (AM and direct writing (DW for radio frequency (RF components including antennas, filters, transmission lines, and interconnects have recently garnered much attention due to the ease of use, efficiency, and low-cost benefits of the AM/DW tools readily available. The quality and performance of these printed components often do not align with their simulated counterparts due to losses associated with the base materials, surface roughness, and print resolution. These drawbacks preclude the community from realizing printed low loss RF components comparable to those fabricated with traditional subtractive manufacturing techniques. This review discusses the challenges facing low loss RF components, which has mostly been material limited by the robustness of the metal and the availability of AM-compatible dielectrics. We summarize the effective printing methods, review ink formulation, and the postprint processing steps necessary for targeted RF properties. We then detail the structure-property relationships critical to obtaining enhanced conductivities necessary for printed RF passive components. Finally, we give examples of demonstrations for various types of printed RF components and provide an outlook on future areas of research that will require multidisciplinary teams from chemists to RF system designers to fully realize the potential for printed RF components.

Additive manufacturing of RF absorbers

Science.gov (United States)

Mills, Matthew S.

The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

A HIGH-LEVEL PYTHON INTERFACE TO THE FERMILAB ACNET CONTROL SYSTEM

Energy Technology Data Exchange (ETDEWEB)

Piot, P. [Fermilab; Halavanau, A. [Fermilab

2016-10-19

This paper discusses the implementation of a python- based high-level interface to the Fermilab acnet control system. The interface has been successfully employed during the commissioning of the Fermilab Accelerator Science & Technology (FAST) facility. Specifically, we present examples of applications at FAST which include the interfacing of the elegant program to assist lattice matching, an automated emittance measurement via the quadrupole-scan method and tranverse transport matrix measurement of a superconducting RF cavity.

Test results of the AGS Booster low frequency RF system

International Nuclear Information System (INIS)

Sanders, R.T.; Cameron, P.; Damm, R.; Dunbar, A.; Goldman, M.; Kasha, D.; McNerney, A.; Meth, M.; Ratti, A.; Spitz, R.

1993-01-01

The Band II RF system was originally built to support the Booster operations during the acceleration of heavy ions. Designed to sweep from 0.6 to 2.5 MHz, it was build and successfully tested over a much broader range reaching 4 MHz. Voltages up to more than 20 kV were reached over the design frequency range. The system consists of two stations, each of which is made of one single gap cavity directly driven by a grounded cathode push pull power amplifier. The low Q high permeability ferrites needed in the coaxial cavity in order to reach the lower end of the band make tuning extremely easy. Both systems were thoroughly tested both at single frequencies and on a sweep and are now installed in the ring, ready for operations. Static measurements showed no high-loss effects. The Band 11 system has been fully described in a previous paper; presented here are the results of the ''bench'' tests that lead to important performance improvements

Shallow ground burial of low-level waste

International Nuclear Information System (INIS)

Camilleri, A.; Cooper, M.B.; Hargrave, N.J.; Munslow-Davies, L.

1989-01-01

Acceptance criteria for the disposal of low-level radioactive wastes are presented for adoption throughout Australia, a continent in which there are readily available areas in arid, sparsely inhabited places, likely to be suitable as sites for shallow ground burial. Drawing upon overseas practices and experiences, criteria have been developed for low-level waste disposal and are intended to be applicable and relevant to the Australian situation. Concentration levels have been derived for a shallow ground burial facility assuming a realistic institutional control period of 200 years. A comparison is made between this period and institutional control for 100 years and 300 years. Longer institutional control periods enable the acceptance of higher concentrations of radionuclides of intermediate half-lives. Scenarios, which have been considered, include current Australian pastoral practices and traditional Aboriginal occupancy. The derived radionuclide concentration levels for the disposal of low level wastes are not dissimilar to those developed in other countries. 17 refs., 6 tabs., 1 fig

Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring-High Energy Ring at the Positron-Electron Project

International Nuclear Information System (INIS)

Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.

2007-01-01

A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored

SSRL photocathode RF gun test stand

International Nuclear Information System (INIS)

Hernandez, M.; Baltay, M.; Boyce, A.

1995-01-01

A photocathode RF gun test stand designed for the production and study of high brightness electron beams will be constructed at SSRL. The beam will be generated from a laser driven third generation photocathode RF gun being developed in collaboration with BNL, LBL, and UCLA. The 3-5 [MeV] beam from the gun will be accelerated using a SLAC three meter S-band accelerator section, in order to achieve the desired low emittance beam, emittance compensation with solenoidal focusing will be employed

Longitudinal beam dynamics with rf noise

International Nuclear Information System (INIS)

Shih, H.J.; Ellison, J.A.; Cogburn, R.; Newberger, B.S.

1993-06-01

The Dome-Krinsky-Wang (DKW) diffusion-inaction theory for rf-noise-induced emittance dilution is reviewed and related to recent work on the approximation of stochastic processes by Markov processes. An accurate and efficient numerical procedure is developed to integrate the diffusion equation of the DKW theory. Tracking simulations are undertaken to check the validity of the theory in the parameter range of the Superconducting Super Collider (SSC) and to provide additional information. The study of effects of rf noise is applied to two problems of interest at the SSC: (1) determination of noise tolerance levels in the rf system, and (2) feasibility of beam extraction using crystal channeling

Design of 250-MW CW RF system for APT

International Nuclear Information System (INIS)

Rees, D.

1997-01-01

The design for the RF systems for the APT (Accelerator Production of Tritium) proton linac will be presented. The linac produces a continuous beam power of 130 MW at 1300 MeV with the installed capability to produce up to a 170 MW beam at 1700 MeV. The linac is comprised of a 350 MHz RFQ to 7 MeV followed in sequence by a 700 MHz coupled-cavity drift tube linac, coupled-cavity linac, and superconducting (SC) linac to 1700 MeV. At the 1700 MeV, 100 mA level the linac requires 213 MW of continuous-wave (CW) RF power. This power will be supplied by klystrons with a nominal output power of 1.0 MW. 237 kystrons are required with all but three of these klystrons operating at 700 MHz. The klystron count includes redundancy provisions that will be described which allow the RF systems to meet an operational availability in excess of 95 percent. The approach to achieve this redundancy will be presented for both the normal conducting (NC) and SC accelerators. Because of the large amount of CW RF power required for the APT linac, efficiency is very important to minimize operating cost. Operation and the RF system design, including in-progress advanced technology developments which improve efficiency, will be discussed. RF system performance will also be predicted. Because of the simultaneous pressures to increase RF system reliability, reduce tunnel envelope, and minimize RF system cost, the design of the RF vacuum windows has become an important issue. The power from a klystron will be divided into four equal parts to minimize the stress on the RF vacuum windows. Even with this reduction, the RF power level at the window is at the upper boundary of the power levels employed at other CW accelerator facilities. The design of a 350 MHz, coaxial vacuum window will be presented as well as test results and high power conditioning profiles. The transmission of 950 kW, CW, power through this window has been demonstrated with only minimal high power conditioning

Simulation of rarefied low pressure RF plasma flow around the sample

Science.gov (United States)

Zheltukhin, V. S.; Shemakhin, A. Yu

2017-01-01

The paper describes a mathematical model of the flow of radio frequency plasma at low pressure. The hybrid mathematical model includes the Boltzmann equation for the neutral component of the RF plasma, the continuity and the thermal equations for the charged component. Initial and boundary conditions for the corresponding equations are described. The electron temperature in the calculations is 1-4 eV, atoms temperature in the plasma clot is (3-4) • 103 K, in the plasma jet is (3.2-10) • 102 K, the degree of ionization is 10-7-10-5, electron density is 1015-1019 m-3. For calculations plasma parameters is developed soft package on C++ program language, that uses the OpenFOAM library package. Simulations for the vacuum chamber in the presence of a sample and the free jet flow were carried out.

All-Digital I/Q RF-DAC

NARCIS (Netherlands)

Alavi, S.M.

2014-01-01

Due to the severe cost pressure of consumer electronics, a migration to an advanced nanoscale CMOS processes, which is primarily developed for fast and low-power digital circuits operating at low supply voltages, is necessary, but it forces wireless RF transceivers to exploit more and more digital

Dose controlled low energy electron irradiator for biomolecular films.

Science.gov (United States)

Kumar, S V K; Tare, Satej T; Upalekar, Yogesh V; Tsering, Thupten

2016-03-01

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at -20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

Dose controlled low energy electron irradiator for biomolecular films

Energy Technology Data Exchange (ETDEWEB)

Kumar, S. V. K., E-mail: svkk@tifr.res.in; Tare, Satej T.; Upalekar, Yogesh V.; Tsering, Thupten [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

2016-03-15

We have developed a multi target, Low Energy Electron (LEE), precise dose controlled irradiator for biomolecular films. Up to seven samples can be irradiated one after another at any preset electron energy and dose under UHV conditions without venting the chamber. In addition, one more sample goes through all the steps except irradiation, which can be used as control for comparison with the irradiated samples. All the samples are protected against stray electron irradiation by biasing them at −20 V during the entire period, except during irradiation. Ethernet based communication electronics hardware, LEE beam control electronics and computer interface were developed in house. The user Graphical User Interface to control the irradiation and dose measurement was developed using National Instruments Lab Windows CVI. The working and reliability of the dose controlled irradiator has been fully tested over the electron energy range of 0.5 to 500 eV by studying LEE induced single strand breaks to ΦX174 RF1 dsDNA.

Rf system considerations for a large hadron collider

International Nuclear Information System (INIS)

Raka, E.

1988-01-01

In this paper, we shall discuss how we arrive at a particular choice of voltage and frequency; the type of acceleration structure that would be suitable for obtaining the required voltage and resonant impedance; static beam loading including a simplified beam stability criterion involving the beam current and total rf system shunt impedance; the basic principle of rf phase and frequency control loops; and the effect of rf noise and its interaction with these loops. Finally, we shall consider the need for and design of rf systems to damp independently coherent oscillations of individual bunches or groups of bunches. 30 refs., 17 figs., 2 tabs

Tilt optimized flip uniformity (TOFU) RF pulse for uniform image contrast at low specific absorption rate levels in combination with a surface breast coil at 7 Tesla

NARCIS (Netherlands)

van Kalleveen, Irene M. L.; Boer, VO; Luijten, Peter R.; Klomp, DWJ

Purpose: Going to ultrahigh field MRI (e. g., 7 Tesla [ T]), the nonuniformity of the B_1 field and the increased radiofrequency (RF) power deposition become challenging. While surface coils improve the power efficiency in B_1, its field remains nonuniform. In this work, an RF pulse was designed

Improving the beam quality of rf guns by correction of rf and space-charge effects

International Nuclear Information System (INIS)

Serafini, L.

1992-01-01

In this paper we describe two possible strategies to attain ultra-low emittance electron beam generation by laser-driven RF guns. The first one is based on the exploitation of multi-mode resonant cavities to neutralize the emittance degradation induced by RF effects. Accelerating cigar-like (long and thin) electron bunches in multi-mode operated RF guns the space charge induced emittance is strongly decreased at the same time: high charged bunches, as typically requested by future TeV e - e + colliders, can be delivered by the gun at a quite low transverse emittance and good behaviour in the longitudinal phase space, so that they can be magnetically compressed to reach higher peak currents. The second strategy consists in using disk-like electron bunches, produced by very short laser pulses illuminating the photocathode. By means of an analytical study a new regime has been found, where the normalized transverse emittance scales like the inverse of the peak current, provided that the laser pulse intensity distribution is properly shaped in the transverse direction. Preliminary numerical simulations confirm the analytical predictions and show that the minimum emittance achievable is set up, in this new regime, by the wake-field interaction between the bunch and the cathode metallic wall

Efficient RF energy harvesting by using a fractal structured rectenna system

Science.gov (United States)

Oh, Sechang; Ramasamy, Mouli; Varadan, Vijay K.

2014-04-01

A rectenna system delivers, collects, and converts RF energy into direct current to power the electronic devices or recharge batteries. It consists of an antenna for receiving RF power, an input filter for processing energy and impedance matching, a rectifier, an output filter, and a load resistor. However, the conventional rectenna systems have drawback in terms of power generation, as the single resonant frequency of an antenna can generate only low power compared to multiple resonant frequencies. A multi band rectenna system is an optimal solution to generate more power. This paper proposes the design of a novel rectenna system, which involves developing a multi band rectenna with a fractal structured antenna to facilitate an increase in energy harvesting from various sources like Wi-Fi, TV signals, mobile networks and other ambient sources, eliminating the limitation of a single band technique. The usage of fractal antennas effects certain prominent advantages in terms of size and multiple resonances. Even though, a fractal antenna incorporates multiple resonances, controlling the resonant frequencies is an important aspect to generate power from the various desired RF sources. Hence, this paper also describes the design parameters of the fractal antenna and the methods to control the multi band frequency.

Water Level Loggers as a Low-Cost Tool for Monitoring of Stormwater Control Measures

Directory of Open Access Journals (Sweden)

Laura Toran

2016-08-01

Full Text Available Stormwater control measures (SCMs are a key component of watershed health in urbanized areas. SCMs are used to increase infiltration and reduce discharge to streams or storm sewer systems during rain events. Monitoring is important for the evaluation of design and causes of failure in SCMs. However, the expense of monitoring means it is not always included in stormwater control planning. This study shows how low-cost water level loggers can be used to answer certain questions about SCM performance. Five case studies are presented that use water level loggers to evaluate the overflow of basins, compare a traditional stormpipe trench with an infiltration trench, monitor timing of blue roof storage, show the effects of retrofitting a basin, and provide long term performance data. Water level loggers can be used to answer questions about the timing and location of stormwater overflows, which helps to evaluate the effectiveness of SCMs. More expensive monitoring and modeling can be used as a follow up if needed to more thoroughly assess a site. Nonetheless, low-cost monitoring can be a first step in identifying sites that need improvement or additional monitoring.

Confinement improvement with rf poloidal current drive in the reversed-field pinch

International Nuclear Information System (INIS)

Hokin, S.; Sarff, J.; Sovinec, C.; Uchimoto, E.

1994-01-01

External control of the current profile in a reversed-field pinch (RFP), by means such as rf poloidal current drive, may have beneficial effects well beyond the direct reduction of Ohmic input power due to auxiliary heating. Reduction of magnetic turbulence associated with the dynamo, which drives poloidal current in a conventional RFP, may allow operation at lower density and higher electron temperature, for which rf current drive becomes efficient and the RFP operates in a more favorable regime on the nτ vs T diagram. Projected parameters for RFX at 2 MA axe studied as a concrete example. If rf current drive allows RFX to operate with β = 10% (plasma energy/magnetic energy) at low density (3 x 10 19 m -3 ) with classical resistivity (i.e. without dynamo-enhanced power input), 40 ms energy confinement times and 3 keV temperatures will result, matching the performance of tokamaks of similar size

System control and data acquisition of the two new FWCD RF systems at DIII-D

International Nuclear Information System (INIS)