Interlock system for machine protection of the KOMAC 100-MeV proton linac

NASA Astrophysics Data System (ADS)

Song, Young-Gi

2015-02-01

The 100-MeV proton linear accelerator of the Korea Multi-purpose Accelerator Complex (KOMAC) has been developed. The beam service started this year after performing the beam commissioning. If the very sensitive and essential equipment is to be protected during machine operation, a machine interlock system is required, and the interlock system has been implemented. The purpose of the interlock system is to shut off the beam when the radio-frequency (RF) and ion source are unstable or a beam loss occurs. The interlock signal of the KOMAC linac includes a variety of sources, such as the beam loss, RF and high-voltage converter modulator faults, and fast closing valves of the vacuum window at the beam lines and so on. This system consists of a hardware-based interlock system using analog circuits and a software-based interlock system using an industrial programmable logic controller (PLC). The hardware-based interlock system has been fabricated, and the requirement has been satisfied with the results being within 10 µs. The software logic interlock system using the PLC has been connected to the framework of with the experimental physics and industrial control system (EPICS) to integrate a variety of interlock signals and to control the machine components when an interlock occurs. This paper will describe the design and the construction of the machine interlock system for the KOMAC 100-MeV linac.

Beam transport and monitoring for laser plasma accelerators

NASA Astrophysics Data System (ADS)

Nakamura, K.; Sokollik, T.; van Tilborg, J.; Gonsalves, A. J.; Shaw, B.; Shiraishi, S.; Mittal, R.; De Santis, S.; Byrd, J. M.; Leemans, W.

2012-12-01

The controlled transport and imaging of relativistic electron beams from laser plasma accelerators (LPAs) are critical for their diagnostics and applications. Here we present the design and progress in the implementation of the transport and monitoring system for an undulator based electron beam diagnostic. Miniature permanent-magnet quadrupoles (PMQs) are employed to realize controlled transport of the LPA electron beams, and cavity based electron beam position monitors for non-invasive beam position detection. Also presented is PMQ calibration by using LPA electron beams with broadband energy spectrum. The results show promising performance for both transporting and monitoring. With the proper transport system, XUV-photon spectra from THUNDER will provide the momentum distribution of the electron beam with the resolution above what can be achieved by the magnetic spectrometer currently used in the LOASIS facility.

RFI-Based Ion Linac Systems

NASA Astrophysics Data System (ADS)

Swenson, Donald A.

A new company, Ion Linac Systems, Inc., has been formed to promote the development, manufacture, and marketing of intense, RFI-based, Ion Linac Systems. The Rf Focused Interdigital (RFI) linac structure was invented by the author while at Linac Systems, LLC. The first step, for the new company, will be to correct a flaw in an existing RFI-based linac system and to demonstrate "good transmission" through the system. The existing system, aimed at the BNCT medical application, is designed to produce a beam of 2.5 MeV protons with an average beam current of 20 mA. In conjunction with a lithium target, it will produce an intense beam of epithermal neutrons. This system is very efficient, requiring only 180 kW of rf power to produce a 50 kW proton beam. In addition to the BNCT medical application, the RFI-based systems should represent a powerful neutron generator for homeland security, defence applications, cargo container inspection, and contraband detection. The timescale to the demonstration of "good transmission" is early fall of this year. Our website is www.ionlinacs.com.

Integrated control system for electron beam processes

NASA Astrophysics Data System (ADS)

Koleva, L.; Koleva, E.; Batchkova, I.; Mladenov, G.

2018-03-01

The ISO/IEC 62264 standard is widely used for integration of the business systems of a manufacturer with the corresponding manufacturing control systems based on hierarchical equipment models, functional data and manufacturing operations activity models. In order to achieve the integration of control systems, formal object communication models must be developed, together with manufacturing operations activity models, which coordinate the integration between different levels of control. In this article, the development of integrated control system for electron beam welding process is presented as part of a fully integrated control system of an electron beam plant, including also other additional processes: surface modification, electron beam evaporation, selective melting and electron beam diagnostics.

A system for online beam emittance measurements and proton beam characterization

NASA Astrophysics Data System (ADS)

Nesteruk, K. P.; Auger, M.; Braccini, S.; Carzaniga, T. S.; Ereditato, A.; Scampoli, P.

2018-01-01

A system for online measurement of the transverse beam emittance was developed. It is named 4PrOBεaM (4-Profiler Online Beam Emittance Measurement) and was conceived to measure the emittance in a fast and efficient way using the multiple beam profiler method. The core of the system is constituted by four consecutive UniBEaM profilers, which are based on silica fibers passing across the beam. The 4PrOBεaM system was deployed for characterization studies of the 18 MeV proton beam produced by the IBA Cyclone 18 MeV cyclotron at Bern University Hospital (Inselspital). The machine serves daily radioisotope production and multi-disciplinary research, which is carried out with a specifically conceived Beam Transport Line (BTL). The transverse RMS beam emittance of the cyclotron was measured as a function of several machine parameters, such as the magnetic field, RF peak voltage, and azimuthal angle of the stripper. The beam emittance was also measured using the method based on the quadrupole strength variation. The results obtained with both techniques were compared and a good agreement was found. In order to characterize the longitudinal dynamics, the proton energy distribution was measured. For this purpose, a method was developed based on aluminum absorbers of different thicknesses, a UniBEaM detector, and a Faraday cup. The results were an input for a simulation of the BTL developed in the MAD-X software. This tool allows machine parameters to be tuned online and the beam characteristics to be optimized for specific applications.

3D beam shape estimation based on distributed coaxial cable interferometric sensor

NASA Astrophysics Data System (ADS)

Cheng, Baokai; Zhu, Wenge; Liu, Jie; Yuan, Lei; Xiao, Hai

2017-03-01

We present a coaxial cable interferometer based distributed sensing system for 3D beam shape estimation. By making a series of reflectors on a coaxial cable, multiple Fabry-Perot cavities are created on it. Two cables are mounted on the beam at proper locations, and a vector network analyzer (VNA) is connected to them to obtain the complex reflection signal, which is used to calculate the strain distribution of the beam in horizontal and vertical planes. With 6 GHz swept bandwidth on the VNA, the spatial resolution for distributed strain measurement is 0.1 m, and the sensitivity is 3.768 MHz mɛ -1 at the interferogram dip near 3.3 GHz. Using displacement-strain transformation, the shape of the beam is reconstructed. With only two modified cables and a VNA, this system is easy to implement and manage. Comparing to optical fiber based sensor systems, the coaxial cable sensors have the advantage of large strain and robustness, making this system suitable for structure health monitoring applications.

Beam transport and monitoring for laser plasma accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakamura, K.; Sokollik, T.; Tilborg, J. van

The controlled transport and imaging of relativistic electron beams from laser plasma accelerators (LPAs) are critical for their diagnostics and applications. Here we present the design and progress in the implementation of the transport and monitoring system for an undulator based electron beam diagnostic. Miniature permanent-magnet quadrupoles (PMQs) are employed to realize controlled transport of the LPA electron beams, and cavity based electron beam position monitors for non-invasive beam position detection. Also presented is PMQ calibration by using LPA electron beams with broadband energy spectrum. The results show promising performance for both transporting and monitoring. With the proper transport system,more » XUV-photon spectra from THUNDER will provide the momentum distribution of the electron beam with the resolution above what can be achieved by the magnetic spectrometer currently used in the LOASIS facility.« less

Focused electron and ion beam systems

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

2004-07-27

An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

Development of a simple, low cost, indirect ion beam fluence measurement system for ion implanters, accelerators

NASA Astrophysics Data System (ADS)

Suresh, K.; Balaji, S.; Saravanan, K.; Navas, J.; David, C.; Panigrahi, B. K.

2018-02-01

We developed a simple, low cost user-friendly automated indirect ion beam fluence measurement system for ion irradiation and analysis experiments requiring indirect beam fluence measurements unperturbed by sample conditions like low temperature, high temperature, sample biasing as well as in regular ion implantation experiments in the ion implanters and electrostatic accelerators with continuous beam. The system, which uses simple, low cost, off-the-shelf components/systems and two distinct layers of in-house built softwarenot only eliminates the need for costly data acquisition systems but also overcomes difficulties in using properietry software. The hardware of the system is centered around a personal computer, a PIC16F887 based embedded system, a Faraday cup drive cum monitor circuit, a pair of Faraday Cups and a beam current integrator and the in-house developed software include C based microcontroller firmware and LABVIEW based virtual instrument automation software. The automatic fluence measurement involves two important phases, a current sampling phase lasting over 20-30 seconds during which the ion beam current is continuously measured by intercepting the ion beam and the averaged beam current value is computed. A subsequent charge computation phase lasting 700-900 seconds is executed making the ion beam to irradiate the samples and the incremental fluence received by the sampleis estimated usingthe latest averaged beam current value from the ion beam current sampling phase. The cycle of current sampling-charge computation is repeated till the required fluence is reached. Besides simplicity and cost-effectiveness, other important advantages of the developed system include easy reconfiguration of the system to suit customisation of experiments, scalability, easy debug and maintenance of the hardware/software, ability to work as a standalone system. The system was tested with different set of samples and ion fluences and the results were verified using Rutherford backscattering technique which showed the satisfactory functioning of the system. The accuracy of the fluence measurements is found to be less than 2% which meets the demands of the irradiation experiments undertaken using the developed set up. The system was incorporated for regular use at the existing ultra high vacuum (UHV) ion irradiation chamber of 1.7 MV Tandem accelerator and several ion implantation experiments on a variety of samples like SS304, D9, ODS alloys have been successfully carried out.

Micro-controller based air pressure monitoring instrumentation system using optical fibers as sensor

NASA Astrophysics Data System (ADS)

Hazarika, D.; Pegu, D. S.

2013-03-01

This paper describes a micro-controller based instrumentation system to monitor air pressure using optical fiber sensors. The principle of macrobending is used to develop the sensor system. The instrumentation system consists of a laser source, a beam splitter, two multi mode optical fibers, two Light Dependent Resistance (LDR) based timer circuits and a AT89S8252 micro-controller. The beam splitter is used to divide the laser beam into two parts and then these two beams are launched into two multi mode fibers. One of the multi mode fibers is used as the sensor fiber and the other one is used as the reference fiber. The use of the reference fiber is to eliminate the environmental effects while measuring the air pressure magnitude. The laser beams from the sensor and reference fibers are applied to two identical LDR based timer circuits. The LDR based timer circuits are interfaced to a micro-controller through its counter pins. The micro-controller samples the frequencies of the timer circuits using its counter-0 and counter-1 and the counter values are then processed to provide the measure of air pressure magnitude.

Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry.

PubMed

Wang, G; Wu, K; Hu, H; Li, G; Wang, L J

2016-10-01

To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

Ultra-low-frequency vertical vibration isolator based on a two-stage beam structure for absolute gravimetry

NASA Astrophysics Data System (ADS)

Wang, G.; Wu, K.; Hu, H.; Li, G.; Wang, L. J.

2016-10-01

To reduce seismic and environmental vibration noise, ultra-low-frequency vertical vibration isolation systems play an important role in absolute gravimetry. For this purpose, an isolator based on a two-stage beam structure is proposed and demonstrated. The isolator has a simpler and more robust structure than the present ultra-low-frequency vertical active vibration isolators. In the system, two beams are connected to a frame using flexural pivots. The upper beam is suspended from the frame with a normal hex spring and the lower beam is suspended from the upper one using a zero-length spring. The pivot of the upper beam is not vertically above the pivot of the lower beam. With this special design, the attachment points of the zero-length spring to the beams can be moved to adjust the effective stiffness. A photoelectric detector is used to detect the angle between the two beams, and a voice coil actuator attached to the upper beam is controlled by a feedback circuit to keep the angle at a fixed value. The system can achieve a natural period of 100 s by carefully moving the attachment points of the zero-length spring to the beams and tuning the feedback parameters. The system has been used as an inertial reference in the T-1 absolute gravimeter. The experiment results demonstrate that the system has significant vibration isolation performance that holds promise in applications such as absolute gravimeters.

A Computer-Based, Interactive Videodisc Job Aid and Expert System for Electron Beam Lithography Integration and Diagnostic Procedures.

ERIC Educational Resources Information Center

Stevenson, Kimberly

This master's thesis describes the development of an expert system and interactive videodisc computer-based instructional job aid used for assisting in the integration of electron beam lithography devices. Comparable to all comprehensive training, expert system and job aid development require a criterion-referenced systems approach treatment to…

Accelerated Electron-Beam Formation with a High Capture Coefficient in a Parallel Coupled Accelerating Structure

NASA Astrophysics Data System (ADS)

Chernousov, Yu. D.; Shebolaev, I. V.; Ikryanov, I. M.

2018-01-01

An electron beam with a high (close to 100%) coefficient of electron capture into the regime of acceleration has been obtained in a linear electron accelerator based on a parallel coupled slow-wave structure, electron gun with microwave-controlled injection current, and permanent-magnet beam-focusing system. The high capture coefficient was due to the properties of the accelerating structure, beam-focusing system, and electron-injection system. Main characteristics of the proposed systems are presented.

An ion beam facility based on a 3 MV tandetron accelerator in Sichuan University, China

NASA Astrophysics Data System (ADS)

Han, Jifeng; An, Zhu; Zheng, Gaoqun; Bai, Fan; Li, Zhihui; Wang, Peng; Liao, Xiaodong; Liu, Mantian; Chen, Shunli; Song, Mingjiang; Zhang, Jun

2018-03-01

A new ion beam facility based on a 3 MV tandetron accelerator system has been installed in Sichuan University, China. The facility was developed by High Voltage Engineering Europa and consists of three high-energy beam lines including the ion beam analysis, ion implantation and nuclear physics experiment end stations, respectively. The terminal voltage stability of the accelerator is better than ±30 V, and the brightness of the proton beam is approximately 5.06 A/rad2/m2/eV. The system demonstrates a great application potential in fields such as nuclear, material and environmental studies.

Propagation of a general-type beam through a truncated fractional Fourier transform optical system.

PubMed

Zhao, Chengliang; Cai, Yangjian

2010-03-01

Paraxial propagation of a general-type beam through a truncated fractional Fourier transform (FRT) optical system is investigated. Analytical formulas for the electric field and effective beam width of a general-type beam in the FRT plane are derived based on the Collins formula. Our formulas can be used to study the propagation of a variety of laser beams--such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams--through a FRT optical system with or without truncation. The propagation properties of a Hermite-cos-Gaussian beam passing through a rectangularly truncated FRT optical system are studied as a numerical example. Our results clearly show that the truncated FRT optical system provides a convenient way for laser beam shaping.

A Lunar-Based Spacecraft Propulsion Concept - The Ion Beam Sail

NASA Technical Reports Server (NTRS)

Brown, Ian G.; Lane, John E.; Youngquist, Robert C.

2006-01-01

We describe a concept for spacecraft propulsion by means of an energetic ion beam, with the ion source fixed at the spacecraft starting point (e.g., a lunar-based ion beam generator) and not onboard the vessel. This approach avoids the substantial mass penalty associated with the onboard ion source and power supply hardware, and vastly more energetic ion beam systems can be entertained. We estimate the ion beam parameters required for various scenarios, and consider some of the constraints limiting the concept. We find that the "ion beam sail' approach can be viable and attractive for journey distances not too great, for example within the Earth-Moon system, and could potentially provide support for journeys to the inner planets.

Medipix2 as a tool for proton beam characterization

NASA Astrophysics Data System (ADS)

Bisogni, M. G.; Cirrone, G. A. P.; Cuttone, G.; Del Guerra, A.; Lojacono, P.; Piliero, M. A.; Romano, F.; Rosso, V.; Sipala, V.; Stefanini, A.

2009-08-01

Proton therapy is a technique used to deliver a highly accurate and effective dose for the treatment of a variety of tumor diseases. The possibility to have an instrument able to give online information could reduce the time necessary to characterize the proton beam. To this aim we propose a detection system for online proton beam characterization based on the Medipix2 chip. Medipix2 is a detection system based on a single event counter read-out chip, bump-bonded to silicon pixel detector. The read-out chip is a matrix of 256×256 cells, 55×55 μm 2 each. To demonstrate the capabilities of Medipix2 as a proton detector, we have used a 62 MeV flux proton beam at the CATANA beam line of the LNS-INFN laboratory. The measurements performed confirmed the good imaging performances of the Medipix2 system also for the characterization of proton beams.

Performance Test of the Next Generation X-Ray Beam Position Monitor System for The APS Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, B.; Lee, S.; Westferro, F.

The Advanced Photon Source is developing its next major upgrade (APS-U) based on the multi-bend achromat lattice. Improved beam stability is critical for the upgrade and will require keeping short-time beam angle change below 0.25 µrad and long-term angle drift below 0.6 µrad. A reliable white x-ray beam diagnostic system in the front end will be a key part of the planned beam stabilization system. This system includes an x-ray beam position monitor (XBPM) based on x-ray fluorescence (XRF) from two specially designed GlidCop A-15 absorbers, a second XBPM using XRF photons from the Exit Mask, and two white beammore » intensity monitors using XRF from the photon shutter and Compton-scattered photons from the front end beryllium window or a retractable diamond film in windowless front ends. We present orbit stability data for the first XBPM used in the feedback control during user operations, as well as test data from the second XBPM and the intensity monitors. They demonstrate that the XBPM system meets APS-U beam stability requirements.« less

On finding the analytic dependencies of the external field potential on the control function when optimizing the beam dynamics

NASA Astrophysics Data System (ADS)

Ovsyannikov, A. D.; Kozynchenko, S. A.; Kozynchenko, V. A.

2017-12-01

When developing a particle accelerator for generating the high-precision beams, the injection system design is of importance, because it largely determines the output characteristics of the beam. At the present paper we consider the injection systems consisting of electrodes with given potentials. The design of such systems requires carrying out simulation of beam dynamics in the electrostatic fields. For external field simulation we use the new approach, proposed by A.D. Ovsyannikov, which is based on analytical approximations, or finite difference method, taking into account the real geometry of the injection system. The software designed for solving the problems of beam dynamics simulation and optimization in the injection system for non-relativistic beams has been developed. Both beam dynamics and electric field simulations in the injection system which use analytical approach and finite difference method have been made and the results presented in this paper.

Interleaved Training and Training-Based Transmission Design for Hybrid Massive Antenna Downlink

NASA Astrophysics Data System (ADS)

Zhang, Cheng; Jing, Yindi; Huang, Yongming; Yang, Luxi

2018-06-01

In this paper, we study the beam-based training design jointly with the transmission design for hybrid massive antenna single-user (SU) and multiple-user (MU) systems where outage probability is adopted as the performance measure. For SU systems, we propose an interleaved training design to concatenate the feedback and training procedures, thus making the training length adaptive to the channel realization. Exact analytical expressions are derived for the average training length and the outage probability of the proposed interleaved training. For MU systems, we propose a joint design for the beam-based interleaved training, beam assignment, and MU data transmissions. Two solutions for the beam assignment are provided with different complexity-performance tradeoff. Analytical results and simulations show that for both SU and MU systems, the proposed joint training and transmission designs achieve the same outage performance as the traditional full-training scheme but with significant saving in the training overhead.

Space fabrication demonstration system, technical volume

NASA Technical Reports Server (NTRS)

1979-01-01

The automatic beam builder ABB was developed, fabricated, and demonstrated within the established contract cost and schedule constraints. The ABB demonstrated the feasibility of: producing lightweight beams automatically within the required rate of 1 to 5 ft of completed beam per minute and producing structurally sound beams with axial design load of 5538 N based on the Grumman photovoltaic satellite solar power system design reference structure.

An automatic alignment system for measuring optical path of transmissometer based on light beam scanning

NASA Astrophysics Data System (ADS)

Zhou, Shudao; Ma, Zhongliang; Wang, Min; Peng, Shuling

2018-05-01

This paper proposes a novel alignment system based on the measurement of optical path using a light beam scanning mode in a transmissometer. The system controls both the probe beam and the receiving field of view while scanning in two vertical directions. The system then calculates the azimuth angle of the transmitter and the receiver to determine the precise alignment of the optical path. Experiments show that this method can determine the alignment angles in less than 10 min with errors smaller than 66 μrad in the azimuth. This system also features high collimation precision, process automation and simple installation.

SU-E-T-186: Cloud-Based Quality Assurance Application for Linear Accelerator Commissioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogers, J

2015-06-15

Purpose: To identify anomalies and safety issues during data collection and modeling for treatment planning systems Methods: A cloud-based quality assurance system (AQUIRE - Automated QUalIty REassurance) has been developed to allow the uploading and analysis of beam data aquired during the treatment planning system commissioning process. In addition to comparing and aggregating measured data, tools have also been developed to extract dose from the treatment planning system for end-to-end testing. A gamma index is perfomed on the data to give a dose difference and distance-to-agreement for validation that a beam model is generating plans consistent with the beam datamore » collection. Results: Over 20 linear accelerators have been commissioning using this platform, and a variety of errors and potential saftey issues have been caught through the validation process. For example, the gamma index of 2% dose, 2mm DTA is quite sufficient to see curves not corrected for effective point of measurement. Also, data imported into the database is analyzed against an aggregate of similar linear accelerators to show data points that are outliers. The resulting curves in the database exhibit a very small standard deviation and imply that a preconfigured beam model based on aggregated linear accelerators will be sufficient in most cases. Conclusion: With the use of this new platform for beam data commissioning, errors in beam data collection and treatment planning system modeling are greatly reduced. With the reduction in errors during acquisition, the resulting beam models are quite similar, suggesting that a common beam model may be possible in the future. Development is ongoing to create routine quality assurance tools to compare back to the beam data acquired during commissioning. I am a medical physicist for Alzyen Medical Physics, and perform commissioning services.« less

An optimal beam alignment method for large-scale distributed space surveillance radar system

NASA Astrophysics Data System (ADS)

Huang, Jian; Wang, Dongya; Xia, Shuangzhi

2018-06-01

Large-scale distributed space surveillance radar is a very important ground-based equipment to maintain a complete catalogue for Low Earth Orbit (LEO) space debris. However, due to the thousands of kilometers distance between each sites of the distributed radar system, how to optimally implement the Transmitting/Receiving (T/R) beams alignment in a great space using the narrow beam, which proposed a special and considerable technical challenge in the space surveillance area. According to the common coordinate transformation model and the radar beam space model, we presented a two dimensional projection algorithm for T/R beam using the direction angles, which could visually describe and assess the beam alignment performance. Subsequently, the optimal mathematical models for the orientation angle of the antenna array, the site location and the T/R beam coverage are constructed, and also the beam alignment parameters are precisely solved. At last, we conducted the optimal beam alignment experiments base on the site parameters of Air Force Space Surveillance System (AFSSS). The simulation results demonstrate the correctness and effectiveness of our novel method, which can significantly stimulate the construction for the LEO space debris surveillance equipment.

SPS phase control system performance via analytical simulation

NASA Technical Reports Server (NTRS)

Lindsey, W. C.; Kantak, A. V.; Chie, C. M.; Booth, R. W. D.

1979-01-01

A solar power satellite transmission system which incorporates automatic beam forming, steering, and phase control is discussed. The phase control concept centers around the notation of an active retrodirective phased array as a means of pointing the beam to the appropriate spot on Earth. The transmitting antenna (spacetenna) directs the high power beam so that it focuses on the ground-based receiving antenna (rectenna). A combination of analysis and computerized simulation was conducted to determine the far field performance of the reference distribution system, and the beam forming and microwave power generating systems.

Propagation of flat-topped multi-Gaussian beams through a double-lens system with apertures.

PubMed

Gao, Yanqi; Zhu, Baoqiang; Liu, Daizhong; Lin, Zunqi

2009-07-20

A general model for different apertures and flat-topped laser beams based on the multi-Gaussian function is developed. The general analytical expression for the propagation of a flat-topped beam through a general double-lens system with apertures is derived using the above model. Then, the propagation characteristics of the flat-topped beam through a spatial filter are investigated by using a simplified analytical expression. Based on the Fluence beam contrast and the Fill factor, the influences of a pinhole size on the propagation of the flat-topped multi-Gaussian beam (FMGB) through the spatial filter are illustrated. An analytical expression for the propagation of the FMGB through the spatial filter with a misaligned pinhole is presented, and the influences of the pinhole offset are evaluated.

Hybrid Automated Diagnosis of Discrete/Continuous Systems

NASA Technical Reports Server (NTRS)

Park, Han; James, Mark; MacKey, Ryan; Cannon, Howard; Bajwa, Anapa; Maul, William

2007-01-01

A recently conceived method of automated diagnosis of a complex electromechanical system affords a complete set of capabilities for hybrid diagnosis in the case in which the state of the electromechanical system is characterized by both continuous and discrete values (as represented by analog and digital signals, respectively). The method is an integration of two complementary diagnostic systems: (1) beacon-based exception analysis for multi-missions (BEAM), which is primarily useful in the continuous domain and easily performs diagnoses in the presence of transients; and (2) Livingstone, which is primarily useful in the discrete domain and is typically restricted to quasi-steady conditions. BEAM has been described in several prior NASA Tech Briefs articles: "Software for Autonomous Diagnosis of Complex Systems" (NPO-20803), Vol. 26, No. 3 (March 2002), page 33; "Beacon-Based Exception Analysis for Multimissions" (NPO-20827), Vol. 26, No. 9 (September 2002), page 32; "Wavelet-Based Real-Time Diagnosis of Complex Systems" (NPO-20830), Vol. 27, No. 1 (January 2003), page 67; and "Integrated Formulation of Beacon-Based Exception Analysis for Multimissions" (NPO-21126), Vol. 27, No. 3 (March 2003), page 74. Briefly, BEAM is a complete data-analysis method, implemented in software, for real-time or off-line detection and characterization of faults. The basic premise of BEAM is to characterize a system from all available observations and train the characterization with respect to normal phases of operation. The observations are primarily continuous in nature. BEAM isolates anomalies by analyzing the deviations from nominal for each phase of operation. Livingstone is a model-based reasoner that uses a model of a system, controller commands, and sensor observations to track the system s state, and detect and diagnose faults. Livingstone models a system within the discrete domain. Therefore, continuous sensor readings, as well as time, must be discretized. To reason about continuous systems, Livingstone uses monitors that discretize the sensor readings using trending and thresholding techniques. In development of the a hybrid method, BEAM results were sent to Livingstone to serve as an independent source of evidence that is in addition to the evidence gathered by Livingstone standard monitors. The figure depicts the flow of data in an early version of a hybrid system dedicated to diagnosing a simulated electromechanical system. In effect, BEAM served as a "smart" monitor for Livingstone. BEAM read the simulation data, processed the data to form observations, and stored the observations in a file. A monitor stub synchronized the events recorded by BEAM with the output of the Livingstone standard monitors according to time tags. This information was fed to a real-time interface, which buffered and fed the information to Livingstone, and requested diagnoses at the appropriate times. In a test, the hybrid system was found to correctly identify a failed component in an electromechanical system for which neither BEAM nor Livingstone alone yielded the correct diagnosis.

Local divergence and curvature divergence in first order optics

NASA Astrophysics Data System (ADS)

Mafusire, Cosmas; Krüger, Tjaart P. J.

2018-06-01

The far-field divergence of a light beam propagating through a first order optical system is presented as a square root of the sum of the squares of the local divergence and the curvature divergence. The local divergence is defined as the ratio of the beam parameter product to the beam width whilst the curvature divergence is a ratio of the space-angular moment also to the beam width. It is established that the beam’s focusing parameter can be defined as a ratio of the local divergence to the curvature divergence. The relationships between the two divergences and other second moment-based beam parameters are presented. Their various mathematical properties are presented such as their evolution through first order systems. The efficacy of the model in the analysis of high power continuous wave laser-based welding systems is briefly discussed.

Development of a MeV proton beam irradiation system.

PubMed

Park, Bum-Sik; Cho, Yong-Sub; Hong, In-Seok

2008-02-01

A proton beam irradiation system for the application of the MeV class proton beam, such as an implantation for a power semiconductor device and a smart-cut technology for a semiconductor production process, has been developed. This system consists of a negative ion source, an Einzel lens for a low energy beam transport, accelerating tubes, a gas stripper, a Cockroft-Walton high voltage power supply with 1 MV, a vacuum pumping system, and a high pressure insulating gas system. The negative hydrogen ion source is based on TRIUMF's design. Following the tandem accelerator, a pair of magnets is installed for raster scanning of the MeV proton beam to obtain a uniform irradiation pattern on the target. The system is 7 m long from the ion source to the target and is optimized for the proton beam irradiation. The details of the system development will be described.

Development of a bunch-by-bunch longitudinal feedback system with a wide dynamic range for the HIGS facility

NASA Astrophysics Data System (ADS)

Wu, W. Z.; Kim, Y.; Li, J. Y.; Teytelman, D.; Busch, M.; Wang, P.; Swift, G.; Park, I. S.; Ko, I. S.; Wu, Y. K.

2011-03-01

Electron beam coupled-bunch instabilities can limit and degrade the performance of storage ring based light sources. A longitudinal feedback system has been developed for the Duke storage ring to suppress multi-bunch beam instabilities which prevent stable, high-current operation of the storage ring based free-electron lasers (FELs) and an FEL driven Compton gamma source, the high intensity gamma-ray source (HIGS) at Duke University. In this work, we report the development of a state-of-the-art second generation longitudinal feedback system which employs a field programmable gate array (FPGA) based processor, and a broadband, high shunt-impedance kicker cavity. With two inputs and two outputs, the kicker cavity was designed with a resonant frequency of 937 MHz, a bandwidth of 97 MHz, and a shunt impedance of 1530 Ω. We also developed an S-matrix based technique to fully characterize the performance of the kicker cavity in the cold test. This longitudinal feedback system has been commissioned and optimized to stabilize high-current electron beams with a wide range of electron beam energies (250 MeV to 1.15 GeV) and a number of electron beam bunch modes, including the single-bunch mode and all possible symmetric bunch modes. This feedback system has become a critical instrument to ensure stable, high-flux operation of HIGS to produce nearly monochromatic, highly polarized Compton gamma-ray beams.

The study of laser beam riding guided system based on 980nm diode laser

NASA Astrophysics Data System (ADS)

Qu, Zhou; Xu, Haifeng; Sui, Xin; Yang, Kun

2015-10-01

With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

A gamma beam profile imager for ELI-NP Gamma Beam System

NASA Astrophysics Data System (ADS)

Cardarelli, P.; Paternò, G.; Di Domenico, G.; Consoli, E.; Marziani, M.; Andreotti, M.; Evangelisti, F.; Squerzanti, S.; Gambaccini, M.; Albergo, S.; Cappello, G.; Tricomi, A.; Veltri, M.; Adriani, O.; Borgheresi, R.; Graziani, G.; Passaleva, G.; Serban, A.; Starodubtsev, O.; Variola, A.; Palumbo, L.

2018-06-01

The Gamma Beam System of ELI-Nuclear Physics is a high brilliance monochromatic gamma source based on the inverse Compton interaction between an intense high power laser and a bright electron beam with tunable energy. The source, currently being assembled in Magurele (Romania), is designed to provide a beam with tunable average energy ranging from 0.2 to 19.5 MeV, rms energy bandwidth down to 0.5% and flux of about 108 photons/s. The system includes a set of detectors for the diagnostic and complete characterization of the gamma beam. To evaluate the spatial distribution of the beam a gamma beam profile imager is required. For this purpose, a detector based on a scintillator target coupled to a CCD camera was designed and a prototype was tested at INFN-Ferrara laboratories. A set of analytical calculations and Monte Carlo simulations were carried out to optimize the imager design and evaluate the performance expected with ELI-NP gamma beam. In this work the design of the imager is described in detail, as well as the simulation tools used and the results obtained. The simulation parameters were tuned and cross-checked with the experimental measurements carried out on the assembled prototype using the beam from an x-ray tube.

Generation of arbitrary order Bessel beams via 3D printed axicons at the terahertz frequency range.

PubMed

Wei, Xuli; Liu, Changming; Niu, Liting; Zhang, Zhongqi; Wang, Kejia; Yang, Zhengang; Liu, Jinsong

2015-12-20

We present the generation of arbitrary order Bessel beams at 0.3 THz through the implementation of suitably designed axicons based on 3D printing technology. The helical axicons, which possess thickness gradients in both radial and azimuthal directions, can convert the incident Gaussian beam into a high-order Bessel beam with spiral phase structure. The evolution of the generated Bessel beams are characterized experimentally with a three-dimensional field scanner. Moreover, the topological charges carried by the high-order Bessel beams are determined by the fork-like interferograms. This 3D-printing-based Bessel beam generation technique is useful not only for THz imaging systems with zero-order Bessel beams but also for future orbital-angular-momentum-based THz free-space communication with higher-order Bessel beams.

Comparisons of selected laser beam power missions to conventionally powered missions

NASA Technical Reports Server (NTRS)

Bozek, John M.; Oleson, Steven R.; Landis, Geoffrey A.; Stavnes, Mark W.

1993-01-01

Earth-based laser sites beaming laser power to space assets have shown benefits over competing power system concepts for specific missions. Missions analyzed in this report that show benefits of laser beam power are low Earth orbit (LEO) to geosynchronous Earth orbit (GEO) transfer, LEO to low lunar orbit (LLO) cargo missions, and lunar-base power. Both laser- and solar-powered orbit-transfer vehicles (OTV's) make a 'tug' concept viable, which substantially reduces cumulative initial mass to LEO in comparison to chemical propulsion concepts. Lunar cargo missions utilizing laser electric propulsion from Earth-orbit to LLO show substantial mass saving to LEO over chemical propulsion systems. Lunar-base power system options were compared on a landed-mass basis. Photovoltaics with regenerative fuel cells, reactor-based systems, and laser-based systems were sized to meet a generic lunar-base power profile. A laser-based system begins to show landed mass benefits over reactor-based systems when proposed production facilities on the Moon require power levels greater than approximately 300 kWe. Benefit/cost ratios of laser power systems for an OTV, both to GEO and LLO, and for a lunar base were calculated to be greater than 1.

Optical-beam wavefront control based on the atmospheric backscatter signal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banakh, V A; Razenkov, I A; Rostov, A P

2015-02-28

The feasibility of compensating for aberrations of the optical-beam initial wavefront by aperture sounding, based on the atmospheric backscatter signal from an additional laser source with a different wavelength, is experimentally studied. It is shown that the adaptive system based on this principle makes it possible to compensate for distortions of the initial beam wavefront on a surface path in atmosphere. Specifically, the beam divergence decreases, while the level of the detected mean backscatter power from the additional laser source increases. (light scattering)

Design of interferometer system on Versatile Experiment Spherical Torus (VEST) at Seoul National University

NASA Astrophysics Data System (ADS)

Choi, D. H.; An, Y. H.; Chung, K. J.; Hwang, Y. S.

2012-01-01

A 94 GHz heterodyne interferometer system was designed to measure the plasma density of VEST (Versatile Experiment Spherical Torus), which was recently built at Seoul National University. Two 94 GHz Gunn oscillators with a frequency difference of 40 MHz were used in the microwave electronics part of a heterodyne interferometer system. A compact beam focusing system utilizing a pair of plano-convex lenses and a concave mirror was designed to maximize the effective beam reception and spatial resolution. Beam path analysis based on Gaussian optics was used in the design of the beam focusing system. The design of the beam focusing system and the beam path analysis were verified with a couple of experiments that were done within an experimental framework that considered the real dimensions of a vacuum vessel. Optimum distances between the optical components and the beam radii along the beam path obtained from the experiments were in good agreement with the beam path analysis using the Gaussian optics. Both experimentation and numerical calculations confirmed that the designed beam focusing system maximized the spatial resolution of the measurement; moreover, the beam waist was located at the center of the plasma to generate a phase shift more effectively in plasmas. The interferometer system presented in this paper is expected to be used in the measurements of line integrated plasma densities during the start-up phase of VEST.

New Beam Scanning Device for Active Beam Delivery System (BDS) in Proton Therapy

NASA Astrophysics Data System (ADS)

Variale, V.; Mastromarco, M.; Colamaria, F.; Colella, D.

A new Beam Delivery System (BDS) has been studied in the framework of a new proton therapy project, called AMIDERHA. It is characterized by an active scanning system for target irradiation with a pencil beam. The project is based on the use of a Linac with variable final energy and the Robotized Patient Positioning System instead of the traditional gantry. As a consequence, in the active BDS of AMIDERHA a pencil beam scanning system with a relatively long Source to Axis Distance (SAD) can be used. In this contribution, the idea of using a unique new device capable of both horizontal and vertical beam scansion for the AMIDERHA active BDS will be presented and discussed. Furthermore, a preliminary design of that device will be shown, together with the results of simulations.

Image-based tracking system for vibration measurement of a rotating object using a laser scanning vibrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dongkyu, E-mail: akein@gist.ac.kr; Khalil, Hossam; Jo, Youngjoon

2016-06-28

An image-based tracking system using laser scanning vibrometer is developed for vibration measurement of a rotating object. The proposed system unlike a conventional one can be used where the position or velocity sensor such as an encoder cannot be attached to an object. An image processing algorithm is introduced to detect a landmark and laser beam based on their colors. Then, through using feedback control system, the laser beam can track a rotating object.

Design and evaluation of an electromagnetic beam waveguide for measuring electrical properties of materials

NASA Technical Reports Server (NTRS)

Bailey, M. C.

1994-01-01

A beam waveguide was designed that is based upon the propagation characteristics of the fundamental Gaussian beam and the focusing properties of spherical dielectric lenses. The 20-GHz, two-horn, four-lens system was constructed and experimentally evaluated by probing the field in a plane perpendicular to the beam axis at the center of the beam waveguide system. The critical parameters were determined by numerical sensitivity studies, and the lens-horn critical spacing was adjusted to better focus the beam at the probe plane. The measured performance was analyzed by consideration of higher order Gaussian-Laguerre beam modes. The beam waveguide system was successfully used in the measurements of the electromagnetic transmission properties of Shuttle thermal-protection tiles while the tile surface was being heated to reentry-level temperatures with a high-power laser.

Phase-locking of combination-cylinder discharge CO2 laser

NASA Astrophysics Data System (ADS)

Xu, Yonggen

2014-05-01

A new type of laser resonator is presented to obtained good coherent beam and the parameters of the laser beam are calculated. The principle of phase-locking is described based on the injection-locking, the properties of the injected beam in the resonator are studied in detail. The output beam from output mirror is an annular laser beam with zero central intensity. An analytical expression for the annular laser beam through the ABCD optical system is derived. Typical numerical examples are calculated to confirm our analytical results. It is shown that the good coherent beam can be obtained through phase-locking, and the central intensity of annular beam through ABCD optical system will become maximum when the parameters of laser beam are selected reasonably.

Remarks on the derivation of the governing equations for the dynamics of a nonlinear beam to a non ideal shaft coupling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenili, André; Lopes Rebello da Fonseca Brasil, Reyolando Manoel; Balthazar, José M., E-mail: jmbaltha@gmail.com

We derive nonlinear governing equations without assuming that the beam is inextensible. The derivation couples the equations that govern a weak electric motor, which is used to rotate the base of the beam, to those that govern the motion of the beam. The system is considered non-ideal in the sense that the response of the motor to an applied voltage and the motion of the beam must be obtained interactively. The moment that the motor exerts on the base of the beam cannot be determined without solving for the motion of the beam.

Hollow Gaussian Schell-model beam and its propagation

NASA Astrophysics Data System (ADS)

Wang, Li-Gang; Wang, Li-Qin

2008-03-01

In this paper, we present a new model, hollow Gaussian Schell-model beams (HGSMBs), to describe the practical dark hollow beams. An analytical propagation formula for HGSMBs passing through a paraxial first-order optical system is derived based on the theory of coherence. Based on the derived formula, an application example showing the influence of spatial coherence on the propagation of beams is illustrated. It is found that the beam propagating properties of HGSMBs will be greatly affected by their spatial coherence. Our model provides a very convenient way for analyzing the propagation properties of partially coherent dark hollow beams.

The upgraded data acquisition system for beam loss monitoring at the Fermilab Tevatron and Main Injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baumbaugh, A.; Briegel, C.; Brown, B.C.

2011-11-01

A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beam-loss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. Themore » system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and show a number of examples of its use in both the Main Injector and Tevatron.« less

The upgraded data acquisition system for beam loss monitoring at the Fermilab Tevatron and Main Injector

NASA Astrophysics Data System (ADS)

Baumbaugh, A.; Briegel, C.; Brown, B. C.; Capista, D.; Drennan, C.; Fellenz, B.; Knickerbocker, K.; Lewis, J. D.; Marchionni, A.; Needles, C.; Olson, M.; Pordes, S.; Shi, Z.; Still, D.; Thurman-Keup, R.; Utes, M.; Wu, J.

2011-11-01

A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beam-loss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. The system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and show a number of examples of its use in both the Main Injector and Tevatron.

PC based graphic display real-time particle beam uniformity

NASA Technical Reports Server (NTRS)

Huebner, M. A.; Malone, C. J.; Smith, L. S.; Soli, G. A.

1989-01-01

A technique has been developed to support the study of the effects of cosmic rays on integrated circuits. The system is designed to determine the particle distribution across the surface of an integrated circuit accurately while the circuit is bombarded by a particle beam. The system uses photomultiplier tubes, an octal discriminator, a computer-controlled NIM quad counter, and an IBM PC. It provides real-time operator feedback for fast beam tuning and monitors momentary fluctuations in the particle beam. The hardware, software, and system performance are described.

Design of optical axis jitter control system for multi beam lasers based on FPGA

NASA Astrophysics Data System (ADS)

Ou, Long; Li, Guohui; Xie, Chuanlin; Zhou, Zhiqiang

2018-02-01

A design of optical axis closed-loop control system for multi beam lasers coherent combining based on FPGA was introduced. The system uses piezoelectric ceramics Fast Steering Mirrors (FSM) as actuator, the Fairfield spot detection of multi beam lasers by the high speed CMOS camera for optical detecting, a control system based on FPGA for real-time optical axis jitter suppression. The algorithm for optical axis centroid detecting and PID of anti-Integral saturation were realized by FPGA. Optimize the structure of logic circuit by reuse resource and pipeline, as a result of reducing logic resource but reduced the delay time, and the closed-loop bandwidth increases to 100Hz. The jitter of laser less than 40Hz was reduced 40dB. The cost of the system is low but it works stably.

STATUS OF VARIOUS SNS DIAGNOSTIC SYSTEMS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blokland, Willem; Purcell, J David; Patton, Jeff

2007-01-01

The Spallation Neutron Source (SNS) accelerator systems are ramping up to deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. Enhancements or additions have been made to several instrument systems to support the ramp up in intensity, improve reliability, and/or add functionality. The Beam Current Monitors now support increased rep rates, the Harp system now includes charge density calculations for the target, and a new system has been created to collect data for the beam accounting and present the data over the web and to the operator consoles. The majority of themore » SNS beam instruments are PC-based and their configuration files are now managed through the Oracle relational database. A new version for the wire scanner software was developed to add features to correlate the scan with beam loss, parking in the beam, and measuring the longitudinal beam current. This software is currently being tested. This paper also includes data from the selected instruments.« less

Implementation of a SVWP-based laser beam shaping technique for generation of 100-mJ-level picosecond pulses.

PubMed

Adamonis, J; Aleknavičius, A; Michailovas, K; Balickas, S; Petrauskienė, V; Gertus, T; Michailovas, A

2016-10-01

We present implementation of the energy-efficient and flexible laser beam shaping technique in a high-power and high-energy laser amplifier system. The beam shaping is based on a spatially variable wave plate (SVWP) fabricated by femtosecond laser nanostructuring of glass. We reshaped the initially Gaussian beam into a super-Gaussian (SG) of the 12th order with efficiency of about 50%. The 12th order of the SG beam provided the best compromise between large fill factor, low diffraction on the edges of the active media, and moderate intensity distribution modification during free-space propagation. We obtained 150 mJ pulses of 532 nm radiation. High-energy, pulse duration of 85 ps and the nearly flat-top spatial profile of the beam make it ideal for pumping optical parametric chirped pulse amplification systems.

Applications of power beaming from space-based nuclear power stations. [Laser beaming to airplanes; microwave beaming to ground

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, J.R.; Botts, T.E.; Hertzberg, A.

1981-01-01

Power beaming from space-based reactor systems is examined using an advanced compact, lightweight Rotating Bed Reactor (RBR). Closed Brayton power conversion efficiencies in the range of 30 to 40% can be achieved with turbines, with reactor exit temperatures on the order of 2000/sup 0/K and a liquid drop radiator to reject heat at temperatures of approx. 500/sup 0/K. Higher RBR coolant temperatures (up to approx. 3000/sup 0/K) are possible, but gains in power conversion efficiency are minimal, due to lower expander efficiency (e.g., a MHD generator). Two power beaming applications are examined - laser beaming to airplanes and microwave beamingmore » to fixed ground receivers. Use of the RBR greatly reduces system weight and cost, as compared to solar power sources. Payback times are a few years at present prices for power and airplane fuel.« less

Propagation properties of hollow sinh-Gaussian beams through fractional Fourier transform optical systems

NASA Astrophysics Data System (ADS)

Tang, Bin; Jiang, ShengBao; Jiang, Chun; Zhu, Haibin

2014-07-01

A hollow sinh-Gaussian beam (HsG) is an appropriate model to describe the dark-hollow beam. Based on Collins integral formula and the fact that a hard-edged-aperture function can be expanded into a finite sum of complex Gaussian functions, the propagation properties of a HsG beam passing through fractional Fourier transform (FRFT) optical systems with and without apertures have been studied in detail by some typical numerical examples. The results obtained using the approximate analytical formula are in good agreement with those obtained using numerical integral calculation. Further, the studies indicate that the normalized intensity distribution of the HsG beam in FRFT plane is closely related with not only the fractional order but also the beam order and the truncation parameter. The FRFT optical systems provide a convenient way for laser beam shaping.

Novel Space-based Solar Power Technologies and Architectures for Earth and Beyond

NASA Technical Reports Server (NTRS)

Howell, Joe T.; Fikes, John C.; O'Neill, Mark J.

2005-01-01

Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. Power beaming or wireless power transmission (WPT) can involve lasers or microwaves along with the associated power interfaces. Microwave and laser transmission techniques have been studied with several promising approaches to safe and efficient WPT identified. These investigations have included microwave phased array transmitters, as well as laser transmission and associated optics. There is a need to produce "proof-of-concept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space to surface sites. This paper briefly discusses achieving a promising approach to the solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) for both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars.

A resonant force sensor based on ionic polymer metal composites

NASA Astrophysics Data System (ADS)

Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

2008-02-01

In this paper a novel force sensor, based on ionic polymer metal composites (IPMCs), is presented. The system has DC sensing capabilities and is able to work in the range of a few millinewtons. IPMCs are emerging materials used to realize motion actuators and sensors. An IPMC strip is activated in a beam fixed/simply-supported configuration. The beam is tightened at the simply-supported end by a force. This influences the natural resonant frequency of the beam; the value of the resonant frequency is used in the proposed system to estimate the force applied in the axial direction. The performance of the system based on the IPMC material has proved to be comparable with that of sensors based on other sensing mechanisms. This suggests the possibility of using this class of polymeric devices to realize PMEMS (plastic micro electrical mechanical systems) sensors.

Flight-Tested Prototype of BEAM Software

NASA Technical Reports Server (NTRS)

Mackey, Ryan; Tikidjian, Raffi; James, Mark; Wang, David

2006-01-01

Researchers at JPL have completed a software prototype of BEAM (Beacon-based Exception Analysis for Multi-missions) and successfully tested its operation in flight onboard a NASA research aircraft. BEAM (see NASA Tech Briefs, Vol. 26, No. 9; and Vol. 27, No. 3) is an ISHM (Integrated Systems Health Management) technology that automatically analyzes sensor data and classifies system behavior as either nominal or anomalous, and further characterizes anomalies according to strength, duration, and affected signals. BEAM (see figure) can be used to monitor a wide variety of physical systems and sensor types in real time. In this series of tests, BEAM monitored the engines of a Dryden Flight Research Center F-18 aircraft, and performed onboard, unattended analysis of 26 engine sensors from engine startup to shutdown. The BEAM algorithm can detect anomalies based solely on the sensor data, which includes but is not limited to sensor failure, performance degradation, incorrect operation such as unplanned engine shutdown or flameout in this example, and major system faults. BEAM was tested on an F-18 simulator, static engine tests, and 25 individual flights totaling approximately 60 hours of flight time. During these tests, BEAM successfully identified planned anomalies (in-flight shutdowns of one engine) as well as minor unplanned anomalies (e.g., transient oil- and fuel-pressure drops), with no false alarms or suspected false-negative results for the period tested. BEAM also detected previously unknown behavior in the F- 18 compressor section during several flights. This result, confirmed by direct analysis of the raw data, serves as a significant test of BEAM's capability.

Light-sheet generation in inhomogeneous media using self-reconstructing beams and the STED-principle.

PubMed

Gohn-Kreuz, Cristian; Rohrbach, Alexander

2016-03-21

Self-reconstruction of Bessel beams in inhomogeneous media is beneficial in light-sheet based microscopy. Although the beam's ring system enables propagation stability, the resulting image contrast is reduced. Here, we show that by a combination of two self-reconstructing beams with different orbital angular momenta it is possible to inhibit fluorescence from the ring system by using stimulated emission depletion (STED) even in strongly scattering media. Our theoretical study shows that the remaining fluorescence γ depends non-linearly on the beams' relative radial and orbital angular momenta. For various scattering media we demonstrate that γ remains remarkably stable over long beam propagation distances.

Beam propagation factor based on the Rényi entropy.

PubMed

Vaveliuk, Pablo; da Silva, Marcone Lopes

2008-09-15

A beam width measure based on Rényi entropy was introduced by Luis [Opt. Lett 31, 3644 (2006)]. That one-dimensional analysis was limited to beam profiles with rectangular symmetry. In this Letter, we derive a general Rényi beam width measure that accounts for the diffraction properties of beams with profiles of arbitrary symmetry. We also show that the square of this measure has a quadratic dependence as a function of the propagation coordinate, so that it can be applied to propagation through arbitrary ABCD paraxial systems. The Rényi beam propagation factor, here introduced, is discussed in examples where the M(2) factor seems to have a limited effectiveness in describing the beam spreading.

Controlling Second Harmonic Efficiency of Laser Beam Interactions

NASA Technical Reports Server (NTRS)

Barnes, Norman P. (Inventor); Walsh, Brian M. (Inventor); Reichle, Donald J. (Inventor)

2011-01-01

A method is provided for controlling second harmonic efficiency of laser beam interactions. A laser system generates two laser beams (e.g., a laser beam with two polarizations) for incidence on a nonlinear crystal having a preferred direction of propagation. Prior to incidence on the crystal, the beams are optically processed based on the crystal's beam separation characteristics to thereby control a position in the crystal along the preferred direction of propagation at which the beams interact.

Integrated Formulation of Beacon-Based Exception Analysis for Multimissions

NASA Technical Reports Server (NTRS)

Mackey, Ryan; James, Mark; Park, Han; Zak, Mickail

2003-01-01

Further work on beacon-based exception analysis for multimissions (BEAM), a method of real-time, automated diagnosis of a complex electromechanical systems, has greatly expanded its capability and suitability of application. This expanded formulation, which fully integrates physical models and symbolic analysis, is described. The new formulation of BEAM expands upon previous advanced techniques for analysis of signal data, utilizing mathematical modeling of the system physics, and expert-system reasoning,

Thermoelectric Figures of Merit of Zn4Sb3 and Zrnisn-based Half-heusler Compounds Influenced by Mev Ion-beam Bombardments

NASA Astrophysics Data System (ADS)

Budak, S.; Guner, S.; Muntele, C. I.; Ila, D.

Semiconducting β-Zn4Sb3 and ZrNiSn-based half-Heusler compound thin films with applications as thermoelectric (TE) materials were prepared using ion beam assisted deposition (IBAD). High-purity solid zinc (Zn) and antimony (Sb) were evaporated by electron beam to grow the β-Zn4Sb3 thin film while high-purity zirconium (Zr) powder and nickel (Ni) tin (Sn) powders were evaporated by electron beam to grow the ZrNiSn-based half-Heusler compound thin film. Rutherford backscattering spectrometry (RBS) was used to analyze the composition of the thin films. The grown thin films were subjected to 5 MeV Si ions bombardment for generation of nanostructures in the films. We measured the thermal conductivity, Seebeck coefficient, and electrical conductivity of these two systems before and after 5 MeV Si ions beam bombardment. The two material systems have been identified as promising TE materials for the application of thermal-to-electrical energy conversion, but the efficiency still limits their applications. The electronic energy deposited due to ionization in the track of MeV ion beam couldcause localized crystallization. The nanostructures produced by MeV ion beam can cause significant change in both the electrical and the thermal conductivity of thin films, thereby improving the efficiency. We used the 3ω-method (3rd harmonic) measurement system to measure the cross-plane thermal conductivity, the van der Pauw measurement system to measure the electrical conductivity, and the Seebeck-coefficient measurement system to measure the cross-plane Seebeck coefficient. The thermoelectric figures of merit of the two material systems were then derived by calculations using the measurement results. The MeV ion-beam bombardment was found to decrease the thermal conductivity of thin films and increase the efficiency of thermal-to-electrical energy conversion.

CA resist with high sensitivity and sub-100-nm resolution for advanced mask making

NASA Astrophysics Data System (ADS)

Huang, Wu-Song; Kwong, Ranee W.; Hartley, John G.; Moreau, Wayne M.; Angelopoulos, Marie; Magg, Christopher; Lawliss, Mark

2000-07-01

Recently, there is significant interest in using CA resist for electron beam (E-beam) applications including mask making, direct write, and projection printing. CA resists provide superior lithographic performance in comparison to traditional non-CA E-beam resist in particular high contrast, resolution, and sensitivity. However, most of the commercially available CA resist have the concern of airborne base contaminants and sensitivity to PAB and/or PEB temperatures. In this presentation, we will discuss a new improved ketal resists system referred to as KRS-XE which exhibits excellent lithography, is robust toward airborne base, compatible with 0.263N TMAH aqueous developer and exhibits excellent lithography, is robust toward airborne base, compatible with 0.263N TMAH aqueous developer and exhibits a large PAB/PEB latitude. With the combination of a high performance mask making E-beam exposure tool, high kV shaped beam system EL4+ and the KRS-XE resist, we have printed 75nm lines/space feature with excellent profile control at a dose of 13(mu) C/cm2 at 75kV. The shaped beam vector scan system used here provides a unique property in resolving small features in lithography and throughput. Overhead in EL4+$ limits the systems ability to fully exploit the sensitivity of the new resist for throughput. The EL5 system has sufficiently low overhead that it is projected to print a 4X, 16G DRAM mask with OPC in under 3 hours with the CA resist. We will discuss the throughput advantages of the next generation EL5 system over the existing EL4+.

Analysis and experimental demonstration of conformal adaptive phase-locked fiber array for laser communications and beam projection applications

NASA Astrophysics Data System (ADS)

Liu, Ling

The primary goal of this research is the analysis, development, and experimental demonstration of an adaptive phase-locked fiber array system for free-space optical communications and laser beam projection applications. To our knowledge, the developed adaptive phase-locked system composed of three fiber collimators (subapertures) with tip-tilt wavefront phase control at each subaperture represents the first reported fiber array system that implements both phase-locking control and adaptive wavefront tip-tilt control capabilities. This research has also resulted in the following innovations: (a) The first experimental demonstration of a phase-locked fiber array with tip-tilt wave-front aberration compensation at each fiber collimator; (b) Development and demonstration of the fastest currently reported stochastic parallel gradient descent (SPGD) system capable of operation at 180,000 iterations per second; (c) The first experimental demonstration of a laser communication link based on a phase-locked fiber array; (d) The first successful experimental demonstration of turbulence and jitter-induced phase distortion compensation in a phase-locked fiber array optical system; (e) The first demonstration of laser beam projection onto an extended target with a randomly rough surface using a conformal adaptive fiber array system. Fiber array optical systems, the subject of this study, can overcome some of the draw-backs of conventional monolithic large-aperture transmitter/receiver optical systems that are usually heavy, bulky, and expensive. The primary experimental challenges in the development of the adaptive phased-locked fiber-array included precise (<5 microrad) alignment of the fiber collimators and development of fast (100kHz-class) phase-locking and wavefront tip-tilt control systems. The precise alignment of the fiber collimator array is achieved through a specially developed initial coarse alignment tool based on high precision piezoelectric picomotors and a dynamic fine alignment mechanism implemented with specially designed and manufactured piezoelectric fiber positioners. Phase-locking of the fiber collimators is performed by controlling the phases of the output beams (beamlets) using integrated polarization-maintaining (PM) fiber-coupled LiNbO3 phase shifters. The developed phase-locking controllers are based on either the SPGD algorithm or the multi-dithering technique. Subaperture wavefront phase tip-tilt control is realized using piezoelectric fiber positioners that are controlled using a computer-based SPGD controller. Both coherent (phase-locked) and incoherent beam combining in the fiber array system are analyzed theoretically and experimentally. Two special fiber-based beam-combining testbeds have been built to demonstrate the technical feasibility of phase-locking compensation prior to free-space operation. In addition, the reciprocity of counter-propagating beams in a phase-locked fiber array system has been investigated. Coherent beam combining in a phase-locking system with wavefront phase tip-tilt compensation at each subaperture is successfully demonstrated when laboratory-simulated turbulence and wavefront jitters are present in the propagation path of the beamlets. In addition, coherent beam combining with a non-cooperative extended target in the control loop is successfully demonstrated.

A disturbance observer-based adaptive control approach for flexure beam nano manipulators.

PubMed

Zhang, Yangming; Yan, Peng; Zhang, Zhen

2016-01-01

This paper presents a systematic modeling and control methodology for a two-dimensional flexure beam-based servo stage supporting micro/nano manipulations. Compared with conventional mechatronic systems, such systems have major control challenges including cross-axis coupling, dynamical uncertainties, as well as input saturations, which may have adverse effects on system performance unless effectively eliminated. A novel disturbance observer-based adaptive backstepping-like control approach is developed for high precision servo manipulation purposes, which effectively accommodates model uncertainties and coupling dynamics. An auxiliary system is also introduced, on top of the proposed control scheme, to compensate the input saturations. The proposed control architecture is deployed on a customized-designed nano manipulating system featured with a flexure beam structure and voice coil actuators (VCA). Real time experiments on various manipulating tasks, such as trajectory/contour tracking, demonstrate precision errors of less than 1%. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Method and system for controlling the position of a beam of light

DOEpatents

Steinkraus, Jr., Robert F.; Johnson, Gary W [Livermore, CA; Ruggiero, Anthony J [Livermore, CA

2011-08-09

An method and system for laser beam tracking and pointing is based on a conventional position sensing detector (PSD) or quadrant cell but with the use of amplitude-modulated light. A combination of logarithmic automatic gain control, filtering, and synchronous detection offers high angular precision with exceptional dynamic range and sensitivity, while maintaining wide bandwidth. Use of modulated light enables the tracking of multiple beams simultaneously through the use of different modulation frequencies. It also makes the system resistant to interfering light sources such as ambient light. Beam pointing is accomplished by feeding back errors in the measured beam position to a beam steering element, such as a steering mirror. Closed-loop tracking performance is superior to existing methods, especially under conditions of atmospheric scintillation.

Systems analysis on laser beamed power

NASA Technical Reports Server (NTRS)

Zeiders, Glenn W., Jr.

1993-01-01

The NASA SELENE power beaming program is intended to supply cost-effective power to space assets via Earth-based lasers and active optics systems. Key elements of the program are analyzed, the overall effort is reviewed, and recommendations are presented.

Computers and the design of ion beam optical systems

NASA Astrophysics Data System (ADS)

White, Nicholas R.

Advances in microcomputers have made it possible to maintain a library of advanced ion optical programs which can be used on inexpensive computer hardware, which are suitable for the design of a variety of ion beam systems including ion implanters, giving excellent results. This paper describes in outline the steps typically involved in designing a complete ion beam system for materials modification applications. Two computer programs are described which, although based largely on algorithms which have been in use for many years, make possible detailed beam optical calculations using microcomputers, specifically the IBM PC. OPTICIAN is an interactive first-order program for tracing beam envelopes through complex optical systems. SORCERY is a versatile program for solving Laplace's and Poisson's equations by finite difference methods using successive over-relaxation. Ion and electron trajectories can be traced through these potential fields, and plots of beam emittance obtained.

The propagation of a flattened circular Gaussian beam through an optical system in turbulent atmosphere

NASA Astrophysics Data System (ADS)

Chu, X. X.; Liu, Z. J.; Wu, Y.

2008-07-01

Based on the Huygens-Fresnel integral, the properties of a circular flattened Gaussian beam through a stigmatic optical system in turbulent atmosphere are investigated. Analytical formulas for the average intensity are derived. As elementary examples, the average intensity distributions of a collimated circular flattened Gaussian beam and a focused circular flattened Gaussian beam through a simple optical system are studied. To see the effects of the optical system on the propagation, the average intensity distributions of the beam for direct propagation are also studied. From the analysis, comparison and numerical calculation we can see that there are many differences between the two propagations. These differences are due to the geometrical magnification of the optical system, different diffraction and different turbulence-induced spreading. Namely, an optical system not only affects the diffraction but also affects the turbulence-induced spreading.

R&D around a photoneutralizer-based NBI system (Siphore) in view of a DEMO Tokamak steady state fusion reactor

NASA Astrophysics Data System (ADS)

Simonin, A.; Achard, Jocelyn; Achkasov, K.; Bechu, S.; Baudouin, C.; Baulaigue, O.; Blondel, C.; Boeuf, J. P.; Bresteau, D.; Cartry, G.; Chaibi, W.; Drag, C.; de Esch, H. P. L.; Fiorucci, D.; Fubiani, G.; Furno, I.; Futtersack, R.; Garibaldi, P.; Gicquel, A.; Grand, C.; Guittienne, Ph.; Hagelaar, G.; Howling, A.; Jacquier, R.; Kirkpatrick, M. J.; Lemoine, D.; Lepetit, B.; Minea, T.; Odic, E.; Revel, A.; Soliman, B. A.; Teste, P.

2015-11-01

Since the signature of the ITER treaty in 2006, a new research programme targeting the emergence of a new generation of neutral beam (NB) system for the future fusion reactor (DEMO Tokamak) has been underway between several laboratories in Europe. The specifications required to operate a NB system on DEMO are very demanding: the system has to provide plasma heating, current drive and plasma control at a very high level of power (up to 150 MW) and energy (1 or 2 MeV), including high performances in term of wall-plug efficiency (η  >  60%), high availability and reliability. To this aim, a novel NB concept based on the photodetachment of the energetic negative ion beam is under study. The keystone of this new concept is the achievement of a photoneutralizer where a high power photon flux (~3 MW) generated within a Fabry-Perot cavity will overlap, cross and partially photodetach the intense negative ion beam accelerated at high energy (1 or 2 MeV). The aspect ratio of the beam-line (source, accelerator, etc) is specifically designed to maximize the overlap of the photon beam with the ion beam. It is shown that such a photoneutralized based NB system would have the capability to provide several tens of MW of D0 per beam line with a wall-plug efficiency higher than 60%. A feasibility study of the concept has been launched between different laboratories to address the different physics aspects, i.e. negative ion source, plasma modelling, ion accelerator simulation, photoneutralization and high voltage holding under vacuum. The paper describes the present status of the project and the main achievements of the developments in laboratories.

Application of real-time digitization techniques in beam measurement for accelerators

NASA Astrophysics Data System (ADS)

Zhao, Lei; Zhan, Lin-Song; Gao, Xing-Shun; Liu, Shu-Bin; An, Qi

2016-04-01

Beam measurement is very important for accelerators. In this paper, modern digital beam measurement techniques based on IQ (In-phase & Quadrature-phase) analysis are discussed. Based on this method and high-speed high-resolution analog-to-digital conversion, we have completed three beam measurement electronics systems designed for the China Spallation Neutron Source (CSNS), Shanghai Synchrotron Radiation Facility (SSRF), and Accelerator Driven Sub-critical system (ADS). Core techniques of hardware design and real-time system calibration are discussed, and performance test results of these three instruments are also presented. Supported by National Natural Science Foundation of China (11205153, 10875119), Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the Fundamental Research Funds for the Central Universities (WK2030040029),and the CAS Center for Excellence in Particle Physics (CCEPP).

A system for characterization of DEPFET silicon pixel matrices and test beam results

NASA Astrophysics Data System (ADS)

Furletov, Sergey; DEPFET Collaboration

2011-02-01

The DEPFET pixel detector offers first stage in-pixel amplification by incorporating a field effect transistor in the high resistivity silicon substrate. In this concept, a very small input capacitance can be realized thus allowing for low noise measurements. This makes DEPFET sensors a favorable technology for tracking in particle physics. Therefore a system with a DEPFET pixel matrix was developed to test DEPFET performance for an application as a vertex detector for the Belle II experiment. The system features a current based, row-wise readout of a DEPFET pixel matrix with a designated readout chip, steering chips for matrix control, a FPGA based data acquisition board, and a dedicated software package. The system was successfully operated in both test beam and lab environment. In 2009 new DEPFET matrices have been characterized in a 120 GeV pion beam at the CERN SPS. The current status of the DEPFET system and test beam results are presented.

Development of a beam line for radio-isotope production at the KOMAC

NASA Astrophysics Data System (ADS)

Kim, Han-Sung

2016-09-01

A new beam line of the 100-MeV proton linac at the KOMAC (Korea Multi-purpose Accelerator Complex), aiming for RI (radioisotope) production has been constructed reflecting the increasing demands for various RIs (radioisotopes), such as Sr-82 and Cu-67 for medical applications. Proton beam with beam energy of 100 MeV and an average current of 0.6 mA is directed to the 100-mm-diameter production target through a beam window made of aluminum-beryllium alloy. Major components of the newly-installed beam line include electromagnets for bending and focusing, beam diagnostic systems such as a BPM (beam position monitor) and a BCM (beam current monitor), and a vacuum pumping system based on an ion pump. In this paper, the design features and the installation of the RI-production beam line at the KOMAC are given.

Sweep excitation with order tracking: A new tactic for beam crack analysis

NASA Astrophysics Data System (ADS)

Wei, Dongdong; Wang, KeSheng; Zhang, Mian; Zuo, Ming J.

2018-04-01

Crack detection in beams and beam-like structures is an important issue in industry and has attracted numerous investigations. A local crack leads to global system dynamics changes and produce non-linear vibration responses. Many researchers have studied these non-linearities for beam crack diagnosis. However, most reported methods are based on impact excitation and constant frequency excitation. Few studies have focused on crack detection through external sweep excitation which unleashes abundant dynamic characteristics of the system. Together with a signal resampling technique inspired by Computed Order Tracking, this paper utilize vibration responses under sweep excitations to diagnose crack status of beams. A data driven method for crack depth evaluation is proposed and window based harmonics extracting approaches are studied. The effectiveness of sweep excitation and the proposed method is experimentally validated.

A Fuzzy Logic Based Controller for the Automated Alignment of a Laser-beam-smoothing Spatial Filter

NASA Technical Reports Server (NTRS)

Krasowski, M. J.; Dickens, D. E.

1992-01-01

A fuzzy logic based controller for a laser-beam-smoothing spatial filter is described. It is demonstrated that a human operator's alignment actions can easily be described by a system of fuzzy rules of inference. The final configuration uses inexpensive, off-the-shelf hardware and allows for a compact, readily implemented embedded control system.

Biophysical characteristics of HIMAC clinical irradiation system for heavy-ion radiation therapy.

PubMed

Kanai, T; Endo, M; Minohara, S; Miyahara, N; Koyama-ito, H; Tomura, H; Matsufuji, N; Futami, Y; Fukumura, A; Hiraoka, T; Furusawa, Y; Ando, K; Suzuki, M; Soga, F; Kawachi, K

1999-04-01

The irradiation system and biophysical characteristics of carbon beams are examined regarding radiation therapy. An irradiation system was developed for heavy-ion radiotherapy. Wobbler magnets and a scatterer were used for flattening the radiation field. A patient-positioning system using X ray and image intensifiers was also installed in the irradiation system. The depth-dose distributions of the carbon beams were modified to make a spread-out Bragg peak, which was designed based on the biophysical characteristics of monoenergetic beams. A dosimetry system for heavy-ion radiotherapy was established to deliver heavy-ion doses safely to the patients according to the treatment planning. A carbon beam of 80 keV/microm in the spread-out Bragg peak was found to be equivalent in biological responses to the neutron beam that is produced at cyclotron facility in National Institute Radiological Sciences (NIRS) by bombarding 30-MeV deuteron beam on beryllium target. The fractionation schedule of the NIRS neutron therapy was adapted for the first clinical trials using carbon beams. Carbon beams, 290, 350, and 400 MeV/u, were used for a clinical trial from June of 1994. Over 300 patients have already been treated by this irradiation system by the end of 1997.

Comparative efficiency analysis of fiber-array and conventional beam director systems in volume turbulence.

PubMed

Vorontsov, Mikhail; Filimonov, Grigory; Ovchinnikov, Vladimir; Polnau, Ernst; Lachinova, Svetlana; Weyrauch, Thomas; Mangano, Joseph

2016-05-20

The performance of two prominent laser beam projection system types is analyzed through wave-optics numerical simulations for various atmospheric turbulence conditions, propagation distances, and adaptive optics (AO) mitigation techniques. Comparisons are made between different configurations of both a conventional beam director (BD) using a monolithic-optics-based Cassegrain telescope and a fiber-array BD that uses an array of densely packed fiber collimators. The BD systems considered have equal input power and aperture diameters. The projected laser beam power inside the Airy size disk at the target plane is used as the performance metric. For the fiber-array system, both incoherent and coherent beam combining regimes are considered. We also present preliminary results of side-by-side atmospheric beam projection experiments over a 7-km propagation path using both the AO-enhanced beam projection system with a Cassegrain telescope and the coherent fiber-array BD composed of 21 densely packed fiber collimators. Both wave-optics numerical simulation and experimental results demonstrate that, for similar system architectures and turbulence conditions, coherent fiber-array systems are more efficient in mitigation of atmospheric turbulence effects and generation of a hit spot of the smallest possible size on a remotely located target.

Construction, alignment, and implementation of an acousto-optical deflector-based system for patterned uncaging with ultraviolet light.

PubMed

Civillico, Eugene F; Shoham, Shy; O'Connor, Daniel H; Sarkisov, Dmitry V; Wang, Samuel S-H

2012-08-01

The method of patterned photoactivation is a natural fit for the study of neuronal dendritic integration. Photoactivatable molecules that influence a wide range of extracellular and intracellular neurophysiological functions are available. The choice of photosensitive molecules depends on the research question and will influence the design of the experimental apparatus. An acousto-optical deflector (AOD)-based system can be used for rapid ultraviolet (UV) photolysis in arbitrary spatial and temporal patterns. Photolysis-activated "caged" diffusible molecules or newer light-sensitive membrane proteins can be used in this system. This protocol describes the addition of a UV beam for uncaging to a homebuilt two-photon microscope. The goal is to get UV light from the light source (laser) to the approximate center of the objective's back aperture, passing through a pair of perpendicularly oriented AODs along the way. The protocol also describes the fine alignment of the UV beam and the implementation of AOD-based beam steering. Performing the final alignment with the beam passing through the AODs will ensure that the system is optimized for the idiosyncrasies of the crystals.

Operating characteristics of a new ion source for KSTAR neutral beam injection system.

PubMed

Kim, Tae-Seong; Jeong, Seung Ho; Chang, Doo-Hee; Lee, Kwang Won; In, Sang-Ryul

2014-02-01

A new positive ion source for the Korea Superconducting Tokamak Advanced Research neutral beam injection (KSTAR NBI-1) system was designed, fabricated, and assembled in 2011. The characteristics of the arc discharge and beam extraction were investigated using hydrogen and helium gas to find the optimum operating parameters of the arc power, filament voltage, gas pressure, extracting voltage, accelerating voltage, and decelerating voltage at the neutral beam test stand at the Korea Atomic Energy Research Institute in 2012. Based on the optimum operating condition, the new ion source was then conditioned, and performance tests were primarily finished. The accelerator system with enlarged apertures can extract a maximum 65 A ion beam with a beam energy of 100 keV. The arc efficiency and optimum beam perveance, at which the beam divergence is at a minimum, are estimated to be 1.0 A/kW and 2.5 uP, respectively. The beam extraction tests show that the design goal of delivering a 2 MW deuterium neutral beam into the KSTAR Tokamak plasma is achievable.

TIL system with nonlinear phase conjugation

NASA Astrophysics Data System (ADS)

Khizhnyak, Anatoliy; Markov, Vladimir

2007-09-01

Efficient laser beam delivery on a distant target remains a key problem for practical implementation of tactical laser systems. Since the conventional target-in-the-loop (TIL) concept is generally not effective in such operational environments, new solutions are needed. In this report we discuss an innovative approach for effective compensation of laser beam aberrations in TIL systems. It is based on a recently devised technique that combines optical phase conjugation (OPC) with a TIL system for effective hot-spot formation. The proposed method should enable delivery of enhanced density laser energy to a target within a finite number of iteration cycles. Using the model based on an analogy between the TIL system and laser resonator, pointing of the laser beam on the target is performed at the image plane, resulting in reduced hot-spot formation time.

Electron Beam Diagnostics Of The JLAB UV FEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evtushenko, Pavel; Benson, Stephen; Biallas, George

2011-03-01

In this contribution we describe various systems and aspects of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line at the existing 10 kW IR Upgrade FEL. Here, we describe a set of the following systems. A combination of OTR and phosphor viewers is used for measurements of the transverse beam profile, transverse emittance, and Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A systemmore » of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurement system is used to set up bunch compression in an optimal way, such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of diagnostic systems made a significant contribution in achieving first lasing of the FEL after only about 60 hours of beam operation.« less

Laser beam projection with adaptive array of fiber collimators. II. Analysis of atmospheric compensation efficiency.

PubMed

Lachinova, Svetlana L; Vorontsov, Mikhail A

2008-08-01

We analyze the potential efficiency of laser beam projection onto a remote object in atmosphere with incoherent and coherent phase-locked conformal-beam director systems composed of an adaptive array of fiber collimators. Adaptive optics compensation of turbulence-induced phase aberrations in these systems is performed at each fiber collimator. Our analysis is based on a derived expression for the atmospheric-averaged value of the mean square residual phase error as well as direct numerical simulations. Operation of both conformal-beam projection systems is compared for various adaptive system configurations characterized by the number of fiber collimators, the adaptive compensation resolution, and atmospheric turbulence conditions.

Propagation of Bessel-Gaussian beams through a double-apertured fractional Fourier transform optical system.

PubMed

Tang, Bin; Jiang, Chun; Zhu, Haibin

2012-08-01

Based on the scalar diffraction theory and the fact that a hard-edged aperture function can be expanded into a finite sum of complex Gaussian functions, an approximate analytical solution for Bessel-Gaussian (BG) beams propagating through a double-apertured fractional Fourier transform (FrFT) system is derived in the cylindrical coordinate. By using the approximate analytical formulas, the propagation properties of BG beams passing through a double-apertured FrFT optical system have been studied in detail by some typical numerical examples. The results indicate that the double-apertured FrFT optical system provides a convenient way for controlling the properties of the BG beams by properly choosing the optical parameters.

Beam transport program for FEL project

NASA Astrophysics Data System (ADS)

Sugimoto, Masayoshi; Takao, Masaru

1992-07-01

A beam transport program is developed to design the beam transport line of the free electron laser system at JAERI and to assist the beam diagnosis. The program traces a beam matrix through the elements in the beam transport line and the accelerators. The graphical user interface is employed to access the parameters and to represent the results. The basic computational method is based on the LANL-TRACE program and it is rewritten for personal computers in Pascal.

Content-based fused off-axis object illumination direct-to-digital holography

DOEpatents

Price, Jeffery R.

2006-05-02

Systems and methods are described for content-based fused off-axis illumination direct-to-digital holography. A method includes calculating an illumination angle with respect to an optical axis defined by a focusing lens as a function of data representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object the object beam incident upon the object at the illumination angle; focusing the reference beam and the object beam at a focal plane of a digital recorder to from the content-based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording the content based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

An X-ray beam position monitor based on the photoluminescence of helium gas

NASA Astrophysics Data System (ADS)

Revesz, Peter; White, Jeffrey A.

2005-03-01

A new method for white beam position monitoring for both bend magnet and wiggler synchrotron X-ray radiation has been developed. This method utilizes visible light luminescence generated as a result of ionization by the intense X-ray flux. In video beam position monitors (VBPMs), the luminescence of helium gas at atmospheric pressure is observed through a view port using a CCD camera next to the beam line. The beam position, profile, integrated intensity and FWHM are calculated from the distribution of luminescence intensity in each captured image by custom software. Misalignment of upstream apertures changes the image profile making VBPMs helpful for initial alignment of upstream beam line components. VBPMs can thus provide more information about the X-ray beam than most beam position monitors (BPMs). A beam position calibration procedure, employing a tilted plane-parallel glass plate placed in front of the camera lens, has also been developed. The accuracy of the VBPM system was measured during a bench-top experiment to be better than 1 μm. The He-luminescence-based VBPM system has been operative on three CHESS beam lines (F hard-bend and wiggler, A-line wiggler and G-line wiggler) for about a year. The beam positions are converted to analog voltages and used as feedback signals for beam stabilization. In our paper we discuss details of VBPM construction and describe further results of its performance.

A configurable electronics system for the ESS-Bilbao beam position monitors

NASA Astrophysics Data System (ADS)

Muguira, L.; Belver, D.; Etxebarria, V.; Varnasseri, S.; Arredondo, I.; del Campo, M.; Echevarria, P.; Garmendia, N.; Feuchtwanger, J.; Jugo, J.; Portilla, J.

2013-09-01

A versatile and configurable system has been developed in order to monitorize the beam position and to meet all the requirements of the future ESS-Bilbao Linac. At the same time the design has been conceived to be open and configurable so that it could eventually be used in different kinds of accelerators, independent of the charged particle, with minimal change. The design of the Beam Position Monitors (BPMs) system includes a test bench both for button-type pick-ups (PU) and striplines (SL), the electronic units and the control system. The electronic units consist of two main parts. The first part is an Analog Front-End (AFE) unit where the RF signals are filtered, conditioned and converted to base-band. The second part is a Digital Front-End (DFE) unit which is based on an FPGA board where the base-band signals are sampled in order to calculate the beam position, the amplitude and the phase. To manage the system a Multipurpose Controller (MC) developed at ESSB has been used. It includes the FPGA management, the EPICS integration and Archiver Instances. A description of the system and a comparison between the performance of both PU and SL BPM designs measured with this electronics system are fully described and discussed.

Developments and applications of accelerator system at the Wakasa Wan Energy Research Center

NASA Astrophysics Data System (ADS)

Hatori, S.; Kurita, T.; Hayashi, Y.; Yamada, M.; Yamada, H.; Mori, J.; Hamachi, H.; Kimura, S.; Shimoda, T.; Hiroto, M.; Hashimoto, T.; Shimada, M.; Yamamoto, H.; Ohtani, N.; Yasuda, K.; Ishigami, R.; Sasase, M.; Ito, Y.; Hatashita, M.; Takagi, K.; Kume, K.; Fukuda, S.; Yokohama, N.; Kagiya, G.; Fukumoto, S.; Kondo, M.

2005-12-01

At the Wakasa Wan Energy Research Center (WERC), an accelerator system with a 5 MV tandem accelerator and a 200 MeV proton synchrotron is used for ion beam analyses and irradiation experiments. The study of cancer therapy with a proton beam is also performed. Therefore, the stable operation and efficient sharing of beam time of the system are required, based on the treatment standard. Recent developments and the operation status of the system put stress on the tandem accelerator operation, magnifying the problems.

Multi-carrier mobile TDMA system with active array antenna

NASA Technical Reports Server (NTRS)

Suzuki, Ryutaro; Matsumoto, Yasushi; Hamamoto, Naokazu

1990-01-01

A multi-carrier time division multiple access (TDMA) is proposed for the future mobile satellite communications systems that include a multi-satellite system. This TDMA system employs the active array antenna in which the digital beam forming technique is adopted to control the antenna beam direction. The antenna beam forming is carried out at the base band frequency by using the digital signal processing technique. The time division duplex technique is applied for the TDM/TDMA burst format, in order not to overlap transmit and receive timing.

A gas circulation and purification system for gas-cell-based low-energy RI-beam production.

PubMed

Sonoda, T; Tsubota, T; Wada, M; Katayama, I; Kojima, T M; Reponen, M

2016-06-01

A gas circulation and purification system was developed at the RIKEN Radioactive Isotope Beam Factory that can be used for gas-cell-based low-energy RI-beam production. A high-flow-rate gas cell filled with one atmosphere of buffer gas (argon or helium) is used for the deceleration and thermalization of high-energy RI-beams. The exhausted buffer gas is efficiently collected using a compact dry pump and returned to the gas cell with a recovery efficiency of >97%. The buffer gas is efficiently purified using two gas purifiers as well as collision cleaning, which eliminates impurities in the gas. An impurity level of one part per billion is achieved with this method.

A gas circulation and purification system for gas-cell-based low-energy RI-beam production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sonoda, T.; Wada, M.; Katayama, I.

A gas circulation and purification system was developed at the RIKEN Radioactive Isotope Beam Factory that can be used for gas-cell-based low-energy RI-beam production. A high-flow-rate gas cell filled with one atmosphere of buffer gas (argon or helium) is used for the deceleration and thermalization of high-energy RI-beams. The exhausted buffer gas is efficiently collected using a compact dry pump and returned to the gas cell with a recovery efficiency of >97%. The buffer gas is efficiently purified using two gas purifiers as well as collision cleaning, which eliminates impurities in the gas. An impurity level of one part permore » billion is achieved with this method.« less

Transverse beam stability measurement and analysis for the SNS accumulator ring

DOE PAGES

Xie, Zaipeng; Deibele, Craig; Schulte, Michael J.; ...

2015-07-01

In a Field-programmable gate array (FPGA) based transverse feedback damper system we implemented in the Spallation Neutron Source (SNS) accumulator ring with the intention to stabilize the electron-proton (e-p) instability in a frequency range from 1 MHz to 300 MHz. The transverse damper could also be used as a diagnostic tool by measuring the beam transfer function (BTF). An analysis of the BTF measurement provides the stability diagram for the production beam at SNS. Our paper describes the feedback damper system and its set-up as the BTF diagnostic tool. Experimental BTF results are presented and beam stability analysis is performedmore » based on the BTF measurements for the SNS accumulator ring.« less

A metrology system for a high resolution cavity beam position monitor system

NASA Astrophysics Data System (ADS)

Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Pete; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Hinton, Shantell; Honda, Yosuke; Khainovski, Oleg; Kolomensky, Yury; Loscutoff, Peter; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; Thomson, Mark; Urakawa, Junji; Vogel, Vladimir; Ward, David; White, Glen

2013-11-01

International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will likely be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved-ideally using a beam-based stability measurement. We developed a high resolution RF cavity Beam Position Monitor (BPM) system. A triplet of these BPMs, installed in the extraction line of the KEK Accelerator Test Facility (ATF) and tested with its ultra-low emittance beam, achieved a position measurement resolution of 15 nm. A metrology system for the three BPMs was subsequently installed. This system employed optical encoders to measure each BPM's position and orientation relative to a zero-coefficient of thermal expansion carbon fiber frame. We have demonstrated that the three BPMs behave as a rigid-body at the level of less than 5 nm.

Photoluminescence-based quality control for thin film absorber layers of photovoltaic devices

DOEpatents

Repins, Ingrid L.; Kuciauskas, Darius

2015-07-07

A time-resolved photoluminescence-based system providing quality control during manufacture of thin film absorber layers for photovoltaic devices. The system includes a laser generating excitation beams and an optical fiber with an end used both for directing each excitation beam onto a thin film absorber layer and for collecting photoluminescence from the absorber layer. The system includes a processor determining a quality control parameter such as minority carrier lifetime of the thin film absorber layer based on the collected photoluminescence. In some implementations, the laser is a low power, pulsed diode laser having photon energy at least great enough to excite electron hole pairs in the thin film absorber layer. The scattered light may be filterable from the collected photoluminescence, and the system may include a dichroic beam splitter and a filter that transmit the photoluminescence and remove scattered laser light prior to delivery to a photodetector and a digital oscilloscope.

Neural network approximation of nonlinearity in laser nano-metrology system based on TLMI

NASA Astrophysics Data System (ADS)

Olyaee, Saeed; Hamedi, Samaneh

2011-02-01

In this paper, an approach based on neural network (NN) for nonlinearity modeling in a nano-metrology system using three-longitudinal-mode laser heterodyne interferometer (TLMI) for length and displacement measurements is presented. We model nonlinearity errors that arise from elliptically and non-orthogonally polarized laser beams, rotational error in the alignment of laser head with respect to the polarizing beam splitter, rotational error in the alignment of the mixing polarizer, and unequal transmission coefficients in the polarizing beam splitter. Here we use a neural network algorithm based on the multi-layer perceptron (MLP) network. The simulation results show that multi-layer feed forward perceptron network is successfully applicable to real noisy interferometer signals.

2D imaging X-ray diagnostic for measuring the current density distribution in a wide-area electron beam produced in a multiaperture diode with plasma cathode

NASA Astrophysics Data System (ADS)

Kurkuchekov, V.; Kandaurov, I.; Trunev, Y.

2018-05-01

A simple and inexpensive X-ray diagnostic tool was designed for measuring the cross-sectional current density distribution in a low-relativistic pulsed electron beam produced in a source based on an arc-discharge plasma cathode and multiaperture diode-type electron optical system. The beam parameters were as follows: Uacc = 50–110 kV, Ibeam = 20–100 A, τbeam = 0.1–0.3 ms. The beam effective diameter was ca. 7 cm. Based on a pinhole camera, the diagnostic allows one to obtain a 2D profile of electron beam flux distribution on a flat metal target in a single shot. The linearity of the diagnostic system response to the electron flux density was established experimentally. Spatial resolution of the diagnostic was also estimated in special test experiments. The optimal choice of the main components of the diagnostic technique is discussed.

Design study of beam position monitors for measuring second-order moments of charged particle beams

NASA Astrophysics Data System (ADS)

Yanagida, Kenichi; Suzuki, Shinsuke; Hanaki, Hirofumi

2012-01-01

This paper presents a theoretical investigation on the multipole moments of charged particle beams in two-dimensional polar coordinates. The theoretical description of multipole moments is based on a single-particle system that is expanded to a multiparticle system by superposition, i.e., summing over all single-particle results. This paper also presents an analysis and design method for a beam position monitor (BPM) that detects higher-order (multipole) moments of a charged particle beam. To calculate the electric fields, a numerical analysis based on the finite difference method was created and carried out. Validity of the numerical analysis was proven by comparing the numerical with the analytical results for a BPM with circular cross section. Six-electrode BPMs with circular and elliptical cross sections were designed for the SPring-8 linac. The results of the numerical calculations show that the second-order moment can be detected for beam sizes ≧420μm (circular) and ≧550μm (elliptical).

Infrared Smartt Interferometer As An Alignment Tool For Carbon Dioxide Laser Fusion Systems

NASA Astrophysics Data System (ADS)

Viswanathan, V. K.; Bolen, P. D.

1980-11-01

It is essential to minimize the pointing and focusing errors at the focal plane for many applications involving infrared laser systems. In the case of the LASL CO2 laser fusion systems, with two beams in the Gemini System and eight beams in the Helios System, this is particularly important. The LASL Helios CO2 Laser Fusion System has eight 34-cm diameter beams emerging from the power amplifier and each beam is brought to focus by an off-aperture parabola (nearly 77.3-cm focal length) resulting in a nearly F/2.4 beam at the focal plane. The design tolerance at the focal plane for pointing accuracy is +/- 25 microns and for focusing accuracy is +/- 50 microns for this system. This paper describes an alignment scheme based on the use of the infrared Smartt interferometer' and compares the results obtained using this technique and the autocollimating Hartmann scheme2 in a laboratory setup duplicating the target chamber region of one of the beams of the Helios System. The results using the Smartt interferometer show that pointing accuracy of +/- 12.5 microns and focusing accuracies of ± 15 microns are obtained at the focal plane of the system.

A novel convolution-based approach to address ionization chamber volume averaging effect in model-based treatment planning systems

NASA Astrophysics Data System (ADS)

Barraclough, Brendan; Li, Jonathan G.; Lebron, Sharon; Fan, Qiyong; Liu, Chihray; Yan, Guanghua

2015-08-01

The ionization chamber volume averaging effect is a well-known issue without an elegant solution. The purpose of this study is to propose a novel convolution-based approach to address the volume averaging effect in model-based treatment planning systems (TPSs). Ionization chamber-measured beam profiles can be regarded as the convolution between the detector response function and the implicit real profiles. Existing approaches address the issue by trying to remove the volume averaging effect from the measurement. In contrast, our proposed method imports the measured profiles directly into the TPS and addresses the problem by reoptimizing pertinent parameters of the TPS beam model. In the iterative beam modeling process, the TPS-calculated beam profiles are convolved with the same detector response function. Beam model parameters responsible for the penumbra are optimized to drive the convolved profiles to match the measured profiles. Since the convolved and the measured profiles are subject to identical volume averaging effect, the calculated profiles match the real profiles when the optimization converges. The method was applied to reoptimize a CC13 beam model commissioned with profiles measured with a standard ionization chamber (Scanditronix Wellhofer, Bartlett, TN). The reoptimized beam model was validated by comparing the TPS-calculated profiles with diode-measured profiles. Its performance in intensity-modulated radiation therapy (IMRT) quality assurance (QA) for ten head-and-neck patients was compared with the CC13 beam model and a clinical beam model (manually optimized, clinically proven) using standard Gamma comparisons. The beam profiles calculated with the reoptimized beam model showed excellent agreement with diode measurement at all measured geometries. Performance of the reoptimized beam model was comparable with that of the clinical beam model in IMRT QA. The average passing rates using the reoptimized beam model increased substantially from 92.1% to 99.3% with 3%/3 mm and from 79.2% to 95.2% with 2%/2 mm when compared with the CC13 beam model. These results show the effectiveness of the proposed method. Less inter-user variability can be expected of the final beam model. It is also found that the method can be easily integrated into model-based TPS.

Hollow vortex Gaussian beams

NASA Astrophysics Data System (ADS)

Zhou, GuoQuan; Cai, YangJian; Dai, ChaoQing

2013-05-01

A kind of hollow vortex Gaussian beam is introduced. Based on the Collins integral, an analytical propagation formula of a hollow vortex Gaussian beam through a paraxial ABCD optical system is derived. Due to the special distribution of the optical field, which is caused by the initial vortex phase, the dark region of a hollow vortex Gaussian beam will not disappear upon propagation. The analytical expressions for the beam propagation factor, the kurtosis parameter, and the orbital angular momentum density of a hollow vortex Gaussian beam passing through a paraxial ABCD optical system are also derived, respectively. The beam propagation factor is determined by the beam order and the topological charge. The kurtosis parameter and the orbital angular momentum density depend on beam order n, topological charge m, parameter γ, and transfer matrix elements A and D. As a numerical example, the propagation properties of a hollow vortex Gaussian beam in free space are demonstrated. The hollow vortex Gaussian beam has eminent propagation stability and has crucial application prospects in optical micromanipulation.

MEMS-based beam-steerable free-space optical communication link for reconfigurable wireless data center

NASA Astrophysics Data System (ADS)

Deng, Peng; Kavehrad, Mohsen; Lou, Yan

2017-01-01

Flexible wireless datacenter networks based on free space optical communication (FSO) links are being considered as promising solutions to meet the future datacenter demands of high throughput, robustness to dynamic traffic patterns, cabling complexity and energy efficiency. Robust and precise steerable FSO links over dynamic traffic play a key role in the reconfigurable optical wireless datacenter inter-rack network. In this work, we propose and demonstrate a reconfigurable 10Gbps FSO system incorporated with smart beam acquisition and tracking mechanism based on gimballess two-axis MEMS micro-mirror and retro-reflective film marked aperture. The fast MEMS-based beam acquisition switches laser beam of FSO terminal from one rack to the next for reconfigurable networks, and the precise beam tracking makes FSO device auto-correct the misalignment in real-time. We evaluate the optical power loss and bit error rate performance of steerable FSO links at various directions. Experimental results suggest that the MEMS based beam steerable FSO links hold considerable promise for the future reconfigurable wireless datacenter networks.

Electro-optic voltage sensor for sensing voltage in an E-field

DOEpatents

Woods, G.K.; Renak, T.W.

1999-04-06

A miniature electro-optic voltage sensor system capable of accurate operation at high voltages is disclosed. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam`s polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured. 18 figs.

Electro-optical voltage sensor head

DOEpatents

Woods, G.K.

1998-03-24

A miniature electro-optic voltage sensor system capable of accurate operation at high voltages is disclosed. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam`s polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured. 6 figs.

Star Tracker Based ATP System Conceptual Design and Pointing Accuracy Estimation

NASA Technical Reports Server (NTRS)

Orfiz, Gerardo G.; Lee, Shinhak

2006-01-01

A star tracker based beaconless (a.k.a. non-cooperative beacon) acquisition, tracking and pointing concept for precisely pointing an optical communication beam is presented as an innovative approach to extend the range of high bandwidth (> 100 Mbps) deep space optical communication links throughout the solar system and to remove the need for a ground based high power laser as a beacon source. The basic approach for executing the ATP functions involves the use of stars as the reference sources from which the attitude knowledge is obtained and combined with high bandwidth gyroscopes for propagating the pointing knowledge to the beam pointing mechanism. Details of the conceptual design are presented including selection of an orthogonal telescope configuration and the introduction of an optical metering scheme to reduce misalignment error. Also, estimates are presented that demonstrate that aiming of the communications beam to the Earth based receive terminal can be achieved with a total system pointing accuracy of better than 850 nanoradians (3 sigma) from anywhere in the solar system.

Neutron measurements from beam-target reactions at the ELISE neutral beam test facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xufei, X., E-mail: xiexufei@pku.edu.cn; Fan, T.; Nocente, M.

2014-11-15

Measurements of 2.5 MeV neutron emission from beam-target reactions performed at the ELISE neutral beam test facility are presented in this paper. The measurements are used to study the penetration of a deuterium beam in a copper dump, based on the observation of the time evolution of the neutron counting rate from beam-target reactions with a liquid scintillation detector. A calculation based on a local mixing model of deuterium deposition in the target up to a concentration of 20% at saturation is used to evaluate the expected neutron yield for comparison with data. The results are of relevance to understandmore » neutron emission associated to beam penetration in a solid target, with applications to diagnostic systems for the SPIDER and MITICA Neutral Beam Injection prototypes.« less

Adaptive positive position feedback control with a feedforward compensator of a magnetostrictive beam for vibration suppression

NASA Astrophysics Data System (ADS)

Bian, Leixiang; Zhu, Wei

2018-07-01

In this paper, a Fe–Ga alloy magnetostrictive beam is designed as an actuator to restrain the vibration of a supported mass. Dynamic modeling of the system based on the transfer matrix method of multibody system is first shown, and then a hybrid controller is developed to achieve vibration control. The proposed vibration controller combines a multi-mode adaptive positive position feedback (APPF) with a feedforward compensator. In the APPF control, an adaptive natural frequency estimator based on the recursive least-square method is developed to be used. In the feedforward compensator, the hysteresis of the magnetostrictive beam is linearized based on a Bouc–Wen model. The further remarkable vibration suppression capability of the proposed hybrid controller is demonstrated experimentally and compared with the positive position feedback controller. Experiment results show that the proposed controller is applicable to the magnetostrictive beam for improving vibration control effectiveness.

MO-FG-CAMPUS-TeP3-03: Calculation of Proton Pencil Beam Properties with Full Beamline Model in TOPAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wulff, J; Abel, E

2016-06-15

Purpose: Introducing Monte Carlo based dose calculation algorithms into proton therapy planning systems (TPS) leads to improved accuracy. However accurate modelling of the proton pencil beam impinging the patient is necessary. Current approaches rely on measurement-driven reconstruction of phase-space and spectrum properties, typically constrained to analytical model functions. In this study a detailed Monte Carlo model of the complete cyclotron-based delivery system was created with the aim of providing more representative beam properties at treatment position. Methods: A model of the Varian Probeam proton system from the cyclotron exit to isocenter was constructed in the TOPAS Monte Carlo framework. Themore » beam evolution through apertures and magnetic elements was validated using Transport/Turtle calculations and additionally against measurements from the Probeam™ system at Scripps Proton Therapy Center (SPTC) in San Diego, CA. A voxelized water phantom at isocenter allowed for comparison of the dose-depth curve from the Probeam model with that of a corresponding Gaussian beam over the entire energy range (70–240 MeV). Measurements of relative beam fluence cross-profiles and depth-dose curves at and around isocenter were also compared to the MC results. Results: The simulated TOPAS beam envelope was found to agree with both the Transport/Turtle and measurements to within 5% for most of the beamline. The MC predicted energy spectrum at isocenter was found to deviate increasingly from Gaussian at energies below 160 MeV. The corresponding effects on the depth dose curve agreed well with measurements. Conclusion: Given the flexibility of TOPAS and available details of the delivery system, an accurate characterization of a proton pencil beam at isocenter is possible. Incorporation of the MC derived properties of the proton pencil beam can eliminate analytical approximations and ultimately increase treatment plan accuracy and quality. Both authors are employees of Varian Medical Systems.« less

Polarized millijoule fiber laser system with high beam quality and pulse shaping ability

NASA Astrophysics Data System (ADS)

Zhang, Rui; Tian, Xiaocheng; Xu, Dangpeng; Zhou, Dandan; Zong, Zhaoyu; Li, Hongxun; Fan, Mengqiu; Huang, Zhihua; Zhu, Na; Su, Jingqin; Zhu, Qihua; Jing, Feng

2017-05-01

The coherent amplification network (CAN) aims at developing a laser system based on the coherent combination of multiple laser beams, which are produced through a network of high beam quality optical fiber amplifiers. The scalability of the CAN laser facilitates the development of many novel applications, such as fiber-based acceleration, orbital debris removal and inertial confinement fusion energy. According to the requirements of CAN and the front end of high-power laser facilities, a millijoule polarized fiber laser system was studied in this paper. Using polarization maintaining Ytterbium-fiber laser system as the seed, and 10-μm core Yb-doped fiber amplifier as the first power amplifier and 40-μm core polarizing (PZ) photonic crystal fiber (PCF) as the second power amplifier, the all-fiber laser system outputs 1.06-mJ energy at 10 ns and diffraction limited mode quality. Using 85-μm rod-type PCF as the third power amplifiers, 2.5-mJ energy at 10-ns pulse width was obtained with better than 500:1 peak-to-foot pulse shaping ability and fundamental mode beam quality. The energy fluctuation of the system is 1.3% rms with 1-mJ output in one hour. When using phase-modulated pulse as the seed, the frequency modulation to amplitude modulation (FM-to-AM) conversion ratio of the system is better than 5%. This fiber laser system has the advantages of high beam quality, high beam shaping ability, good stability, small volume and free of maintenance, which can be used in many applications.

Sub-μrad laser beam tracking

NASA Astrophysics Data System (ADS)

Buske, Ivo; Riede, Wolfgang

2006-09-01

We compare active optical elements based on different technologies to accomplish the requirements of a 2-dim. fine tracking control system. A cascaded optically and electrically addressable spatial light modulator (OASLM) based on liquid crystals (LC) is used for refractive beam steering. Spatial light modulators provide a controllable phase wedge to generate a beam deflection. Additionally, a tip/tilt mirror approach operating with piezo-electric actuators is investigated. A digital PID controller is implemented for closed-loop control. Beam tracking with a root-mean-squared accuracy of Δα=30 nrad has been laboratory-confirmed.

A NEW DIFFERENTIAL AND ERRANT BEAM CURRENT MONITOR FOR THE SNS* ACCELERATOR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blokland, Willem; Peters, Charles C

2013-01-01

A new Differential and errant Beam Current Monitor (DBCM) is being implemented for both the Spallation Neutron Source's Medium Energy Beam Transport (MEBT) and the Super Conducting Linac (SCL) accelerator sections. These new current monitors will abort the beam when the difference between two toroidal pickups exceeds a threshold. The MEBT DBCM will protect the MEBT chopper target, while the SCL DBCM will abort beam to minimize fast beam losses in the SCL cavities. The new DBCM will also record instances of errant beam, such as beam dropouts, to assist in further optimization of the SNS Accelerator. A software Errantmore » Beam Monitor was implemented on the regular BCM hardware to study errant beam pulses. The new system will take over this functionality and will also be able to abort beam on pulse-to-pulse variations. Because the system is based on the FlexRIO hardware and programmed in LabVIEW FPGA, it will be able to abort beam in about 5 us. This paper describes the development, implementation, and initial test results of the DBCM, as well as errant beam examples.« less

High removal rate laser-based coating removal system

DOEpatents

Matthews, Dennis L.; Celliers, Peter M.; Hackel, Lloyd; Da Silva, Luiz B.; Dane, C. Brent; Mrowka, Stanley

1999-11-16

A compact laser system that removes surface coatings (such as paint, dirt, etc.) at a removal rate as high as 1000 ft.sup.2 /hr or more without damaging the surface. A high repetition rate laser with multiple amplification passes propagating through at least one optical amplifier is used, along with a delivery system consisting of a telescoping and articulating tube which also contains an evacuation system for simultaneously sweeping up the debris produced in the process. The amplified beam can be converted to an output beam by passively switching the polarization of at least one amplified beam. The system also has a personal safety system which protects against accidental exposures.

First-order approximation error analysis of Risley-prism-based beam directing system.

PubMed

Zhao, Yanyan; Yuan, Yan

2014-12-01

To improve the performance of a Risley-prism system for optical detection and measuring applications, it is necessary to be able to determine the direction of the outgoing beam with high accuracy. In previous works, error sources and their impact on the performance of the Risley-prism system have been analyzed, but their numerical approximation accuracy was not high. Besides, pointing error analysis of the Risley-prism system has provided results for the case when the component errors, prism orientation errors, and assembly errors are certain. In this work, the prototype of a Risley-prism system was designed. The first-order approximations of the error analysis were derived and compared with the exact results. The directing errors of a Risley-prism system associated with wedge-angle errors, prism mounting errors, and bearing assembly errors were analyzed based on the exact formula and the first-order approximation. The comparisons indicated that our first-order approximation is accurate. In addition, the combined errors produced by the wedge-angle errors and mounting errors of the two prisms together were derived and in both cases were proved to be the sum of errors caused by the first and the second prism separately. Based on these results, the system error of our prototype was estimated. The derived formulas can be implemented to evaluate beam directing errors of any Risley-prism beam directing system with a similar configuration.

Excitation of Ion Cyclotron Waves by Ion and Electron Beams in Compensated-current System

NASA Astrophysics Data System (ADS)

Xiang, L.; Wu, D. J.; Chen, L.

2018-04-01

Ion cyclotron waves (ICWs) can play important roles in the energization of plasma particles. Charged particle beams are ubiquitous in space, and astrophysical plasmas and can effectively lead to the generation of ICWs. Based on linear kinetic theory, we consider the excitation of ICWs by ion and electron beams in a compensated-current system. We also investigate the competition between reactive and kinetic instabilities. The results show that ion and electron beams both are capable of generating ICWs. For ICWs driven by ion beams, there is a critical beam velocity, v bi c , and critical wavenumber, k z c , for a fixed beam density; the reactive instability dominates the growth of ICWs when the ion-beam velocity {v}{bi}> {v}{bi}c and the wavenumber {k}z< {k}zc, and the maximal growth rate is reached at {k}z≃ 2{k}zc/3 for a given {v}{bi}> {v}{bi}c. For the slow ion beams with {v}{bi}< {v}{bi}c, the kinetic instability can provide important growth rates of ICWs. On the other hand, ICWs driven by electron beams are excited only by the reactive instability, but require a critical velocity, {v}{be}c\\gg {v}{{A}} (the Alfvén velocity). In addition, the comparison between the approximate analytical results based on the kinetic theory and the exact numerical calculation based on the fluid model demonstrates that the reactive instabilities can well agree quantitatively with the numerical results by the fluid model. Finally, some possible applications of the present results to ICWs observed in the solar wind are briefly discussed.

Conversion of the high-mode solitons in strongly nonlocal nonlinear media

NASA Astrophysics Data System (ADS)

Zhang, Xiaping

2017-01-01

The conversion of high-mode solitons propagating in Strongly Nonlocal Nonlinear Media (SNNM) in three coordinate systems, namely, the elliptic coordinate system, the rectangular coordinate system and the cylindrical coordinate system, based on the Snyder-Mitchell Model that describes the paraxial beam propagating in SNNM, is discussed. Through constituting the trial solution with modulating the Gaussian beam by Ince polynomials, the closed-solution of Gaussian beams in elliptic coordinate is accessed. The Ince-Gaussian (IG) beams constitute the exact and continuous transition modes between Hermite-Gaussian beams and Laguerre-Gaussian (LG) beams, which is controlled by the elliptic parameter. The conditions of conversion in the three types of solitons are given in relation to the Gouy phase invariability in stable propagation. The profiles of the IG breather at a different propagating distance are numerically obtained, and the conversions of a few IG solitons are illustrated. The difference between the IG soliton and the corresponding LG soliton is remarkable from the Poynting vector and phase plots at their profiles along the propagating axis.

Development of a portable graphite calorimeter for radiation dosimetry.

PubMed

Sakama, Makoto; Kanai, Tatsuaki; Fukumura, Akifumi

2008-01-01

We developed and performance-tested a portable graphite calorimeter designed to measure the absolute dosimetry of various beams including heavy-ion beams, based on a flexible and convenient means of measurement. This measurement system is fully remote-controlled by the GPIB system. This system uses a digital PID (Proportional, Integral, Derivative) control method based on the LabVIEW software. It was possible to attain stable conditions in a shorter time by this system. The standard deviation of the measurements using the calorimeter was 0.79% at a dose rate of 0.8 Gy/min in 17 calorimeter runs for a (60)Co photon beam. The overall uncertainties for the absorbed dose to graphite and water of the (60)Co photon beam using the developed calorimeter were 0.89% and 1.35%, respectively. Estimations of the correction factors due to vacuum gaps, impurities in the core, the dose gradient and the radiation profile were included in the uncertainties. The absorbed doses to graphite and water irradiated by the (60)Co photon beam were compared with dosimetry measurements obtained using three ionization chambers. The absorbed doses to graphite and water estimated by the two dosimetry methods agreed within 0.1% and 0.3%, respectively.

Development of Metal Cluster-Based Energetic Materials at NSWC-IHD

DTIC Science & Technology

2011-01-01

reactivity of NixAly + clusters with nitromethane was investigated using a gas-phase molecular beam system. Results indicate that nitromethane is highly...clusters make up the subunit of a molecular metal-based energetic material. The reactivity of NixAly+ clusters with nitromethane was investigated using...a gas-phase molecular beam system. Results indicate that nitromethane is highly reactive toward the NixAly+ clusters and suggests it would not make

Practical application of noise diffusion in U-70 synchrotron

NASA Astrophysics Data System (ADS)

Ivanov, S. V.; Lebedev, O. P.

2016-12-01

This paper briefly outlines the physical substantiation and the engineering implementation of technological systems in the U-70 synchrotron based on controllable noise diffusion of the beam. They include two systems of stochastic slow beam extraction (for high and intermediate energy) and the system of longitudinal noise RF gymnastics designated for flattening the bunch distribution over the azimuth.

Opto-microwave Butler matrixes based front-end for a multi-beam large direct radiating array antenna

NASA Astrophysics Data System (ADS)

Piqueras, M. A.; Mengual, T.; Navasquillo, O.; Sotom, M.; Caille, G.

2017-09-01

The evolution of broadband communication satellites shows a clear trend towards beam forming and beam-switching systems with efficient multiple access schemes with wide bandwidths, for which to be economically viable, the communication price shall be as low as possible.

Design update and recent results of the Apollon 10 PW facility

NASA Astrophysics Data System (ADS)

Le Garrec, B.; Papadopoulos, D. N.; Le Blanc, C.; Zou, J. P.; Chériaux, G.; Georges, P.; Druon, F.; Martin, L.; Fréneaux, L.; Beluze, A.; Lebas, N.; Mathieu, F.; Audebert, P.

2017-05-01

In this paper we are giving a summary of the Apollon 10 PW facility laser design together with updated laser performance. The Apollon facility is currently under construction in France. The APOLLON laser system is a laser designed for delivering pulses as short as 15 fs (10-15 s) with an energy exceeding 150 Joules on target. The peak power delivered by this laser system will be 10 Petawatts (1016W). The Apollon laser system will be delivering 4 beams: one 10 PW beam (F1 beam 400 mm diameter), one 1 PW beam (F2 beam 140 mm diameter) and two additional probe beams (F3 and F4) at a repetition rate of 1 shot per minute. The laser system is based on Ti-sapphire amplifiers pumped by frequency doubled solid-state lasers. The repetition rate of the high energy part will be 1 shot per minute. The main beam at the output of the last amplifier will be split and dispatched to two experimental areas. The main laser beam is delivering 30 J before compression at a repetition rate of 1 shot per minute and we are currently increasing to get 100J.

Wave Propagation Analysis of Edge Cracked Circular Beams under Impact Force

PubMed Central

Akbaş, Şeref Doğuşcan

2014-01-01

This paper presents responses of an edge circular cantilever beam under the effect of an impact force. The beam is excited by a transverse triangular force impulse modulated by a harmonic motion. The Kelvin–Voigt model for the material of the beam is used. The cracked beam is modelled as an assembly of two sub-beams connected through a massless elastic rotational spring. The considered problem is investigated within the Bernoulli-Euler beam theory by using energy based finite element method. The system of equations of motion is derived by using Lagrange's equations. The obtained system of linear differential equations is reduced to a linear algebraic equation system and solved in the time domain by using Newmark average acceleration method. In the study, the effects of the location of crack, the depth of the crack, on the characteristics of the reflected waves are investigated in detail. Also, the positions of the cracks are calculated by using reflected waves. PMID:24972050

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center.

PubMed

Chung, Kwangzoo; Han, Youngyih; Kim, Jinsung; Ahn, Sung Hwan; Ju, Sang Gyu; Jung, Sang Hoon; Chung, Yoonsun; Cho, Sungkoo; Jo, Kwanghyun; Shin, Eun Hyuk; Hong, Chae-Seon; Shin, Jung Suk; Park, Seyjoon; Kim, Dae-Hyun; Kim, Hye Young; Lee, Boram; Shibagaki, Gantaro; Nonaka, Hideki; Sasai, Kenzo; Koyabu, Yukio; Choi, Changhoon; Huh, Seung Jae; Ahn, Yong Chan; Pyo, Hong Ryull; Lim, Do Hoon; Park, Hee Chul; Park, Won; Oh, Dong Ryul; Noh, Jae Myung; Yu, Jeong Il; Song, Sanghyuk; Lee, Ji Eun; Lee, Bomi; Choi, Doo Ho

2015-12-01

The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

CRionScan: A stand-alone real time controller designed to perform ion beam imaging, dose controlled irradiation and proton beam writing

NASA Astrophysics Data System (ADS)

Daudin, L.; Barberet, Ph.; Serani, L.; Moretto, Ph.

2013-07-01

High resolution ion microbeams, usually used to perform elemental mapping, low dose targeted irradiation or ion beam lithography needs a very flexible beam control system. For this purpose, we have developed a dedicated system (called “CRionScan”), on the AIFIRA facility (Applications Interdisciplinaires des Faisceaux d'Ions en Région Aquitaine). It consists of a stand-alone real-time scanning and imaging instrument based on a Compact Reconfigurable Input/Output (Compact RIO) device from National Instruments™. It is based on a real-time controller, a Field Programmable Gate Array (FPGA), input/output modules and Ethernet connectivity. We have implemented a fast and deterministic beam scanning system interfaced with our commercial data acquisition system without any hardware development. CRionScan is built under LabVIEW™ and has been used on AIFIRA's nanobeam line since 2009 (Barberet et al., 2009, 2011) [1,2]. A Graphical User Interface (GUI) embedded in the Compact RIO as a web page is used to control the scanning parameters. In addition, a fast electrostatic beam blanking trigger has been included in the FPGA and high speed counters (15 MHz) have been implemented to perform dose controlled irradiation and on-line images on the GUI. Analog to Digital converters are used for the beam current measurement and in the near future for secondary electrons imaging. Other functionalities have been integrated in this controller like LED lighting using Pulse Width Modulation and a “NIM Wilkinson ADC” data acquisition.

Six-beam homodyne laser Doppler vibrometry based on silicon photonics technology.

PubMed

Li, Yanlu; Zhu, Jinghao; Duperron, Matthieu; O'Brien, Peter; Schüler, Ralf; Aasmul, Soren; de Melis, Mirko; Kersemans, Mathias; Baets, Roel

2018-02-05

This paper describes an integrated six-beam homodyne laser Doppler vibrometry (LDV) system based on a silicon-on-insulator (SOI) full platform technology, with on-chip photo-diodes and phase modulators. Electronics and optics are also implemented around the integrated photonic circuit (PIC) to enable a simultaneous six-beam measurement. Measurement of a propagating guided elastic wave in an aluminum plate (speed ≈ 909 m/s @ 61.5 kHz) is demonstrated.

A high bandwidth three-axis out-of-plane motion measurement system based on optical beam deflection

NASA Astrophysics Data System (ADS)

Piyush, P.; Giridhar, M. S.; Jayanth, G. R.

2018-03-01

Multi-axis measurement of motion is indispensable for characterization of dynamic systems and control of motion stages. This paper presents an optical beam deflection-based measurement system to simultaneously measure three-axis out-of-plane motion of both micro- and macro-scale targets. Novel strategies are proposed to calibrate the sensitivities of the measurement system. Subsequently the measurement system is experimentally realized and calibrated. The system is employed to characterize coupled linear and angular motion of a piezo-actuated stage. The measured motion is shown to be in agreement with theoretical expectation. Next, the high bandwidth of the measurement system has been showcased by utilizing it to measure coupled two-axis transient motion of a Radio Frequency Micro-Electro-Mechanical System switch with a rise time of about 60 μs. Finally, the ability of the system to measure out-of-plane angular motion about the second axis has been demonstrated by measuring the deformation of a micro-cantilever beam.

TFTR neutral beam control and monitoring for DT operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

O`Connor, T.; Kamperschroer, J.; Chu, J.

1995-12-31

Record fusion power output has recently been obtained in TFTR with the injection of deuterium and tritium neutral beams. This significant achievement was due in part to the controls, software, and data processing capabilities added to the neutral beam system for DT operations. Chief among these improvements was the addition of SUN workstations and large dynamic data storage to the existing Central Instrumentation Control and Data Acquisition (CICADA) system. Essentially instantaneous look back over the recent shot history has been provided for most beam waveforms and analysis results. Gas regulation controls allowing remote switchover between deuterium and tritium were alsomore » added. With these tools, comparison of the waveforms and data of deuterium and tritium for four test conditioning pulses quickly produced reliable tritium setpoints. Thereafter, all beam conditioning was performed with deuterium, thus saving the tritium supply for the important DT injection shots. The lookback capability also led to modifications of the gas system to improve reliability and to control ceramic valve leakage by backbiasing. Other features added to improve the reliability and availability of DT neutral beam operations included master beamline controls and displays, a beamline thermocouple interlock system, a peak thermocouple display, automatic gas inventory and cryo panel gas loading monitoring, beam notching controls, a display of beam/plasma interlocks, and a feedback system to control beam power based on plasma conditions.« less

Neutral Beam Injection System for the SHIP Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdrashitov, G.F.; Abdrashitov, A.G.; Anikeev, A.V.

2005-01-15

The injector ion source is based on an arcdischarge plasma box. The plasma emitter is produced by a 1 kA arc discharge in deuterium. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a 4-electrodes ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a spherical curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were found by means of numerical simulation tomore » provide precise beam formation. The measured angular divergence of the beam is 0.025 rad, which corresponds to a 4.7 cm Gaussian radius of the beam profile measured at focal point.« less

Genetic algorithm based active vibration control for a moving flexible smart beam driven by a pneumatic rod cylinder

NASA Astrophysics Data System (ADS)

Qiu, Zhi-cheng; Shi, Ming-li; Wang, Bin; Xie, Zhuo-wei

2012-05-01

A rod cylinder based pneumatic driving scheme is proposed to suppress the vibration of a flexible smart beam. Pulse code modulation (PCM) method is employed to control the motion of the cylinder's piston rod for simultaneous positioning and vibration suppression. Firstly, the system dynamics model is derived using Hamilton principle. Its standard state-space representation is obtained for characteristic analysis, controller design, and simulation. Secondly, a genetic algorithm (GA) is applied to optimize and tune the control gain parameters adaptively based on the specific performance index. Numerical simulations are performed on the pneumatic driving elastic beam system, using the established model and controller with tuned gains by GA optimization process. Finally, an experimental setup for the flexible beam driven by a pneumatic rod cylinder is constructed. Experiments for suppressing vibrations of the flexible beam are conducted. Theoretical analysis, numerical simulation and experimental results demonstrate that the proposed pneumatic drive scheme and the adopted control algorithms are feasible. The large amplitude vibration of the first bending mode can be suppressed effectively.

The EPICS-based remote control system for muon beam line devices at J-PARC MUSE

NASA Astrophysics Data System (ADS)

Ito, T. U.; Nakahara, K.; Kawase, M.; Fujimori, H.; Kobayashi, Y.; Higemoto, W.; Miyake, Y.

2010-04-01

The remote control system for muon beam line devices of J-PARC MUSE has been developed with the Experimental Physics and Industrial Control System (EPICS). The EPICS input/output controller was installed in standard Linux PCs for slow control of the devices. Power supplies for 21 magnetic elements and four slit controllers for the decay-surface muon beam line in the Materials and Life Science Experimental Facility are now accessible via Ethernet from a graphical user interface which has been composed using the Motif Editor and Display Manger.

Medical beam monitor—Pre-clinical evaluation and future applications

NASA Astrophysics Data System (ADS)

Frais-Kölbl, Helmut; Griesmayer, Erich; Schreiner, Thomas; Georg, Dietmar; Pernegger, Heinz

2007-10-01

Future medical ion beam applications for cancer therapy which are based on scanning technology will require advanced beam diagnostics equipment. For a precise analysis of beam parameters we want to resolve time structures in the range of microseconds to nanoseconds. A prototype of an advanced beam monitor was developed by the University of Applied Sciences Wiener Neustadt and its research subsidiary Fotec in co-operation with CERN RD42, Ohio State University and the Jožef Stefan Institute in Ljubljana. The detector is based on polycrystalline Chemical Vapor Deposition (pCVD) diamond substrates and is equipped with readout electronics up to 2 GHz analog bandwidth. In this paper we present the design of the pCVD-detector system and results of tests performed in various particle accelerator based facilities. Measurements performed in clinical high energy photon beams agreed within 1.2% with results obtained by standard ionization chambers.

Development of ion source with a washer gun for pulsed neutral beam injection.

PubMed

Asai, T; Yamaguchi, N; Kajiya, H; Takahashi, T; Imanaka, H; Takase, Y; Ono, Y; Sato, K N

2008-06-01

A new type of economical neutral beam source has been developed by using a single washer gun, pulsed operation, and a simple electrode system. We replaced the conventional hot filaments for arc-discharge-type plasma formation with a single stainless-steel washer gun, eliminating the entire dc power supply for the filaments and the cooling system for the electrodes. Our initial experiments revealed successful beam extraction up to 10 kV and 8.6 A, based on spatial profile measurements of density and temperature in the plasma source. The system also shows the potential to control the beam profile by controlling the plasma parameters in the ion accumulation chamber.

High-power beam combining: a step to a future laser weapon system

NASA Astrophysics Data System (ADS)

Protz, Rudolf; Zoz, Jürgen; Geidek, Franz; Dietrich, Stephan; Fall, Michael

2012-11-01

Due to the enormous progress in the field of high-power fiber lasers during the last years commercial industrial fiber lasers are now available, which deliver a near-diffraction limited beam with power levels up to10kW. For the realization of a future laser weapon system, which can be used for Counter-RAM or similar air defence applications, a laser source with a beam power at the level of 100kW or more is required. At MBDA Germany the concept for a high-energy laser weapon system is investigated, which is based on such existing industrial laser sources as mentioned before. A number of individual high-power fiber laser beams are combined together, using one common beam director telescope. By this "geometric" beam coupling scheme, sufficient laser beam power for an operational laser weapon system can be achieved. The individual beams from the different lasers are steered by servo-loops, using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at the common focal point on a distant target, also allowing fine tracking of target movements and first order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated using several experimental set-ups. Different experiments were performed, to investigate laser beam target interaction and target fine tracking also at large distances. Content and results of these investigations are reported. An example for the lay-out of an Air Defence High Energy Laser Weapon (ADHELW ) is given. It can be concluded, that geometric high-power beam combining is an important step for the realization of a laser weapon system in the near future.

A beam splitter of natural light guiding system based on dichroic prism for ecological illumination

NASA Astrophysics Data System (ADS)

Li, Yu-Chi; Chen, Yi-Yung; Whang, Allen Jong-Woei

2009-08-01

In thremmatology, many researches focus on ecological illumination for improving the growing speed of animal or plant. According to the Trichromatic theory, any specific color can be made up of red, green, and blue light. Sunlight has full spectrum so it is the most applicable source. A Natural Light Guiding System includes collecting, transmitting, and lighting parts. In our research, we would like to design a beam splitter in the transmitting part to separate the sunlight into red, green, and blue light for ecological illumination. We use high pass and low pass dichroic coatings in a prism, called dichroic prism, to be the beam splitter to separate the wavelength. For measuring the spectra of the exit beams, we build a space with the Natural Light Guiding System. In the space, the spectra of sunlight outside and inside the space and the exit beams of the beam splitter are measured. Finally, we use prismatic structure to design the beam splitter, and optimize the surface of the element with aspheric surface and Fresnel surface to reduce the beam angle of exit light.

Electro-optical voltage sensor head

DOEpatents

Woods, Gregory K.

1998-01-01

A miniature electro-optic voltage sensor system capable of accurate operation at high voltages. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.

Electro-optic voltage sensor for sensing voltage in an E-field

DOEpatents

Woods, Gregory K.; Renak, Todd W.

1999-01-01

A miniature electro-optic voltage sensor system capable of accurate operation at high voltages. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.

Spatial resolution test of a beam diagnostic system for DESIREE

NASA Astrophysics Data System (ADS)

Das, Susanta; Kallberg, A.

2010-11-01

A diagnostic system based on the observation of low energy ( ˜ 10 eV) secondary electrons (SE) produced by a beam, striking a metallic foil has been built to monitor and to cover the wide range of beam intensities and energies for Double ElectroStatic Ion Ring ExpEriment [1,2].The system consists of a Faraday cup to measure the beam current, a collimator with circular apertures of different diameters to measure the spatial resolution of the system, a beam profile monitoring system (BPMS), and a control unit. The BPMS, in turn, consists of an aluminim (Al) foil, a grid placed in front of the Al foil to accelerate the SE, position sensitive MCP, fluorescent screen, and a CCD camera to capture the images. The collimator contains a set of circular holes of different diameters and separations (d) between them. The collimator cuts out from the beam areas equal to the holes with separation d mm between the beams centers and creates well separated (distinguishable) narrow beams of approximately same intensity close to each other. A 10 keV proton beam was used. The spatial resolution of the system was tested for different Al plate and MCP voltages and resolution of better than 2 mm was achieved. Ref.: 1. K. Kruglov {et al}., NIM A 441 (2000) 595; 701 (2002) 193c, 2. MSL and Atomic Physics, Stockholm Univ.(www.msl.se, http://www.atom.physto.se/Cederquist/desiree/web/hc.html).

A light-weight compact proton gantry design with a novel dose delivery system for broad-energetic laser-accelerated beams

NASA Astrophysics Data System (ADS)

Masood, U.; Cowan, T. E.; Enghardt, W.; Hofmann, K. M.; Karsch, L.; Kroll, F.; Schramm, U.; Wilkens, J. J.; Pawelke, J.

2017-07-01

Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra. For the application of laser-driven beams in PT, new solutions for beam transport, such as beam capture, integrated energy selection, beam shaping and delivery systems are required due to the specific beam parameters. The generation of these beams are limited by the low repetition rate of high-power lasers and this limitation would require alternative solutions for tumour irradiation which can efficiently utilize the available high proton fluence and broad-energy spectra per proton bunch to keep treatment times short. This demands new dose delivery system and irradiation field formation schemes. In this paper, we present a multi-functional light-weight and compact proton gantry design for laser-driven sources based on iron-less pulsed high-field magnets. This achromatic design includes improved beam capturing and energy selection systems, with a novel beam shaping and dose delivery system, so-called ELPIS. ELPIS system utilizes magnetic fields, instead of physical scatterers, for broadening the spot-size of broad-energetic beams while capable of simultaneously scanning them in lateral directions. To investigate the clinical feasibility of this gantry design, we conducted a treatment planning study with a 3D treatment planning system augmented for the pulsed beams with optimizable broad-energetic widths and selectable beam spot sizes. High quality treatment plans could be achieved with such unconventional beam parameters, deliverable via the presented gantry and ELPIS dose delivery system. The conventional PT gantries are huge and require large space for the gantry to rotate the beam around the patient, which could be reduced up to 4 times with the presented pulse powered gantry system. The further developments in the next generation petawatt laser systems and laser-targets are crucial to reach higher proton energies. However, if proton energies required for therapy applications are reached it could be possible in future to reduce the footprint of the PT facilities, without compromising on clinical standards.

A light-weight compact proton gantry design with a novel dose delivery system for broad-energetic laser-accelerated beams.

PubMed

Masood, U; Cowan, T E; Enghardt, W; Hofmann, K M; Karsch, L; Kroll, F; Schramm, U; Wilkens, J J; Pawelke, J

2017-07-07

Proton beams may provide superior dose-conformity in radiation therapy. However, the large sizes and costs limit the widespread use of proton therapy (PT). The recent progress in proton acceleration via high-power laser systems has made it a compelling alternative to conventional accelerators, as it could potentially reduce the overall size and cost of the PT facilities. However, the laser-accelerated beams exhibit different characteristics than conventionally accelerated beams, i.e. very intense proton bunches with large divergences and broad-energy spectra. For the application of laser-driven beams in PT, new solutions for beam transport, such as beam capture, integrated energy selection, beam shaping and delivery systems are required due to the specific beam parameters. The generation of these beams are limited by the low repetition rate of high-power lasers and this limitation would require alternative solutions for tumour irradiation which can efficiently utilize the available high proton fluence and broad-energy spectra per proton bunch to keep treatment times short. This demands new dose delivery system and irradiation field formation schemes. In this paper, we present a multi-functional light-weight and compact proton gantry design for laser-driven sources based on iron-less pulsed high-field magnets. This achromatic design includes improved beam capturing and energy selection systems, with a novel beam shaping and dose delivery system, so-called ELPIS. ELPIS system utilizes magnetic fields, instead of physical scatterers, for broadening the spot-size of broad-energetic beams while capable of simultaneously scanning them in lateral directions. To investigate the clinical feasibility of this gantry design, we conducted a treatment planning study with a 3D treatment planning system augmented for the pulsed beams with optimizable broad-energetic widths and selectable beam spot sizes. High quality treatment plans could be achieved with such unconventional beam parameters, deliverable via the presented gantry and ELPIS dose delivery system. The conventional PT gantries are huge and require large space for the gantry to rotate the beam around the patient, which could be reduced up to 4 times with the presented pulse powered gantry system. The further developments in the next generation petawatt laser systems and laser-targets are crucial to reach higher proton energies. However, if proton energies required for therapy applications are reached it could be possible in future to reduce the footprint of the PT facilities, without compromising on clinical standards.

Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments.

PubMed

Anda, G; Dunai, D; Lampert, M; Krizsanóczi, T; Németh, J; Bató, S; Nam, Y U; Hu, G H; Zoletnik, S

2018-01-01

A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (<20 s) discharges. A set of new beam diagnostic and manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments

NASA Astrophysics Data System (ADS)

Anda, G.; Dunai, D.; Lampert, M.; Krizsanóczi, T.; Németh, J.; Bató, S.; Nam, Y. U.; Hu, G. H.; Zoletnik, S.

2018-01-01

A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (<20 s) discharges. A set of new beam diagnostic and manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

Non-perturbative measurement of low-intensity charged particle beams

NASA Astrophysics Data System (ADS)

Fernandes, M.; Geithner, R.; Golm, J.; Neubert, R.; Schwickert, M.; Stöhlker, T.; Tan, J.; Welsch, C. P.

2017-01-01

Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of 30 {nA}.

A 128-channel picoammeter system and its application on charged particle beam current distribution measurements.

PubMed

Yu, Deyang; Liu, Junliang; Xue, Yingli; Zhang, Mingwu; Cai, Xiaohong; Hu, Jianjun; Dong, Jinmei; Li, Xin

2015-11-01

A 128-channel picoammeter system is constructed based on instrumentation amplifiers. Taking advantage of a high electric potential and narrow bandwidth in DC energetic charged beam measurements, a current resolution better than 5 fA can be achieved. Two sets of 128-channel strip electrodes are implemented on printed circuit boards and are employed for ion and electron beam current distribution measurements. Tests with 60 keV O(3+) ions and 2 keV electrons show that it can provide exact boundaries when a positive charged particle beam current distribution is measured.

Evaluation and utilization of beam simulation codes for the SNS ion source and low energy beam transport developmenta)

NASA Astrophysics Data System (ADS)

Han, B. X.; Welton, R. F.; Stockli, M. P.; Luciano, N. P.; Carmichael, J. R.

2008-02-01

Beam simulation codes PBGUNS, SIMION, and LORENTZ-3D were evaluated by modeling the well-diagnosed SNS base line ion source and low energy beam transport (LEBT) system. Then, an investigation was conducted using these codes to assist our ion source and LEBT development effort which is directed at meeting the SNS operational and also the power-upgrade project goals. A high-efficiency H- extraction system as well as magnetic and electrostatic LEBT configurations capable of transporting up to 100mA is studied using these simulation tools.

Phase and amplitude beam shaping with two deformable mirrors implementing input plane and Fourier plane phase modifications.

PubMed

Wu, Chensheng; Ko, Jonathan; Rzasa, John R; Paulson, Daniel A; Davis, Christopher C

2018-03-20

We find that ideas in optical image encryption can be very useful for adaptive optics in achieving simultaneous phase and amplitude shaping of a laser beam. An adaptive optics system with simultaneous phase and amplitude shaping ability is very desirable for atmospheric turbulence compensation. Atmospheric turbulence-induced beam distortions can jeopardize the effectiveness of optical power delivery for directed-energy systems and optical information delivery for free-space optical communication systems. In this paper, a prototype adaptive optics system is proposed based on a famous image encryption structure. The major change is to replace the two random phase plates at the input plane and Fourier plane of the encryption system, respectively, with two deformable mirrors that perform on-demand phase modulations. A Gaussian beam is used as an input to replace the conventional image input. We show through theory, simulation, and experiments that the slightly modified image encryption system can be used to achieve arbitrary phase and amplitude beam shaping within the limits of stroke range and influence function of the deformable mirrors. In application, the proposed technique can be used to perform mode conversion between optical beams, generate structured light signals for imaging and scanning, and compensate atmospheric turbulence-induced phase and amplitude beam distortions.

Speckle-metric-optimization-based adaptive optics for laser beam projection and coherent beam combining.

PubMed

Vorontsov, Mikhail; Weyrauch, Thomas; Lachinova, Svetlana; Gatz, Micah; Carhart, Gary

2012-07-15

Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control.

Beam energy tracking system on Optima XEx high energy ion implanter

DOE Office of Scientific and Technical Information (OSTI.GOV)

David, Jonathan; Satoh, Shu; Wu Xiangyang

2012-11-06

The Axcelis Optima XEx high energy implanter is an RF linac-based implanter with 12 RF resonators for beam acceleration. Even though each acceleration field is an alternating, sinusoidal RF field, the well known phase-focusing principle produces a beam with a sharp quasi-monoenergetic energy spectrum. A magnetic energy filter after the linac further attenuates the low energy continuum in the energy spectrum often associated with RF acceleration. The final beam energy is a function of the phase and amplitude of the 12 resonators in the linac. When tuning a beam, the magnetic energy filter is set to the desired energy, andmore » each linac parameter is tuned to maximize the transmission through the filter. Once a beam is set up, all the parameters are stored in a recipe, which can be easily tuned and has proven to be quite repeatable. The magnetic field setting of the energy filter selects the beam energy from the RF Linac accelerator, and in-situ verification of beam energy in addition to the magnetic energy filter setting has long been desired. An independent energy tracking system was developed for this purpose, using the existing electrostatic beam scanner as a deflector to construct an in-situ electrostatic energy analyzer. This paper will describe the system and performance of the beam energy tracking system.« less

Beam Stability R&D for the APS MBA Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sereno, Nicholas S.; Arnold, Ned D.; Bui, Hanh D.

2015-01-01

Beam diagnostics required for the APS Multi-bend acromat (MBA) are driven by ambitious beam stability requirements. The major AC stability challenge is to correct rms beam motion to 10% the rms beam size at the insertion device source points from0.01 to 1000 Hz. The vertical plane represents the biggest challenge forAC stability, which is required to be 400 nm rms for a 4-micron vertical beam size. In addition to AC stability, long-term drift over a period of seven days is required to be 1 micron or less. Major diagnostics R&D components include improved rf beam position processing using commercially availablemore » FPGA-based BPM processors, new X-ray beam position monitors based on hard X-ray fluorescence from copper and Compton scattering off diamond, mechanical motion sensing to detect and correct long-term vacuum chamber drift, a new feedback system featuring a tenfold increase in sampling rate, and a several-fold increase in the number of fast correctors and BPMs in the feedback algorithm. Feedback system development represents a major effort, and we are pursuing development of a novel algorithm that integrates orbit correction for both slow and fast correctors down to DC simultaneously. Finally, a new data acquisition system (DAQ) is being developed to simultaneously acquire streaming data from all diagnostics as well as the feedback processors for commissioning and fault diagnosis. Results of studies and the design effort are reported.« less

High Bandwidth Optical Links for Micro-Satellite Support

NASA Technical Reports Server (NTRS)

Chao, Tien-Hsin (Inventor); Wilson, Keith E. (Inventor); Coste, Keith (Inventor)

2016-01-01

A method, systems, apparatus and device enable high bandwidth satellite communications. An onboard tracking detector, installed in a low-earth orbit satellite, detects a position of an incoming optical beam received/transmitted from a first ground station of one or more ground stations. Tracker electronics determine orientation information of the incoming optical beam based on the position. Control electronics receive the orientation information from the tracker electronics, and control a waveguide drive electronics. The waveguide drive electronics control a voltage that is provided to an electro-optic waveguide beam steering device. The electro-optic waveguide beam steering device steers an outgoing optical beam to one of the one or more ground stations based on the voltage.

Beam rider for an Articulated Robot Manipulator (ARM) accurate positioning of long flexible manipulators

NASA Technical Reports Server (NTRS)

Malachowski, M. J.

1990-01-01

Laser beam positioning and beam rider modules were incorporated into the long hollow flexible segment of an articulated robot manipulator (ARM). Using a single laser beam, the system determined the position of the distal ARM endtip, with millimetric precision, in six degrees of freedom, at distances of up to 10 meters. Preliminary designs, using space rated technology for the critical systems, of a two segmented physical ARM, with a single and a dual degree of freedom articulation, were developed, prototyped, and tested. To control the positioning of the physical ARM, an indirect adaptive controller, which used the mismatch between the position of the laser beam under static and dynamic conditions, was devised. To predict the behavior of the system and test the concept, a computer simulation model was constructed. A hierarchical artificially intelligent real time ADA operating system program structure was created. The software was designed for implementation on a dedicated VME bus based Intel 80386 administered parallel processing multi-tasking computer system.

A singular value decomposition linear programming (SVDLP) optimization technique for circular cone based robotic radiotherapy.

PubMed

Liang, Bin; Li, Yongbao; Wei, Ran; Guo, Bin; Xu, Xuang; Liu, Bo; Li, Jiafeng; Wu, Qiuwen; Zhou, Fugen

2018-01-05

With robot-controlled linac positioning, robotic radiotherapy systems such as CyberKnife significantly increase freedom of radiation beam placement, but also impose more challenges on treatment plan optimization. The resampling mechanism in the vendor-supplied treatment planning system (MultiPlan) cannot fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy. The SVDLP approach initializes the input beams by simulating the process of covering the entire target volume with equivalent beam tapers. The requirements on dosimetry distribution are modeled as hard and soft constraints, and the sparsity of the treatment plan is achieved by compressive sensing. The proposed linear programming (LP) model optimizes beam weights by minimizing the deviation of soft constraints subject to hard constraints, with a constraint on the l 1 norm of the beam weight. A singular value decomposition (SVD) based acceleration technique was developed for the LP model. Based on the degeneracy of the influence matrix, the model is first compressed into lower dimension for optimization, and then back-projected to reconstruct the beam weight. After beam weight optimization, the number of beams is reduced by removing the beams with low weight, and optimizing the weights of the remaining beams using the same model. This beam reduction technique is further validated by a mixed integer programming (MIP) model. The SVDLP approach was tested on a lung case. The results demonstrate that the SVD acceleration technique speeds up the optimization by a factor of 4.8. Furthermore, the beam reduction achieves a similar plan quality to the globally optimal plan obtained by the MIP model, but is one to two orders of magnitude faster. Furthermore, the SVDLP approach is tested and compared with MultiPlan on three clinical cases of varying complexities. In general, the plans generated by the SVDLP achieve steeper dose gradient, better conformity and less damage to normal tissues. In conclusion, the SVDLP approach effectively improves the quality of treatment plan due to the use of the complete beam search space. This challenging optimization problem with the complete beam search space is effectively handled by the proposed SVD acceleration.

A singular value decomposition linear programming (SVDLP) optimization technique for circular cone based robotic radiotherapy

NASA Astrophysics Data System (ADS)

Liang, Bin; Li, Yongbao; Wei, Ran; Guo, Bin; Xu, Xuang; Liu, Bo; Li, Jiafeng; Wu, Qiuwen; Zhou, Fugen

2018-01-01

With robot-controlled linac positioning, robotic radiotherapy systems such as CyberKnife significantly increase freedom of radiation beam placement, but also impose more challenges on treatment plan optimization. The resampling mechanism in the vendor-supplied treatment planning system (MultiPlan) cannot fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy. The SVDLP approach initializes the input beams by simulating the process of covering the entire target volume with equivalent beam tapers. The requirements on dosimetry distribution are modeled as hard and soft constraints, and the sparsity of the treatment plan is achieved by compressive sensing. The proposed linear programming (LP) model optimizes beam weights by minimizing the deviation of soft constraints subject to hard constraints, with a constraint on the l 1 norm of the beam weight. A singular value decomposition (SVD) based acceleration technique was developed for the LP model. Based on the degeneracy of the influence matrix, the model is first compressed into lower dimension for optimization, and then back-projected to reconstruct the beam weight. After beam weight optimization, the number of beams is reduced by removing the beams with low weight, and optimizing the weights of the remaining beams using the same model. This beam reduction technique is further validated by a mixed integer programming (MIP) model. The SVDLP approach was tested on a lung case. The results demonstrate that the SVD acceleration technique speeds up the optimization by a factor of 4.8. Furthermore, the beam reduction achieves a similar plan quality to the globally optimal plan obtained by the MIP model, but is one to two orders of magnitude faster. Furthermore, the SVDLP approach is tested and compared with MultiPlan on three clinical cases of varying complexities. In general, the plans generated by the SVDLP achieve steeper dose gradient, better conformity and less damage to normal tissues. In conclusion, the SVDLP approach effectively improves the quality of treatment plan due to the use of the complete beam search space. This challenging optimization problem with the complete beam search space is effectively handled by the proposed SVD acceleration.

Design of laser afocal zoom expander system

NASA Astrophysics Data System (ADS)

Jiang, Lian; Zeng, Chun-Mei; Hu, Tian-Tian

2018-01-01

Laser afocal zoom expander system due to the beam diameter variable, can be used in the light sheet illumination microscope to observe the samples of different sizes. Based on the principle of afocal zoom system, the laser collimation and beam expander system with a total length of less than 110mm, 6 pieces of spherical lens and a beam expander ratio of 10 is designed by using Zemax software. The system is focused on laser with a wavelength of 532nm, divergence angle of less than 4mrad and incident diameter of 4mm. With the combination of 6 spherical lens, the beam divergence angle is 0.4mrad at the maximum magnification ratio, and the RMS values at different rates are less than λ/4. This design is simple in structure and easy to process and adjust. It has certain practical value.

Linear time-to-space mapping system using double electrooptic beam deflectors.

PubMed

Hisatake, Shintaro; Tada, Keiji; Nagatsuma, Tadao

2008-12-22

We propose and demonstrate a linear time-to-space mapping system, which is based on two times electrooptic sinusoidal beam deflection. The direction of each deflection is set to be mutually orthogonal with the relative deflection phase of pi/2 rad so that the circular optical beam trajectory can be achieved. The beam spot at the observation plane moves with an uniform velocity and as a result linear time-to-space mapping (an uniform temporal resolution through the mapping) can be realized. The proof-of-concept experiment are carried out and the temporal resolution of 5 ps has been demonstrated using traveling-wave type quasi-velosity-matched electrooptic beam deflectors. The developed system is expected to be applied to characterization of ultrafast optical signal or optical arbitrary waveform shaping for modulated microwave/millimeter-wave generation.

A reconstruction method for cone-beam differential x-ray phase-contrast computed tomography.

PubMed

Fu, Jian; Velroyen, Astrid; Tan, Renbo; Zhang, Junwei; Chen, Liyuan; Tapfer, Arne; Bech, Martin; Pfeiffer, Franz

2012-09-10

Most existing differential phase-contrast computed tomography (DPC-CT) approaches are based on three kinds of scanning geometries, described by parallel-beam, fan-beam and cone-beam. Due to the potential of compact imaging systems with magnified spatial resolution, cone-beam DPC-CT has attracted significant interest. In this paper, we report a reconstruction method based on a back-projection filtration (BPF) algorithm for cone-beam DPC-CT. Due to the differential nature of phase contrast projections, the algorithm restrains from differentiation of the projection data prior to back-projection, unlike BPF algorithms commonly used for absorption-based CT data. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a micro-focus x-ray tube source. Moreover, the numerical simulation and experimental results demonstrate that the proposed method can deal with several classes of truncated cone-beam datasets. We believe that this feature is of particular interest for future medical cone-beam phase-contrast CT imaging applications.

AN/SLQ-32 EW System Model: and Expandable, Object-Oriented, Process- Based Simulation

DTIC Science & Technology

1992-09-01

CONST threshold = 0.1; timetol = 0.01; orientol = 5.8; VAR rec, recLast :BufferBeamRecType; time,power : REAL; powerl,orientation : REAL; BEGIN NEW...PulseGroup); rec:-ASK BufferBeam Removed; time: =rec. time; orientation: =rec. orientation; OUTPUT ( "ORIENREFI, orientation); recLast :=ASK BufferBeam Last...TO Add(rec); IF (rec= recLast ) EXIT; END IF; rec :=ASK BufferBeam Remove o; ELSE ASK BufferBeam TO Add(rec); IF (rec = recLast ) EXIT; END IF; rec

Elegant Hermite-Airy beams

NASA Astrophysics Data System (ADS)

Zhou, Guoquan; Zhang, Lijun; Ru, Guoyun

2015-09-01

As Ai(x)Ai(-x) can be approximated by \\text{exp}≤ft(-{{x}2}/2\\right) , a kind of elegant Hermite-Airy (EHA) beam that is similar to the elegant Hermite-Gaussian (EHG) beam is introduced in this paper. Analytical expression of the EHA beams passing through an ABCD paraxial optical system is derived. By using the method of numerical fitting, the approximate expressions of 02> , 04> , <\\Thetaj2> , <\\Thetaj4> , and 02\\Thetaj2> for an EHA beam are presented, respectively. When the transverse mode number is larger than 2, 02> , 04> , <\\Thetaj2> , <\\Thetaj4> , and 02\\Thetaj2> of an EHA beam are all larger than those of the EHG beam. Based on the higher-order intensity moments, one can calculate the beam propagation factor, the beam half width, and the kurtosis parameter of the EHA beam passing through an ABCD paraxial optical system. As a numerical example, the propagation characteristics of the EHA beam are demonstrated in free space. Moreover, the propagation properties of the EHA beam are compared with those of the corresponding EHG beam. The evolutionary process of the EHA beam is far slower than that of the corresponding EHG beam. The research denotes that the EHA beams can be used to describe specially distributed optical beams that can not be characterized by the existing EHG beam model. The EHA beam model enriches and replenishes the existing beam model.

Errors and optics study of a permanent magnet quadrupole system

NASA Astrophysics Data System (ADS)

Schillaci, F.; Maggiore, M.; Rifuggiato, D.; Cirrone, G. A. P.; Cuttone, G.; Giove, D.

2015-05-01

Laser-based accelerators are gaining interest in recent years as an alternative to conventional machines [1]. Nowadays, energy and angular spread of the laser-driven beams are the main issues in application and different solutions for dedicated beam-transport lines have been proposed [2,3]. In this context a system of permanent magnet quadrupoles (PMQs) is going to be realized by INFN [2] researchers, in collaboration with SIGMAPHI [3] company in France, to be used as a collection and pre-selection system for laser driven proton beams. The definition of well specified characteristics, both in terms of performances and field quality, of the magnetic lenses is crucial for the system realization, for an accurate study of the beam dynamics and the proper matching with a magnetic selection system already realized [6,7]. Hence, different series of simulations have been used for studying the PMQs harmonic contents and stating the mechanical and magnetic tolerances in order to have reasonable good beam quality downstream the system. In this paper is reported the method used for the analysis of the PMQs errors and its validation. Also a preliminary optics characterization is presented in which are compared the effects of an ideal PMQs system with a perturbed system on a monochromatic proton beams.

Review on structured optical field generated from array beams

NASA Astrophysics Data System (ADS)

Hou, Tianyue; Zhou, Pu; Ma, Yanxing; Zhi, Dong

2018-03-01

Structured optical field (SOF), which includes vortex beams, non-diffraction beams, cylindrical vector beams and so on, has been under intensive investigation theoretically and experimentally in recent years. Generally, current research focus on the extraordinary properties (non-diffraction propagation, helical wavefront, rotation of electrical field, et al), which can be widely applied in micro-particle manipulation, super-resolution imaging, free-space communication and so on. There are mainly two technical routes, that is, inner-cavity and outer-cavity (spatial light modulators, diffractive phase holograms, q-plates). To date, most of the SOFs generated from both technical routes involves with single monolithic beam. As a novel technical route, SOF based on array beams has the advantage in more flexible freedom degree and power scaling potential. In this paper, research achievements in SOF generation based on array beams are arranged and discussed in detail. Moreover, experiment of generating exotic beam by array beams is introduced, which illustrates that SOF generated from array beams is theoretically valid and experimentally feasible. SOF generated from array beams is also beneficial for capacity increasing and data receiving for free-space optical communication systems at long distance.

Propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere

NASA Astrophysics Data System (ADS)

Zhao, Chengliang; Cai, Yangjian

2011-05-01

Based on the generalized Huygens-Fresnel integral, propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere was investigated. Analytical propagation formulae were derived for the cross-spectral densities of partially coherent Lorentz and Lorentz-Gauss beams. As an application example, the focusing properties of partially coherent Gaussian, Lorentz and Lorentz-Gauss beams in a turbulent atmosphere and in free space were studied numerically and comparatively. It is found that the focusing properties of such beams are closely related to the initial coherence length and the structure constant of turbulence. By choosing a suitable initial coherence length, a partially coherent Lorentz beam can be focused more tightly than a Gaussian or Lorentz-Gauss beam in free space or in a turbulent atmosphere with small structure constant at the geometrical focal plane.

Beam-folding ultraviolet-visible Fourier transform spectrometry and underwater cytometry for in situ measurement of marine phytoplankton

NASA Astrophysics Data System (ADS)

Wang, Xuzhu

The system complexity and hence high cost needed for generating the high-resolution and precise position-sampling triggers over very long distances is one of main hindrances to the popularization of the UV-visible Fourier transform spectrometer (FTS). In part one of this thesis, the specially designed beam-folding and improved beam-folding methods to optically subdivide the laser fringes are presented. The Near-UV to Near-infrared FTSs based on 4-fold beam-folding systems were developed. The experimental results have demonstrated that these techniques are promising methods to produce the high-resolution and high-precision sampling triggers of scanning mechanism of UV-visible FTSs without the need for complicated optics, sophisticated detector electronics and high-stability motion control systems. The FTS based on the beam-folding technique can reach a spectral resolution of ˜4 cm-1 (0.1nm) in the visible wavelengths; The FTS based on the improved beam-folding technique can achieve a spectral resolution of ˜0.28 cm-1 (0.01nm) in the visible wavelengths. In the improved beam-folding FTS, The adoption of retroreflectors and the symmetrical arrangement of two back-to back interferometers produced much higher performance than that of the beam-folding FTS employing prism mirrors. The replacement of prism mirrors by retroreflectors and the symmetrical optical arrangement maintain the FTS in perfect optical alignment during scanning process by keeping all beams parallel with the incident beams. The vertex of the movable retroreflector in the measurement interferometer is arranged very close to the midpoint of the vertices of the movable retroreflectors in the tracking interferometer so that the optical symmetrical axes for both interferometers always keep in line with each other. That is, the change of the OPD of the tracking interferometer always remains synchronous to that of the OPD of the measurement interferometer even for any moving misalignments, making the FTS itself insensitive to these fluctuations. In addition, an attempt on fast-scanning visible IFTS based on the improved beam-folding technique was done. Preliminary experimental results demonstrated the feasibility of the fast-scanning visible IFTS based on the improved beam-folding technique. In part two, an underwater cytometer for in situ measurement of marine phytoplankton using a combining technique of laser-induced fluorescence (LIF) and laser differential Doppler velocimetry (LDDV) was developed. The advancement compared to the previous work done in the laboratory is to realize an in situ underwater measurement system by means of improving the optical design. The experimental results in June and August 2004 in the coastal area of Hong Kong demonstrated that the new cytometer can be used for in situ measurement of marine phytoplankton. The mean concentration detected by this instrument agreed closely with the experimental data measured by the traditional cell counting under a microscope. With an underwater optical sensing unit that does not rely on an electrical power source, the sensing unit can stay submerged underwater for long periods, making a long-term real-time monitoring system possible.

Simultaneous phase-shifting interferometry study based on the common-path Fizeau interferometer

NASA Astrophysics Data System (ADS)

Liu, Feng-wei; Wu, Yong-qian

2014-09-01

A simultaneous phase-shifting interferometry(SPSI) based on the common-path Fizeau interferometer has been discussed.In this system,two orthogonal polarized beams, using as the reference beam and test beam ,are detached by a particular Wollaston prism at a very small angle,then four equal sub-beams are achieved by a combination of three non-polarizing beam splitters(NPBS),and the phase shifts are introduced by four polarizers whose polarization azimuths are 0°, 45°, 90°, 135° with the horizontal direction respectively,the four phase shift interferograms are collected simultaneously by controlling the CCDs working at the same time .The SPSI principle is studied at first,then is the error analysis, finally we emulate the process of surface recovery by four steps phase shifts algorithm,the results indicate that, to ensure the feasibility of the SPSI system, we have to control the polarization azimuth error of the polarizer in +/- 0.5°.

Scintillating fiber-based photon beam profiler for the Jefferson Lab tagged photon beam line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zorn, C.; Barbosa, F.J.; Freyberger, A.

2000-10-01

A scintillating fiber hodoscope has been built for use as a photon beam profiler in the bremsstrahlung tagged photon beam in Hall B of the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The device consists of a linear array of 64 2-2 mm2 scintillating fibers glued to a corresponding set of light guide fibers. Both fiber types use double-clad technology for maximum intensity. The light guide fibers are gently bent into a square array of holes and air-gap coupled to four compact position-sensitive photomultipliers (16 channel Hamamatsu R5900-M16). Custom electronics amplifies and converts the analog outputs to ECL pulses whichmore » are counted by VME-based scalars. The device consisting of the fibers, photomultipliers, and electronics is sealed within a light-tight aluminum box. Two modules make up a beam imaging 2-D system. The system has been tested successfully during an experimental run« less

Laser beam riding guided system principle and design research

NASA Astrophysics Data System (ADS)

Qu, Zhou; Jin, Yi; Xu, Zhou; Xing, Hao

2016-01-01

With the development of science and technology, precision-strike weapons has been considered to be important for winning victory in military field. Laser guidance is a major method to execute precision-strike in modern warfare. At present, the problems of primary stage of Laser guidance has been solved with endeavors of countries. Several technical aspects of laser-beam riding guided system have been mature, such as atmosphere penetration of laser beam, clutter inhibition on ground, laser irradiator, encoding and decoding of laser beam. Further, laser beam quality, equal output power and atmospheric transmission properties are qualified for warfare situation. Riding guidance instrument is a crucial element of Laser-beam riding guided system, and is also a vital element of airborne, vehicle-mounted and individual weapon. The optical system mainly consist of sighting module and laser-beam guided module. Photoelectric detector is the most important sensing device of seeker, and also the key to acquire the coordinate information of target space. Currently, in consideration of the 1.06 u m of wavelength applied in all the semi-active laser guided weapons systems, lithium drifting silicon photodiode which is sensitive to 1.06 u m of wavelength is used in photoelectric detector. Compared to Solid and gas laser, diode laser has many merits such as small volume, simple construction, light weight, long life, low lost and easy modulation. This article introduced the composition and operating principle of Laser-beam riding guided system based on 980 nm diode laser, and made a analysis of key technology; for instance, laser irradiator, modulating disk of component, laser zooming system. Through the use of laser diode, Laser-beam riding guided system is likely to have smaller shape and very light.

Dual-view-zone tabletop 3D display system based on integral imaging.

PubMed

He, Min-Yang; Zhang, Han-Le; Deng, Huan; Li, Xiao-Wei; Li, Da-Hai; Wang, Qiong-Hua

2018-02-01

In this paper, we propose a dual-view-zone tabletop 3D display system based on integral imaging by using a multiplexed holographic optical element (MHOE) that has the optical properties of two sets of microlens arrays. The MHOE is recorded by a reference beam using the single-exposure method. The reference beam records the wavefronts of a microlens array from two different directions. Thus, when the display beam is projected on the MHOE, two wavefronts with the different directions will be rebuilt and the 3D virtual images can be reconstructed in two viewing zones. The MHOE has angle and wavelength selectivity. Under the conditions of the matched wavelength and the angle of the display beam, the diffraction efficiency of the MHOE is greatest. Because the unmatched light just passes through the MHOE, the MHOE has the advantage of a see-through display. The experimental results confirm the feasibility of the dual-view-zone tabletop 3D display system.

3D algebraic iterative reconstruction for cone-beam x-ray differential phase-contrast computed tomography.

PubMed

Fu, Jian; Hu, Xinhua; Velroyen, Astrid; Bech, Martin; Jiang, Ming; Pfeiffer, Franz

2015-01-01

Due to the potential of compact imaging systems with magnified spatial resolution and contrast, cone-beam x-ray differential phase-contrast computed tomography (DPC-CT) has attracted significant interest. The current proposed FDK reconstruction algorithm with the Hilbert imaginary filter will induce severe cone-beam artifacts when the cone-beam angle becomes large. In this paper, we propose an algebraic iterative reconstruction (AIR) method for cone-beam DPC-CT and report its experiment results. This approach considers the reconstruction process as the optimization of a discrete representation of the object function to satisfy a system of equations that describes the cone-beam DPC-CT imaging modality. Unlike the conventional iterative algorithms for absorption-based CT, it involves the derivative operation to the forward projections of the reconstructed intermediate image to take into account the differential nature of the DPC projections. This method is based on the algebraic reconstruction technique, reconstructs the image ray by ray, and is expected to provide better derivative estimates in iterations. This work comprises a numerical study of the algorithm and its experimental verification using a dataset measured with a three-grating interferometer and a mini-focus x-ray tube source. It is shown that the proposed method can reduce the cone-beam artifacts and performs better than FDK under large cone-beam angles. This algorithm is of interest for future cone-beam DPC-CT applications.

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center

PubMed Central

Chung, Kwangzoo; Kim, Jinsung; Ahn, Sung Hwan; Ju, Sang Gyu; Jung, Sang Hoon; Chung, Yoonsun; Cho, Sungkoo; Jo, Kwanghyun; Shin, Eun Hyuk; Hong, Chae-Seon; Shin, Jung Suk; Park, Seyjoon; Kim, Dae-Hyun; Kim, Hye Young; Lee, Boram; Shibagaki, Gantaro; Nonaka, Hideki; Sasai, Kenzo; Koyabu, Yukio; Choi, Changhoon; Huh, Seung Jae; Ahn, Yong Chan; Pyo, Hong Ryull; Lim, Do Hoon; Park, Hee Chul; Park, Won; Oh, Dong Ryul; Noh, Jae Myung; Yu, Jeong Il; Song, Sanghyuk; Lee, Ji Eun; Lee, Bomi; Choi, Doo Ho

2015-01-01

Purpose The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. Materials and Methods The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. Results The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. Conclusion The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015. PMID:26756034

Neutron beam optimization based on a 7Li(p,n)7Be reaction for treatment of deep-seated brain tumors by BNCT

NASA Astrophysics Data System (ADS)

Zahra Ahmadi, Ganjeh; S. Farhad, Masoudi

2014-10-01

Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy (BNCT) is investigated using a 7Li(p,n)7Be reaction. Design and optimization have been carried out for the target, cooling system, moderator, filter, reflector, and collimator to achieve a high flux of epithermal neutron and satisfy the IAEA criteria. Also, the performance of the designed beam in tissue is assessed by using a simulated Snyder head phantom. The results show that the optimization of the collimator and reflector is critical to finding the best neutron beam based on the 7Li(p,n)7Be reaction. Our designed beam has 2.49×109n/cm2s epithermal neutron flux and is suitable for BNCT of deep-seated brain tumors.

Influence of foundation mass and surface roughness on dynamic response of beam on dynamic foundation subjected to the moving load

NASA Astrophysics Data System (ADS)

Tran Quoc, Tinh; Khong Trong, Toan; Luong Van, Hai

2018-04-01

In this paper, Improved Moving Element Method (IMEM) is used to analyze the dynamic response of Euler-Bernoulli beam structures on the dynamic foundation model subjected to the moving load. The effects of characteristic foundation model parameters such as Winkler stiffness, shear layer based on the Pasternak model, viscoelastic dashpot and characteristic parameter of mass on foundation. Beams are modeled by moving elements while the load is fixed. Based on the principle of the publicly virtual balancing and the theory of moving element method, the motion differential equation of the system is established and solved by means of the numerical integration based on the Newmark algorithm. The influence of mass on foundation and the roughness of the beam surface on the dynamic response of beam are examined in details.

Studies on the S-band bunching system with the Hybrid Bunching-accelerating Structure

NASA Astrophysics Data System (ADS)

Pei, Shi-Lun; Gao, Bin

2018-04-01

Generally, a standard bunching system is composed of a standing-wave (SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure. In the industrial area, the bunching system is usually simplified by eliminating the PB and integrating the B and the standard accelerating structure together to form a β-varied accelerating structure. The beam capturing efficiency for this kind of simplified system is often worse than that for the standard one. The hybrid buncher (HB) has been proved to be a successful attempt to reduce the cost but preserve the beam quality as much as possible. Here we propose to exclusively simplify the standard bunching system by integrating the PB, the B and the standard accelerating structure together to form a Hybrid Bunching-accelerating Structure (HBaS). Compared to the standard bunching system, the one based on the HBaS is more compact, and the cost is lowered to the largest extent. With almost the same beam transportation efficiency (∼70%) from the electron gun to the linac exit, the peak-to-peak (p-to-p) beam energy spread and the 1 σ emittance of the linac with the HBaS are ∼20% and ∼60% bigger than those of the linac based on the split PB/B/standard accelerating structure system. Nonetheless, the proposed HBaS can be widely applied in the industrial linacs to greatly increase the beam capturing efficiency without fairly increasing the construction cost.

Telescope-based cavity for negative ion beam neutralization in future fusion reactors.

PubMed

Fiorucci, Donatella; Hreibi, Ali; Chaibi, Walid

2018-03-01

In future fusion reactors, heating system efficiency is of the utmost importance. Photo-neutralization substantially increases the neutral beam injector (NBI) efficiency with respect to the foreseen system in the International Thermonuclear Experimental Reactor (ITER) based on a gaseous target. In this paper, we propose a telescope-based configuration to be used in the NBI photo-neutralizer cavity of the demonstration power plant (DEMO) project. This configuration greatly reduces the total length of the cavity, which likely solves overcrowding issues in a fusion reactor environment. Brought to a tabletop experiment, this cavity configuration is tested: a 4 mm beam width is obtained within a ≃1.5  m length cavity. The equivalent cavity g factor is measured to be 0.038(3), thus confirming the cavity stability.

Overview of laser systems for the Orion facility at the AWE.

PubMed

Hopps, Nicholas; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hillier, David; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

2013-05-20

The commissioning of the Orion laser facility at the Atomic Weapons Establishment (AWE) in the UK has recently been completed. The facility is a twelve beam Nd:glass-based system for studying high energy density physics. It consists of ten frequency-tripled beam-lines operating with nanosecond pulses, synchronized with two beam-lines with subpicosecond pulses, each capable of delivering 500 J to target. One of the short pulse beams has the option of frequency doubling, at reduced aperture, to yield up to 100 J at 527 nm in a subpicosecond pulse with high temporal contrast. An extensive array of target diagnostics is provided. This article describes the laser design and commissioning and presents key performance data of the facility's laser systems.

CA resist with high sensitivity and sub-100-nm resolution for advanced mask and device making

NASA Astrophysics Data System (ADS)

Kwong, Ranee W.; Huang, Wu-Song; Hartley, John G.; Moreau, Wayne M.; Robinson, Christopher F.; Angelopoulos, Marie; Magg, Christopher; Lawliss, Mark

2000-07-01

Recently, there is significant interest in using CA resists for electron beam (E-Beam) applications including mask making, direct write, and projection printing. CA resists provide superior lithographic performance in comparison to traditional non CA E-beam resists in particular high contrast, resolution, and sensitivity. However, most of the commercially available CA resists have the concern of airborne base contaminants and sensitivity to PAB and/or PEB temperatures. In this presentation, we will discuss a new improved ketal resist system referred to as KRS-XE which exhibits excellent lithography, is robust toward airborne base, compatible with 0.263 N TMAH aqueous developer and exhibits a large PAB/PEB latitude. With the combination of a high performance mask making E-beam exposure tool, high kV (75 kV) shaped beam system EL4+ and the KRS-XE resist, we have printed 75 nm lines/space features with excellent profile control at a dose of 13 (mu) C/cm2 at 75 kV. The shaped beam vector scan system used here provides an unique property in resolving small features in lithography and throughput. Overhead in EL4+ limits the systems ability to fully exploit the sensitivity of the new resist for throughput. The EL5 system, currently in the build phase, has sufficiently low overhead that it is projected to print a 4X, 16G, DRAM mask with OPC in under 3 hours with the CA resist. We will discuss the throughput advantages of the next generation EL5 system over the existing EL4+. In addition we will show the resolution of KRS-XE down to 70 nm using the PREVAIL projection printing system.

Generation of three-dimensional optical cusp beams with ultrathin metasurfaces.

PubMed

Liu, Weiwei; Zhang, Yuchao; Gao, Jie; Yang, Xiaodong

2018-06-22

Cusp beams are one type of complex structured beams with unique multiple self-accelerating channels and needle-like field structures owning great potentials to advance applications such as particle micromanipulation and super-resolution imaging. The traditional method to generate optical catastrophe is based on cumbrous reflective diffraction optical elements, which makes optical system complicated and hinders the nanophotonics integration. Here we design geometric phase based ultrathin plasmonic metasurfaces made of nanoslit antennas to produce three-dimensional (3D) optical cusp beams with variable numbers of self-accelerating channels in a broadband wavelength range. The entire beam propagation profiles of the cusp beams generated from the metasurfaces are mapped theoretically and experimentally. The special self-accelerating behavior and caustics concentration property of the cups beams are also demonstrated. Our results provide great potentials for promoting metasurface-enabled compact photonic devices used in wide applications of light-matter interactions.

Automated beam monitoring and diagnosis for CO2 lasers

NASA Astrophysics Data System (ADS)

Mann, Stefan; Boeske, Lars; Kaierle, Stefan; Kreutz, Ernst-Wolfgang; Poprawe, Reinhart

2002-06-01

The usage of a quality management, in combination with a standard certification, is nearly inevitable for today's industrial manufacturing. In laser materials processing, a periodical beam diagnosis is to be executed as a quality-maintaining measure with any change of the workpiece geometry to guarantee an unambiguous allocation of the beam quality factors. Otherwise changes in the beam quality, caused by pollution, aging or defect of the optical components, remain unidentified for a long time, leading to impairments of the treatment quality or even costly down-times. As a solution a diagnosis system is integrated into a laser system. Data sources like measuring instruments, sensors and laser control transmit the diagnosis data to a diagnosis PC. A user-friendly software, based on Fuzzy algorithms, enables the operator to retrace changes in the beam quality to failures of the laser system. All diagnosis data are getting archived in a databank. The access to the archived data through the World Wide Web allows remote diagnoses. With the help of the beam diagnosis system failures can be discovered in advance, and losses of production can be avoided. The gained transparency of the beam characteristic values facilitates the integration of the laser system in the quality management. A prototype installation has been realized and latest results will be demonstrated.

Tunable Q-Factor RF Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balcazar, Mario D.; Yonehara, Katsuya; Moretti, Alfred

Intense neutrino beam is a unique probe for researching beyond the standard model. Fermilab is the main institution to produce the most powerful and widespectrum neutrino beam. From that respective, a radiation robust beam diagnostic system is a critical element in order to maintain the quality of the neutrino beam. Within this context, a novel radiation-resistive beam profile monitor based on a gasfilled RF cavity is proposed. The goal of this measurement is to study a tunable Qfactor RF cavity to determine the accuracy of the RF signal as a function of the quality factor. Specifically, measurement error of themore » Q-factor in the RF calibration is investigated. Then, the RF system will be improved to minimize signal error.« less

Beam-based compensation of extracted-beam displacement caused by field ringing of pulsed kicker magnets in the 3 GeV rapid cycling synchrotron of the Japan Proton Accelerator Research Complex

NASA Astrophysics Data System (ADS)

Harada, Hiroyuki; Saha, Pranab Kumar; Tamura, Fumihiko; Meigo, Shin-ichiro; Hotchi, Hideaki; Hayashi, Naoki; Kinsho, Michikazu; Hasegawa, Kazuo

2017-09-01

Commissioned in October 2007, the 3 GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex was designed for a high-intensity output beam power of 1 MW. The RCS extracts 3 GeV proton beams of two bunches by using eight pulsed kicker magnets and three DC septum magnets with 25 Hz repetition. These beams are delivered to a materials and life science experimental facility (MLF) and a 50 GeV main ring synchrotron (MR). However, the flat-top fields of the kicker magnets experience ringing that displaces the position of the extracted beam. This displacement is a major issue from the viewpoint of target integrity at the MLF and emittance growth at MR injection. To understand the flat-top uniformity of the total field of all the kickers, the uniformity was measured as the displacement of the extracted beams by using a shorter bunched beam and scanning the entire trigger timing of the kickers. The beam displacement of the first bunch exceeded the required range. Therefore, we performed beam-based measurements kicker by kicker to understand each field-ringing effect, and then we understood the characteristics (strength and temporal structure) of each ringing field. We managed to cancel out the ringing by using all the beam-based measurement data and optimizing each trigger timing. As a result, the field-ringing effect of the kickers was successfully compensated by optimizing the trigger timing of each kicker without hardware upgrades or improvements to the kicker system. By developing an automatic monitoring and correction system, we now have a higher stability of extracted beams during routine user operation. In this paper, we report our procedure for ringing compensation and present supporting experimental results.

High removal rate laser-based coating removal system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, D.L.; Celliers, P.M.; Hackel, L.

1999-11-16

A compact laser system is disclosed that removes surface coatings (such as paint, dirt, etc.) at a removal rate as high as 1,000 ft{sup 2}/hr or more without damaging the surface. A high repetition rate laser with multiple amplification passes propagating through at least one optical amplifier is used, along with a delivery system consisting of a telescoping and articulating tube which also contains an evacuation system for simultaneously sweeping up the debris produced in the process. The amplified beam can be converted to an output beam by passively switching the polarization of at least one amplified beam. The systemmore » also has a personal safety system which protects against accidental exposures.« less

Hybrid diagnostic system: beacon-based exception analysis for multimissions - Livingstone integration

NASA Technical Reports Server (NTRS)

Park, Han G.; Cannon, Howard; Bajwa, Anupa; Mackey, Ryan; James, Mark; Maul, William

2004-01-01

This paper describes the initial integration of a hybrid reasoning system utilizing a continuous domain feature-based detector, Beacon-based Exceptions Analysis for Multimissions (BEAM), and a discrete domain model-based reasoner, Livingstone.

High power diode laser Master Oscillator-Power Amplifier (MOPA)

NASA Technical Reports Server (NTRS)

Andrews, John R.; Mouroulis, P.; Wicks, G.

1994-01-01

High power multiple quantum well AlGaAs diode laser master oscillator - power amplifier (MOPA) systems were examined both experimentally and theoretically. For two pass operation, it was found that powers in excess of 0.3 W per 100 micrometers of facet length were achievable while maintaining diffraction-limited beam quality. Internal electrical-to-optical conversion efficiencies as high as 25 percent were observed at an internal amplifier gain of 9 dB. Theoretical modeling of multiple quantum well amplifiers was done using appropriate rate equations and a heuristic model of the carrier density dependent gain. The model gave a qualitative agreement with the experimental results. In addition, the model allowed exploration of a wider design space for the amplifiers. The model predicted that internal electrical-to-optical conversion efficiencies in excess of 50 percent should be achievable with careful system design. The model predicted that no global optimum design exists, but gain, efficiency, and optical confinement (coupling efficiency) can be mutually adjusted to meet a specific system requirement. A three quantum well, low optical confinement amplifier was fabricated using molecular beam epitaxial growth. Coherent beam combining of two high power amplifiers injected from a common master oscillator was also examined. Coherent beam combining with an efficiency of 93 percent resulted in a single beam having diffraction-limited characteristics. This beam combining efficiency is a world record result for such a system. Interferometric observations of the output of the amplifier indicated that spatial mode matching was a significant factor in the less than perfect beam combining. Finally, the system issues of arrays of amplifiers in a coherent beam combining system were investigated. Based upon experimentally observed parameters coherent beam combining could result in a megawatt-scale coherent beam with a 10 percent electrical-to-optical conversion efficiency.

An accelerator-based neutron microbeam system for studies of radiation effects

PubMed Central

Xu, Yanping; Randers-Pehrson, Gerhard; Marino, Stephen A.; Bigelow, Alan W.; Akselrod, Mark S.; Sykora, Jeff G.; Brenner, David J.

2011-01-01

A novel neutron microbeam is being developed at the Radiological Research Accelerator Facility (RARAF) of Columbia University. The RARAF microbeam facility has been used for studies of radiation bystander effects in mammalian cells for many years. Now a prototype neutron microbeam is being developed that can be used for bystander effect studies. The neutron microbeam design here is based on the existing charged particle microbeam technology at the RARAF. The principle of the neutron microbeam is to use the proton beam with a micrometre-sized diameter impinging on a very thin lithium fluoride target system. From the kinematics of the 7Li(p,n)7Be reaction near the threshold of 1.881 MeV, the neutron beam is confined within a narrow, forward solid angle. Calculations show that the neutron spot using a target with a 17-µm thick gold backing foil will be <20 µm in diameter for cells attached to a 3.8-µm thick propylene-bottomed cell dish in contact with the target backing. The neutron flux will roughly be 2000 per second based on the current beam setup at the RARAF singleton accelerator. The dose rate will be about 200 mGy min−1. The principle of this neutron microbeam system has been preliminarily tested at the RARAF using a collimated proton beam. The imaging of the neutron beam was performed using novel fluorescent nuclear track detector technology based on Mg-doped luminescent aluminum oxide single crystals and confocal laser scanning fluorescent microscopy. PMID:21131327

Polarized muon beams for muon collider

NASA Astrophysics Data System (ADS)

Skrinsky, A. N.

1996-11-01

An option for the production of intense and highly polarized muon beams, suitable for a high-luminosity muon collider, is described briefly. It is based on a multi-channel pion-collection system, narrow-band pion-to-muon decay channels, proper muon spin gymnastics, and ionization cooling to combine all of the muon beams into a single bunch of ultimately low emittance.

Booster-to-AGS Multiwires and an Evolution of the Application Profile Display

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahrens,L.

2008-07-01

Follow up on BtA multiwire beam measurements taken during the 2008 polarized proton run has led to a number of better understandings (for the author) associated with the beam instrumentation involved. This history will be reviewed--some 'beam-based' results noted--and the present state of the application for these monitors described. The BtA multiwire system seems to be fundamentally an excellent diagnostic for allowing us to get the BtA line well under control in a defendable way. When beam is available in BtA, carrying out some systematic measurements with the system can get us there.

An optical system to transform the output beam of a quantum cascade laser to be uniform

NASA Astrophysics Data System (ADS)

Jacobson, Jordan M.

Quantum cascade lasers (QCLs) are a candidate for calibration sources in space-based remote sensing applications. However, the output beam from a QCL has some characteris- tics that are undesirable in a calibration source. The output beam from a QCL is polarized, both temporally and spatially coherent, and has a non-uniform bivariate Gaussian prole. These characteristics need to be mitigated before QCLs can be used as calibration sources. This study presents the design and implementation of an optical system that manipulates the output beam from a QCL so that it is spatially and angularly uniform with reduced coherence and polarization. (85 pages).

Note: Design of transverse electron gun for electron beam based reactive evaporation system.

PubMed

Maiti, Namita; Barve, U D; Bhatia, M S; Das, A K

2011-05-01

In this paper design of a 10 kV, 10 kW transverse electron gun, suitable for reactive evaporation, supported by simulation and modeling, is presented. Simulation of the electron beam trajectory helps in locating the emergence aperture after 90° bend and also in designing the crucible on which the beam is finally incident after 270° bend. The dimension of emergence aperture plays a vital role in designing the differential pumping system between the gun chamber and the substrate chamber. Experimental validation is done for beam trajectory by piercing a stainless steel plate at 90° position which is kept above the crucible.

Dosimetric characteristics of electron beams produced by a mobile accelerator for IORT.

PubMed

Pimpinella, M; Mihailescu, D; Guerra, A S; Laitano, R F

2007-10-21

Energy and angular distributions of electron beams with different energies were simulated by Monte Carlo calculations. These beams were generated by the NOVAC7 system (Hitesys, Italy), a mobile electron accelerator specifically dedicated to intra-operative radiation therapy (IORT). The electron beam simulations were verified by comparing the measured dose distributions with the corresponding calculated distributions. As expected, a considerable difference was observed in the energy and angular distributions between the IORT beams studied in the present work and the electron beams produced by conventional accelerators for non-IORT applications. It was also found that significant differences exist between the IORT beams used in this work and other IORT beams with different collimation systems. For example, the contribution from the scattered electrons to the total dose was found to be up to 15% higher in the NOVAC7 beams. The water-to-air stopping power ratios of the IORT beams used in this work were calculated on the basis of the beam energy distributions obtained by the Monte Carlo simulations. These calculated stopping power ratios, s(w,air), were compared with the corresponding s(w,air) values recommended by the TRS-381 and TRS-398 IAEA dosimetry protocols in order to estimate the deviations between a dosimetry based on generic parameters and a dosimetry based on parameters specifically obtained for the actual IORT beams. The deviations in the s(w,air) values were found to be as large as up to about 1%. Therefore, we recommend that a preliminary analysis should always be made when dealing with IORT beams in order to assess to what extent the possible differences in the s(w,air) values have to be accounted for or may be neglected on the basis of the specific accuracy needed in clinical dosimetry.

Analysis of de-noising methods to improve the precision of the ILSF BPM electronic readout system

NASA Astrophysics Data System (ADS)

Shafiee, M.; Feghhi, S. A. H.; Rahighi, J.

2016-12-01

In order to have optimum operation and precise control system at particle accelerators, it is required to measure the beam position with the precision of sub-μm. We developed a BPM electronic readout system at Iranian Light Source Facility and it has been experimentally tested at ALBA accelerator facility. The results show the precision of 0.54 μm in beam position measurements. To improve the precision of this beam position monitoring system to sub-μm level, we have studied different de-noising methods such as principal component analysis, wavelet transforms, filtering by FIR, and direct averaging method. An evaluation of the noise reduction was given to testify the ability of these methods. The results show that the noise reduction based on Daubechies wavelet transform is better than other algorithms, and the method is suitable for signal noise reduction in beam position monitoring system.

Focus detection by shearing interference of vortex beams for non-imaging systems.

PubMed

Li, Xiongfeng; Zhan, Shichao; Liang, Yiyong

2018-02-10

In focus detection of non-imaging systems, the common image-based methods are not available. Also, interference techniques are seldom used because only the degree with hardly any direction of defocus can be derived from the fringe spacing. In this paper, we propose a vortex-beam-based shearing interference system to do focus detection for a focused laser direct-writing system, where a vortex beam is already involved. Both simulated and experimental results show that fork-like features are added in the interference patterns due to the existence of an optical vortex, which makes it possible to distinguish the degree and direction of defocus simultaneously. The theoretical fringe spacing and resolution of this method are derived. A resolution of 0.79 μm can be achieved under the experimental combination of parameters, and it can be further improved with the help of the image processing algorithm and closed-loop controlling in the future. Finally, the influence of incomplete collimation and the wedge angle of the shear plate is discussed. This focus detection approach is extremely appropriate for those non-imaging systems containing one or more focused vortex beams.

Compensation of orbit distortion due to quadrupole motion using feed-forward control at KEK ATF

NASA Astrophysics Data System (ADS)

Bett, D. R.; Charrondière, C.; Patecki, M.; Pfingstner, J.; Schulte, D.; Tomás, R.; Jeremie, A.; Kubo, K.; Kuroda, S.; Naito, T.; Okugi, T.; Tauchi, T.; Terunuma, N.; Burrows, P. N.; Christian, G. B.; Perry, C.

2018-07-01

The high luminosity requirement for a future linear collider sets a demanding limit on the beam quality at the Interaction Point (IP). One potential source of luminosity loss is the motion of the ground itself. The resulting misalignments of the quadrupole magnets cause distortions to the beam orbit and hence an increase in the beam emittance. This paper describes a technique for compensating this orbit distortion by using seismometers to monitor the misalignment of the quadrupole magnets in real-time. The first demonstration of the technique was achieved at the Accelerator Test Facility (ATF) at KEK in Japan. The feed-forward system consisted of a seismometer-based quadrupole motion monitoring system, an FPGA-based feed-forward processor and a stripline kicker plus associated electronics. Through the application of a kick calculated from the position of a single quadruple, the system was able to remove about 80% of the component of the beam jitter that was correlated to the motion of the quadrupole. As a significant fraction of the orbit jitter in the ATF final focus is due to sources other than quadrupole misalignment, this amounted to an approximately 15% reduction in the absolute beam jitter.

Surface profiling interferometer

DOEpatents

Takacs, Peter Z.; Qian, Shi-Nan

1989-01-01

The design of a long-trace surface profiler for the non-contact measurement of surface profile, slope error and curvature on cylindrical synchrotron radiation (SR) mirrors. The optical system is based upon the concept of a pencil-beam interferometer with an inherent large depth-of-field. The key feature of the optical system is the zero-path-difference beam splitter, which separates the laser beam into two colinear, variable-separation probe beams. A linear array detector is used to record the interference fringe in the image, and analysis of the fringe location as a function of scan position allows one to reconstruct the surface profile. The optical head is mounted on an air bearing slide with the capability to measure long aspheric optics, typical of those encountered in SR applications. A novel feature of the optical system is the use of a transverse "outrigger" beam which provides information on the relative alignment of the scan axis to the cylinder optic symmetry axis.

Creating an EPICS Based Test Stand Development System for a BPM Digitizer of the Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2011-06-22

The Linac Coherent Light Source (LCLS) is required to deliver a high quality electron beam for producing coherent X-rays. As a result, high resolution beam position monitoring is required. The Beam Position Monitor (BPM) digitizer acquires analog signals from the beam line and digitizes them to obtain beam position data. Although Matlab is currently being used to test the BPM digitizer?s functions and capability, the Controls Department at SLAC prefers to use Experimental Physics and Industrial Control Systems (EPICS). This paper discusses the transition of providing similar as well as enhanced functionalities, than those offered by Matlab, to test themore » digitizer. Altogether, the improved test stand development system can perform mathematical and statistical calculations with the waveform signals acquired from the digitizer and compute the fast Fourier transform (FFT) of the signals. Finally, logging of meaningful data into files has been added.« less

Development of a negative ion-based neutral beam injector in Novosibirsk.

PubMed

Ivanov, A A; Abdrashitov, G F; Anashin, V V; Belchenko, Yu I; Burdakov, A V; Davydenko, V I; Deichuli, P P; Dimov, G I; Dranichnikov, A N; Kapitonov, V A; Kolmogorov, V V; Kondakov, A A; Sanin, A L; Shikhovtsev, I V; Stupishin, N V; Sorokin, A V; Popov, S S; Tiunov, M A; Belov, V P; Gorbovsky, A I; Kobets, V V; Binderbauer, M; Putvinski, S; Smirnov, A; Sevier, L

2014-02-01

A 1000 keV, 5 MW, 1000 s neutral beam injector based on negative ions is being developed in the Budker Institute of Nuclear Physics, Novosibirsk in collaboration with Tri Alpha Energy, Inc. The innovative design of the injector features the spatially separated ion source and an electrostatic accelerator. Plasma or photon neutralizer and energy recuperation of the remaining ion species is employed in the injector to provide an overall energy efficiency of the system as high as 80%. A test stand for the beam acceleration is now under construction. A prototype of the negative ion beam source has been fabricated and installed at the test stand. The prototype ion source is designed to produce 120 keV, 1.5 A beam.

Studies on a Q/A selector for the SECRAL electron cyclotron resonance ion source.

PubMed

Yang, Y; Sun, L T; Feng, Y C; Fang, X; Lu, W; Zhang, W H; Cao, Y; Zhang, X Z; Zhao, H W

2014-08-01

Electron cyclotron resonance ion sources are widely used in heavy ion accelerators in the world because they are capable of producing high current beams of highly charged ions. However, the design of the Q/A selector system for these devices is challenging, because it must have a sufficient ion resolution while controlling the beam emittance growth. Moreover, this system has to be matched for a wide range of ion beam species with different intensities. In this paper, research on the Q/A selector system at the SECRAL (Superconducting Electron Cyclotron Resonance ion source with Advanced design in Lanzhou) platform both in experiment and simulation is presented. Based on this study, a new Q/A selector system has been designed for SECRAL II. The features of the new design including beam simulations are also presented.

Cyclotron-based neutron source for BNCT

NASA Astrophysics Data System (ADS)

Mitsumoto, T.; Yajima, S.; Tsutsui, H.; Ogasawara, T.; Fujita, K.; Tanaka, H.; Sakurai, Y.; Maruhashi, A.

2013-04-01

Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation & treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutron collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8×109 neutrons/cm2/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with 10B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.

Cyclotron-based neutron source for BNCT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitsumoto, T.; Yajima, S.; Tsutsui, H.

2013-04-19

Kyoto University Research Reactor Institute (KURRI) and Sumitomo Heavy Industries, Ltd. (SHI) have developed a cyclotron-based neutron source for Boron Neutron Capture Therapy (BNCT). It was installed at KURRI in Osaka prefecture. The neutron source consists of a proton cyclotron named HM-30, a beam transport system and an irradiation and treatment system. In the cyclotron, H- ions are accelerated and extracted as 30 MeV proton beams of 1 mA. The proton beams is transported to the neutron production target made by a beryllium plate. Emitted neutrons are moderated by lead, iron, aluminum and calcium fluoride. The aperture diameter of neutronmore » collimator is in the range from 100 mm to 250 mm. The peak neutron flux in the water phantom is 1.8 Multiplication-Sign 109 neutrons/cm{sup 2}/sec at 20 mm from the surface at 1 mA proton beam. The neutron source have been stably operated for 3 years with 30 kW proton beam. Various pre-clinical tests including animal tests have been done by using the cyclotron-based neutron source with {sup 10}B-p-Borono-phenylalanine. Clinical trials of malignant brain tumors will be started in this year.« less

PRECISE ANGLE MONITOR BASED ON THE CONCEPT OF PENCIL-BEAM INTERFEROMETRY

DOE Office of Scientific and Technical Information (OSTI.GOV)

QIAN,S.; TAKACS,P.

2000-07-30

The precise angle monitoring is a very important metrology task for research, development and industrial applications. Autocollimator is one of the most powerful and widely applied instruments for small angle monitoring, which is based on the principle of geometric optics. In this paper the authors introduce a new precise angle monitoring system, Pencil-beam Angle Monitor (PAM), base on pencil beam interferometry. Its principle of operation is a combination of physical and geometrical optics. The angle calculation method is similar to the autocollimator. However, the autocollimator creates a cross image but the precise pencil-beam angle monitoring system produces an interference fringemore » on the focal plane. The advantages of the PAM are: high angular sensitivity, long-term stability character making angle monitoring over long time periods possible, high measurement accuracy in the order of sub-microradian, simultaneous measurement ability in two perpendicular directions or on two different objects, dynamic measurement possibility, insensitive to the vibration and air turbulence, automatic display, storage and analysis by use of the computer, small beam diameter making the alignment extremely easy and longer test distance. Some test examples are presented.« less

Control of Space-Based Electron Beam Free Form Fabrication

NASA Technical Reports Server (NTRS)

Seifzer. W. J.; Taminger, K. M.

2007-01-01

Engineering a closed-loop control system for an electron beam welder for space-based additive manufacturing is challenging. For earth and space based applications, components must work in a vacuum and optical components become occluded with metal vapor deposition. For extraterrestrial applications added components increase launch weight, increase complexity, and increase space flight certification efforts. Here we present a software tool that closely couples path planning and E-beam parameter controls into the build process to increase flexibility. In an environment where data collection hinders real-time control, another approach is considered that will still yield a high quality build.

Linear beam raster magnet driver based on H-bridge technique

DOEpatents

Sinkine, Nikolai I.; Yan, Chen; Apeldoorn, Cornelis; Dail, Jeffrey Glenn; Wojcik, Randolph Frank; Gunning, William

2006-06-06

An improved raster magnet driver for a linear particle beam is based on an H-bridge technique. Four branches of power HEXFETs form a two-by-two switch. Switching the HEXFETs in a predetermined order and at the right frequency produces a triangular current waveform. An H-bridge controller controls switching sequence and timing. The magnetic field of the coil follows the shape of the waveform and thus steers the beam using a triangular rather than a sinusoidal waveform. The system produces a raster pattern having a highly uniform raster density distribution, eliminates target heating from non-uniform raster density distributions, and produces higher levels of beam current.

A Performance-Based Training Qualification Guide/Checklist Developed for Reactor Operators at the High Flux Beam Reactor at Brookhaven National Laboratory.

ERIC Educational Resources Information Center

McNair, Robert C.

A Performance-Based Training (PBT) Qualification Guide/Checklist was developed that would enable a trainee to attain the skills, knowledge, and attitude required to operate the High Flux Beam Reactor at Brookhaven National Laboratory. Design of this guide/checklist was based on the Instructional System Design Model. The needs analysis identified…

Overview of ion source characterization diagnostics in INTF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bandyopadhyay, M., E-mail: mainak@iter-india.org; Sudhir, Dass; Bhuyan, M.

2016-02-15

INdian Test Facility (INTF) is envisaged to characterize ITER diagnostic neutral beam system and to establish the functionality of its eight inductively coupled RF plasma driver based negative hydrogen ion source and its beamline components. The beam quality mainly depends on the ion source performance and therefore, its diagnostics plays an important role for its safe and optimized operation. A number of diagnostics are planned in INTF to characterize the ion source performance. Negative ions and its cesium contents in the source will be monitored by optical emission spectroscopy (OES) and cavity ring down spectroscopy. Plasma near the extraction regionmore » will be studied using standard electrostatic probes. The beam divergence and negative ion stripping losses are planned to be measured using Doppler shift spectroscopy. During initial phase of ion beam characterization, carbon fiber composite based infrared imaging diagnostics will be used. Safe operation of the beam will be ensured by using standard thermocouples and electrical voltage-current measurement sensors. A novel concept, based on plasma density dependent plasma impedance measurement using RF electrical impedance matching parameters to characterize the RF driver plasma, will be tested in INTF and will be validated with OES data. The paper will discuss about the overview of the complete INTF diagnostics including its present status of procurement, experimentation, interface with mechanical systems in INTF, and integration with INTF data acquisition and control systems.« less

Overview of ion source characterization diagnostics in INTF

NASA Astrophysics Data System (ADS)

Bandyopadhyay, M.; Sudhir, Dass; Bhuyan, M.; Soni, J.; Tyagi, H.; Joshi, J.; Yadav, A.; Rotti, C.; Parmar, Deepak; Patel, H.; Pillai, S.; Chakraborty, A.

2016-02-01

INdian Test Facility (INTF) is envisaged to characterize ITER diagnostic neutral beam system and to establish the functionality of its eight inductively coupled RF plasma driver based negative hydrogen ion source and its beamline components. The beam quality mainly depends on the ion source performance and therefore, its diagnostics plays an important role for its safe and optimized operation. A number of diagnostics are planned in INTF to characterize the ion source performance. Negative ions and its cesium contents in the source will be monitored by optical emission spectroscopy (OES) and cavity ring down spectroscopy. Plasma near the extraction region will be studied using standard electrostatic probes. The beam divergence and negative ion stripping losses are planned to be measured using Doppler shift spectroscopy. During initial phase of ion beam characterization, carbon fiber composite based infrared imaging diagnostics will be used. Safe operation of the beam will be ensured by using standard thermocouples and electrical voltage-current measurement sensors. A novel concept, based on plasma density dependent plasma impedance measurement using RF electrical impedance matching parameters to characterize the RF driver plasma, will be tested in INTF and will be validated with OES data. The paper will discuss about the overview of the complete INTF diagnostics including its present status of procurement, experimentation, interface with mechanical systems in INTF, and integration with INTF data acquisition and control systems.

Optical phase conjugation: principles, techniques, and applications

NASA Astrophysics Data System (ADS)

He, Guang S.

2002-05-01

Over the last three decades, optical phase conjugation (OPC) has been one of the major research subjects in the field of nonlinear optics and quantum electronics. OPC defines usually a special relationship between two coherent optical beams propagating in opposite directions with reversed wave front and identical transverse amplitude distributions. The unique feature of a pair of phase-conjugate beams is that the aberration influence imposed on the forward beam passed through an inhomogeneous or disturbing medium can be automatically removed for the backward beam passed through the same disturbing medium. To date there have been three major technical approaches that can efficiently produce the backward phase-conjugate beam. The first approach is based on the degenerate (or partially degenerate) four-wave mixing processes, the second is based on various backward simulated (Brillouin, Raman, Rayleigh-wing or Kerr) scattering processes, and the third is based on one-photon or multi-photon pumped backward stimulated emission (lasing) processes. Among these three different approaches, there is a common physical mechanism that plays the same essential role in generating a backward phase-conjugate beam, which is the formation of the induced holographic grating and the subsequent wave-front restoration via a backward reading beam. In most experimental studies, certain types of resonance enhancements of induced refractive-index changes are desirable for obtaining higher grating-refraction efficiency. The momentum of OPC studies has recently become even stronger because there are more prospective potentials and achievements for applications. OPC-associated techniques can be successfully utilized in many different application areas: such as high-brightness laser oscillator/amplifier systems, cavity-less lasing devices, laser target-aiming systems, aberration correction for coherent-light transmission and reflection through disturbing media, long distance optical fiber communications with ultra-high bit-rate, optical phase locking and coupling systems, and novel optical data storage and processing systems.

Conceptual design of a space-based O2 laser for defense

NASA Astrophysics Data System (ADS)

Takehisa, K.

2016-10-01

A new concept of a space-based-laser (SBL) defense system is proposed. It is based on a chemical oxygen laser (COL) which has been investigated to achieve its oscillation 1-3). A COL is suitable as a high energy laser (HEL) directed energy weapon (DEW) 4) because it could produce a giant pulse of 0.1 ms which can damage a target by a single shot without producing plasma during the propagation. However since the beam cannot propagate for a long distance due to the absorption in air, it should be used in space considering the capability of operation without electric power supply. Therefore a new SBL defense system using a COL is proposed in order to destroy a ballistic missile in its boost phase. It is based on an SBL at geostationary Earth orbit (GEO) with the altitude of 36,000 km. Since the beam needs to propagate for a long distance, the focused beam diameter is 8 m even if the initial beam diameter is 8 m. Therefore an 8 m-diameter focusing mirror, carried by a high altitude airship (HAA) flying at the altitude of more than 20 km, could be used to focus the beam at the target. Although such a large focusing mirror is necessary, the focused spot size can be <1 cm at 30 km away. Thus, much less than 100 kJ pulse can cause a fatal damage. Unlike a conventional SBL defense system based on SBLs and/or relay-mirror satellites in low Earth orbit (LEO), the new defense system needs only a single SBL and a single relay mirror HAA (RM HAA) to intercept a ballistic missile if the enemy is a small country since the HAA can always stay close to the enemy's missile site. Another concept of the defense system is also proposed, which is based on a COL equipped with anther HAA because a COL can be lightweight. These geostationary defense systems can also intercept a submarine-launched ballistic missile (SLBM) if the submarine's location is monitored.

Multipoint vibrometry with dynamic and static holograms.

PubMed

Haist, T; Lingel, C; Osten, W; Winter, M; Giesen, M; Ritter, F; Sandfort, K; Rembe, C; Bendel, K

2013-12-01

We report on two multipoint vibrometers with user-adjustable position of the measurement spots. Both systems are using holograms for beam deflection. The measurement is based on heterodyne interferometry with a frequency difference of 5 MHz between reference and object beam. One of the systems uses programmable positioning of the spots in the object volume but is limited concerning the light efficiency. The other system is based on static holograms in combination with mechanical adjustment of the measurement spots and does not have such a general efficiency restriction. Design considerations are given and we show measurement results for both systems. In addition, we analyze the sensitivity of the systems which is a major limitation compared to single point scanning systems.

Novel high-brightness fiber coupled diode laser device

NASA Astrophysics Data System (ADS)

Haag, Matthias; Köhler, Bernd; Biesenbach, Jens; Brand, Thomas

2007-02-01

High brightness becomes more and more important in diode laser applications for fiber laser pumping and materials processing. For OEM customers fiber coupled devices have great advantages over direct beam modules: the fiber exit is a standardized interface, beam guiding is easy with nearly unlimited flexibility. In addition to the transport function the fiber serves as homogenizer: the beam profile of the laser radiation emitted from a fiber is symmetrical with highly repeatable beam quality and pointing stability. However, efficient fiber coupling requires an adaption of the slow-axis beam quality to the fiber requirements. Diode laser systems based on standard 10mm bars usually employ beam transformation systems to rearrange the highly asymmetrical beam of the laser bar or laser stack. These beam transformation systems (prism arrays, lens arrays, fiber bundles etc.) are expensive and become inefficient with increasing complexity. This is especially true for high power devices with small fiber diameters. On the other hand, systems based on single emitters are claimed to have good potential in cost reduction. Brightness of the inevitable fiber bundles, though, is limited due to inherent fill-factor losses. At DILAS a novel diode laser device has been developed combining the advantages of diode bars and single emitters: high brightness at high reliability with single emitter cost structure. Heart of the device is a specially tailored laser bar (T-Bar), which epitaxial and lateral structure was designed such that only standard fast- and slow-axis collimator lenses are required to couple the beam into a 200μm fiber. Up to 30 of these T-Bars of one wavelength can be combined to reach a total of > 500W ex fiber in the first step. Going to a power level of today's single emitter diodes even 1kW ex 200μm fiber can be expected.

High-energy laser activities at MBDA Germany

NASA Astrophysics Data System (ADS)

Mohring, Bernd; Dietrich, Stephan; Tassini, Leonardo; Protz, Rudolf; Geidek, Franz; Zoz, Jürgen

2013-05-01

At MBDA Germany a concept for a high-energy laser weapon system is investigated, which is based on existing industrial laser sources. Due to the enormous progress in the field of high-power fiber lasers, commercial industrial fiber lasers are now available delivering a nearly-diffraction limited beam quality with power levels of up to 10 kW. By using a geometric beam coupling scheme, a number of individual high-power fiber laser beams are combined together using one common beam director telescope. A total laser beam power of more than 100 kW can be achieved, which is sufficient for an operational laser weapon system. The individual beams from the different lasers are steered by servo-loops using fast tip-tilt mirrors. This principle enables the concentration of the total laser beam power at one common focal point on a distant target, also allowing fine tracking of target movements and first-order compensation of turbulence effects on laser beam propagation. The proposed beam combination concept was demonstrated by using different experimental set-ups. A number of experiments were performed successfully to investigate laser beam target interaction and target fine tracking, also at large distances and at moving targets. Content and results of these investigations are reported, which demonstrate the complete engagement sequence for a C-RAM scenario. This includes subsequent steps of target acquisition by radar and IR optics, followed by large angle coarse tracking, active fine tracking and destruction of the target by the laser system. This successful implementation of geometric beam combining is an important step for the realization of a laser weapon system in the near future.

System using a megawatt class millimeter wave source and a high-power rectenna to beam power to a suspended platform

DOEpatents

Caplan, Malcolm; Friedman, Herbert W.

2005-07-19

A system for beaming power to a high altitude platform is based upon a high power millimeter gyrotron source, optical transmission components, and a high-power receiving antenna (i.e., a rectenna) capable of rectifying received millimeter energy and converting such energy into useable electrical power.

Propagation of rotational Risley-prism-array-based Gaussian beams in turbulent atmosphere

NASA Astrophysics Data System (ADS)

Chen, Feng; Ma, Haotong; Dong, Li; Ren, Ge; Qi, Bo; Tan, Yufeng

2018-03-01

Limited by the size and weight of prism and optical assembling, Rotational Risley-prism-array system is a simple but effective way to realize high power and superior beam quality of deflecting laser output. In this paper, the propagation of the rotational Risley-prism-array-based Gaussian beam array in atmospheric turbulence is studied in detail. An analytical expression for the average intensity distribution at the receiving plane is derived based on nonparaxial ray tracing method and extended Huygens-Fresnel principle. Power in the diffraction-limited bucket is chosen to evaluate beam quality. The effect of deviation angle, propagation distance and intensity of turbulence on beam quality is studied in detail by quantitative simulation. It reveals that with the propagation distance increasing, the intensity distribution gradually evolves from multiple-petal-like shape into the pattern that contains one main-lobe in the center with multiple side-lobes in weak turbulence. The beam quality of rotational Risley-prism-array-based Gaussian beam array with lower deviation angle is better than its counterpart with higher deviation angle when propagating in weak and medium turbulent (i.e. Cn2 < 10-13m-2/3), the beam quality of higher deviation angle arrays degrades faster as the intensity of turbulence gets stronger. In the case of propagating in strong turbulence, the long propagation distance (i.e. z > 10km ) and deviation angle have no influence on beam quality.

MR-guided adaptive focusing of therapeutic ultrasound beams in the human head

PubMed Central

Marsac, Laurent; Chauvet, Dorian; Larrat, Benoît; Pernot, Mathieu; Robert, B.; Fink, Mathias; Boch, Anne-Laure; Aubry, Jean-François; Tanter, Mickaël

2012-01-01

Purpose This study aims to demonstrate, using human cadavers the feasibility of energy-based adaptive focusing of ultrasonic waves using Magnetic Resonance Acoustic Radiation Force Imaging (MR-ARFI) in the framework of non-invasive transcranial High Intensity Focused Ultrasound (HIFU) therapy. Methods Energy-based adaptive focusing techniques were recently proposed in order to achieve aberration correction. We evaluate this method on a clinical brain HIFU system composed of 512 ultrasonic elements positioned inside a full body 1.5 T clinical Magnetic Resonance (MR) imaging system. Cadaver heads were mounted onto a clinical Leksell stereotactic frame. The ultrasonic wave intensity at the chosen location was indirectly estimated by the MR system measuring the local tissue displacement induced by the acoustic radiation force of the ultrasound (US) beams. For aberration correction, a set of spatially encoded ultrasonic waves was transmitted from the ultrasonic array and the resulting local displacements were estimated with the MR-ARFI sequence for each emitted beam. A non-iterative inversion process was then performed in order to estimate the spatial phase aberrations induced by the cadaver skull. The procedure was first evaluated and optimized in a calf brain using a numerical aberrator mimicking human skull aberrations. The full method was then demonstrated using a fresh human cadaver head. Results The corrected beam resulting from the direct inversion process was found to focus at the targeted location with an acoustic intensity 2.2 times higher than the conventional non corrected beam. In addition, this corrected beam was found to give an acoustic intensity 1.5 times higher than the focusing pattern obtained with an aberration correction using transcranial acoustic simulation based on X-ray computed tomography (CT) scans. Conclusion The proposed technique achieved near optimal focusing in an intact human head for the first time. These findings confirm the strong potential of energy-based adaptive focusing of transcranial ultrasonic beams for clinical applications. PMID:22320825

Exact free vibration of multi-step Timoshenko beam system with several attachments

NASA Astrophysics Data System (ADS)

Farghaly, S. H.; El-Sayed, T. A.

2016-05-01

This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded multi-step Timoshenko beam combined system carrying several attachments. The influence of system design and the proposed sub-system non-dimensional parameters on the combined system characteristics are the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system for each span are included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. A sub-system having two degrees of freedom is located at the beam ends and at any of the intermediate stations and acts as a support and/or a suspension. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including the shear force term, due to the sub-system, have been formulated. Exact global coefficient matrices for the combined modal frequencies, the modal shape and for the discrete sub-system have been derived. Based on these formulae, detailed parametric studies of the combined system are carried out. The applied mathematical model is valid for wide range of applications especially in mechanical, naval and structural engineering fields.

Electro-optic high voltage sensor

DOEpatents

Davidson, James R.; Seifert, Gary D.

2003-09-16

A small sized electro-optic voltage sensor capable of accurate measurement of high voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation. A polarization beam displacer separates the input beam into two beams with orthogonal linear polarizations and causes one linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels effect elliptically polarizes the beam as it travels through the crystal. A reflector redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization. The system may include a detector for converting the output beams into electrical signals and a signal processor for determining the voltage based on an analysis of the output beams.

Active Vibration damping of Smart composite beams based on system identification technique

NASA Astrophysics Data System (ADS)

Bendine, Kouider; Satla, Zouaoui; Boukhoulda, Farouk Benallel; Nouari, Mohammed

2018-03-01

In the present paper, the active vibration control of a composite beam using piezoelectric actuator is investigated. The space state equation is determined using system identification technique based on the structure input output response provided by ANSYS APDL finite element package. The Linear Quadratic (LQG) control law is designed and integrated into ANSYS APDL to perform closed loop simulations. Numerical examples for different types of excitation loads are presented to test the efficiency and the accuracy of the proposed model.

Front-end simulation of injector for terawatt accumulator.

PubMed

Kropachev, G N; Balabin, A I; Kolomiets, A A; Kulevoy, T V; Pershin, V I; Shumshurov, A V

2008-02-01

A terawatt accumulator (TWAC) accelerator/storage ring complex with the laser ion source is in progress at ITEP. The new injector I4 based on the radio frequency quadrupole (RFQ) and interdigital H-mode (IH) linear accelerator is under construction. The front end of the new TWAC injector consists of a laser ion source, an extraction system, and a low energy beam transport (LEBT). The KOBRA3-INP was used for the simulation and optimization of the ion source extraction system. The optimization parameter is the maximum brightness of the beam generated by the laser ion source. Also the KOBRA3-INP code was used for LEBT investigation. The LEBT based on electrostatic grid lenses is chosen for injector I4. The results of the extraction system and LEBT investigations for ion beam matching with RFQ are presented.

Conceptual Design of Electron-Beam Generated Plasma Tools

NASA Astrophysics Data System (ADS)

Agarwal, Ankur; Rauf, Shahid; Dorf, Leonid; Collins, Ken; Boris, David; Walton, Scott

2015-09-01

Realization of the next generation of high-density nanostructured devices is predicated on etching features with atomic layer resolution, no damage and high selectivity. High energy electron beams generate plasmas with unique features that make them attractive for applications requiring monolayer precision. In these plasmas, high energy beam electrons ionize the background gas and the resultant daughter electrons cool to low temperatures via collisions with gas molecules and lack of any accelerating fields. For example, an electron temperature of <0.6 eV with densities comparable to conventional plasma sources can be obtained in molecular gases. The chemistry in such plasmas can significantly differ from RF plasmas as the ions/radicals are produced primarily by beam electrons rather than those in the tail of a low energy distribution. In this work, we will discuss the conceptual design of an electron beam based plasma processing system. Plasma properties will be discussed for Ar, Ar/N2, and O2 plasmas using a computational plasma model, and comparisons made to experiments. The fluid plasma model is coupled to a Monte Carlo kinetic model for beam electrons which considers gas phase collisions and the effect of electric and magnetic fields on electron motion. The impact of critical operating parameters such as magnetic field, beam energy, and gas pressure on plasma characteristics in electron-beam plasma processing systems will be discussed. Partially supported by the NRL base program.

Continuous single pulse resolved measurement of beam diameters at 200 kHz using optical transmission filters

NASA Astrophysics Data System (ADS)

Fruechtenicht, Johannes; Letsch, Andreas; Voss, Andreas; Abdou Ahmed, Marwan; Graf, Thomas

2012-02-01

We present a novel laser beam measurement setup which allows the determination of the beam diameter for each single pulse of a pulsed laser beam at repetition rates of up to 200 kHz. This is useful for online process-parameter control e.g. in micromachining or for laser source characterization. Basically, the developed instrument combines spatial transmission filters specially designed for instantaneous optical determination of the second order moments of the lateral intensity distribution of the light beam and photodiodes coupled to customized electronics. The acquisition is computer-based, enabling real-time operation for online monitoring or control. It also allows data storage for a later analysis and visualization of the measurement results. The single-pulse resolved beam diameter can be measured and recorded without any interruption for an unlimited number of pulses. It is only limited by the capacity of the data storage means. In our setup a standard PC and hard-disk provided 2 hours uninterrupted operation and recording of varying beam diameters at 200 kHz. This is about three orders of magnitude faster than other systems. To calibrate our device we performed experiments in cw and pulsed regimes and the obtained results were compared to those obtained with a commercial camera based system. Only minor deviations of the beam diameter values between the two instruments were observed, proving the reliability of our approach.

Facilitating Integration of Electron Beam Lithography Devices with Interactive Videodisc, Computer-Based Simulation and Job Aids.

ERIC Educational Resources Information Center

Von Der Linn, Robert Christopher

A needs assessment of the Grumman E-Beam Systems Group identified the requirement for additional skill mastery for the engineers who assemble, integrate, and maintain devices used to manufacture integrated circuits. Further analysis of the tasks involved led to the decision to develop interactive videodisc, computer-based job aids to enable…

A compact control system to achieve stable voltage and low jitter trigger for repetitive intense electron-beam accelerator based on resonant charging

NASA Astrophysics Data System (ADS)

Qiu, Yongfeng; Liu, Jinliang; Yang, Jianhua; Cheng, Xinbing; Yang, Xiao

2017-08-01

A compact control system based on Delphi and Field Programmable Gate Array(FPGA) is developed for a repetitive intense electron-beam accelerator(IEBA), whose output power is 10GW and pulse duration is 160ns. The system uses both hardware and software solutions. It comprises a host computer, a communication module and a main control unit. A device independent applications programming interface, devised using Delphi, is installed on the host computer. Stability theory of voltage in repetitive mode is analyzed and a detailed overview of the hardware and software configuration is presented. High voltage experiment showed that the control system fulfilled the requests of remote operation and data-acquisition. The control system based on a time-sequence control method is used to keep constant of the voltage of the primary capacitor in every shot, which ensured the stable and reliable operation of the electron beam accelerator in the repetitive mode during the experiment. Compared with the former control system based on Labview and PIC micro-controller developed in our laboratory, the present one is more compact, and with higher precision in the time dimension. It is particularly useful for automatic control of IEBA in the high power microwave effects research experiments where pulse-to-pulse reproducibility is required.

Dynamics analysis of microsphere in a dual-beam fiber-optic trap with transverse offset.

PubMed

Chen, Xinlin; Xiao, Guangzong; Luo, Hui; Xiong, Wei; Yang, Kaiyong

2016-04-04

A comprehensive dynamics analysis of microsphere has been presented in a dual-beam fiber-optic trap with transverse offset. As the offset distance between two counterpropagating beams increases, the motion type of the microsphere starts with capture, then spiral motion, then orbital rotation, and ends with escape. We analyze the transformation process and mechanism of the four motion types based on ray optics approximation. Dynamic simulations show that the existence of critical offset distances at which different motion types transform. The result is an important step toward explaining physical phenomena in a dual-beam fiber-optic trap with transverse offset, and is generally applicable to achieving controllable motions of microspheres in integrated systems, such as microfluidic systems and lab-on-a-chip systems.

Performance of a Nanometer Resolution BPM System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walston, S.; Chung, C.; Fitsos, P.

2007-04-24

International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. It is important to the ILC design effort to demonstrate that these tolerances can be achieved ideally using beam-based stability measurements. It has been estimated that RF cavity beam position monitors (BPMs) could provide position measurement resolutions of less than one nanometer and could form the basis of the desired beam-based stability measurement. We have developed a high resolution RF cavity BPM system. A triplet of these BPMs has been installed in the extraction line of the KEK Acceleratormore » Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on variable-length struts which allow movement in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a calibration algorithm which is immune to beam jitter. To date, we have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of +/- 20 microns. We report on the progress of these ongoing tests.« less

A new method for incoherent combining of far-field laser beams based on multiple faculae recognition

NASA Astrophysics Data System (ADS)

Ye, Demao; Li, Sichao; Yan, Zhihui; Zhang, Zenan; Liu, Yuan

2018-03-01

Compared to coherent beam combining, incoherent beam combining can complete the output of high power laser beam with high efficiency, simple structure, low cost and high thermal damage resistance, and it is easy to realize in engineering. Higher target power is achieved by incoherent beam combination which using technology of multi-channel optical path correction. However, each channel forms a spot in the far field respectively, which cannot form higher laser power density with low overlap ratio of faculae. In order to improve the combat effectiveness of the system, it is necessary to overlap different faculae that improve the target energy density. Hence, a novel method for incoherent combining of far-field laser beams is present. The method compromises piezoelectric ceramic technology and evaluation algorithm of faculae coincidence degree which based on high precision multi-channel optical path correction. The results show that the faculae recognition algorithm is low-latency(less than 10ms), which can meet the needs of practical engineering. Furthermore, the real time focusing ability of far field faculae is improved which was beneficial to the engineering of high-energy laser weapon or other laser jamming systems.

Beam shaping for cosmetic hair removal

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.; Tuttle, Tracie

2007-09-01

Beam shaping has the potential to provide comfort to people who require or seek laser based cosmetic skin procedures. Of immediate interest is the procedure of aesthetic hair removal. Hair removal is performed using a variety of wavelengths from 480 to 1200 nm by means of filtered Xenon flash lamps (pulsed light) or 810 nm diode lasers. These wavelengths are considered the most efficient means available for hair removal applications, but current systems use simple reflector designs and plane filter windows to direct the light to the surface being exposed. Laser hair removal is achieved when these wavelengths at sufficient energy levels are applied to the epidermis. The laser energy is absorbed by the melanin (pigment) in the hair and hair follicle which in turn is transformed into heat. This heat creates the coagulation process, which causes the removal of the hair and prevents growth of new hair [1]. This paper outlines a technique of beam shaping that can be applied to a non-contact based hair removal system. Several features of the beam shaping technique including beam uniformity and heat dispersion across its operational treatment area will be analyzed. A beam shaper design and its fundamental testing will be discussed in detail.

Long-Wavelength Beam Steerer Based on a Micro-Electromechanical Mirror

PubMed Central

Kos, Anthony B; Gerecht, Eyal

2013-01-01

Commercially available mirrors for scanning long-wavelength beams are too large for high-speed imaging. There is a need for a smaller, more agile pointing apparatus to provide images in seconds, not minutes or hours. A fast long-wavelength beam steerer uses a commercial micro-electro-mechanical system (MEMS) mirror controlled by a high-performance digital signal processor (DSP). The DSP allows high-speed raster scanning of the incident radiation, which is focused to a small waist onto the 9mm2, gold-coated, MEMS mirror surface, while simultaneously acquiring an undistorted, high spatial-resolution image of an object. The beam steerer hardware, software and performance are described. The system can also serve as a miniaturized, high-performance long-wavelength beam chopper for lock-in detection. PMID:26401426

An electron cyclotron resonance ion source based low energy ion beam platform.

PubMed

Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z

2008-02-01

To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.

Generation of dark hollow beam by focusing a sine-Gaussian beam using a cylindrical lens and a focusing lens

NASA Astrophysics Data System (ADS)

Tang, Huiqin; Zhu, Kaicheng

2013-12-01

Based on the generalized Huygens-Fresnel diffraction integral, a closed-form propagation equation related to sine-Gaussian beams through a cylindrical lens and a focusing lens is derived and illustrated with numerical methods. It is found that a sine-Gaussian beam through such a system may be converted into a dark hollow beam (DHB) with topological charge index one and its bright enclosure is approximately an elongated ellipse with very high ellipticity. Moreover, the parameter values at which the DHBs have perfect intensity patterns are designed. The optimal relative orientation between the dislocation line of the input sine-Gaussian beam and the axial orientation of the cylindrical lens is specified. And the ellipticity of the elliptical DHBs is mainly defined by the focal length of the cylindrical lens and the Fresnel number of the optical system.

Collimation system design for beam loss localization with slipstacking injection in the Fermilab Main Injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drozhdin, A.I.; Brown, B.C.; Johnson, D.E.

2007-06-01

Results of modeling with the 3-D STRUCT and MARS15 codes of beam loss localization and related radiation effects are presented for the slipstacking injection to the Fermilab Main Injector. Simulations of proton beam loss are done using multi-turn tracking with realistic accelerator apertures, nonlinear fields in the accelerator magnets and time function of the RF manipulations to explain the results of beam loss measurements. The collimation system consists of one primary and four secondary collimators. It intercepts a beam power of 1.6 kW at a scraping rate of 5% of 5.5E+13 ppp, with a beam loss rate in the ringmore » outside the collimation region of 1 W/m or less. Based on thorough energy deposition and radiation modeling, a corresponding collimator design was developed that satisfies all the radiation and engineering constraints.« less

The Supervisory Control System for the HL-2A Neutral Beam Injector

NASA Astrophysics Data System (ADS)

Li, Bo; Li, Li; Feng, Kun; Wang, Xueyun; Yang, Jiaxing; Huang, Zhihui; Kang, Zihua; Wang, Mingwei; Zhang, Guoqing; Lei, Guangjiu; Rao, Jun

2009-06-01

Supervisory control and protection system of the neutral beam injector (NBI) in the HL-2A tokamak is presented. The system is used for a safe coordination of all the main NBI subsystems. Because the system is based on computer networks with its transmission medium of optical fiber, its advantages in high operational stability, reliability, security and flexible functional expandability are clearly shown during the NBI commissioning and heating experiment in HL-2A.

Laser beam uniformity and stability using homogenizer-based fiber optic launch method: square core fiber delivery

NASA Astrophysics Data System (ADS)

Lizotte, Todd E.

2011-03-01

Over the years, technological achievements within the laser medical diagnostic, treatment, and therapy markets have led to ever increasing requirements for greater control of critical laser beam parameters. Increased laser power/energy stabilization, temporal and spatial beam shaping and flexible laser beam delivery systems with ergonomic focusing or imaging lens systems are sought by leading medical laser system producers. With medical procedures that utilize laser energy, there is a constant emphasis on reducing adverse effects that come about by the laser itself or its optical system, but even when these variables are well controlled the medical professional will still need to deal with the multivariate nature of the human body. Focusing on the variables that can be controlled, such as accurate placement of the laser beam where it will expose a surface being treated as well as laser beam shape and uniformity is critical to minimizing adverse conditions. This paper covers the use of fiber optic beam delivery as a means of defining the beam shape (intensity/power distribution uniformity) at the target plane as well as the use of fiber delivery as a means to allow more flexible articulation of the laser beam over the surface being treated. The paper will present a new concept of using a square core fiber beam delivery design utilizing a unique micro lens array (MLA) launch method that improves the overall stability of the system, by minimizing the impact of the laser instability. The resulting performance of the prototype is presented to demonstrate its stability in comparison to simple lens launch techniques, with an emphasis on homogenization and articulated fiber delivery.

A prototype scintillating fibre beam profile monitor for Ion Therapy beams

NASA Astrophysics Data System (ADS)

Leverington, B. D.; Dziewiecki, M.; Renner, L.; Runze, R.

2018-05-01

A prototype plastic scintillating fibre based beam profile monitor was tested at the Heidelberg Ion Therapy Centre/Heidelberg Ionenstrahl Therapiezentrum (HIT) in 2016 to determine its beam property reconstruction performance and the feasibility of further developing an expanded system. At HIT protons, helium, carbon, and oxygen ions are available for therapy and experiments. The beam can be scanned in two dimensions using fast deflection magnets. A tracking system is used to monitor beam position and to adjust scanning magnet currents online. A new detector system with a finer granularity and without the drift time delay of the current MWPC system with a similar amount of material along the beamline would prove valuable in patient treatment. The sensitive detector components in the tested prototype detector are double-clad Kuraray SCSF-78MJ scintillating fibres with a diameter of 0.250 mm wound as a thin multi-layer ribbon. The scintillation light is detected at the end of the ribbon with Hamamatsu S11865-64 photodiode arrays with a pitch of 0.8 mm. Commercial or readily available readout electronics have been used to evaluate the system feasibility. The results shown in this paper include the linearity with respect to beam intensity, the RMS of the beam intensity as measured by two planes, along with the RMS of the mean position, and the measured beam width RMS. The Signal-to-Noise ratio of the current system is also measured as an indicator of potential performance. Additionally, the non-linear light yield of the scintillating fibres as measured by the photodiode arrays is compared to two models which describe the light yield as a function of the ion stopping power and Lorentz β.

Beam tracking phase tomography with laboratory sources

NASA Astrophysics Data System (ADS)

Vittoria, F. A.; Endrizzi, M.; Kallon, G. K. N.; Hagen, C. K.; Diemoz, P. C.; Zamir, A.; Olivo, A.

2018-04-01

An X-ray phase-contrast laboratory system is presented, based on the beam-tracking method. Beam-tracking relies on creating micro-beamlets of radiation by placing a structured mask before the sample, and analysing them by using a detector with sufficient resolution. The system is used in tomographic configuration to measure the three dimensional distribution of the linear attenuation coefficient, difference from unity of the real part of the refractive index, and of the local scattering power of specimens. The complementarity of the three signals is investigated, together with their potential use for material discrimination.

Charge Exchange Recombination Spectroscopy Based on Diagnostic Neutral Beam in HT-7 Tokamak

NASA Astrophysics Data System (ADS)

Shi, Yuejiang; Fu, Jia; Li, Yingying; William, Rowan; Huang, He; Wang, Fudi; Gao, Huixian; Huang, Juann; Zhou, Qian; Liu, Sheng; Zhang, Jian; Li, Jun; Xie, Yuanlai; Liu, Zhimin; Huang, Yiyun; Hu, Chundong; Wan, Baonian

2010-02-01

Charge exchange recombination spectroscopy (CXRS) based on a diagnostic neutral beam (DNB) installed in the HT-7 tokamak is introduced. DNB can provide a 6 A extracted current at 50 kV for 0.1 s in hydrogen. It can penetrate into the core plasma in HT-7. The CXRS system is designed to observe charge exchange (CX) transitions in the visible spectrum. CX light from the beam is focused onto 10 optical fibers, which view the plasma from -5 cm to 20 cm. The CXRS system can measure the ion temperature as low as 0.1 keV. With CXRS, the local ion temperature profile in HT-7 was obtained for the first time.

Study of repeater technology for advanced multifunctional communications satellites

NASA Technical Reports Server (NTRS)

1972-01-01

Investigations are presented concerning design concepts and implementation approaches for the satellite communication repeater subsystems of advanced multifunctional satellites. In such systems the important concepts are the use of multiple antenna beams, repeater switching (routing), and efficient spectrum utilization through frequency reuse. An information base on these techniques was developed and tradeoff analyses were made of repeater design concepts, with the work design taken in a broad sense to include modulation beam coverage patterns. There were five major areas of study: requirements analysis and processing; study of interbeam interference in multibeam systems; characterization of multiple-beam switching repeaters; estimation of repeater weight and power for a number of alternatives; and tradeoff analyses based on these weight and power data.

Modified hollow Gaussian beam and its paraxial propagation

NASA Astrophysics Data System (ADS)

Cai, Yangjian; Chen, Chiyi; Wang, Fei

2007-10-01

A model named modified hollow Gaussian beam (HGB) is proposed to describe a dark hollow beam with adjustable beam spot size, central dark size and darkness factor. In this modified model, both the beam spot size and the central dark size will be convergent to finite constants as the beam order approaches infinity, which are much different from that of the previous unmodified model, where the beam spot size and the central dark size will not be convergent as the beam order approaches infinity. The dependences of the propagation factor of modified and unmodified HGBs on the beam order are found to be the same. Based on the Collins integral, analytical formulas for the modified HGB propagating through aligned and misaligned optical system are derived. Some numerical examples are given.

Initial alignment method for free space optics laser beam

NASA Astrophysics Data System (ADS)

Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

2016-08-01

The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

GAPD: a GPU-accelerated atom-based polychromatic diffraction simulation code.

PubMed

E, J C; Wang, L; Chen, S; Zhang, Y Y; Luo, S N

2018-03-01

GAPD, a graphics-processing-unit (GPU)-accelerated atom-based polychromatic diffraction simulation code for direct, kinematics-based, simulations of X-ray/electron diffraction of large-scale atomic systems with mono-/polychromatic beams and arbitrary plane detector geometries, is presented. This code implements GPU parallel computation via both real- and reciprocal-space decompositions. With GAPD, direct simulations are performed of the reciprocal lattice node of ultralarge systems (∼5 billion atoms) and diffraction patterns of single-crystal and polycrystalline configurations with mono- and polychromatic X-ray beams (including synchrotron undulator sources), and validation, benchmark and application cases are presented.

Commercialization of an S-band standing-wave electron accelerator for industrial applications

NASA Astrophysics Data System (ADS)

Moon, Jin-Hyeok; Kwak, Gyeong-Il; Han, Jae-Ik; Lee, Gyu-Baek; Jeon, Seong-Hwan; Kim, Jae-Young; Hwang, Cheol-Bin; Lee, Gi-Yong; Kim, Young-Man; Park, Sung-Ju

2016-09-01

An electron accelerator system has been developed for use in industrial, as well as possible medical, applications. Based on our experiences achieved during prototype system development and various electron beam acceleration tests, we have built a stable and compact system for sales purposes. We have integrated a self-developed accelerating cavity, an E-gun pulse driver, a radio-frequency (RF) power system, a vacuum system, a cooling system, etc. into a frame with a size of 1800 × 1000 × 1500 mm3. The accelerating structure is a side-coupled standing-wave type operating in the π/2 mode (tuned to~3 GHz). The RF power is provided by using a magnetron driven by a solid-state modulator. The electron gun is a triode type with a dispenser cathode (diameter of 11 mm). The system is capable of delivering a maximum 900-W average electron beam power with tight focusing at the target. Until now, we have performed various electron beam tests and X-ray beam tests after having built the system, have completed the beam assessment for commercializations, and have been preparing full-fledged sales activity. This article reports on our system development processes and on some of our early test results for commercializations.

Performance comparison of an active matrix flat panel imager, computed radiography system, and a screen-film system at four standard radiation qualities.

PubMed

Monnin, P; Gutierrez, D; Bulling, S; Lepori, D; Valley, J F; Verdun, F R

2005-02-01

Four standard radiation qualities (from RQA 3 to RQA 9) were used to compare the imaging performance of a computed radiography (CR) system (general purpose and high resolution phosphor plates of a Kodak CR 9000 system), a selenium-based direct flat panel detector (Kodak Direct View DR 9000), and a conventional screen-film system (Kodak T-MAT L/RA film with a 3M Trimax Regular screen of speed 400) in conventional radiography. Reference exposure levels were chosen according to the manufacturer's recommendations to be representative of clinical practice (exposure index of 1700 for digital systems and a film optical density of 1.4). With the exception of the RQA 3 beam quality, the exposure levels needed to produce a mean digital signal of 1700 were higher than those needed to obtain a mean film optical density of 1.4. In spite of intense developments in the field of digital detectors, screen-film systems are still very efficient detectors for most of the beam qualities used in radiology. An important outcome of this study is the behavior of the detective quantum efficiency of the digital radiography (DR) system as a function of beam energy. The practice of users to increase beam energy when switching from a screen-film system to a CR system, in order to improve the compromise between patient dose and image quality, might not be appropriate when switching from screen-film to selenium-based DR systems.

Generation of dark hollow beams by using a fractional radial Hilbert transform system

NASA Astrophysics Data System (ADS)

Xie, Qiansen; Zhao, Daomu

2007-07-01

The radial Hilbert transform has been extend to the fractional field, which could be called the fractional radial Hilbert transform (FRHT). Using edge-enhancement characteristics of this transform, we convert a Gaussian light beam into a variety of dark hollow beams (DHBs). Based on the fact that a hard-edged aperture can be expanded approximately as a finite sum of complex Gaussian functions, the analytical expression of a Gaussian beam passing through a FRHT system has been derived. As a numerical example, the properties of the DHBs with different fractional orders are illustrated graphically. The calculation results obtained by use of the analytical method and the integral method are also compared.

Bunch-by-bunch detection of coherent transverse modes from digitized single-bpm signals in the Tevatron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stancari, G.; Valishev, A.; Semenov, A.

2010-05-01

A system was developed for bunch-by-bunch detection of transverse proton and antiproton coherent oscillations based on the signal from a single beam-position monitor (BPM) located in a region of the ring with large amplitude functions. The signal is digitized over a large number of turns and Fourier-analyzed offline with a dedicated algorithm. To enhance the signal, the beam is excited with band-limited noise for about one second, and this was shown not to significantly affect the circulating beams even at high luminosity. The system is used to measure betatron tunes of individual bunches and to study beam-beam effects. In particular,more » it is one of the main diagnostic tools in an ongoing study of nonlinear beam-beam compensation studies with Gaussian electron lenses. We present the design and operation of this tool, together with results obtained with proton and antiproton bunches.« less

Experimental investigation of optimum beam size for FSO uplink

NASA Astrophysics Data System (ADS)

Kaushal, Hemani; Kaddoum, Georges; Jain, Virander Kumar; Kar, Subrat

2017-10-01

In this paper, the effect of transmitter beam size on the performance of free space optical (FSO) communication has been determined experimentally. Irradiance profile for varying turbulence strength is obtained using optical turbulence generating (OTG) chamber inside laboratory environment. Based on the results, an optimum beam size is investigated using the semi-analytical method. Moreover, the combined effects of atmospheric scintillation and beam wander induced pointing errors are considered in order to determine the optimum beam size that minimizes the bit error rate (BER) of the system for a fixed transmitter power and link length. The results show that the optimum beam size for FSO uplink depends upon Fried parameter and outer scale of the turbulence. Further, it is observed that the optimum beam size increases with the increase in zenith angle but has negligible effect with the increase in fade threshold level at low turbulence levels and has a marginal effect at high turbulence levels. Finally, the obtained outcome is useful for FSO system design and BER performance analysis.

Plasma Charge Current for Controlling and Monitoring Electron Beam Welding with Beam Oscillation

PubMed Central

Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

2012-01-01

Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process. PMID:23242276

Plasma charge current for controlling and monitoring electron beam welding with beam oscillation.

PubMed

Trushnikov, Dmitriy; Belenkiy, Vladimir; Shchavlev, Valeriy; Piskunov, Anatoliy; Abdullin, Aleksandr; Mladenov, Georgy

2012-12-14

Electron beam welding (EBW) shows certain problems with the control of focus regime. The electron beam focus can be controlled in electron-beam welding based on the parameters of a secondary signal. In this case, the parameters like secondary emissions and focus coil current have extreme relationships. There are two values of focus coil current which provide equal value signal parameters. Therefore, adaptive systems of electron beam focus control use low-frequency scanning of focus, which substantially limits the operation speed of these systems and has a negative effect on weld joint quality. The purpose of this study is to develop a method for operational control of the electron beam focus during welding in the deep penetration mode. The method uses the plasma charge current signal as an additional informational parameter. This parameter allows identification of the electron beam focus regime in electron-beam welding without application of additional low-frequency scanning of focus. It can be used for working out operational electron beam control methods focusing exactly on the welding. In addition, use of this parameter allows one to observe the shape of the keyhole during the welding process.

A simple and highly sensitive spectroscopic fluorescence-detection system for multi-channel plastic-microchip electrophoresis based on side-entry laser-beam zigzag irradiation.

PubMed

Anazawa, Takashi; Uchiho, Yuichi; Yokoi, Takahide; Chalkidis, George; Yamazaki, Motohiro

2017-06-27

A five-color fluorescence-detection system for eight-channel plastic-microchip electrophoresis was developed. In the eight channels (with effective electrophoretic lengths of 10 cm), single-stranded DNA fragments were separated (with single-base resolution up to 300 bases within 10 min), and seventeen-loci STR genotyping for forensic human identification was successfully demonstrated. In the system, a side-entry laser beam is passed through the eight channels (eight A channels), with alternately arrayed seven sacrificial channels (seven B channels), by a technique called "side-entry laser-beam zigzag irradiation." Laser-induced fluorescence from the eight A channels and Raman-scattered light from the seven B channels are then simultaneously, uniformly, and spectroscopically detected, in the direction perpendicular to the channel array plane, through a transmission grating and a CCD camera. The system is therefore simple and highly sensitive. Because the microchip is fabricated by plastic-injection molding, it is inexpensive and disposable and thus suitable for actual use in various fields.

A closed form of a kurtosis parameter of a hypergeometric-Gaussian type-II beam

NASA Astrophysics Data System (ADS)

F, Khannous; A, A. A. Ebrahim; A, Belafhal

2016-04-01

Based on the irradiance moment definition and the analytical expression of waveform propagation for hypergeometric-Gaussian type-II beams passing through an ABCD system, the kurtosis parameter is derived analytically and illustrated numerically. The kurtosis parameters of the Gaussian beam, modified Bessel modulated Gaussian beam with quadrature radial and elegant Laguerre-Gaussian beams are obtained by treating them as special cases of the present treatment. The obtained results show that the kurtosis parameter depends on the change of the beam order m and the hollowness parameter p, such as its decrease with increasing m and increase with increasing p.

Complementary equipment for controlling multiple laser beams on single scanner MPLSM systems

NASA Astrophysics Data System (ADS)

Helm, P. Johannes; Nase, Gabriele; Heggelund, Paul; Reppen, Trond

2010-02-01

Multi-Photon-Laser-Scanning-Microscopy (MPLSM) now stands as one of the most powerful experimental tools in biology. Specifically, MPLSM based in-vivo studies of structures and processes in the brains of small rodents and imaging in brain-slices have led to considerable progress in the field of neuroscience. Equipment allowing for independent control of two laser-beams, one for imaging and one for photochemical manipulation, strongly enhances any MPLSM platform. Some industrial MPLSM producers have introduced double scanner options in MPLSM systems. Here, we describe the upgrade of a single scanner MPLSM system with equipment that is suitable for independently controlling the beams of two Titanium Sapphire lasers. The upgrade is compatible with any actual MPLSM system and can be combined with any commercial or self assembled system. Making use of the pixel-clock, frame-active and line-active signals provided by the scanner-electronics of the MPLSM, the user can, by means of an external unit, select individual pixels or rectangular ROIs within the field of view of an overview-scan to be exposed, or not exposed, to the beam(s) of one or two lasers during subsequent scans. The switching processes of the laser-beams during the subsequent scans are performed by means of Electro-Optical-Modulators (EOMs). While this system does not provide the flexibility of two-scanner modules, it strongly enhances the experimental possibilities of one-scanner systems provided a second laser and two independent EOMs are available. Even multi-scanner-systems can profit from this development, which can be used to independently control any number of laser beams.

SU-E-J-127: Implementation of An Online Replanning Tool for VMAT Using Flattening Filter-Free Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ates, O; Ahunbay, E; Li, X

2015-06-15

Purpose: This is to report the implementation of an online replanning tool based on segment aperture morphing (SAM) for VMAT with flattening filter free (FFF) beams. Methods: Previously reported SAM algorithm modified to accommodate VMAT with FFF beams was implemented in a tool that was interfaced with a treatment planning system (Monaco, Elekta). The tool allows (1) to output the beam parameters of the original VMAT plan from Monaco, and (2) to input the apertures generated from the SAM algorithm into Monaco for the dose calculation on daily CT/CBCT/MRI in the following steps:(1) Quickly generating target contour based on themore » image of the day, using an auto-segmentation tool (ADMIRE, Elekta) with manual editing if necessary; (2) Morphing apertures based on the SAM in the original VMAT plan to account for the interfractional change of the target from the planning to the daily images; (3) Calculating dose distribution for new apertures with the same numbers of MU as in the original plan; (4) Transferring the new plan into a record & verify system (MOSAIQ, Elekta); (5) Performing a pre-delivery QA based on software; (6) Delivering the adaptive plan for the fraction.This workflow was implemented on a 16-CPU (2.6 GHz dual-core) hardware with GPU and was tested for sample cases of prostate, pancreas and lung tumors. Results: The online replanning process can be completed within 10 minutes. The adaptive plans generally have improved the plan quality when compared to the IGRT repositioning plans. The adaptive plans with FFF beams have better normal tissue sparing as compared with those of FF beams. Conclusion: The online replanning tool based on SAM can quickly generate adaptive VMAT plans using FFF beams with improved plan quality than those from the IGRT repositioning plans based on daily CT/CBCT/MRI and can be used clinically. This research was supported by Elekta Inc. (Crawley, UK)« less

Video-based beam position monitoring at CHESS

NASA Astrophysics Data System (ADS)

Revesz, Peter; Pauling, Alan; Krawczyk, Thomas; Kelly, Kevin J.

2012-10-01

CHESS has pioneered the development of X-ray Video Beam Position Monitors (VBPMs). Unlike traditional photoelectron beam position monitors that rely on photoelectrons generated by the fringe edges of the X-ray beam, with VBPMs we collect information from the whole cross-section of the X-ray beam. VBPMs can also give real-time shape/size information. We have developed three types of VBPMs: (1) VBPMs based on helium luminescence from the intense white X-ray beam. In this case the CCD camera is viewing the luminescence from the side. (2) VBPMs based on luminescence of a thin (~50 micron) CVD diamond sheet as the white beam passes through it. The CCD camera is placed outside the beam line vacuum and views the diamond fluorescence through a viewport. (3) Scatter-based VBPMs. In this case the white X-ray beam passes through a thin graphite filter or Be window. The scattered X-rays create an image of the beam's footprint on an X-ray sensitive fluorescent screen using a slit placed outside the beam line vacuum. For all VBPMs we use relatively inexpensive 1.3 Mega-pixel CCD cameras connected via USB to a Windows host for image acquisition and analysis. The VBPM host computers are networked and provide live images of the beam and streams of data about the beam position, profile and intensity to CHESS's signal logging system and to the CHESS operator. The operational use of VBPMs showed great advantage over the traditional BPMs by providing direct visual input for the CHESS operator. The VBPM precision in most cases is on the order of ~0.1 micron. On the down side, the data acquisition frequency (50-1000ms) is inferior to the photoelectron based BPMs. In the future with the use of more expensive fast cameras we will be able create VBPMs working in the few hundreds Hz scale.

C-arm based cone-beam CT using a two-concentric-arc source trajectory: system evaluation

NASA Astrophysics Data System (ADS)

Zambelli, Joseph; Zhuang, Tingliang; Nett, Brian E.; Riddell, Cyril; Belanger, Barry; Chen, Guang-Hong

2008-03-01

The current x-ray source trajectory for C-arm based cone-beam CT is a single arc. Reconstruction from data acquired with this trajectory yields cone-beam artifacts for regions other than the central slice. In this work we present the preliminary evaluation of reconstruction from a source trajectory of two concentric arcs using a flat-panel detector equipped C-arm gantry (GE Healthcare Innova 4100 system, Waukesha, Wisconsin). The reconstruction method employed is a summation of FDK-type reconstructions from the two individual arcs. For the angle between arcs studied here, 30°, this method offers a significant reduction in the visibility of cone-beam artifacts, with the additional advantages of simplicity and ease of implementation due to the fact that it is a direct extension of the reconstruction method currently implemented on commercial systems. Reconstructed images from data acquired from the two arc trajectory are compared to those reconstructed from a single arc trajectory and evaluated in terms of spatial resolution, low contrast resolution, noise, and artifact level.

C-arm based cone-beam CT using a two-concentric-arc source trajectory: system evaluation.

PubMed

Zambelli, Joseph; Zhuang, Tingliang; Nett, Brian E; Riddell, Cyril; Belanger, Barry; Chen, Guang-Hong

2008-01-01

The current x-ray source trajectory for C-arm based cone-beam CT is a single arc. Reconstruction from data acquired with this trajectory yields cone-beam artifacts for regions other than the central slice. In this work we present the preliminary evaluation of reconstruction from a source trajectory of two concentric arcs using a flat-panel detector equipped C-arm gantry (GE Healthcare Innova 4100 system, Waukesha, Wisconsin). The reconstruction method employed is a summation of FDK-type reconstructions from the two individual arcs. For the angle between arcs studied here, 30°, this method offers a significant reduction in the visibility of cone-beam artifacts, with the additional advantages of simplicity and ease of implementation due to the fact that it is a direct extension of the reconstruction method currently implemented on commercial systems. Reconstructed images from data acquired from the two arc trajectory are compared to those reconstructed from a single arc trajectory and evaluated in terms of spatial resolution, low contrast resolution, noise, and artifact level.

Fiber-optic beam control systems using microelectromechanical systems

NASA Astrophysics Data System (ADS)

Sumriddetchkajorn, Sarun

This dissertation, for the first time, proposes, studies, and experimentally demonstrated novel fiber-optic beam control systems based on the use of microelectromechanical system (MEMS) technology in which the miniaturized versions of mechanical systems can be obtained. Beam control modules include optical add/drop filters, optical switches, variable photonic delay lines (VPDLs), and variable optical attenuators (VOAs). The optical add/drop filter functions as a multiwavelength optical switch that offers the ability to drop and add a certain number of desired wavelengths at an intermediate location where access to all the propagating optical channels is not required between transmission terminals. The VOA can also be used in networks where stocking and tracking of fixed attenuators is difficult. Other specific applications of the VOA are optical gain equalization and polarization dependent loss and gain compensation required in high data-rate wavelength division multiplexed (WDM) lightwave systems. A VPDL can be used to adjust timing amongst multiwavelength optical signals in order to reduce timing jitter and burst traffic in photonic packet switching and parallel signal processing systems. In this dissertation, a small tilt micromirror device is proposed for the implementation of all fiber-optic beam control modules. In particular, the macro-pixel approach where several micromirrors are used to manipulate the desired optical beam is introduced to realize high speed and fault tolerant beam control modules. To eliminate the need of careful optical alignment, an all fiber-connectorized multiwavelength optical switch structure is presented and experimentally demonstrated by using a fiber-loop mirror concept with polarization control. In addition, liquid crystal (LC) devices are studied and are used to implement a compact retro- reflective 2 x 2 fiber-optic switch. Compared to MEMS- based mirror technology, the LC technology is more sensitive to temperature, thereby inappropriate to deploy in a harsh environment. With the benefit provided by WDM systems, wavelength sensitive fiber-optic beam controllers are proposed, offering wavelength sensitive time delay and amplitude controls that can be applied in several applications ranging from optical communications to high speed parallel signal processing. (Abstract shortened by UMI.)

An image-guided precision proton radiation platform for preclinical in vivo research

NASA Astrophysics Data System (ADS)

Ford, E.; Emery, R.; Huff, D.; Narayanan, M.; Schwartz, J.; Cao, N.; Meyer, J.; Rengan, R.; Zeng, J.; Sandison, G.; Laramore, G.; Mayr, N.

2017-01-01

There are many unknowns in the radiobiology of proton beams and other particle beams. We describe the development and testing of an image-guided low-energy proton system optimized for radiobiological research applications. A 50 MeV proton beam from an existing cyclotron was modified to produce collimated beams (as small as 2 mm in diameter). Ionization chamber and radiochromic film measurements were performed and benchmarked with Monte Carlo simulations (TOPAS). The proton beam was aligned with a commercially-available CT image-guided x-ray irradiator device (SARRP, Xstrahl Inc.). To examine the alternative possibility of adapting a clinical proton therapy system, we performed Monte Carlo simulations of a range-shifted 100 MeV clinical beam. The proton beam exhibits a pristine Bragg Peak at a depth of 21 mm in water with a dose rate of 8.4 Gy min-1 (3 mm depth). The energy of the incident beam can be modulated to lower energies while preserving the Bragg peak. The LET was: 2.0 keV µm-1 (water surface), 16 keV µm-1 (Bragg peak), 27 keV µm-1 (10% peak dose). Alignment of the proton beam with the SARRP system isocenter was measured at 0.24 mm agreement. The width of the beam changes very little with depth. Monte Carlo-based calculations of dose using the CT image data set as input demonstrate in vivo use. Monte Carlo simulations of the modulated 100 MeV clinical proton beam show a significantly reduced Bragg peak. We demonstrate the feasibility of a proton beam integrated with a commercial x-ray image-guidance system for preclinical in vivo studies. To our knowledge this is the first description of an experimental image-guided proton beam for preclinical radiobiology research. It will enable in vivo investigations of radiobiological effects in proton beams.

A method to incorporate the effect of beam quality on image noise in a digitally reconstructed radiograph (DRR) based computer simulation for optimisation of digital radiography

NASA Astrophysics Data System (ADS)

Moore, Craig S.; Wood, Tim J.; Saunderson, John R.; Beavis, Andrew W.

2017-09-01

The use of computer simulated digital x-radiographs for optimisation purposes has become widespread in recent years. To make these optimisation investigations effective, it is vital simulated radiographs contain accurate anatomical and system noise. Computer algorithms that simulate radiographs based solely on the incident detector x-ray intensity (‘dose’) have been reported extensively in the literature. However, while it has been established for digital mammography that x-ray beam quality is an important factor when modelling noise in simulated images there are no such studies for diagnostic imaging of the chest, abdomen and pelvis. This study investigates the influence of beam quality on image noise in a digital radiography (DR) imaging system, and incorporates these effects into a digitally reconstructed radiograph (DRR) computer simulator. Image noise was measured on a real DR imaging system as a function of dose (absorbed energy) over a range of clinically relevant beam qualities. Simulated ‘absorbed energy’ and ‘beam quality’ DRRs were then created for each patient and tube voltage under investigation. Simulated noise images, corrected for dose and beam quality, were subsequently produced from the absorbed energy and beam quality DRRs, using the measured noise, absorbed energy and beam quality relationships. The noise images were superimposed onto the noiseless absorbed energy DRRs to create the final images. Signal-to-noise measurements in simulated chest, abdomen and spine images were within 10% of the corresponding measurements in real images. This compares favourably to our previous algorithm where images corrected for dose only were all within 20%.

Backstepping boundary control: an application to the suppression of flexible beam vibration

NASA Astrophysics Data System (ADS)

Boonkumkrong, Nipon; Asadamongkon, Pichai; Chinvorarat, Sinchai

2018-01-01

This paper presents a backstepping boundary control for vibration suppression of flexible beam. The applications are such as industrial robotic arms, space structures, etc. Most slender beams can be modelled using a shear beam. The shear beam is more complex than the conventional Euler-Bernoulli beam in that a shear deformation is additionally taken into account. At present, the application of this method in industry is rather limited, because the application of controllers to the beam is difficult. In this research, we use the shear beam with moving base as a model. The beam is cantilever type. This design method allows us to deal directly with the beam’s partial differential equations (PDEs) without resorting to approximations. An observer is used to estimate the deflections along the beam. Gain kernel of the system is calculated and then used in the control law design. The control setup is anti-collocation, i.e. a sensor is placed at the beam tip and an actuator is placed at the beam moving base. Finite difference equations are used to solve the PDEs and the partial integro-differential equations (PIDEs). Control parameters are varied to see their influences that affect the control performance. The results of the control are presented via computer simulation to verify that the control scheme is effective.

Space-Wave Routing via Surface Waves Using a Metasurface System.

PubMed

Achouri, Karim; Caloz, Christophe

2018-05-15

We introduce the concept of a metasurface system able to route space waves via surface waves. This concept may be used to laterally shift or modulate the beam width of scattered waves. The system is synthesized based on a momentum transfer approach using phase-gradient metasurfaces. The concept is experimentally verified in an "electromagnetic periscope". Additionally, we propose two other potential applications namely a beam expander and a multi-wave refractor.

Optical levitation particle delivery system for a dual beam fiber optic trap.

PubMed

Gauthier, R C; Frangioudakis, A

2000-01-01

We combine a radiation-pressure-based levitation system with a dual fiber, laser trapping system to demonstrate the potential of delivering single particles into the fiber trap. The forces versus position and the trajectory of the particle subjected to the laser beams are examined with an enhanced ray optics model. A sequence of video images taken from the experimental apparatus demonstrates the principle of particle delivery, trapping, and further manipulation.

A CMOS-MEMS clamped–clamped beam displacement amplifier for resonant switch applications

NASA Astrophysics Data System (ADS)

Liu, Jia-Ren; Lu, Shih-Chuan; Tsai, Chun-Pu; Li, Wei-Chang

2018-06-01

This paper presents a micromechanical clamped–clamped beam (CC-beam) displacement amplifier based on a CMOS-MEMS fabrication process platform. In particular, a 2.0 MHz resonant displacement amplifier composed of two identical CC-beams coupled by a mechanical beam at locations where the two beams have mismatched velocities exhibits a larger displacement, up to 9.96×, on one beam than that of the other. The displacement amplification prevents unwanted input impacting—the structure switches only to the output but not the input—required by resonant switch-based mechanical circuits (Kim et al 2009 22nd IEEE Int. Conf. on Micro Electro Mechanical Systems; Lin et al 2009 15th Int. Conf. on Solid-State Sensors, Actuators, & Microsystems (TRANSDUCERS’09) Li et al 2013 17th Int. Conf. on Solid-State Sensors, Actuators, & Microsystems (TRANSDUCERS’13)). Compared to a single CC-beam displacement amplifier, theory predicts that the displacement amplifying CC-beam array yields a larger overall output displacement for displacement gain beyond 1.13 thanks to the preserved input driving force. A complete analytical model predicts the resultant stiffness and displacement gain of the coupled CC-beam displacement amplifier that match well with finite element analysis (FEA) prediction and measured results.

Entropy studies on beam distortion by atmospheric turbulence

NASA Astrophysics Data System (ADS)

Wu, Chensheng; Ko, Jonathan; Davis, Christopher C.

2015-09-01

When a beam propagates through atmospheric turbulence over a known distance, the target beam profile deviates from the projected profile of the beam on the receiver. Intuitively, the unwanted distortion provides information about the atmospheric turbulence. This information is crucial for guiding adaptive optic systems and improving beam propagation results. In this paper, we propose an entropy study based on the image from a plenoptic sensor to provide a measure of information content of atmospheric turbulence. In general, lower levels of atmospheric turbulence will have a smaller information size while higher levels of atmospheric turbulence will cause significant expansion of the information size, which may exceed the maximum capacity of a sensing system and jeopardize the reliability of an AO system. Therefore, the entropy function can be used to analyze the turbulence distortion and evaluate performance of AO systems. In fact, it serves as a metric that can tell the improvement of beam correction in each iteration step. In addition, it points out the limitation of an AO system at optimized correction as well as the minimum information needed for wavefront sensing to achieve certain levels of correction. In this paper, we will demonstrate the definition of the entropy function and how it is related to evaluating information (randomness) carried by atmospheric turbulence.

Multipoint vibrometry with dynamic and static holograms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haist, T.; Lingel, C.; Osten, W.

2013-12-15

We report on two multipoint vibrometers with user-adjustable position of the measurement spots. Both systems are using holograms for beam deflection. The measurement is based on heterodyne interferometry with a frequency difference of 5 MHz between reference and object beam. One of the systems uses programmable positioning of the spots in the object volume but is limited concerning the light efficiency. The other system is based on static holograms in combination with mechanical adjustment of the measurement spots and does not have such a general efficiency restriction. Design considerations are given and we show measurement results for both systems. Inmore » addition, we analyze the sensitivity of the systems which is a major limitation compared to single point scanning systems.« less

Directly solar-pumped iodine laser for beamed power transmission in space

NASA Technical Reports Server (NTRS)

Choi, S. H.; Meador, W. E.; Lee, J. H.

1992-01-01

A new approach for development of a 50-kW directly solar-pumped iodine laser (DSPIL) system as a space-based power station was made using a confocal unstable resonator (CUR). The CUR-based DSPIL has advantages, such as performance enhancement, reduction of total mass, and simplicity which alleviates the complexities inherent in the previous system, master oscillator/power amplifier (MOPA) configurations. In this design, a single CUR-based DSPIL with 50-kW output power was defined and compared to the MOPA-based DSPIL. Integration of multiple modules for power requirements more than 50-kW is physically and structurally a sound approach as compared to building a single large system. An integrated system of multiple modules can respond to various mission power requirements by combining and aiming the coherent beams at the user's receiver.

Planned Experiments on the Princeton Advanced Test Stand

NASA Astrophysics Data System (ADS)

Stepanov, A.; Gilson, E. P.; Grisham, L.; Kaganovich, I.; Davidson, R. C.

2010-11-01

The Princeton Advanced Test Stand (PATS) device is an experimental facility based on the STS-100 high voltage test stand transferred from LBNL. It consists of a multicusp RF ion source, a pulsed extraction system capable of forming high-perveance 100keV ion beams, and a large six-foot-long vacuum with convenient access for beam diagnostics. This results in a flexible system for studying high perveance ion beams relevant to NDCX-I/II, including experiments on beam neutralization by ferroelectric plasma sources (FEPS) being developed at PPPL. Research on PATS will concern the basic physics of beam-plasma interactions, such as the effects of volume neutralization on beam emittance, as well as optimizing technology of the FEPS. PATS combines the advantage of an ion beam source and a large-volume plasma source in a chamber with ample access for diagnostics, resulting in a robust setup for investigating and improving relevant aspects of neutralized drift. There are also plans for running the ion source with strongly electro-negative gases such as chlorine, making it possible to extract positive or negative ion beams.

The FONT5 Bunch-by-Bunch Position and Angle Feedback System at ATF2

NASA Astrophysics Data System (ADS)

Apsimon, R. J.; Bett, D. R.; Burrows, P. N.; Christian, G. B.; Constance, B.; Davis, M. R.; Gerbershagen, A.; Perry, C.; Resta-Lopez, J.

The FONT5 upstream beam-based feedback system at ATF2 is designed to correct the position and angle jitter at the entrance to the ATF2 final-focus system, and also to demonstrate a prototype intra-train feedback system for the International Linear Collider interaction point. We discuss the hardware, from stripline BPMs to kickers, and RF and digital signal processing, as well as presenting results from the latest beam tests at ATF2.

Design and fabrication of vibration based energy harvester using microelectromechanical system piezoelectric cantilever for low power applications.

PubMed

Kim, Moonkeun; Lee, Sang-Kyun; Yang, Yil Suk; Jeong, Jaehwa; Min, Nam Ki; Kwon, Kwang-Ho

2013-12-01

We fabricated dual-beam cantilevers on the microelectromechanical system (MEMS) scale with an integrated Si proof mass. A Pb(Zr,Ti)O3 (PZT) cantilever was designed as a mechanical vibration energy-harvesting system for low power applications. The resonant frequency of the multilayer composition cantilevers were simulated using the finite element method (FEM) with parametric analysis carried out in the design process. According to simulations, the resonant frequency, voltage, and average power of a dual-beam cantilever was 69.1 Hz, 113.9 mV, and 0.303 microW, respectively, at optimal resistance and 0.5 g (gravitational acceleration, m/s2). Based on these data, we subsequently fabricated cantilever devices using dual-beam cantilevers. The harvested power density of the dual-beam cantilever compared favorably with the simulation. Experiments revealed the resonant frequency, voltage, and average power density to be 78.7 Hz, 118.5 mV, and 0.34 microW, respectively. The error between the measured and simulated results was about 10%. The maximum average power and power density of the fabricated dual-beam cantilever at 1 g were 0.803 microW and 1322.80 microW cm(-3), respectively. Furthermore, the possibility of a MEMS-scale power source for energy conversion experiments was also tested.

Real-Time Phase Correction Based on FPGA in the Beam Position and Phase Measurement System

NASA Astrophysics Data System (ADS)

Gao, Xingshun; Zhao, Lei; Liu, Jinxin; Jiang, Zouyi; Hu, Xiaofang; Liu, Shubin; An, Qi

2016-12-01

A fully digital beam position and phase measurement (BPPM) system was designed for the linear accelerator (LINAC) in Accelerator Driven Sub-critical System (ADS) in China. Phase information is obtained from the summed signals from four pick-ups of the Beam Position Monitor (BPM). Considering that the delay variations of different analog circuit channels would introduce phase measurement errors, we propose a new method to tune the digital waveforms of four channels before summation and achieve real-time error correction. The process is based on the vector rotation method and implemented within one single Field Programmable Gate Array (FPGA) device. Tests were conducted to evaluate this correction method and the results indicate that a phase correction precision better than ± 0.3° over the dynamic range from -60 dBm to 0 dBm is achieved.

Investigation of Fiber Optics Based Phased Locked Diode Lasers

NASA Technical Reports Server (NTRS)

Burke, Paul D.; Gregory, Don A.

1997-01-01

Optical power beaming requires a high intensity source and a system to address beam phase and location. A synthetic aperture array of phased locked sources can provide the necessary power levels as well as a means to correct for phase errors. A fiber optic phase modulator with a master oscillator and power amplifier (MOPA) using an injection-locking semiconductor optical amplifier has proven to be effective in correcting phase errors as large as 4pi in an interferometer system. Phase corrections with the piezoelectric fiber stretcher were made from 0 - 10 kHz, with most application oriented corrections requiring only 1 kHz. The amplifier did not lose locked power output while the phase was changed, however its performance was below expectation. Results of this investigation indicate fiber stretchers and amplifiers can be incorporated into a MOPA system to achieve successful earth based power beaming.

The dynamic micro computed tomography at SSRF

NASA Astrophysics Data System (ADS)

Chen, R.; Xu, L.; Du, G.; Deng, B.; Xie, H.; Xiao, T.

2018-05-01

Synchrotron radiation micro-computed tomography (SR-μCT) is a critical technique for quantitative characterizing the 3D internal structure of samples, recently the dynamic SR-μCT has been attracting vast attention since it can evaluate the three-dimensional structure evolution of a sample. A dynamic μCT method, which is based on monochromatic beam, was developed at the X-ray Imaging and Biomedical Application Beamline at Shanghai Synchrotron Radiation Facility, by combining the compressed sensing based CT reconstruction algorithm and hardware upgrade. The monochromatic beam based method can achieve quantitative information, and lower dose than the white beam base method in which the lower energy beam is absorbed by the sample rather than contribute to the final imaging signal. The developed method is successfully used to investigate the compression of the air sac during respiration in a bell cricket, providing new knowledge for further research on the insect respiratory system.

Lock-In Imaging System for Detecting Disturbances in Fluid

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor); Dimarcantonio, Albert L. (Inventor)

2014-01-01

A lock-in imaging system is configured for detecting a disturbance in air. The system includes an airplane, an interferometer, and a telescopic imaging camera. The airplane includes a fuselage and a pair of wings. The airplane is configured for flight in air. The interferometer is operatively disposed on the airplane and configured for producing an interference pattern by splitting a beam of light into two beams along two paths and recombining the two beams at a junction point in a front flight path of the airplane during flight. The telescopic imaging camera is configured for capturing an image of the beams at the junction point. The telescopic imaging camera is configured for detecting the disturbance in air in an optical path, based on an index of refraction of the image, as detected at the junction point.

Synthesis of neutron-rich superheavy nuclei with radioactive beams within the dinuclear system model

NASA Astrophysics Data System (ADS)

Wu, Zhi-Han; Zhu, Long; Li, Fan; Yu, Xiao-Bin; Su, Jun; Guo, Chen-Chen

2018-06-01

The production of neutron-rich superheavy nuclei with Z =105 -118 in neutron evaporation channels is investigated within the dinuclear system model. The different stable and radioactive beam-induced hot fusion reactions are studied systematically. The prospect for synthesizing neutron-rich superheavy nuclei using radioactive beams is evaluated quantitatively based on the beam intensities proposed by Argonne Tandem Linac Accelerator System [B. B. Back and C. L. Jiang, Argonne National Laboratory Report No. ANL-06/55, 2006 (unpublished)]. All possible combinations (with projectiles of Z =16 -22 and half-lives longer than 1 ms; with targets of half-lives longer than 30 days), which can be performed in available experimental equipment, for producing several unknown neutron-rich superheavy nuclei in neutron evaporation channels are investigated and the most promising reactions are predicted. It is found that the stable beams still show great advantages for producing most of superheavy nuclei. The calculated results are also compared with production cross sections in the p x n and α x n evaporation channels [Hong et al., Phys. Lett. B 764, 42 (2017), 10.1016/j.physletb.2016.11.002]. We find that the radioactive beam-induced reactions are comparable to the stable beam-induced reactions in charged particle evaporation channels. To obtain more experimental achievements, the beam intensities of modern radioactive beam facilities need to be further improved in the future.

Beam shaping for laser-based adaptive optics in astronomy.

PubMed

Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; González-Núñez, Héctor; Zúñiga, Sebastián; Escarate, Pedro; Guzman, Dani

2014-06-02

The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%.

Development of inorganic resists for electron beam lithography: Novel materials and simulations

NASA Astrophysics Data System (ADS)

Jeyakumar, Augustin

Electron beam lithography is gaining widespread utilization as the semiconductor industry progresses towards both advanced optical and non-optical lithographic technologies for high resolution patterning. The current resist technologies are based on organic systems that are imaged most commonly through chain scission, networking, or a chemically amplified polarity change in the material. Alternative resists based on inorganic systems were developed and characterized in this research for high resolution electron beam lithography and their interactions with incident electrons were investigated using Monte Carlo simulations. A novel inorganic resist imaging scheme was developed using metal-organic precursors which decompose to form metal oxides upon electron beam irradiation that can serve as inorganic hard masks for hybrid bilayer inorganic-organic imaging systems and also as directly patternable high resolution metal oxide structures. The electron beam imaging properties of these metal-organic materials were correlated to the precursor structure by studying effects such as interactions between high atomic number species and the incident electrons. Optimal single and multicomponent precursors were designed for utilization as viable inorganic resist materials for sub-50nm patterning in electron beam lithography. The electron beam imaging characteristics of the most widely used inorganic resist material, hydrogen silsesquioxane (HSQ), was also enhanced using a dual processing imaging approach with thermal curing as well as a sensitizer catalyzed imaging approach. The interaction between incident electrons and the high atomic number species contained in these inorganic resists was also studied using Monte Carlo simulations. The resolution attainable using inorganic systems as compared to organic systems can be greater for accelerating voltages greater than 50 keV due to minimized lateral scattering in the high density inorganic systems. The effects of loading nanoparticles in an electron beam resist was also investigated using a newly developed hybrid Monte Carlo approach that accounts for multiple components in a solid film. The resolution of the nanocomposite resist process was found to degrade with increasing nanoparticle loading. Finally, the electron beam patterning of self-assembled monolayers, which were found to primarily utilize backscattered electrons from the high atomic number substrate materials to form images, was also investigated and characterized. It was found that backscattered electrons limit the resolution attainable at low incident electron energies.

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators.

PubMed

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi; Minoshima, Kaoru

2013-09-01

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailed description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.

Propagation and stability characteristics of a 500-m-long laser-based fiducial line for high-precision alignment of long-distance linear accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suwada, Tsuyoshi; Satoh, Masanori; Telada, Souichi

2013-09-15

A laser-based alignment system with a He-Ne laser has been newly developed in order to precisely align accelerator units at the KEKB injector linac. The laser beam was first implemented as a 500-m-long fiducial straight line for alignment measurements. We experimentally investigated the propagation and stability characteristics of the laser beam passing through laser pipes in vacuum. The pointing stability at the last fiducial point was successfully obtained with the transverse displacements of ±40 μm level in one standard deviation by applying a feedback control. This pointing stability corresponds to an angle of ±0.08 μrad. This report contains a detailedmore » description of the experimental investigation for the propagation and stability characteristics of the laser beam in the laser-based alignment system for long-distance linear accelerators.« less

Transmission calculation and intensity suppression for a proton therapy system

NASA Astrophysics Data System (ADS)

Chen, Wei; Yang, Jun; Qin, Bin; Liang, ZhiKai; Chen, Qushan; Liu, Kaifeng; Li, Dong; Fan, Mingwu

2018-02-01

A proton therapy project HUST-PTF (HUST Proton Therapy Facility) based on a 250 MeV isochronous superconducting cyclotron is under development in Huazhong University of Science and Technology (HUST). In this paper we report the main design features of the beam line in HUST-PTF project. The energy selection system (ESS) for energy modulation is discussed in detail, including the collimators, momentum slit and transmission calculation. Due to significant difference among the transmissions of ESS for different energies, the intensity suppression scheme by defocusing beam at high energies on collimators in the beam line is proposed and discussed. Finally, the ratios of beam intensities between low and high energies are expected to be controlled within 10 to meet the clinical requirement, and the beam optics of each energy step after intensity suppression is studied respectively.

A technique for simultaneous detection of individual vortex states of Laguerre-Gaussian beams transmitted through an aqueous suspension of microparticles

NASA Astrophysics Data System (ADS)

Khonina, S. N.; Karpeev, S. V.; Paranin, V. D.

2018-06-01

A technique for simultaneous detection of individual vortex states of the beams propagating in a randomly inhomogeneous medium is proposed. The developed optical system relies on the correlation method that is invariant to the beam wandering. The intensity distribution formed at the optical system output does not require digital processing. The proposed technique based on a multi-order phase diffractive optical element (DOE) is studied numerically and experimentally. The developed detection technique is used for the analysis of Laguerre-Gaussian vortex beams propagating under conditions of intense absorption, reflection, and scattering in transparent and opaque microparticles in aqueous suspensions. The performed experimental studies confirm the relevance of the vortex phase dependence of a laser beam under conditions of significant absorption, reflection, and scattering of the light.

Spectral and spatial shaping of a laser-produced ion beam for radiation-biology experiments

NASA Astrophysics Data System (ADS)

Pommarel, L.; Vauzour, B.; Mégnin-Chanet, F.; Bayart, E.; Delmas, O.; Goudjil, F.; Nauraye, C.; Letellier, V.; Pouzoulet, F.; Schillaci, F.; Romano, F.; Scuderi, V.; Cirrone, G. A. P.; Deutsch, E.; Flacco, A.; Malka, V.

2017-03-01

The study of radiation biology on laser-based accelerators is most interesting due to the unique irradiation conditions they can produce, in terms of peak current and duration of the irradiation. In this paper we present the implementation of a beam transport system to transport and shape the proton beam generated by laser-target interaction for in vitro irradiation of biological samples. A set of four permanent magnet quadrupoles is used to transport and focus the beam, efficiently shaping the spectrum and providing a large and relatively uniform irradiation surface. Real time, absolutely calibrated, dosimetry is installed on the beam line, to enable shot-to-shot control of dose deposition in the irradiated volume. Preliminary results of cell sample irradiation are presented to validate the robustness of the full system.

Experiments with neutron-rich isomeric beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rykaczewski, K.; Grzywacz, R.; Lewitowicz, M.

1998-01-01

A review of experimental results obtained on microsecond-isomeric states in neutron-rich nuclei produced in fragmentation reactions and studied with SISSI-Alpha-LISE3 spectrometer system at GANIL Caen is given. The perspectives of experiments based on secondary reactions with isomeric beams are presented.

Portable Electron-Beam Free-Form Fabrication System

NASA Technical Reports Server (NTRS)

Watson, J. Kevin; Petersen, Daniel D.; Taminger, Karen M.; Hafley, Robert A.

2005-01-01

A portable electron-beam free-form fabrication (EB F3) system, now undergoing development, is intended to afford a capability for manufacturing metal parts in nearly net sizes and shapes. Although the development effort is oriented toward the eventual use of systems like this one to supply spare metal parts aboard spacecraft in flight, the basic system design could also be adapted to terrestrial applications in which there are requirements to supply spare parts on demand at locations remote from warehouses and conventional manufacturing facilities. Prior systems that have been considered for satisfying the same requirements (including prior free-form fabrication systems) are not easily portable because of their bulk and massive size. The mechanical properties of the components that such systems produce are often inferior to the mechanical properties of the corresponding original, conventionally fabricated components. In addition, the prior systems are not efficient in the utilization of energy and of feedstock. In contrast, the present developmental system is designed to be sufficiently compact and lightweight to be easily portable, to utilize both energy and material more efficiently, and to produce components that have mechanical properties approximating those of the corresponding original components. The developmental EB F3 system will include a vacuum chamber and associated vacuum pumps, an electron-beam gun and an associated power supply, a multiaxis positioning subsystem, a precise wire feeder, and an instrumentation system for monitoring and control. The electron-beam gun, positioning subsystem, and wire feeder will be located inside the vacuum chamber (see figure). The electron beam gun and the wire feeder will be mounted in fixed positions inside the domed upper portion of the vacuum chamber. The positioning subsystem and ports for the vacuum pumps will be located on a base that could be dropped down to provide full access to the interior of the chamber when not under vacuum. During operation, wire will be fed to a fixed location, entering the melted pool created by the electron beam. Heated by the electron beam, the wire will melt and fuse to either the substrate or with the previously deposited metal wire fused on top of the positioning table. Based on a computer aided design (CAD) model and controlled by a computer, the positioning subsystem

The pixel tracking telescope at the Fermilab Test Beam Facility

DOE PAGES

Kwan, Simon; Lei, CM; Menasce, Dario; ...

2016-03-01

An all silicon pixel telescope has been assembled and used at the Fermilab Test Beam Facility (FTBF) since 2009 to provide precise tracking information for different test beam experiments with a wide range of Detectors Under Test (DUTs) requiring high resolution measurement of the track impact point. The telescope is based on CMS pixel modules left over from the CMS forward pixel production. Eight planes are arranged to achieve a resolution of less than 8 μm on the 120 GeV proton beam transverse coordinate at the DUT position. In order to achieve such resolution with 100 × 150 μm 2more » pixel cells, the planes were tilted to 25 degrees to maximize charge sharing between pixels. Crucial for obtaining this performance is the alignment software, called Monicelli, specifically designed and optimized for this system. This paper will describe the telescope hardware, the data acquisition system and the alignment software constituting this particle tracking system for test beam users.« less

Green high-power tunable external-cavity GaN diode laser at 515  nm.

PubMed

Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

2016-09-15

A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

Ion source development for a photoneutralization based NBI system for fusion reactors

NASA Astrophysics Data System (ADS)

Simonin, A.; de Esch, H. P. L.; Garibaldi, P.; Grand, C.; Bechu, S.; Bès, A.; Lacoste, A.

2015-04-01

The next step after ITER is to demonstrate the viability and generation of electricity by a future fusion reactor (DEMO). The specifications required to operate an NBI system on DEMO are very demanding. The system has to provide a very high level of power and energy, ~100MW of D° beam at 1MeV, including high wall-plug efficiency (η > 60%). For this purpose, a new injector concept, called Siphore, is under investigation between CEA and French universities. Siphore is based on the stripping of the accelerated negative ions by photo-detachment provided by several Fabry-Perot cavities (3.5MW of light power per cavity) implemented along the D- beam. The beamline is designed to be tall and narrow in order that the photon flux overlaps the entire negative ion beam. The paper will describe the present R&D at CEA which addresses the development of an ion source and pre-accelerator prototypes for Siphore, the main goal being to produce an intense negative ion beam sheet. The negative ion source Cybele is based on a magnetized plasma column where hot electrons are emitted from the source center. Parametric studies of the source are performed using Langmuir probes in order to characterize the plasma and to compare with numerical models being developed in French universities.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

PubMed

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-12-16

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection

PubMed Central

Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

2016-01-01

In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering. PMID:27999245

Optimal design of a beam-based dynamic vibration absorber using fixed-points theory

NASA Astrophysics Data System (ADS)

Hua, Yingyu; Wong, Waion; Cheng, Li

2018-05-01

The addition of a dynamic vibration absorber (DVA) to a vibrating structure could provide an economic solution for vibration suppressions if the absorber is properly designed and located onto the structure. A common design of the DVA is a sprung mass because of its simple structure and low cost. However, the vibration suppression performance of this kind of DVA is limited by the ratio between the absorber mass and the mass of the primary structure. In this paper, a beam-based DVA (beam DVA) is proposed and optimized for minimizing the resonant vibration of a general structure. The vibration suppression performance of the proposed beam DVA depends on the mass ratio, the flexural rigidity and length of the beam. In comparison with the traditional sprung mass DVA, the proposed beam DVA shows more flexibility in vibration control design because it has more design parameters. With proper design, the beam DVA's vibration suppression capability can outperform that of the traditional DVA under the same mass constraint. The general approach is illustrated using a benchmark cantilever beam as an example. The receptance theory is introduced to model the compound system consisting of the host beam and the attached beam-based DVA. The model is validated through comparisons with the results from Abaqus as well as the Transfer Matrix method (TMM) method. Fixed-points theory is then employed to derive the analytical expressions for the optimum tuning ratio and damping ratio of the proposed beam absorber. A design guideline is then presented to choose the parameters of the beam absorber. Comparisons are finally presented between the beam absorber and the traditional DVA in terms of the vibration suppression effect. It is shown that the proposed beam absorber can outperform the traditional DVA by following this proposed guideline.

Diffraction-based optical correlator

NASA Technical Reports Server (NTRS)

Spremo, Stevan M. (Inventor); Fuhr, Peter L. (Inventor); Schipper, John F. (Inventor)

2005-01-01

Method and system for wavelength-based processing of a light beam. A light beam, produced at a chemical or physical reaction site and having at least first and second wavelengths, ?1 and ?2, is received and diffracted at a first diffraction grating to provide first and second diffracted beams, which are received and analyzed in terms of wavelength and/or time at two spaced apart light detectors. In a second embodiment, light from first and second sources is diffracted and compared in terms of wavelength and/or time to determine if the two beams arise from the same source. In a third embodiment, a light beam is split and diffracted and passed through first and second environments to study differential effects. In a fourth embodiment, diffracted light beam components, having first and second wavelengths, are received sequentially at a reaction site to determine whether a specified reaction is promoted, based on order of receipt of the beams. In a fifth embodiment, a cylindrically shaped diffraction grating (uniform or chirped) is rotated and translated to provide a sequence of diffracted beams with different wavelengths. In a sixth embodiment, incident light, representing one or more symbols, is successively diffracted from first and second diffraction gratings and is received at different light detectors, depending upon the wavelengths present in the incident light.

Level crossing statistics for optical beam wander in a turbulent atmosphere with applications to ground-to-space laser communications.

PubMed

Yura, Harold T; Fields, Renny A

2011-06-20

Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.

CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry

NASA Astrophysics Data System (ADS)

Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J.; Winograd, Nicholas

2016-09-01

The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure.

Full-Duplex Digital Communication on a Single Laser Beam

NASA Technical Reports Server (NTRS)

Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

2006-01-01

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Production of an 15O beam using a stable oxygen ion beam for in-beam PET imaging

NASA Astrophysics Data System (ADS)

Mohammadi, Akram; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

2017-03-01

In advanced ion therapy, the 15O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an 15O beam by projectile fragmentation of a stable 16O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors' group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of 15O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of 15O fragments. The highest production rate of 15O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the 16O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the 15O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the 16O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is sufficiently high. In-beam PET imaging was also performed for all produced beams using the OpenPET system. The purity improvement of the produced 15O beams was confirmed from the PET images.

Comparison-based optical study on a point-line-coupling-focus system with linear Fresnel heliostats.

PubMed

Dai, Yanjun; Li, Xian; Zhou, Lingyu; Ma, Xuan; Wang, Ruzhu

2016-05-16

Concentrating the concept of a beam-down solar tower with linear Fresnel heliostat (PLCF) is one of the feasible choices and has great potential in reducing spot size and improving optical efficiency. Optical characteristics of a PLCF system with the hyperboloid reflector are introduced and investigated theoretically. Taking into account solar position and optical surface errors, a Monte Carlo ray-tracing (MCRT) analysis model for a PLCF system is developed and applied in a comparison-based study on the optical performance between the PLCF system and the conventional beam-down solar tower system with flat and spherical heliostats. The optimal square facet of linear Fresnel heliostat is also proposed for matching with the 3D-CPC receiver.

Visualization of the influence of the air conditioning system to the high-power laser beam quality with the modulation coherent imaging method.

PubMed

Tao, Hua; Veetil, Suhas P; Pan, Xingchen; Liu, Cheng; Zhu, Jianqiang

2015-08-01

Air conditioning systems can lead to dynamic phase change in the laser beams of high-power laser facilities for the inertial confinement fusion, and this kind of phase change cannot be measured by most of the commonly employed Hartmann wavefront sensor or interferometry due to some uncontrollable factors, such as too large laser beam diameters and the limited space of the facility. It is demonstrated that this problem can be solved using a scheme based on modulation coherent imaging, and thus the influence of the air conditioning system on the performance of the high-power facility can be evaluated directly.

Next Generation H- Ion Sources for the SNS

NASA Astrophysics Data System (ADS)

Welton, R. F.; Stockli, M. P.; Murray, S. N.; Crisp, D.; Carmichael, J.; Goulding, R. H.; Han, B.; Tarvainen, O.; Pennisi, T.; Santana, M.

2009-03-01

The U.S. Spallation Neutron Source (SNS) is the leading accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to insure meeting operational requirements as well as providing for future facility beam power upgrades, a multifaceted H- ion source development program is ongoing. This work discusses several aspects of this program, specifically the design and first beam measurements of an RF-driven, external antenna H- ion source based on an A1N ceramic plasma chamber, elemental and chromate Cs-systems, and plasma ignition gun. Unanalyzed beam currents of up to ˜100 mA (60 Hz, 1 ms) have been observed and sustained currents >60 mA (60 Hz, 1 ms) have been demonstrated on the test stand. Accelerated beam currents of ˜40 mA have also been demonstrated into the SNS front end. Data are also presented describing the first H- beam extraction experiments from a helicon plasma generator based on the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine design.

AlGaSb Buffer Layers for Sb-Based Transistors

DTIC Science & Technology

2010-01-01

transistor ( HEMT ), molecular beam epitaxy (MBE), field-effect transistor (FET), buffer layer INTRODUCTION High-electron-mobility transistors ( HEMTs ) with InAs...monolayers/s. The use of thinner buffer layers reduces molecular beam epitaxial growth time and source consumption. The buffer layers also exhibit...source. In addition, some of the flux from an Sb cell in a molecular beam epitaxy (MBE) system will deposit near the mouth of the cell, eventually

Voltage sensing systems and methods for passive compensation of temperature related intrinsic phase shift

DOEpatents

Davidson, James R.; Lassahn, Gordon D.

2001-01-01

A small sized electro-optic voltage sensor capable of accurate measurement of high levels of voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation into the sensor. A polarization beam displacer serves as a filter to separate the input beam into two beams with orthogonal linear polarizations. The beam displacer is oriented in such a way as to rotate the linearly polarized beams such that they enter a Pockels crystal at a preferred angle of 45 degrees. The beam displacer is therefore capable of causing a linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels electro-optic effect induces a differential phase shift on the major and minor axes of the input beam as it travels through the Pockels crystal, which causes the input beam to be elliptically polarized. A reflecting prism redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization representing the major and minor axes. In crystals that introduce a phase differential attributable to temperature, a compensating crystal is provided to cancel the effect of temperature on the phase differential of the input beam. The system may include a detector for converting the output beams into electrical signals, and a signal processor for determining the voltage based on an analysis of the output beams. The output beams are amplitude modulated by the frequency of the electric field and the amplitude of the output beams is proportional to the magnitude of the electric field, which is related to the voltage being measured.

WE-DE-BRA-11: A Study of Motion Tracking Accuracy of Robotic Radiosurgery Using a Novel CCD Camera Based End-To-End Test System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L; M Yang, Y; Nelson, B

Purpose: A novel end-to-end test system using a CCD camera and a scintillator based phantom (XRV-124, Logos Systems Int’l) capable of measuring the beam-by-beam delivery accuracy of Robotic Radiosurgery (CyberKnife) was developed and reported in our previous work. This work investigates its application in assessing the motion tracking (Synchrony) accuracy for CyberKnife. Methods: A QA plan with Anterior and Lateral beams (with 4 different collimator sizes) was created (Multiplan v5.3) for the XRV-124 phantom. The phantom was placed on a motion platform (superior and inferior movement), and the plans were delivered on the CyberKnife M6 system using four motion patterns:more » static, Sine- wave, Sine with 15° phase shift, and a patient breathing pattern composed of 2cm maximum motion with 4 second breathing cycle. Under integral recording mode, the time-averaged beam vectors (X, Y, Z) were measured by the phantom and compared with static delivery. In dynamic recording mode, the beam spots were recorded at a rate of 10 frames/second. The beam vector deviation from average position was evaluated against the various breathing patterns. Results: The average beam position of the six deliveries with no motion and three deliveries with Synchrony tracking on ideal motion (sinewave without phase shift) all agree within −0.03±0.00 mm, 0.10±0.04, and 0.04±0.03 in the X, Y, and X directions. Radiation beam width (FWHM) variations are within ±0.03 mm. Dynamic video record showed submillimeter tracking stability for both regular and irregular breathing pattern; however the tracking error up to 3.5 mm was observed when a 15 degree phase shift was introduced. Conclusion: The XRV-124 system is able to provide 3D and 4D targeting accuracy for CyberKnife delivery with Synchrony. The experimental results showed sub-millimeter delivery in phantom with excellent correlation in target to breathing motion. The accuracy was degraded when irregular motion and phase shift was introduced.« less

The Closed Orbit Measurement System at the DELTA Synchrotron Radiation Facility And First Investigations Concerning the Installation of a Beam Based BPM Calibration System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jankowiak, A.; Wille, K.; /Dortmund U. /SLAC

2011-08-25

For a synchrotron radiation source it is necessary to operate a monitoring system to determine the beam position with high resolution and accuracy with respect to the axis of the quadrupole magnets. In this paper the present closed orbit measurement system of the DELTA SR-Facility, concerning the hardware setup, data processing and the calibration methods, will be presented. The results of the calibration measurements and the recent operating experience will be discussed. These results show, that the system is close to the design resolution. But the BPM offsets with respect to the magnetic center of the quadrupole magnets turn outmore » to be not acceptable. For some BPMs they are in the order of several 100 micro m. Therefore it was decided to install a beam based BPM calibration system in the near future . This system should allow to determine the BPM offsets relative to the center of the quadrupole magnets for all 40 BPMs. It is planned to install a system in order to change the focussing strength of each quadrupole individually either in a static or dynamic way.« less

Shaping propagation invariant laser beams

NASA Astrophysics Data System (ADS)

Soskind, Michael; Soskind, Rose; Soskind, Yakov

2015-11-01

Propagation-invariant structured laser beams possess several unique properties and play an important role in various photonics applications. The majority of propagation invariant beams are produced in the form of laser modes emanating from stable laser cavities. Therefore, their spatial structure is limited by the intracavity mode formation. We show that several types of anamorphic optical systems (AOSs) can be effectively employed to shape laser beams into a variety of propagation invariant structured fields with different shapes and phase distributions. We present a propagation matrix approach for designing AOSs and defining mode-matching conditions required for preserving propagation invariance of the output shaped fields. The propagation matrix approach was selected, as it provides a more straightforward approach in designing AOSs for shaping propagation-invariant laser beams than the alternative technique based on the Gouy phase evolution, especially in the case of multielement AOSs. Several practical configurations of optical systems that are suitable for shaping input laser beams into a diverse variety of structured propagation invariant laser beams are also presented. The laser beam shaping approach was applied by modeling propagation characteristics of several input laser beam types, including Hermite-Gaussian, Laguerre-Gaussian, and Ince-Gaussian structured field distributions. The influence of the Ince-Gaussian beam semifocal separation parameter and the azimuthal orientation between the input laser beams and the AOSs onto the resulting shape of the propagation invariant laser beams is presented as well.

A technique for measurement of material damping in metals. [absorption of structural vibration

NASA Technical Reports Server (NTRS)

Heine, J. C.

1976-01-01

The paper outlines the theory, design, and application of an apparatus based on the single beam resonant dwell technique to determine the damping capacity of metallic materials by measuring the response of a structural element to excitation at a modal frequency. In this apparatus, a cantilever beam specimen of a test material is clamped to a bar which is connected at one end to an electromagnetic shaker and at the other to a heavy base. The thickness of the bar at the base end is reduced by two saw cuts to provide a pivot around which the remainder of the bar can rotate when excited by the shaker which is connected to the bar by a rod passing through a hole in the base. The response of the supporting system to shaker excitation is measured with an accelerometer mounted on the bar at the root of the specimen. Specimen response is measured optically with a low-power microscope with a reticle. Specimen loss factor is determined in terms of acceleration at the beam root, beam tip displacement, and the beam natural frequency.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanehira, T; Sutherland, K; Matsuura, T

Purpose: To evaluate density inhomogeneities which can effect dose distributions for real-time image gated spot-scanning proton therapy (RGPT), a dose calculation system, using treatment planning system VQA (Hitachi Ltd., Tokyo) spot position data, was developed based on Geant4. Methods: A Geant4 application was developed to simulate spot-scanned proton beams at Hokkaido University Hospital. A CT scan (0.98 × 0.98 × 1.25 mm) was performed for prostate cancer treatment with three or four inserted gold markers (diameter 1.5 mm, volume 1.77 mm3) in or near the target tumor. The CT data was read into VQA. A spot scanning plan was generatedmore » and exported to text files, specifying the beam energy and position of each spot. The text files were converted and read into our Geant4-based software. The spot position was converted into steering magnet field strength (in Tesla) for our beam nozzle. Individual protons were tracked from the vacuum chamber, through the helium chamber, steering magnets, dose monitors, etc., in a straight, horizontal line. The patient CT data was converted into materials with variable density and placed in a parametrized volume at the isocenter. Gold fiducial markers were represented in the CT data by two adjacent voxels (volume 2.38 mm3). 600,000 proton histories were tracked for each target spot. As one beam contained about 1,000 spots, approximately 600 million histories were recorded for each beam on a blade server. Two plans were considered: two beam horizontal opposed (90 and 270 degree) and three beam (0, 90 and 270 degree). Results: We are able to convert spot scanning plans from VQA and simulate them with our Geant4-based code. Our system can be used to evaluate the effect of dose reduction caused by gold markers used for RGPT. Conclusion: Our Geant4 application is able to calculate dose distributions for spot scanned proton therapy.« less

Dual-beam laser autofocusing system based on liquid lens

NASA Astrophysics Data System (ADS)

Zhang, Fumin; Yao, Yannan; Qu, Xinghua; Zhang, Tong; Pei, Bing

2017-02-01

A dual-beam laser autofocusing system is designed in this paper. The autofocusing system is based on a liquid lens with less moving parts and fast response time, which makes the system simple, reliable, compact and fast. A novel scheme ;Time-sharing focus, fast conversion; is innovatively proposed. The scheme effectively solves the problem that the guiding laser and the working laser cannot focus at the same target point because of the existence of chromatic aberration. This scheme not only makes both guiding laser and working laser achieve optimal focusing in guiding stage and working stage respectively, but also greatly reduces the system complexity and simplifies the focusing process as well as makes autofocusing time of the working laser reduce to about 10 ms. In the distance range of 1 m to 30 m, the autofocusing spot size is kept under 4.3 mm at 30 m and just 0.18 mm at 1 m. The spot size is much less influenced by the target distance compared with the collimated laser with a micro divergence angle for its self-adaptivity. The dual-beam laser autofocusing system based on liquid lens is fully automatic, compact and efficient. It is fully meet the need of dynamicity and adaptivity and it will play an important role in a number of long-range control applications.

SU-E-T-781: Using An Electronic Portal Imaging Device (EPID) for Correlating Linac Photon Beam Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaddanapudi, S; Cai, B; Sun, B

2015-06-15

Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful for measuring several parameters of interest in linear accelerator (linac) quality assurance (QA). The purpose of this project was to evaluate the feasibility of using EPIDs for determining linac photon beam energies. Methods: Two non-clinical Varian TrueBeam linacs (Varian Medical Systems, Palo Alto, CA) with 6MV and 10MV photon beams were used to perform the measurements. The linacs were equipped with an amorphous silicon based EPIDs (aSi1000) that were used for the measurements. We compared the use of flatness versus percent depth dose (PDD) for predicting changes in linacmore » photon beam energy. PDD was measured in 1D water tank (Sun Nuclear Corporation, Melbourne FL) and the profiles were measured using 2D ion-chamber array (IC-Profiler, Sun Nuclear) and the EPID. Energy changes were accomplished by varying the bending magnet current (BMC). The evaluated energies conformed with the AAPM TG142 tolerance of ±1% change in PDD. Results: BMC changes correlating with a ±1% change in PDD corresponded with a change in flatness of ∼1% to 2% from baseline values on the EPID. IC Profiler flatness values had the same correlation. We observed a similar trend for the 10MV beam energy changes. Our measurements indicated a strong correlation between changes in linac photon beam energy and changes in flatness. For all machines and energies, beam energy changes produced change in the uniformity (AAPM TG-142), varying from ∼1% to 2.5%. Conclusions: EPID image analysis of beam profiles can be used to determine linac photon beam energy changes. Flatness-based metrics or uniformity as defined by AAPM TG-142 were found to be more sensitive to linac photon beam energy changes than PDD. Research funding provided by Varian Medical Systems. Dr. Sasa Mutic receives compensation for providing patient safety training services from Varian Medical Systems, the sponsor of this study.« less

SU-F-T-214: Re-Thinking the Useful Clinical Beam Energy in Proton Therapy: An Opportunity for Cost Reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bentefour, El H; Lu, H

Purpose: We conducted a retrospective study of the useful clinical proton beam energy based on the beam range data of patients treated over the last 10 years at Massachusetts General Hospital Proton Therapy Center. Methods: Treatment field information were collected for all patients treated over the last 10 years (2005–2015) in the two gantry treatment rooms at MGH. The beam ranges for these fields were retrieved and categorized per treatment site. The 10 prostate patients that required the highest beam range (lateral fields) were selected. For these patients, anterior oblique beams (30–40 degrees) were simulated in a planning system tomore » obtain the required beam ranges including the margins for potential range uncertainties. Results: There were a total of 4033 patients, treated with combined total of 23603 fields. All treatment indications were considered with the exception of ocular tumors generally treated in a fixed beam room. For all non-prostate treatments (21811 fields), only 5 fields for 4 patients (1-pancreas, 1-lumbar chordoma, 2-spine mets) required beam range greater than 25 cm. There were 446 prostate patients (1792 fields), with the required beam range from 22.3 to 29.0 cm; 386 of them had at least one of their lateral beam range greater than 25 cm. For the 10 prostate patients with highest lateral beam ranges (26 to 29 cm), their treatment with anterior oblique beams would drop the beam ranges below 25 cm (17.3 to 18.5 cm). Conclusion: if prostate patients are treated with anterior fields only, the useful maximum beam range is reduced to 25 cm. Thus a proton therapy system with maximum beam energy of 196 MeV is sufficient to treat all tumors sites with very rare exceptions (<0.1%). Designing such PT system would reduce the cost of proton therapy for hospitals and patients and increase the accessibility to the treatment.« less

Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy.

PubMed

Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R

2014-04-01

Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without breaking vacuum, and convenient visual access to the sample and tip inside a superconducting magnet cryostat. A sample/tip handling system is optimized for both the molecular beam epitaxy growth system and the scanning tunneling microscope system. The sample/tip handing system enables in situ STM studies on epitaxially grown samples, and tip exchange in the superconducting magnet cryostat. The hybrid molecular beam epitaxy and low temperature scanning tunneling microscopy system is capable of growing semiconductor-based hetero-structures with controlled accuracy down to a single atomic-layer and imaging them down to atomic resolution.

Interference, focusing and excitation of ultracold atoms

NASA Astrophysics Data System (ADS)

Kandes, M. C.; Fahy, B. M.; Williams, S. R.; Tally, C. H., IV; Bromley, M. W. J.

2011-05-01

One of the pressing technological challenges in atomic physics is to go orders-of-magnitude beyond the limits of photon-based optics by harnessing the wave-nature of dilute clouds of ultracold atoms. We have developed parallelised algorithms to perform numerical calculations of the Gross-Pitaevskii equation in up to three dimensions and with up to three components to simulate Bose-Einstein condensates. A wide-ranging array of the physics associated with atom optics-based systems will be presented including BEC-based Sagnac interferometry in circular waveguides, the focusing of BECs using Laguerre-Gauss beams, and the interactions between BECs and Ince-Gaussian laser beams and their potential applications. One of the pressing technological challenges in atomic physics is to go orders-of-magnitude beyond the limits of photon-based optics by harnessing the wave-nature of dilute clouds of ultracold atoms. We have developed parallelised algorithms to perform numerical calculations of the Gross-Pitaevskii equation in up to three dimensions and with up to three components to simulate Bose-Einstein condensates. A wide-ranging array of the physics associated with atom optics-based systems will be presented including BEC-based Sagnac interferometry in circular waveguides, the focusing of BECs using Laguerre-Gauss beams, and the interactions between BECs and Ince-Gaussian laser beams and their potential applications. Performed on computational resources via NSF grants PHY-0970127, CHE-0947087 and DMS-0923278.

Optical Amplifier Based Space Solar Power

NASA Technical Reports Server (NTRS)

Fork, Richard L.

2001-01-01

The objective was to design a safe optical power beaming system for use in space. Research was focused on identification of strategies and structures that would enable achievement near diffraction limited optical beam quality, highly efficient electrical to optical conversion, and high average power in combination in a single system. Efforts centered on producing high efficiency, low mass of the overall system, low operating temperature, precision pointing and tracking capability, compatibility with useful satellite orbits, component and system reliability, and long component and system life in space. A system based on increasing the power handled by each individual module to an optimum and the number of modules in the complete structure was planned. We were concerned with identifying the most economical and rapid path to commercially viable safe space solar power.

An alternative model for a partially coherent elliptical dark hollow beam

NASA Astrophysics Data System (ADS)

Li, Xu; Wang, Fei; Cai, Yangjian

2011-04-01

An alternative theoretical model named partially coherent hollow elliptical Gaussian beam (HEGB) is proposed to describe a partially coherent beam with an elliptical dark hollow profile. Explicit expression for the propagation factors of a partially coherent HEGB is derived. Based on the generalized Collins formula, analytical formulae for the cross-spectral density and mean-squared beam width of a partially coherent HEGB, propagating through a paraxial ABCD optical system, are derived. Propagation properties of a partially coherent HEGB in free space are studied as a numerical example.

Miniature drag-force anemometer

NASA Technical Reports Server (NTRS)

Krause, L. N.; Fralick, G. C.

1981-01-01

A miniature drag force anemometer is described which is capable of measuring unsteady as well as steady state velocity head and flow direction. It consists of a cantilevered beam with strain gages located at the base of the beam as the force measuring element. The dynamics of the beam are like those of lightly damped second order system with a natural frequency as high as 40 kilohertz depending on beam geometry and material. The anemometer is used in both forward and reversed flow. Anemometer characteristics and several designs are presented along with discussions of several applications.

Compact beam transport system for free-electron lasers driven by a laser plasma accelerator

DOE PAGES

Liu, Tao; Zhang, Tong; Wang, Dong; ...

2017-02-01

Utilizing laser-driven plasma accelerators (LPAs) as a high-quality electron beam source is a promising approach to significantly downsize the x-ray free-electron laser (XFEL) facility. A multi-GeV LPA beam can be generated in several-centimeter acceleration distance, with a high peak current and a low transverse emittance, which will considerably benefit a compact FEL design. However, the large initial angular divergence and energy spread make it challenging to transport the beam and realize FEL radiation. In this paper, a novel design of beam transport system is proposed to maintain the superior features of the LPA beam and a transverse gradient undulator (TGU)more » is also adopted as an effective energy spread compensator to generate high-brilliance FEL radiation. As a result, theoretical analysis and numerical simulations are presented based on a demonstration experiment with an electron energy of 380 MeV and a radiation wavelength of 30 nm.« less

Propagation stability of self-reconstructing Bessel beams enables contrast-enhanced imaging in thick media.

PubMed

Fahrbach, Florian O; Rohrbach, Alexander

2012-01-17

Laser beams that can self-reconstruct their initial beam profile even in the presence of massive phase perturbations are able to propagate deeper into inhomogeneous media. This ability has crucial advantages for light sheet-based microscopy in thick media, such as cell clusters, embryos, skin or brain tissue or plants, as well as scattering synthetic materials. A ring system around the central intensity maximum of a Bessel beam enables its self-reconstruction, but at the same time illuminates out-of-focus regions and deteriorates image contrast. Here we present a detection method that minimizes the negative effect of the ring system. The beam's propagation stability along one straight line enables the use of a confocal line principle, resulting in a significant increase in image contrast. The axial resolution could be improved by nearly 100% relative to the standard light-sheet techniques using scanned Gaussian beams, while demonstrating self-reconstruction also for high propagation depths.

Grey signal processing and data reconstruction in the non-diffracting beam triangulation measurement system

NASA Astrophysics Data System (ADS)

Meng, Hao; Wang, Zhongyu; Fu, Jihua

2008-12-01

The non-diffracting beam triangulation measurement system possesses the advantages of longer measurement range, higher theoretical measurement accuracy and higher resolution over the traditional laser triangulation measurement system. Unfortunately the measurement accuracy of the system is greatly degraded due to the speckle noise, the CCD photoelectric noise and the background light noise in practical applications. Hence, some effective signal processing methods must be applied to improve the measurement accuracy. In this paper a novel effective method for removing the noises in the non-diffracting beam triangulation measurement system is proposed. In the method the grey system theory is used to process and reconstruct the measurement signal. Through implementing the grey dynamic filtering based on the dynamic GM(1,1), the noises can be effectively removed from the primary measurement data and the measurement accuracy of the system can be improved as a result.

Application Research of Horn Array Multi-Beam Antenna in Reference Source System for Satellite Interference Location

NASA Astrophysics Data System (ADS)

Zhou, Ping; Lin, Hui; Zhang, Qi

2018-01-01

The reference source system is a key factor to ensure the successful location of the satellite interference source. Currently, the traditional system used a mechanical rotating antenna which leaded to the disadvantages of slow rotation and high failure-rate, which seriously restricted the system’s positioning-timeliness and became its obvious weaknesses. In this paper, a multi-beam antenna scheme based on the horn array was proposed as a reference source for the satellite interference location, which was used as an alternative to the traditional reference source antenna. The new scheme has designed a small circularly polarized horn antenna as an element and proposed a multi-beamforming algorithm based on planar array. Moreover, the simulation analysis of horn antenna pattern, multi-beam forming algorithm and simulated satellite link cross-ambiguity calculation have been carried out respectively. Finally, cross-ambiguity calculation of the traditional reference source system has also been tested. The comparison between the results of computer simulation and the actual test results shows that the scheme is scientific and feasible, obviously superior to the traditional reference source system.

Optimization of GATE and PHITS Monte Carlo code parameters for uniform scanning proton beam based on simulation with FLUKA general-purpose code

NASA Astrophysics Data System (ADS)

Kurosu, Keita; Takashina, Masaaki; Koizumi, Masahiko; Das, Indra J.; Moskvin, Vadim P.

2014-10-01

Although three general-purpose Monte Carlo (MC) simulation tools: Geant4, FLUKA and PHITS have been used extensively, differences in calculation results have been reported. The major causes are the implementation of the physical model, preset value of the ionization potential or definition of the maximum step size. In order to achieve artifact free MC simulation, an optimized parameters list for each simulation system is required. Several authors have already proposed the optimized lists, but those studies were performed with a simple system such as only a water phantom. Since particle beams have a transport, interaction and electromagnetic processes during beam delivery, establishment of an optimized parameters-list for whole beam delivery system is therefore of major importance. The purpose of this study was to determine the optimized parameters list for GATE and PHITS using proton treatment nozzle computational model. The simulation was performed with the broad scanning proton beam. The influences of the customizing parameters on the percentage depth dose (PDD) profile and the proton range were investigated by comparison with the result of FLUKA, and then the optimal parameters were determined. The PDD profile and the proton range obtained from our optimized parameters list showed different characteristics from the results obtained with simple system. This led to the conclusion that the physical model, particle transport mechanics and different geometry-based descriptions need accurate customization in planning computational experiments for artifact-free MC simulation.

Laser beam shaping for biomedical microscopy techniques

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Kaiser, Peter; Laskin, Vadim; Ostrun, Aleksei

2016-04-01

Uniform illumination of a working field is very important in optical systems of confocal microscopy and various implementations of fluorescence microscopy like TIR, SSIM, STORM, PALM to enhance performance of these laser-based research techniques. Widely used TEM00 laser sources are characterized by essentially non-uniform Gaussian intensity profile which leads usually to non-uniform intensity distribution in a microscope working field or in a field of microlenses array of a confocal microscope optical system, this non-uniform illumination results in instability of measuring procedure and reducing precision of quantitative measurements. Therefore transformation of typical Gaussian distribution of a TEM00 laser to flat-top (top hat) profile is an actual technical task, it is solved by applying beam shaping optics. Due to high demands to optical image quality the mentioned techniques have specific requirements to a uniform laser beam: flatness of phase front and extended depth of field, - from this point of view the microscopy techniques are similar to holography and interferometry. There are different refractive and diffractive beam shaping approaches used in laser industrial and scientific applications, but only few of them are capable to fulfil the optimum conditions for beam quality required in discussed microscopy techniques. We suggest applying refractive field mapping beam shapers πShaper, which operational principle presumes almost lossless transformation of Gaussian to flat-top beam with flatness of output wavefront, conserving of beam consistency, providing collimated low divergent output beam, high transmittance, extended depth of field, negligible wave aberration, and achromatic design provides capability to work with several lasers with different wavelengths simultaneously. The main function of a beam shaper is transformation of laser intensity profile, further beam transformation to provide optimum for a particular technique spot size and shape has to be realized by an imaging optical system which can include microscope objectives and tube lenses. This paper will describe design basics of refractive beam shapers and optical layouts of their applying in microscopy systems. Examples of real implementations and experimental results will be presented as well.

Recent advances in automatic alignment system for the National Ignition Facility

NASA Astrophysics Data System (ADS)

Wilhelmsen, Karl; Awwal, Abdul A. S.; Kalantar, Dan; Leach, Richard; Lowe-Webb, Roger; McGuigan, David; Miller Kamm, Vicki

2011-03-01

The automatic alignment system for the National Ignition Facility (NIF) is a large-scale parallel system that directs all 192 laser beams along the 300-m optical path to a 50-micron focus at target chamber in less than 50 minutes. The system automatically commands 9,000 stepping motors to adjust mirrors and other optics based upon images acquired from high-resolution digital cameras viewing beams at various locations. Forty-five control loops per beamline request image processing services running on a LINUX cluster to analyze these images of the beams and references, and automatically steer the beams toward the target. This paper discusses the upgrades to the NIF automatic alignment system to handle new alignment needs and evolving requirements as related to various types of experiments performed. As NIF becomes a continuously-operated system and more experiments are performed, performance monitoring is increasingly important for maintenance and commissioning work. Data, collected during operations, is analyzed for tuning of the laser and targeting maintenance work. Handling evolving alignment and maintenance needs is expected for the planned 30-year operational life of NIF.

A high brightness proton injector for the Tandetron accelerator at Jožef Stefan Institute

NASA Astrophysics Data System (ADS)

Pelicon, Primož; Podaru, Nicolae C.; Vavpetič, Primož; Jeromel, Luka; Ogrinc Potocnik, Nina; Ondračka, Simon; Gottdang, Andreas; Mous, Dirk J. M.

2014-08-01

Jožef Stefan Institute recently commissioned a high brightness H- ion beam injection system for its existing tandem accelerator facility. Custom developed by High Voltage Engineering Europa, the multicusp ion source has been tuned to deliver at the entrance of the Tandetron™ accelerator H- ion beams with a measured brightness of 17.1 A m-2 rad-2 eV-1 at 170 μA, equivalent to an energy normalized beam emittance of 0.767 π mm mrad MeV1/2. Upgrading the accelerator facility with the new injection system provides two main advantages. First, the high brightness of the new ion source enables the reduction of object slit aperture and the reduction of acceptance angle at the nuclear microprobe, resulting in a reduced beam size at selected beam intensity, which significantly improves the probe resolution for micro-PIXE applications. Secondly, the upgrade strongly enhances the accelerator up-time since H and He beams are produced by independent ion sources, introducing a constant availability of 3He beam for fusion-related research with NRA. The ion beam particle losses and ion beam emittance growth imply that the aforementioned beam brightness is reduced by transport through the ion optical system. To obtain quantitative information on the available brightness at the high-energy side of the accelerator, the proton beam brightness is determined in the nuclear microprobe beamline. Based on the experience obtained during the first months of operation for micro-PIXE applications, further necessary steps are indicated to obtain optimal coupling of the new ion source with the accelerator to increase the normalized high-energy proton beam brightness at the JSI microprobe, currently at 14 A m-2 rad-2 eV-1, with the output current at 18% of its available maximum.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwan, Simon; Lei, CM; Menasce, Dario

An all silicon pixel telescope has been assembled and used at the Fermilab Test Beam Facility (FTBF) since 2009 to provide precise tracking information for different test beam experiments with a wide range of Detectors Under Test (DUTs) requiring high resolution measurement of the track impact point. The telescope is based on CMS pixel modules left over from the CMS forward pixel production. Eight planes are arranged to achieve a resolution of less than 8 μm on the 120 GeV proton beam transverse coordinate at the DUT position. In order to achieve such resolution with 100 × 150 μm 2more » pixel cells, the planes were tilted to 25 degrees to maximize charge sharing between pixels. Crucial for obtaining this performance is the alignment software, called Monicelli, specifically designed and optimized for this system. This paper will describe the telescope hardware, the data acquisition system and the alignment software constituting this particle tracking system for test beam users.« less

An analysis of power beaming for the Moon and Mars

NASA Technical Reports Server (NTRS)

Stavnes, Mark W.

1992-01-01

Operations on the surface of the Moon and Mars will depend on a reliable source of electrical power. At NASA Lewis Research Center, the feasibility of powering lunar and Martian surface sites by power beaming was studied. Constellations of nuclear or solar powered satellites using microwave or laser transmitters were designed to power an equatorial surface base. Additional surface assets, such as rovers, can also be powered from the same orbiting satellites, requiring only the additional mass of a receiver. However, the actual mass and power capabilities of the system are dependent on the location of the surface receiver. The masses of the beam power systems can be reduced by up to 50 percent, by using the power source of an electric propulsion vehicle to power the beam system. The important analyses results and any additional issues that remain unresolved are discussed.

Development of economic MeV-ion microbeam technology at Chiang Mai University

NASA Astrophysics Data System (ADS)

Singkarat, S.; Puttaraksa, N.; Unai, S.; Yu, L. D.; Singkarat, K.; Pussadee, N.; Whitlow, H. J.; Natyanum, S.; Tippawan, U.

2017-08-01

Developing high technologies but in economic manners is necessary and also feasible for developing countries. At Chiang Mai University, Thailand, we have developed MeV-ion microbeam technology based on a 1.7-MV Tandetron tandem accelerator with our limited resources in a cost-effective manner. Instead of using expensive and technically complex electrostatic or magnetic quadrupole focusing lens systems, we have developed cheap MeV-ion microbeams using programmed L-shaped blade aperture and capillary techniques for MeV ion beam lithography or writing and mapping. The programmed L-shaped blade micro-aperture system consists of a pair of L-shaped movable aperture pieces which are controlled by computer to cut off the ion beam for controlling the beam size down to the micrometer order. The capillary technique utilizes our home-fabricated tapered glass capillaries to realize microbeams. Either system can be installed inside the endstation of the MeV ion beam line of the accelerator. Both systems have been applied to MeV-ion beam lithography or writing of micro-patterns for microfluidics applications to fabricate lab-on-chip devices. The capillary technique is being developed for MeV-ion beam mapping of biological samples. The paper reports details of the techniques and introduces some applications.

Solar Power Beaming: From Space to Earth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubenchik, A M; Parker, J M; Beach, R J

Harvesting solar energy in space and power beaming the collected energy to a receiver station on Earth is a very attractive way to help solve mankind's current energy and environmental problems. However, the colossal and expensive 'first step' required in achieving this goal has to-date stifled its initiation. In this paper, we will demonstrate that recent advance advances in laser and optical technology now make it possible to deploy a space-based system capable of delivering 1 MW of energy to a terrestrial receiver station, via a single unmanned commercial launch into Low Earth Orbit (LEO). Figure 1 depicts the overallmore » concept of our solar power beaming system, showing a large solar collector in space, beaming a coherent laser beam to a receiving station on Earth. We will describe all major subsystems and provide technical and economic discussion to support our conclusions.« less

Solar Power Satellite (SPS) pilot beam and communication link subsystem investigation study, phase 1. [ionospheric propagation, radio frequency interference, and microwave transmission

NASA Technical Reports Server (NTRS)

1979-01-01

A preliminary engineering model of ionospheric interactions with the pilot beam was established and used to demonstrate that the dual frequency baseline pilot beam system might not be viable in the presence of an unstable transmission path. Alternate approaches to remove this difficulty are described. Although ionospheric fluctuations will not significantly degrade beam pointing or raise the sidelobe levels, they will reduce transmission efficiency by upwards of 25%. Mitigating strategies to substantially reduce this effect are proposed. Based on the Klystron noise spectrum, the pilot beam transmitter power was determined as a function of frequency offset from the power beam carrier frequency. The RFI from the pilot beam, on the ground and at geosynchronous orbit is shown. Noise levels on the earth's surface due to the SPS are presented as a function of frequency and the number of SPS systems. Analysis of the communication subsystem indicates that a standard telemetry line of 1.544 MB/s would satisfy both voice and data link requirements. Additional links would be required for TV and radio transmissions.

Deuteron Beam Source Based on Mather Type Plasma Focus

NASA Astrophysics Data System (ADS)

Lim, L. K.; Yap, S. L.; Wong, C. S.; Zakaullah, M.

2013-04-01

A 3 kJ Mather type plasma focus system filled with deuterium gas is operated at pressure lower than 1 mbar. Operating the plasma focus in a low pressure regime gives a consistent ion beam which can make the plasma focus a reliable ion beam source. In our case, this makes a good deuteron beam source, which can be utilized for neutron generation by coupling a suitable target. This paper reports ion beam measurements obtained at the filling pressure of 0.05-0.5 mbar. Deuteron beam energy is measured by time of flight technique using three biased ion collectors. The ion beam energy variation with the filling pressure is investigated. Deuteron beam of up to 170 keV are obtained with the strongest deuteron beam measured at 0.1 mbar, with an average energy of 80 keV. The total number of deuterons per shot is in the order of 1018 cm-2.

Electron cooling of a bunched ion beam in a storage ring

NASA Astrophysics Data System (ADS)

Zhao, He; Mao, Lijun; Yang, Jiancheng; Xia, Jiawen; Yang, Xiaodong; Li, Jie; Tang, Meitang; Shen, Guodong; Ma, Xiaoming; Wu, Bo; Wang, Geng; Ruan, Shuang; Wang, Kedong; Dong, Ziqiang

2018-02-01

A combination of electron cooling and rf system is an effective method to compress the beam bunch length in storage rings. A simulation code based on multiparticle tracking was developed to calculate the bunched ion beam cooling process, in which the electron cooling, intrabeam scattering (IBS), ion beam space-charge field, transverse and synchrotron motion are considered. Meanwhile, bunched ion beam cooling experiments have been carried out in the main cooling storage ring (CSRm) of the Heavy Ion Research Facility in Lanzhou, to investigate the minimum bunch length obtained by the cooling method, and study the dependence of the minimum bunch length on beam and machine parameters. The experiments show comparable results to those from simulation. Based on these simulations and experiments, we established an analytical model to describe the limitation of the bunch length of the cooled ion beam. It is observed that the IBS effect is dominant for low intensity beams, and the space-charge effect is much more important for high intensity beams. Moreover, the particles will not be bunched for much higher intensity beam. The experimental results in CSRm show a good agreement with the analytical model in the IBS dominated regime. The simulation work offers us comparable results to those from the analytical model both in IBS dominated and space-charge dominated regimes.

The control system of the multi-strip ionization chamber for the HIMM

NASA Astrophysics Data System (ADS)

Li, Min; Yuan, Y. J.; Mao, R. S.; Xu, Z. G.; Li, Peng; Zhao, T. C.; Zhao, Z. L.; Zhang, Nong

2015-03-01

Heavy Ion Medical Machine (HIMM) is a carbon ion cancer treatment facility which is being built by the Institute of Modern Physics (IMP) in China. In this facility, transverse profile and intensity of the beam at the treatment terminals will be measured by the multi-strip ionization chamber. In order to fulfill the requirement of the beam position feedback to accomplish the beam automatic commissioning, less than 1 ms reaction time of the Data Acquisition (DAQ) of this detector must be achieved. Therefore, the control system and software framework for DAQ have been redesigned and developed with National Instruments Compact Reconfigurable Input/Output (CompactRIO) instead of PXI 6133. The software is Labview-based and developed following the producer-consumer pattern with message mechanism and queue technology. The newly designed control system has been tested with carbon beam at the Heavy Ion Research Facility at Lanzhou-Cooler Storage Ring (HIRFL-CSR) and it has provided one single beam profile measurement in less than 1 ms with 1 mm beam position resolution. The fast reaction time and high precision data processing during the beam test have verified the usability and maintainability of the software framework. Furthermore, such software architecture is easy-fitting to applications with different detectors such as wire scanner detector.

Fast and accurate computation of system matrix for area integral model-based algebraic reconstruction technique

NASA Astrophysics Data System (ADS)

Zhang, Shunli; Zhang, Dinghua; Gong, Hao; Ghasemalizadeh, Omid; Wang, Ge; Cao, Guohua

2014-11-01

Iterative algorithms, such as the algebraic reconstruction technique (ART), are popular for image reconstruction. For iterative reconstruction, the area integral model (AIM) is more accurate for better reconstruction quality than the line integral model (LIM). However, the computation of the system matrix for AIM is more complex and time-consuming than that for LIM. Here, we propose a fast and accurate method to compute the system matrix for AIM. First, we calculate the intersection of each boundary line of a narrow fan-beam with pixels in a recursive and efficient manner. Then, by grouping the beam-pixel intersection area into six types according to the slopes of the two boundary lines, we analytically compute the intersection area of the narrow fan-beam with the pixels in a simple algebraic fashion. Overall, experimental results show that our method is about three times faster than the Siddon algorithm and about two times faster than the distance-driven model (DDM) in computation of the system matrix. The reconstruction speed of our AIM-based ART is also faster than the LIM-based ART that uses the Siddon algorithm and DDM-based ART, for one iteration. The fast reconstruction speed of our method was accomplished without compromising the image quality.

The Belle II Pixel Detector Data Acquisition and Background Suppression System

NASA Astrophysics Data System (ADS)

Lautenbach, K.; Deschamps, B.; Dingfelder, J.; Getzkow, D.; Geßler, T.; Konorov, I.; Kühn, W.; Lange, S.; Levit, D.; Liu, Z.-A.; Marinas, C.; Münchow, D.; Rabusov, A.; Reiter, S.; Spruck, B.; Wessel, C.; Zhao, J.

2017-06-01

The Belle II experiment at the future SuperKEKB collider in Tsukuba, Japan, features a design luminosity of 8 · 1035 cm-2s-1, which is a factor of 40 larger than that of its predecessor Belle. The pixel detector (PXD) with about 8 million pixels is based on the DEPFET technology and will improve the vertex resolution in beam direction by a factor of 2. With an estimated trigger rate of 30 kHz, the PXD is expected to generate a data rate of 20 GBytes/s, which is about 10 times larger than the amount of data generated by all other Belle II subdetectors. Due to the large beam-related background, the PXD requires a data acquisition system with high-bandwidth data links and realtime background reduction by a factor of 30. To achieve this, the Belle II pixel DAQ uses an FPGA-based computing platform with high speed serial links implemented in the ATCA (Advanced Telecommunications Computing Architecture) standard. The architecture and performance of the data acquisition system and data reduction of the PXD will be presented. In April 2016 and February 2017 a prototype PXD-DAQ system operated in a test beam campaign delivered data with the whole readout chain under realistic high rate conditions. Final results from the beam test will be presented.

Metrology Camera System Using Two-Color Interferometry

NASA Technical Reports Server (NTRS)

Dubovitsky, Serge; Liebe, Carl Christian; Peters, Robert; Lay, Oliver

2007-01-01

A metrology system that contains no moving parts simultaneously measures the bearings and ranges of multiple reflective targets in its vicinity, enabling determination of the three-dimensional (3D) positions of the targets with submillimeter accuracy. The system combines a direction-measuring metrology camera and an interferometric range-finding subsystem. Because the system is based partly on a prior instrument denoted the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor and because of its 3D capability, the system is denoted the MSTAR3D. Developed for use in measuring the shape (for the purpose of compensating for distortion) of large structures like radar antennas, it can also be used to measure positions of multiple targets in the course of conventional terrestrial surveying. A diagram of the system is shown in the figure. One of the targets is a reference target having a known, constant distance with respect to the system. The system comprises a laser for generating local and target beams at a carrier frequency; a frequency shifting unit to introduce a frequency shift offset between the target and local beams; a pair of high-speed modulators that apply modulation to the carrier frequency in the local and target beams to produce a series of modulation sidebands, the highspeed modulators having modulation frequencies of FL and FM; a target beam launcher that illuminates the targets with the target beam; optics and a multipixel photodetector; a local beam launcher that launches the local beam towards the multi-pixel photodetector; a mirror for projecting to the optics a portion of the target beam reflected from the targets, the optics being configured to focus the portion of the target beam at the multi-pixel photodetector; and a signal-processing unit connected to the photodetector. The portion of the target beam reflected from the targets produces spots on the multi-pixel photodetector corresponding to the targets, respectively, and the signal-processing unit centroids the spots to determine bearings of the targets, respectively. As the spots oscillate in intensity because they are mixed with the local laser beam that is flood illuminating the focal plane, the phase of oscillation of each spot is measured, the phase of sidebands in the oscillation of each spot being proportional to a distance to the corresponding target relative to the reference target A.

Human-simulated intelligent control of train braking response of bridge with MRB

NASA Astrophysics Data System (ADS)

Li, Rui; Zhou, Hongli; Wu, Yueyuan; Wang, Xiaojie

2016-04-01

The urgent train braking could bring structural response menace to the bridge under passive control. Based on the analysis of breaking dynamics of a train-bridge vibration system, a magnetorheological elastomeric bearing (MRB) whose mechanical parameters are adjustable is designed, tested and modeled. A finite element method (FEM) is carried out to model and optimize a full scale vibration isolation system for railway bridge based on MRB. According to the model above, we also consider the effect of different braking stop positions on the vibration isolation system and classify the bridge longitudinal vibration characteristics into several cases. Because the train-bridge vibration isolation system has multiple vibration states and strongly coupling with nonlinear characteristics, a human-simulated intelligent control (HSIC) algorithm for isolating the bridge vibration under the impact of train braking is proposed, in which the peak shear force of pier top, the displacement of beam and the acceleration of beam are chosen as control goals. The simulation of longitudinal vibration control system under the condition of train braking is achieved by MATLAB. The results indicate that different braking stop positions significantly affect the vibration isolation system and the structural response is the most drastic when the train stops at the third cross-span. With the proposed HSIC smart isolation system, the displacement of bridge beam and peak shear force of pier top is reduced by 53.8% and 34.4%, respectively. Moreover, the acceleration of bridge beam is effectively controlled within limited range.

Flat-panel detector, CCD cameras, and electron-beam-tube-based video for use in portal imaging

NASA Astrophysics Data System (ADS)

Roehrig, Hans; Tang, Chuankun; Cheng, Chee-Way; Dallas, William J.

1998-07-01

This paper provides a comparison of some imaging parameters of four portal imaging systems at 6 MV: a flat panel detector, two CCD cameras and an electron beam tube based video camera. Measurements were made of signal and noise and consequently of signal-to-noise per pixel as a function of the exposure. All systems have a linear response with respect to exposure, and with the exception of the electron beam tube based video camera, the noise is proportional to the square-root of the exposure, indicating photon-noise limitation. The flat-panel detector has a signal-to-noise ratio, which is higher than that observed with both CCD-Cameras or with the electron beam tube based video camera. This is expected because most portal imaging systems using optical coupling with a lens exhibit severe quantum-sinks. The measurements of signal-and noise were complemented by images of a Las Vegas-type aluminum contrast detail phantom, located at the ISO-Center. These images were generated at an exposure of 1 MU. The flat-panel detector permits detection of Aluminum holes of 1.2 mm diameter and 1.6 mm depth, indicating the best signal-to-noise ratio. The CCD-cameras rank second and third in signal-to- noise ratio, permitting detection of Aluminum-holes of 1.2 mm diameter and 2.2 mm depth (CCD_1) and of 1.2 mm diameter and 3.2 mm depth (CCD_2) respectively, while the electron beam tube based video camera permits detection of only a hole of 1.2 mm diameter and 4.6 mm depth. Rank Order Filtering was applied to the raw images from the CCD-based systems in order to remove the direct hits. These are camera responses to scattered x-ray photons which interact directly with the CCD of the CCD-Camera and generate 'Salt and Pepper type noise,' which interferes severely with attempts to determine accurate estimates of the image noise. The paper also presents data on the metal-phosphor's photon gain (the number of light-photons per interacting x-ray photon).

Performance, implementation and network management techniques for a European CDMA-based land-mobile satellite system

NASA Astrophysics Data System (ADS)

Arenaccio, S.; Vernucci, A.; Padovani, R.; Arcidiacono, A.

Results of a detailed comparative performance assessment between two candidate access solutions for the provision of land-mobile services, i.e., FDMA and CDMA, for the European Land-Mobile Satellite Services (LMSS) provision are presented. The design of the CDMA access system and the network architecture, system procedures, network control, operation in fading environments, and implementation aspects of the system are described. The CDMA system is shown to yield superior traffic capability, despite the absence of polarization reuse due to payload design, especially in the second-generation era (multiple spot-beams). In this case, the advantage was found to be largely dependent on the traffic distribution across spot beams. Power control techniques are proposed to cope with the geographical disadvantage suffered by mobile stations located at the beam borders to compensate for fadings.

432- μm laser's beam-waist measurement for the polarimeter/interferometer on the EAST tokamak

NASA Astrophysics Data System (ADS)

Wang, Z. X.; Liu, H. Q.; Jie, Y. X.; Wu, M. Q.; Lan, T.; Zhu, X.; Zou, Z. Y.; Yang, Y.; Wei, X. C.; Zeng, L.; Li, G. S.; Gao, X.

2014-10-01

A far-infrared (FIR) polarimeter/interferometer (PI) system is under development for measurements of the current-density and the electron-density profiles in the EAST tokamak. The system will utilize three identical 432- μm CHCOOH lasers pumped by a CO2 laser. Measurements of the laser beam's waist size and position are basic works. This paper will introduce three methods with a beam profiler and several focusing optical elements. The beam profiler can be used to show the spatial energy distribution of the laser beam. The active area of the profiler is 12.4 × 12.4 mm2. Some focusing optical elements are needed to focus the beam in order for the beam profiler to receive the entire laser beam. Two principles and three methods are used in the measurement. The first and the third methods are based on the same principle, and the second method adopts an other principle. Due to the fast and convenient measurement, although the first method is a special form of the third and it can only give the size of beam waist, it is essential to the development of the experiment and it can provide guidance for the choices of the sizes of the optical elements in the next step. A concave mirror, a high-density polyethylene (HDPE) lens and a polymethylpentene (TPX) lens are each used in the measurement process. The results of these methods are close enough for the design of PI system's optical path.

ALCBEAM - Neutral beam formation and propagation code for beam-based plasma diagnostics

NASA Astrophysics Data System (ADS)

Bespamyatnov, I. O.; Rowan, W. L.; Liao, K. T.

2012-03-01

ALCBEAM is a new three-dimensional neutral beam formation and propagation code. It was developed to support the beam-based diagnostics installed on the Alcator C-Mod tokamak. The purpose of the code is to provide reliable estimates of the local beam equilibrium parameters: such as beam energy fractions, density profiles and excitation populations. The code effectively unifies the ion beam formation, extraction and neutralization processes with beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. This paper describes the physical processes interpreted and utilized by the code, along with exploited computational methods. The description is concluded by an example simulation of beam penetration into plasma of Alcator C-Mod. The code is successfully being used in Alcator C-Mod tokamak and expected to be valuable in the support of beam-based diagnostics in most other tokamak environments. Program summaryProgram title: ALCBEAM Catalogue identifier: AEKU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 66 459 No. of bytes in distributed program, including test data, etc.: 7 841 051 Distribution format: tar.gz Programming language: IDL Computer: Workstation, PC Operating system: Linux RAM: 1 GB Classification: 19.2 Nature of problem: Neutral beams are commonly used to heat and/or diagnose high-temperature magnetically-confined laboratory plasmas. An accurate neutral beam characterization is required for beam-based measurements of plasma properties. Beam parameters such as density distribution, energy composition, and atomic excited populations of the beam atoms need to be known. Solution method: A neutral beam is initially formed as an ion beam which is extracted from the ion source by high voltage applied to the extraction and accelerating grids. The current distribution of a single beamlet emitted from a single pore of IOS depends on the shape of the plasma boundary in the emission region. Total beam extracted by IOS is calculated at every point of 3D mesh as sum of all contributions from each grid pore. The code effectively unifies the ion beam formation, extraction and neutralization processes with neutral beam attenuation and excitation in plasma and neutral gas and beam stopping by the beam apertures. Running time: 10 min for a standard run.

Enhancing performance of next generation FSO communication systems using soft computing-based predictions.

PubMed

Kazaura, Kamugisha; Omae, Kazunori; Suzuki, Toshiji; Matsumoto, Mitsuji; Mutafungwa, Edward; Korhonen, Timo O; Murakami, Tadaaki; Takahashi, Koichi; Matsumoto, Hideki; Wakamori, Kazuhiko; Arimoto, Yoshinori

2006-06-12

The deterioration and deformation of a free-space optical beam wave-front as it propagates through the atmosphere can reduce the link availability and may introduce burst errors thus degrading the performance of the system. We investigate the suitability of utilizing soft-computing (SC) based tools for improving performance of free-space optical (FSO) communications systems. The SC based tools are used for the prediction of key parameters of a FSO communications system. Measured data collected from an experimental FSO communication system is used as training and testing data for a proposed multi-layer neural network predictor (MNNP) used to predict future parameter values. The predicted parameters are essential for reducing transmission errors by improving the antenna's accuracy of tracking data beams. This is particularly essential for periods considered to be of strong atmospheric turbulence. The parameter values predicted using the proposed tool show acceptable conformity with original measurements.

High Power Hydrogen Injector with Beam Focusing for Plasma Heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deichuli, P.P.; Ivanov, A.A.; Korepanov, S.A.

2005-01-15

High power neutral beam injector has been developed with the atom energy of 25 keV, a current of 60 A, and several milliseconds pulse duration. Six of these injectors will be used for upgrade of the atomic injection system at central cell of a Gas Dynamic Trap (GDT) device and 2 injectors are planned for SHIP experiment.The injector ion source is based on an arc discharge plasma box. The plasma emitter is produced by a 1 kA arc discharge in hydrogen. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increasemore » its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a 4-electrodes ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a spherical curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were found with the numerical simulation to provide precise beam formation. The measured angular divergence of the beam is 0.02 rad, which corresponds to the 2.5 cm Gaussian radius of the beam profile measured at focal point.« less

Field-size dependence of doses of therapeutic carbon beams.

PubMed

Kusano, Yohsuke; Kanai, Tatsuaki; Yonai, Shunsuke; Komori, Masataka; Ikeda, Noritoshi; Tachikawa, Yuji; Ito, Atsushi; Uchida, Hirohisa

2007-10-01

To estimate the physical dose at the center of spread-out Bragg peaks (SOBP) for various conditions of the irradiation system, a semiempirical approach was applied. The dose at the center of the SOBP depends on the field size because of large-angle scattering particles in the water phantom. For a small field of 5 x 5 cm2, the dose was reduced to 99.2%, 97.5%, and 96.5% of the dose used for the open field in the case of 290, 350, and 400 MeV/n carbon beams, respectively. Based on the three-Gaussian form of the lateral dose distributions of the carbon pencil beam, which has previously been shown to be effective for describing scattered carbon beams, we reconstructed the dose distributions of the SOBP beam. The reconstructed lateral dose distribution reproduced the measured lateral dose distributions very well. The field-size dependencies calculated using the reconstructed lateral dose distribution of the therapeutic carbon beam agreed with the measured dose dependency very well. The reconstructed beam was also used for irregularly shaped fields. The resultant dose distribution agreed with the measured dose distribution. The reconstructed beams were found to be applicable to the treatment-planning system.

Can we estimate plasma density in ICP driver through electrical parameters in RF circuit?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bandyopadhyay, M., E-mail: mainak@iter-india.org; Sudhir, Dass, E-mail: dass.sudhir@iter-india.org; Chakraborty, A., E-mail: arunkc@iter-india.org

2015-04-08

To avoid regular maintenance, invasive plasma diagnostics with probes are not included in the inductively coupled plasma (ICP) based ITER Neutral Beam (NB) source design. Even non-invasive probes like optical emission spectroscopic diagnostics are also not included in the present ITER NB design due to overall system design and interface issues. As a result, negative ion beam current through the extraction system in the ITER NB negative ion source is the only measurement which indicates plasma condition inside the ion source. However, beam current not only depends on the plasma condition near the extraction region but also on the perveancemore » condition of the ion extractor system and negative ion stripping. Nevertheless, inductively coupled plasma production region (RF driver region) is placed at distance (∼ 30cm) from the extraction region. Due to that, some uncertainties are expected to be involved if one tries to link beam current with plasma properties inside the RF driver. Plasma characterization in source RF driver region is utmost necessary to maintain the optimum condition for source operation. In this paper, a method of plasma density estimation is described, based on density dependent plasma load calculation.« less

Precision shape modification of nanodevices with a low-energy electron beam

DOEpatents

Zettl, Alex; Yuzvinsky, Thomas David; Fennimore, Adam

2010-03-09

Methods of shape modifying a nanodevice by contacting it with a low-energy focused electron beam are disclosed here. In one embodiment, a nanodevice may be permanently reformed to a different geometry through an application of a deforming force and a low-energy focused electron beam. With the addition of an assist gas, material may be removed from the nanodevice through application of the low-energy focused electron beam. The independent methods of shape modification and material removal may be used either individually or simultaneously. Precision cuts with accuracies as high as 10 nm may be achieved through the use of precision low-energy Scanning Electron Microscope scan beams. These methods may be used in an automated system to produce nanodevices of very precise dimensions. These methods may be used to produce nanodevices of carbon-based, silicon-based, or other compositions by varying the assist gas.

Startup of the Kling Center for Proton Therapy

NASA Astrophysics Data System (ADS)

Bloch, C.; Hill, P. M.; Chen, K. L.; Saito, A.; Klein, E. E.

2013-04-01

In November of 2011 Mevion Medical Systems (formerly Still River Systems) delivered the Mevion S250 proton therapy system accelerator to the Kling Center for Proton Therapy at the Siteman Cancer Center in Saint Louis. The Mevion system is unique, with an in-room gantry-mounted superconducting synchrocyclotron. This is the first true single-room proton therapy system and it has a greatly reduced size as well as cost. A month after its arrival, the installation was complete and the superconducting magnet was ramped up to full current (˜2000 amperes). In March of 2012, full energy beam (250 MeV) was extracted and radiation surveys were performed to verify the shielding. Once that was shown to be sufficient, Mevion began fine-tuning the system to provide a highly isocentric beam from the 50 ton system. In June of 2012 the field-shaping system (energy degraders, contoured scatterers and range modulators) were installed and measurements of the clinical beam properties commenced. Monte Carlo simulations (MCNPX) have been performed for the system and validated with beam measurements done at the factory. These simulations have been used for a preliminary commissioning of our treatment planning system. Additionally, predictions of the neutron background have been made and validated with factory measurements. Final commissioning of the treatment planning system and verification of the neutron background will be accomplished with measurements made later in 2012. Based on current progress, patient treatments are scheduled to begin in late 2012. Beam and radiation background data will be presented.

Non-mechanical beam control for entry, descent and landing laser radar (Conference Presentation)

NASA Astrophysics Data System (ADS)

Stockley, Jay E.; Kluttz, Kelly; Hosting, Lance; Serati, Steve; Bradley, Cullen P.; McManamon, Paul F.; Amzajerdian, Farzin

2017-05-01

Laser radar for entry, descent, and landing (EDL) applications as well as the space docking problem could benefit from a low size, weight, and power (SWaP) beam control system. Moreover, an inertia free approach employing non-mechanical beam control is also attractive for laser radar that is intended to be employed aboard space platforms. We are investigating a non-mechanical beam steering (NMBS) sub-system based on liquid crystal polarization grating (LCPG) technology with emphasis placed on improved throughput and significant weight reduction by combining components and drastically reducing substrate thicknesses. In addition to the advantages of non-mechanical, gimbal free beam control, and greatly improved SWaP, our approach also enables wide area scanning using a scalable architecture. An extraterrestrial application entails additional environmental constraints, consequently an environmental test plan tailored to an EDL mission will also be discussed. In addition, we will present advances in continuous fine steering technology which would complement the coarse steering LCPG technology. A low-SWaP, non-mechanical beam control system could be used in many laser radar remote sensing applications including meteorological studies and agricultural or environmental surveys in addition to the entry, descent, and landing application.

Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector.

PubMed

Barbisan, M; Zaniol, B; Pasqualotto, R

2014-11-01

A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H(-)/D(-) ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurement is based on the collection of the Hα/Dα emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled Hα spectra in the case of MITICA experiment.

Displacement and Deflection of AN Optical Beam by Airborne Ultrasound

NASA Astrophysics Data System (ADS)

Caron, James N.

2008-02-01

Gas-Coupled Laser Acoustic Detection enables laser-based sensing of ultrasound from a solid without contact of the surface, and independent of the optical properties of the solid surface. The interaction between the probe beam and acoustic field has typically been modeled as creating a deflection in the optical beam. This paper describes this interaction as a combination of displacement and deflection. Sensing displacement can significantly decrease the system's dependence of length.

Distributed Beam Former for Distributed-Aperture Electronically Steered Antennas

DTIC Science & Technology

2006-11-01

of planar or conformal aperture, it will be replaced by a distributed aperture configuration with a base-band digital network that is used to combine...beam forming network that can be designed with pre-set scanning directions. The beam former for this stage can be realized using a printed Butler...matrix (Bona et al, 2002; Neron and Delisle, 2005), a printed Rotman lens (Kilic and Dahlstrom, 2005) or other switched time delay system. The

50 Mb/s, 220-mW Laser-Array Transmitter

NASA Technical Reports Server (NTRS)

Cornwell, Donald M., Jr.

1992-01-01

Laser transmitter based on injection locking produces single-wavelength, diffraction-limited, single-lobe beam. Output stage is array of laser diodes producing non-diffraction-limited, multi-mode beam in absence of injection locking. Suitable for both free-space and optical-fiber communication systems. Because beam from transmitter focused to spot as small as 5 micrometers, devices usable for reading and writing optical disks at increased information densities. Application also in remote sensing and ranging.

Ultra-Low Threshold Vertical-Cavity Surface-Emitting Lasers for USAF Applications

DTIC Science & Technology

2005-01-01

molecular beam epitaxy , semiconductors, finite element method, modeling and simulation, oxidation furnace 16. SECURITY CLASSIFICATION OF: 19a. NAME OF...Patterson Air Force Base). Device material growth was accomplished by means of molecular beam epitaxy (MBE) using a Varian GENII MBE system owned by the...grown by molecular beam epitaxy on a GaAs substrate. Vertical posts, with square and circular cross sections ranging in size from 5 to 40 microns

Optically-pumped spin-exchange polarized electron source

NASA Astrophysics Data System (ADS)

Pirbhai, Munir Hussein

Polarized electron beams are an indispensable probe of spin-dependent phenomena in fields of atomic and molecular physics, magnetism and biophysics. While their uses have become widespread, the standard source based on negative electron affinity gallium arsenide (GaAs) remains technically complicated. This has hindered progress on many experiments involving spin-polarized electrons, especially those using target gas loads, which tend to adversely affect the performance of GaAs sources. A robust system based on an alternative way to make polarized electron beams has been devised in this study, which builds on previous work done in our lab. It involves spin-exchange collisions between free, unpolarized electrons and oriented rubidium atoms in the presence of a quenching gas. This system has less stringent vacuum requirements than those of GaAs sources, and is capable of operating in background pressures of ~1mTorr. Beams with ~24% polarization and 4μA of current have been recorded, which is comparable to the performance obtained with the earlier version built in our lab. The present system is however not as unstable as in the previous work, and has the potential to be developed into a "turn-key" source of polarized electron beams. It has also allowed us to undertake a study to find factors which affect the beam polarization in this scheme of producing polarized electrons. Such knowledge will help us to design better optically-pumped spin-exchange polarized electron sources.

Conditioning of BPM pickup signals for operations of the Duke storage ring with a wide range of single-bunch current

NASA Astrophysics Data System (ADS)

Xu, Wei; Li, Jing-Yi; Huang, Sen-Lin; Z. Wu, W.; Hao, H.; P., Wang; K. Wu, Y.

2014-10-01

The Duke storage ring is a dedicated driver for the storage ring based oscillator free-electron lasers (FELs), and the High Intensity Gamma-ray Source (HIGS). It is operated with a beam current ranging from about 1 mA to 100 mA per bunch for various operations and accelerator physics studies. High performance operations of the FEL and γ-ray source require a stable electron beam orbit, which has been realized by the global orbit feedback system. As a critical part of the orbit feedback system, the electron beam position monitors (BPMs) are required to be able to precisely measure the electron beam orbit in a wide range of the single-bunch current. However, the high peak voltage of the BPM pickups associated with high single-bunch current degrades the performance of the BPM electronics, and can potentially damage the BPM electronics. A signal conditioning method using low pass filters is developed to reduce the peak voltage to protect the BPM electronics, and to make the BPMs capable of working with a wide range of single-bunch current. Simulations and electron beam based tests are performed. The results show that the Duke storage ring BPM system is capable of providing precise orbit measurements to ensure highly stable FEL and HIGS operations.

Development and reproducibility evaluation of a Monte Carlo-based standard LINAC model for quality assurance of multi-institutional clinical trials.

PubMed

Usmani, Muhammad Nauman; Takegawa, Hideki; Takashina, Masaaki; Numasaki, Hodaka; Suga, Masaki; Anetai, Yusuke; Kurosu, Keita; Koizumi, Masahiko; Teshima, Teruki

2014-11-01

Technical developments in radiotherapy (RT) have created a need for systematic quality assurance (QA) to ensure that clinical institutions deliver prescribed radiation doses consistent with the requirements of clinical protocols. For QA, an ideal dose verification system should be independent of the treatment-planning system (TPS). This paper describes the development and reproducibility evaluation of a Monte Carlo (MC)-based standard LINAC model as a preliminary requirement for independent verification of dose distributions. The BEAMnrc MC code is used for characterization of the 6-, 10- and 15-MV photon beams for a wide range of field sizes. The modeling of the LINAC head components is based on the specifications provided by the manufacturer. MC dose distributions are tuned to match Varian Golden Beam Data (GBD). For reproducibility evaluation, calculated beam data is compared with beam data measured at individual institutions. For all energies and field sizes, the MC and GBD agreed to within 1.0% for percentage depth doses (PDDs), 1.5% for beam profiles and 1.2% for total scatter factors (Scps.). Reproducibility evaluation showed that the maximum average local differences were 1.3% and 2.5% for PDDs and beam profiles, respectively. MC and institutions' mean Scps agreed to within 2.0%. An MC-based standard LINAC model developed to independently verify dose distributions for QA of multi-institutional clinical trials and routine clinical practice has proven to be highly accurate and reproducible and can thus help ensure that prescribed doses delivered are consistent with the requirements of clinical protocols. © The Author 2014. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

A noble refractive optical scanner with linear response

NASA Astrophysics Data System (ADS)

Mega, Yair J.; Lai, Zhenhua; DiMarzio, Charles A.

2013-03-01

Many applications in various fields of science and engineering use steered optical beam systems. Currently, many methods utilize mirrors in order to steer the beam. However, this approach is an off-axis solution, which normally increases the total size of the system as well as its error and complexity. Other methods use a "Risely Prisms" based solution, which is on-axis solution, however it poses some difficulties from an engineering standpoint, and therefore isn't widely used. We present here a novel technique for steering a beam on its optical axis with a linear deflection response. We derived the formulation for the profile required of the refractive optical component necessary for preforming the beam steering. The functionality of the device was simulated analytically using Matlab, as well as using a ray-tracing software, Zemax, and showed agreement with the analytical model. An optical element was manufactured based on the proposed design and the device was tested. The results show agreement with our hypothesis. We also present some proposed geometries of the several other devices, all based on the same concept, which can be used for higher performance applications such as two-dimensional scanner, video rate scanner etc.

Multidimensional electron beam-plasma instabilities in the relativistic regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bret, A.; Gremillet, L.; Dieckmann, M. E.

2010-12-15

The interest in relativistic beam-plasma instabilities has been greatly rejuvenated over the past two decades by novel concepts in laboratory and space plasmas. Recent advances in this long-standing field are here reviewed from both theoretical and numerical points of view. The primary focus is on the two-dimensional spectrum of unstable electromagnetic waves growing within relativistic, unmagnetized, and uniform electron beam-plasma systems. Although the goal is to provide a unified picture of all instability classes at play, emphasis is put on the potentially dominant waves propagating obliquely to the beam direction, which have received little attention over the years. First, themore » basic derivation of the general dielectric function of a kinetic relativistic plasma is recalled. Next, an overview of two-dimensional unstable spectra associated with various beam-plasma distribution functions is given. Both cold-fluid and kinetic linear theory results are reported, the latter being based on waterbag and Maxwell-Juettner model distributions. The main properties of the competing modes (developing parallel, transverse, and oblique to the beam) are given, and their respective region of dominance in the system parameter space is explained. Later sections address particle-in-cell numerical simulations and the nonlinear evolution of multidimensional beam-plasma systems. The elementary structures generated by the various instability classes are first discussed in the case of reduced-geometry systems. Validation of linear theory is then illustrated in detail for large-scale systems, as is the multistaged character of the nonlinear phase. Finally, a collection of closely related beam-plasma problems involving additional physical effects is presented, and worthwhile directions of future research are outlined.« less

Beam-Flattener Design for High Energy Radiographic Inspection

NASA Technical Reports Server (NTRS)

Grandin, Robert; Rudolphi, Thomas

2009-01-01

This report documents the work done to develop a beam flattener for use in the inspection of rocket motors at ATK Space Systems Utah facilities. The following pages provide a brief introduction to the necessity of this project, comprehensive description of the design methodology, and experimentally-based conclusions regarding project success.

The e-Beam Sustained Laser Technology for Space-based Doppler Wind Lidar

NASA Technical Reports Server (NTRS)

Brown, M. J.; Holman, W.; Robinson, R. J.; Schwarzenberger, P. M.; Smith, I. M.; Wallace, S.; Harris, M. R.; Willetts, D. V.; Kurzius, S. C.

1992-01-01

An overview is presented of GEC Avionics activities relating to the Spaceborne Doppler Wind Lidar. In particular, the results of design studies into the use of an e-beam sustained CO2 laser for spaceborne applications, and experimental work on a test bed system are discussed.

Turning the LHC ring into a new physics search machine

NASA Astrophysics Data System (ADS)

Orava, Risto

2017-03-01

The LHC Collider Ring is proposed to be turned into an ultimate automatic search engine for new physics in four consecutive phases: (1) Searches for heavy particles produced in Central Exclusive Process (CEP): pp → p + X + p based on the existing Beam Loss Monitoring (BLM) system of the LHC; (2) Feasibility study of using the LHC Ring as a gravitation wave antenna; (3) Extensions to the current BLM system to facilitate precise registration of the selected CEP proton exit points from the LHC beam vacuum chamber; (4) Integration of the BLM based event tagging system together with the trigger/data acquisition systems of the LHC experiments to facilitate an on-line automatic search machine for the physics of tomorrow.

Exact vibration analysis of a double-nanobeam-systems embedded in an elastic medium by a Hamiltonian-based method

NASA Astrophysics Data System (ADS)

Zhou, Zhenhuan; Li, Yuejie; Fan, Junhai; Rong, Dalun; Sui, Guohao; Xu, Chenghui

2018-05-01

A new Hamiltonian-based approach is presented for finding exact solutions for transverse vibrations of double-nanobeam-systems embedded in an elastic medium. The continuum model is established within the frameworks of the symplectic methodology and the nonlocal Euler-Bernoulli and Timoshenko beam beams. The symplectic eigenfunctions are obtained after expressing the governing equations in a Hamiltonian form. Exact frequency equations, vibration modes and displacement amplitudes are obtained by using symplectic eigenfunctions and end conditions. Comparisons with previously published work are presented to illustrate the accuracy and reliability of the proposed method. The comprehensive results for arbitrary boundary conditions could serve as benchmark results for verifying numerically obtained solutions. In addition, a study on the difference between the nonlocal beam and the nonlocal plate is also included.

Technical Note: Defining cyclotron-based clinical scanning proton machines in a FLUKA Monte Carlo system.

PubMed

Fiorini, Francesca; Schreuder, Niek; Van den Heuvel, Frank

2018-02-01

Cyclotron-based pencil beam scanning (PBS) proton machines represent nowadays the majority and most affordable choice for proton therapy facilities, however, their representation in Monte Carlo (MC) codes is more complex than passively scattered proton system- or synchrotron-based PBS machines. This is because degraders are used to decrease the energy from the cyclotron maximum energy to the desired energy, resulting in a unique spot size, divergence, and energy spread depending on the amount of degradation. This manuscript outlines a generalized methodology to characterize a cyclotron-based PBS machine in a general-purpose MC code. The code can then be used to generate clinically relevant plans starting from commercial TPS plans. The described beam is produced at the Provision Proton Therapy Center (Knoxville, TN, USA) using a cyclotron-based IBA Proteus Plus equipment. We characterized the Provision beam in the MC FLUKA using the experimental commissioning data. The code was then validated using experimental data in water phantoms for single pencil beams and larger irregular fields. Comparisons with RayStation TPS plans are also presented. Comparisons of experimental, simulated, and planned dose depositions in water plans show that same doses are calculated by both programs inside the target areas, while penumbrae differences are found at the field edges. These differences are lower for the MC, with a γ(3%-3 mm) index never below 95%. Extensive explanations on how MC codes can be adapted to simulate cyclotron-based scanning proton machines are given with the aim of using the MC as a TPS verification tool to check and improve clinical plans. For all the tested cases, we showed that dose differences with experimental data are lower for the MC than TPS, implying that the created FLUKA beam model is better able to describe the experimental beam. © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

X-ray luminescence computed tomography imaging based on X-ray distribution model and adaptively split Bregman method

PubMed Central

Chen, Dongmei; Zhu, Shouping; Cao, Xu; Zhao, Fengjun; Liang, Jimin

2015-01-01

X-ray luminescence computed tomography (XLCT) has become a promising imaging technology for biological application based on phosphor nanoparticles. There are mainly three kinds of XLCT imaging systems: pencil beam XLCT, narrow beam XLCT and cone beam XLCT. Narrow beam XLCT can be regarded as a balance between the pencil beam mode and the cone-beam mode in terms of imaging efficiency and image quality. The collimated X-ray beams are assumed to be parallel ones in the traditional narrow beam XLCT. However, we observe that the cone beam X-rays are collimated into X-ray beams with fan-shaped broadening instead of parallel ones in our prototype narrow beam XLCT. Hence we incorporate the distribution of the X-ray beams in the physical model and collected the optical data from only two perpendicular directions to further speed up the scanning time. Meanwhile we propose a depth related adaptive regularized split Bregman (DARSB) method in reconstruction. The simulation experiments show that the proposed physical model and method can achieve better results in the location error, dice coefficient, mean square error and the intensity error than the traditional split Bregman method and validate the feasibility of method. The phantom experiment can obtain the location error less than 1.1 mm and validate that the incorporation of fan-shaped X-ray beams in our model can achieve better results than the parallel X-rays. PMID:26203388

Progress on the Development of the Next Generation X-ray Beam Position Monitors at the Advanced Photon Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S.H.; Yang, B.X.; Decker, G.

Accurate and stable x-ray beam position monitors (XBPMs) are ke y elements in obtaining the desired user beam stability in the Advanced Photon Source (APS). The next generat ion XBPMs for high heat load front ends (HHL FEs) have been designed to meet these requirements by utilizing Cu K-edge x-ray fluorescence (XRF) from a pair of copper absorbers and have been installed at the front ends (FEs) of the APS. Com missioning data showed a significant performance improvement over the existing photoemission-based XBPMs. While a similar design concept can be applied for the canted undulator front ends, where two undulatormore » beams are separated by 1.0-mrad, the lower beam power (< 10 kW) per undulator allows us to explore lower-cost solutions based on Compton scat tering from the diamond blades placed edge-on to the x- ray beam. A prototype of the Compton scattering XBPM system was i nstalled at 24-ID-A in May 2015. In this report, the design and test results for XRF-based XBPM and Compton scattering based XBPM are presented. Ongoing research related to the development of the next generation XBPMs on thermal contac t resistance of a joint between two solid bodies is also discussed« less

Progress on the development of the next generation x-ray beam position monitors at the advanced photon source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S. H., E-mail: shlee@aps.anl.gov; Yang, B. X., E-mail: bxyang@aps.anl.gov; Decker, G., E-mail: decker@aps.anl.gov

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source (APS). The next generation XBPMs for high heat load front ends (HHL FEs) have been designed to meet these requirements by utilizing Cu K-edge x-ray fluorescence (XRF) from a pair of copper absorbers and have been installed at the front ends (FEs) of the APS. Commissioning data showed a significant performance improvement over the existing photoemission-based XBPMs. While a similar design concept can be applied for the canted undulator front ends, where two undulator beams are separatedmore » by 1.0-mrad, the lower beam power (< 10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from the diamond blades placed edge-on to the x-ray beam. A prototype of the Compton scattering XBPM system was installed at 24-ID-A in May 2015. In this report, the design and test results for XRF-based XBPM and Compton scattering based XBPM are presented. Ongoing research related to the development of the next generation XBPMs on thermal contact resistance of a joint between two solid bodies is also discussed.« less

Negative ion source development for a photoneutralization based neutral beam system for future fusion reactors

NASA Astrophysics Data System (ADS)

Simonin, A.; Agnello, R.; Bechu, S.; Bernard, J. M.; Blondel, C.; Boeuf, J. P.; Bresteau, D.; Cartry, G.; Chaibi, W.; Drag, C.; Duval, B. P.; de Esch, H. P. L.; Fubiani, G.; Furno, I.; Grand, C.; Guittienne, Ph; Howling, A.; Jacquier, R.; Marini, C.; Morgal, I.

2016-12-01

In parallel to the developments dedicated to the ITER neutral beam (NB) system, CEA-IRFM with laboratories in France and Switzerland are studying the feasibility of a new generation of NB system able to provide heating and current drive for the future DEMOnstration fusion reactor. For the steady-state scenario, the NB system will have to provide a high NB power level with a high wall-plug efficiency (η ˜ 60%). Neutralization of the energetic negative ions by photodetachment (so called photoneutralization), if feasible, appears to be the ideal solution to meet these performances, in the sense that it could offer a high beam neutralization rate (>80%) and a wall-plug efficiency higher than 60%. The main challenge of this new injector concept is the achievement of a very high power photon flux which could be provided by 3 MW Fabry-Perot optical cavities implanted along the 1 MeV D- beam in the neutralizer stage. The beamline topology is tall and narrow to provide laminar ion beam sheets, which will be entirely illuminated by the intra-cavity photon beams propagating along the vertical axis. The paper describes the present R&D (experiments and modelling) addressing the development of a new ion source concept (Cybele source) which is based on a magnetized plasma column. Parametric studies of the source are performed using Langmuir probes in order to characterize and compare the plasma parameters in the source column with different plasma generators, such as filamented cathodes, radio-frequency driver and a helicon antenna specifically developed at SPC-EPFL satisfying the requirements for the Cybele (axial magnetic field of 10 mT, source operating pressure: 0.3 Pa in hydrogen or deuterium). The paper compares the performances of the three plasma generators. It is shown that the helicon plasma generator is a very promising candidate to provide an intense and uniform negative ion beam sheet.

Addendum to NuMI shielding assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaziri, Kamran; /Fermilab

2007-10-01

The original safety assessment and the Safety Envelope for the NuMI beam line corresponds to 400 kW of beam power. The Main Injector is currently capable of and approved for producing 500 kW of beam power2. However, operation of the NuMI beam line at 400 kW of power brings up the possibility of an occasional excursion above 400 kW due to better than usual tuning in one of the machines upstream of the NuMI beam line. An excursion above the DOE approved Safety Envelope will constitute a safety violation. The purpose of this addendum is to evaluate the radiological issuesmore » and modifications required to operate the NuMI beam line at 500 kW. This upgrade will allow 400 kW operations with a reasonable safety margin. Configuration of the NuMI beam line, boundaries, safety system and the methodologies used for the calculations are as described in the original NuMI SAD. While most of the calculations presented in the original shielding assessment were based on Monte Carlo simulations, which were based on the design geometries, most of the results presented in this addendum are based on the measurements conducted by the AD ES&H radiation safety group.« less

Modeling of Adaptive Optics-Based Free-Space Communications Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilks, S C; Morris, J R; Brase, J M

2002-08-06

We introduce a wave-optics based simulation code written for air-optic laser communications links, that includes a detailed model of an adaptive optics compensation system. We present the results obtained by this model, where the phase of a communications laser beam is corrected, after it propagates through a turbulent atmosphere. The phase of the received laser beam is measured using a Shack-Hartmann wavefront sensor, and the correction method utilizes a MEMS mirror. Strehl improvement and amount of power coupled to the receiving fiber for both 1 km horizontal and 28 km slant paths are presented.

Deformation analysis of tilted primary mirror for an off-axis beam compressor

NASA Astrophysics Data System (ADS)

Clark, James H., III; Penado, F. Ernesto; Dugdale, Joel

2011-09-01

The Navy Prototype Optical Interferometer (NPOI), located near Flagstaff, Arizona, is a ground-based interferometer that collects and transports stellar radiation from six primary flat collectors, known as siderostats, through a common vacuum relay system to a beam combiner where the beams are combined, fringes are obtained and modulated, and data are recorded for further analysis. The current number of observable stellar objects can increase from 6,000 to approximately 47,000 with the addition of down-tilting beam compressors in the optical train. The increase in photon collection area from the beam compressors opens the sky to many additional and fainter stars. The siderostats are capable of redirecting 35 cm stellar beams into the vacuum relay system. Sans beam compressors, any portion of the beam greater than the capacity of the vacuum transport system, 12.5 cm, is wasted. Engineering analysis of previously procured as-built beam compressor optics show the maximum allowable primary mirror surface sag, resulting in λ/10 peak-to-valley wavefront aberration, occurs at 2.8° down-tilt angle. At the NPOI operational down-tilt angle of 20° the wavefront aberration reduces to an unacceptable λ/4. A design modification concept that reduces tilt-induced sag was investigated. Four outwardly applied 4-lb forces on the rear surface of the mirror reduce the sag from 155 nm to 32 nm at 20° down-tilt and reduce peak-to-valley wavefront deviation to λ/8.6. This preliminary effort indicates that this solution path is a viable and economic way to repair an expensive set of optical components. However, it requires further work to optimize the locations, magnitudes, and quantity of the forces within this system and their influence on the mirror surface.

Structural damage detection based on stochastic subspace identification and statistical pattern recognition: I. Theory

NASA Astrophysics Data System (ADS)

Ren, W. X.; Lin, Y. Q.; Fang, S. E.

2011-11-01

One of the key issues in vibration-based structural health monitoring is to extract the damage-sensitive but environment-insensitive features from sampled dynamic response measurements and to carry out the statistical analysis of these features for structural damage detection. A new damage feature is proposed in this paper by using the system matrices of the forward innovation model based on the covariance-driven stochastic subspace identification of a vibrating system. To overcome the variations of the system matrices, a non-singularity transposition matrix is introduced so that the system matrices are normalized to their standard forms. For reducing the effects of modeling errors, noise and environmental variations on measured structural responses, a statistical pattern recognition paradigm is incorporated into the proposed method. The Mahalanobis and Euclidean distance decision functions of the damage feature vector are adopted by defining a statistics-based damage index. The proposed structural damage detection method is verified against one numerical signal and two numerical beams. It is demonstrated that the proposed statistics-based damage index is sensitive to damage and shows some robustness to the noise and false estimation of the system ranks. The method is capable of locating damage of the beam structures under different types of excitations. The robustness of the proposed damage detection method to the variations in environmental temperature is further validated in a companion paper by a reinforced concrete beam tested in the laboratory and a full-scale arch bridge tested in the field.

CO2 Cluster Ion Beam, an Alternative Projectile for Secondary Ion Mass Spectrometry.

PubMed

Tian, Hua; Maciążek, Dawid; Postawa, Zbigniew; Garrison, Barbara J; Winograd, Nicholas

2016-09-01

The emergence of argon-based gas cluster ion beams for SIMS experiments opens new possibilities for molecular depth profiling and 3D chemical imaging. These beams generally leave less surface chemical damage and yield mass spectra with reduced fragmentation compared with smaller cluster projectiles. For nanoscale bioimaging applications, however, limited sensitivity due to low ionization probability and technical challenges of beam focusing remain problematic. The use of gas cluster ion beams based upon systems other than argon offer an opportunity to resolve these difficulties. Here we report on the prospects of employing CO2 as a simple alternative to argon. Ionization efficiency, chemical damage, sputter rate, and beam focus are investigated on model compounds using a series of CO2 and Ar cluster projectiles (cluster size 1000-5000) with the same mass. The results show that the two projectiles are very similar in each of these aspects. Computer simulations comparing the impact of Ar2000 and (CO2)2000 on an organic target also confirm that the CO2 molecules in the cluster projectile remain intact, acting as a single particle of m/z 44. The imaging resolution employing CO2 cluster projectiles is improved by more than a factor of two. The advantage of CO2 versus Ar is also related to the increased stability which, in addition, facilitates the operation of the gas cluster ion beams (GCIB) system at lower backing pressure. Graphical Abstract ᅟ.

Development of Wien filter for small ion gun of surface analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahng, Jungbae; Busan Center, Korea Basic Science Institute, Busan 609-735; Hong, Jonggi

The gas cluster ion beam (GCIB) and liquid metal ion beam have been studied in the context of ion beam usage for analytical equipment in applications such as X-ray photoelectron spectroscopy and secondary ion mass spectroscopy (SIMS). In particular, small ion sources are used for the secondary ion generation and ion etching. To set the context to this study, the SIMS project has been launched to develop ion-gun based analytical equipment for the Korea Basic Science Institute. The objective of the first stage of the project is the generation of argon beams with a GCIB system [A. Kirkpatrick, Nucl. Instrum.more » Methods Phys. Res., Sect. B 206, 830–837 (2003)] that consists of a nozzle, skimmer, ionizer, acceleration tube, separation system, transport system, and target. The Wien filter directs the selected cluster beam to the target system by exploiting the velocity difference of the generated particles from GCIB. In this paper, we present the theoretical modeling and three-dimensional electromagnetic analysis of the Wien filter, which can separate Ar{sup +}{sub 2500} clusters from Ar{sup +}{sub 2400} to Ar{sup +}{sub 2600} clusters with a 1-mm collimator.« less

Gyrator transform of generalized sine-Gaussian beams and conversion an edge-dislocation into a vortex

NASA Astrophysics Data System (ADS)

Zhu, Kaicheng; Tang, Huiqin; Tang, Ying; Xia, Hui

2014-12-01

We proposed a scheme that converts a sine-Gaussian beam with an edge dislocation into a dark hollow beam with a vortex. Based on the gyrator transform (GT) relation, the closed-form field distribution of generalized sine-Gaussian beams passing through a GT system is derived; the intensity distribution and the corresponding phase distribution associated with the transforming generalized sine-Gaussian beams are analyzed. According to the numerical method, the distributions are graphically demonstrated and found that, for appropriate beam parameters and the GT angle, dark hollow vortex beams with topological charge 1 can be achieved using sine-Gaussian beams carrying an edge dislocation. Moreover, the orbital angular momentum content of a GT sine-Gaussian beam is analyzed. It is proved that the GT retains the odd- or even-order spiral harmonics structures of generalized sine-Gaussian beams in the transform process. In particular, it is wholly possible to convert an edge dislocation embedded in sine-Gaussian beams into a vortex with GT. The study also reveals that to obtain a dark hollow beam making use of GT of cos-Gaussian beams is impossible.

Vertical dynamics of a single-span beam subjected to moving mass-suspended payload system with variable speeds

NASA Astrophysics Data System (ADS)

He, Wei

2018-03-01

This paper presents the vertical dynamics of a simply supported Euler-Bernoulli beam subjected to a moving mass-suspended payload system of variable velocities. A planar theoretical model of the moving mass-suspended payload system of variable speeds is developed based on several assumptions: the rope is massless and rigid, and its length keeps constant; the stiffness of the gantry beam is much greater than the supporting beam, and the gantry beam can be treated as a mass particle traveling along the supporting beam; the supporting beam is assumed as a simply supported Bernoulli-Euler beam. The model can be degenerated to consider two classical cases-the moving mass case and the moving payload case. The proposed model is verified using both numerical and experimental methods. To further investigate the effect of possible influential factors, numerical examples are conducted covering a range of parameters, such as variable speeds (acceleration or deceleration), mass ratios of the payload to the total moving load, and the pendulum lengths. The effect of beam flexibility on swing response of the payload is also investigated. It is shown that the effect of a variable speed is significant for the deflections of the beam. The accelerating movement tends to induce larger beam deflections, while the decelerating movement smaller ones. For accelerating or decelerating movements, the moving mass model may underestimate the deflections of the beam compared with the presented model; while for uniform motion, both the moving mass model and the moving mass-payload model lead to same beam responses. Furthermore, it is observed that the swing response of the payload is not sensitive to the stiffness of the beam for operational cases of a moving crane, thus a simple moving payload model can be employed in the swing control of the payload.

Ion source development for a photoneutralization based NBI system for fusion reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simonin, A.; Esch, H. P. L. de; Garibaldi, P.

2015-04-08

The next step after ITER is to demonstrate the viability and generation of electricity by a future fusion reactor (DEMO). The specifications required to operate an NBI system on DEMO are very demanding. The system has to provide a very high level of power and energy, ~100MW of D° beam at 1MeV, including high wall-plug efficiency (η > 60%). For this purpose, a new injector concept, called Siphore, is under investigation between CEA and French universities. Siphore is based on the stripping of the accelerated negative ions by photo-detachment provided by several Fabry-Perot cavities (3.5MW of light power per cavity)more » implemented along the D{sup −} beam. The beamline is designed to be tall and narrow in order that the photon flux overlaps the entire negative ion beam. The paper will describe the present R and D at CEA which addresses the development of an ion source and pre-accelerator prototypes for Siphore, the main goal being to produce an intense negative ion beam sheet. The negative ion source Cybele is based on a magnetized plasma column where hot electrons are emitted from the source center. Parametric studies of the source are performed using Langmuir probes in order to characterize the plasma and to compare with numerical models being developed in French universities.« less

Enhancement of the beam quality of non-uniform output slab laser amplifier with a 39-actuator rectangular piezoelectric deformable mirror.

PubMed

Yang, Ping; Ning, Yu; Lei, Xiang; Xu, Bing; Li, Xinyang; Dong, Lizhi; Yan, Hu; Liu, Wenjing; Jiang, Wenhan; Liu, Lei; Wang, Chao; Liang, Xingbo; Tang, Xiaojun

2010-03-29

We present a slab laser amplifier beam cleanup experimental system based on a 39-actuator rectangular piezoelectric deformable mirror. Rather than use a wave-front sensor to measure distortions in the wave-front and then apply a conjugation wave-front for compensating them, the system uses a Stochastic Parallel Gradient Descent algorithm to maximize the power contained within a far-field designated bucket. Experimental results demonstrate that at the output power of 335W, more than 30% energy concentrates in the 1x diffraction-limited area while the beam quality is enhanced greatly.

Removal of anti-Stokes emission background in STED microscopy by FPGA-based synchronous detection

NASA Astrophysics Data System (ADS)

Castello, M.; Tortarolo, G.; Coto Hernández, I.; Deguchi, T.; Diaspro, A.; Vicidomini, G.

2017-05-01

In stimulated emission depletion (STED) microscopy, the role of the STED beam is to de-excite, via stimulated emission, the fluorophores that have been previously excited by the excitation beam. This condition, together with specific beam intensity distributions, allows obtaining true sub-diffraction spatial resolution images. However, if the STED beam has a non-negligible probability to excite the fluorophores, a strong fluorescent background signal (anti-Stokes emission) reduces the effective resolution. For STED scanning microscopy, different synchronous detection methods have been proposed to remove this anti-Stokes emission background and recover the resolution. However, every method works only for a specific STED microscopy implementation. Here we present a user-friendly synchronous detection method compatible with any STED scanning microscope. It exploits a data acquisition (DAQ) card based on a field-programmable gate array (FPGA), which is progressively used in STED microscopy. In essence, the FPGA-based DAQ card synchronizes the fluorescent signal registration, the beam deflection, and the excitation beam interruption, providing a fully automatic pixel-by-pixel synchronous detection method. We validate the proposed method in both continuous wave and pulsed STED microscope systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhat, C. M.; Bhat, S.

Increasing proton beam power on neutrino production targets is one of the major goals of the Fermilab long term accelerator programs. In this effort, the Fermilab 8 GeV Booster synchrotron plays a critical role for at least the next two decades. Therefore, understanding the Booster in great detail is important as we continue to improve its performance. For example, it is important to know accurately the available RF power in the Booster by carrying out beam-based measurements in order to specify the needed upgrades to the Booster RF system. Since the Booster magnetic field is changing continuously measuring/calibrating the RFmore » voltage is not a trivial task. Here, we present a beam based method for the RF voltage measurements. Data analysis is carried out using computer programs developed in Python and MATLAB. The method presented here is applicable to any RCS which do not have flat-bottom and flat-top in the acceleration magnetic ramps. We have also carried out longitudinal beam tomography at injection and extraction energies with the data used for RF voltage measurements. Beam based RF voltage measurements and beam tomography were never done before for the Fermilab Booster. The results from these investigations will be very useful in future intensity upgrades.« less

Space-Based Solar Power Conversion and Delivery Systems Study. Volume 3: Microwave Power Transmission Studies

NASA Technical Reports Server (NTRS)

1977-01-01

The Microwave Fower Beam Ionosphere effects and critical interfaces between th Microwave Power Transmission System (MPTS) and the Satellite were studied as part of the NASA/MSFC continuing research on the feasibility of power transmission from geosynchronous orbit. Theoretical predications of ionospheric modifications produced by the direct interaction of the MPTS on the earth's upper atmosphere are used to determine their impact on the performance of the Microwave Power Beam and Pilot Beam System as well as on other RF systems effected by the ionosphere. A technology program to quantitatively define these interactions is developed. Critical interface areas between the MPTS and the satellite which could have a major impact on cost and performance of the power system are idenfified and analyzed. The areas selected include: use of either a 20 kV versus 40 kV Amplitron, thermal blockage effects of Amplitron heat radiation by the satellite structure, effect of dielectric carry-through structure on power beam, and effect of material sublimation on performance of the Amplitron in Geosynchronous Orbit.

Three-beam coherent combination experiments based on segmented mirrors and measure of phase characteristics of beams passing through Yb-doped fiber amplifier

NASA Astrophysics Data System (ADS)

Yang, Ping; Yang, Ruo fu; Shen, Feng; Ao, Mingwu; Jiang, Wenhan

2009-05-01

Coherent combination is one of the most promising ways to realize high power laser output. A three- laser-beam coherent combination system based on adaptive optics (AO) technique has been set up in our laboratory. In this system, three 1064nm laser beams are placed side-by-side and compressed by two reflective mirrors. An active segmented deformable mirror (DM) is used to compensate the optical path difference (OPD) among three laser beams. The beams are overlapped onto a 2900Hz CCD camera to form an interference pattern while the peak intensity of the interference pattern is taken as the cost function to optimize by a stochastic parallel gradient descent (SPGD) algorithm. SPGD algorithm is realized on a RT-Linux dual-core industrial computer. A series of experiments have been accomplished and experimental results show that both static distorted aberrations in the beams and active distorted aberrations (which are brought in by a hot iron and the frequency is about 5Hz) can be compensated successfully when the gain coefficients and the perturbation amplitude of SPGD are chosed appropriately, thereby three beams can be well combined. For controlling the phase of fiber lasers, the phase characteristics of beams passing through Yb-doped dual-clad fiber amplifier are measured by means of investigating the interference pattern under different output power through experiments. The frequency of phase fluctuation is evaluated through analyzing the fluctuation of power within a 90um aperture of far-field focal spot. Experimental results show that the phase fluctuation frequencies of laser beam transmitted through fiber amplifier are mainly in the range of 100~1500Hz. As a result, to control the phase fluctuation of beams passing through fiber amplifier, the bandwidth of any potential phase control scheme must be greater than 1.5 kilohertz.

Focusing Intense Charged Particle Beams with Achromatic Effects for Heavy Ion Fusion

NASA Astrophysics Data System (ADS)

Mitrani, James; Kaganovich, Igor

2012-10-01

Final focusing systems designed to minimize the effects of chromatic aberrations in the Neutralized Drift Compression Experiment (NDCX-II) are described. NDCX-II is a linear induction accelerator, designed to accelerate short bunches at high current. Previous experiments showed that neutralized drift compression significantly compresses the beam longitudinally (˜60x) in the z-direction, resulting in a narrow distribution in z-space, but a wide distribution in pz-space. Using simple lenses (e.g., solenoids, quadrupoles) to focus beam bunches with wide distributions in pz-space results in chromatic aberrations, leading to lower beam intensities (J/cm^2). Therefore, the final focusing system must be designed to compensate for chromatic aberrations. The paraxial ray equations and beam envelope equations are numerically solved for parameters appropriate to NDCX-II. Based on these results, conceptual designs for final focusing systems using a combination of solenoids and/or quadrupoles are optimized to compensate for chromatic aberrations. Lens aberrations and emittance growth will be investigated, and analytical results will be compared with results from numerical particle-in-cell (PIC) simulation codes.

Experimental evaluation of tailored chordwise deformable box beam and correlation with theory

NASA Technical Reports Server (NTRS)

Rehfield, Lawrence W.; Zischka, Peter J.; Chang, Stephen; Fentress, Michael L.; Ambur, Damodar R.

1993-01-01

This paper describes an experimental methodology based upon the use of a flexible sling support and load application system that has been created and utilized to evaluate a box beam which incorporates an elastic tailoring technology. The design technique used here for elastically tailoring the composite box beam structure is to produce exaggerated chordwise camber deformation of substantial magnitude to be of practical use in the new composite aircraft wings. The traditional methods such as a four-point bend test to apply constant bending moment with rigid fixtures inhibits the designed chordwise deformation from occurring and, hence, the need for the new test method. The experimental results for global camber and spanwise bending compliances correlate well with theoretical predictions based on a beam-like model.

TU-CD-304-11: Veritas 2.0: A Cloud-Based Tool to Facilitate Research and Innovation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, P; Patankar, A; Etmektzoglou, A

Purpose: We introduce Veritas 2.0, a cloud-based, non-clinical research portal, to facilitate translation of radiotherapy research ideas to new delivery techniques. The ecosystem of research tools includes web apps for a research beam builder for TrueBeam Developer Mode, an image reader for compressed and uncompressed XIM files, and a trajectory log file based QA/beam delivery analyzer. Methods: The research beam builder can generate TrueBeam readable XML file either from scratch or from pre-existing DICOM-RT plans. DICOM-RT plan is first converted to XML format and then researcher can interactively modify or add control points to them. Delivered beam can be verifiedmore » via reading generated images and analyzing trajectory log files. Image reader can read both uncompressed and HND-compressed XIM images. The trajectory log analyzer lets researchers plot expected vs. actual values and deviations among 30 mechanical axes. The analyzer gives an animated view of MLC patterns for the beam delivery. Veritas 2.0 is freely available and its advantages versus standalone software are i) No software installation or maintenance needed, ii) easy accessibility across all devices iii) seamless upgrades and iv) OS independence. Veritas is written using open-source tools like twitter bootstrap, jQuery, flask, and Python-based modules. Results: In the first experiment, an anonymized 7-beam DICOM-RT IMRT plan was converted to XML beam containing 1400 control points. kV and MV imaging points were inserted into this XML beam. In another experiment, a binary log file was analyzed to compare actual vs expected values and deviations among axes. Conclusions: Veritas 2.0 is a public cloud-based web app that hosts a pool of research tools for facilitating research from conceptualization to verification. It is aimed at providing a platform for facilitating research and collaboration. I am full time employee at Varian Medical systems, Palo Alto.« less

Energy based simulation of a Timoshenko beam in non-forced rotation. Influence of the piano hammer shank flexibility on the sound

NASA Astrophysics Data System (ADS)

Chabassier, Juliette; Duruflé, Marc

2014-12-01

A nonlinear model for a vibrating Timoshenko beam in non-forced unknown rotation is derived from the virtual work principle applied to a system of beam with mass at the end. The system represents a piano hammer shank coupled to a hammer head. An energy-based numerical scheme is then provided, obtained by non-classical approaches. A major difficulty for time discretization comes from the nonlinear behavior of the kinetic energy of the system. This new numerical scheme is then coupled to a global energy-preserving numerical solution for the whole piano. The obtained numerical simulations show that the pianistic touch clearly influences the spectrum of the piano sound of equally loud isolated notes. These differences do not come from a possible shock excitation on the structure, or from a changing impact point, or a “longitudinal rubbing motion” on the string, since neither of these features is modeled in our study.

A 50/50 electronic beam splitter in graphene nanoribbons as a building block for electron optics.

PubMed

Lima, Leandro R F; Hernández, Alexis R; Pinheiro, Felipe A; Lewenkopf, Caio

2016-12-21

Based on the investigation of the multi-terminal conductance of a system composed of two graphene nanoribbons, in which one is on top of the other and rotated by [Formula: see text], we propose a setup for a 50/50 electronic beam splitter that neither requires large magnetic fields nor ultra low temperatures. Our findings are based on an atomistic tight-binding description of the system and on the Green function method to compute the Landauer conductance. We demonstrate that this system acts as a perfect 50/50 electronic beam splitter, in which its operation can be switched on and off by varying the doping (Fermi energy). We show that this device is robust against thermal fluctuations and long range disorder, as zigzag valley chiral states of the nanoribbons are protected against backscattering. We suggest that the proposed device can be applied as the fundamental element of the Hong-Ou-Mandel interferometer, as well as a building block of many devices in electron optics.

Upgrade of the Minos+ Experiment Data Acquisition for the High Energy NuMI Beam Run

DOE PAGES

Badgett, William; Hahn, Steve R.; Torretta, Donatella; ...

2016-03-14

The Minos+ experiment is an extension of the Minos experiment at a higher energy and more intense neutrino beam, with the data collection having begun in the fall of 2013. The neutrino beam is provided by the Neutrinos from the Main Injector (NuMI) beam-line at Fermi National Accelerator Laboratory (Fermilab). The detector apparatus consists of two main detectors, one underground at Fermilab and the other in Soudan, Minnesota with the purpose of studying neutrino oscillations at a base line of 735 km. The original data acquisition system has been running for several years collecting data from NuMI, but with themore » extended run from 2013, parts of the system needed to be replaced due to obsolescence, reliability problems, and data throughput limitations. Specifically, we have replaced the front-end readout controllers, event builder, and data acquisition computing and trigger processing farms with modern, modular and reliable devices with few single points of failure. The new system is based on gigabit Ethernet TCP/IP communication to implement the event building and concatenation of data from many front-end VME readout crates. The simplicity and partitionability of the new system greatly eases the debugging and diagnosing process. As a result, the new system improves throughput by about a factor of three compared to the old system, up to 800 megabits per second, and has proven robust and reliable in the current run.« less

Analysis on the propagation characteristics of two multiplexed groups of coaxial OAM beams in atmospheric turbulence

NASA Astrophysics Data System (ADS)

Zheng, Yongping; Tian, Qinghua; Zhang, Wei; Zhang, Qi; Zhu, Lei; Wang, Yongjun; Liu, Bo; Xin, Xiangjun

2018-01-01

Orbital angular momentum (OAM) as a new degree of freedom, greatly improves the spectrum efficiency and channel capacity of optical communication system. It has become the research focus in the field of optical communications. Some scholars have demonstrated that the feasibility of two multiplexed groups of concentric rings of Laguerre-Gaussian (LG) beams with OAM multiplexing transmission in free space. Based on the point, this paper makes the further research on the propagation characteristics of LG beams with this spatial multiplexing structure in atmospheric turbulence. The random phase screen is established by using the modified von Karman power spectrum and the received power and crosstalk power of OAM modes of LG beams are obtained under the Rytov approximation. We investigate the characteristic parameters of LG beams with this spatial multiplexing structure for mitigating turbulence. Simulation results show that the system exists an optimum beam waist related to wavelength in which the received power of OAM modes reaches the maximum. Meanwhile, the BER and aggregate capacity of the system with two multiplexed groups of concentric rings of LG beams with OAM multiplexing are simulated and analyzed under different intensities of atmospheric turbulence. The results reveal that the system with larger mode spacing generally has lower inter-modal crosstalk and larger aggregate capacity than that with the smaller mode spacing. Finally, on the basis of above the analysis and research, some suggestions for efficient OAM multiplexing detection scheme are proposed.

Compact Spreader Schemes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Placidi, M.; Jung, J. -Y.; Ratti, A.

2014-07-25

This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibilitymore » when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.« less

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

NASA Astrophysics Data System (ADS)

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.

Suppressing ghost beams: Backlink options for LISA

NASA Astrophysics Data System (ADS)

Isleif, K.-S.; Gerberding, O.; Penkert, D.; Fitzsimons, E.; Ward, H.; Robertson, D.; Livas, J.; Mueller, G.; Reiche, J.; Heinzel, G.; Danzmann, K.

2017-05-01

In this article we discuss possible design options for the optical phase reference system, the so called backlink, between two moving optical benches in a LISA satellite. The candidates are based on two approaches: Fiber backlinks, with additional features like mode cleaning cavities and Faraday isolators, and free beam backlinks with angle compensation techniques. We will indicate dedicated ghost beam mitigation strategies for the design options and we will point out critical aspects in case of an implementation in LISA.

Design of High Efficiency High Power Electron Accelerator Systems Based on Normal Conducting RF Technology for Energy and Environmental Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolgashev, Valery; Tantawi, Sami

The goal of this project was to perform engineering design studies of three extremely high efficiency electron accelerators with the following parameters [1]: 2 MeV output beam energy and 1 MW average beam power; 10 MeV output energy and 10 MW; 10 MeV output energy and 1 MW. These linacs are intended for energy and environmental applications [2]. We based our designs on normal conducting radio-frequency technology. We have successfully reached this goal where we show rf-to-beam efficiency of 96.7 %, 97.2 %, and 79.6 % for these linacs.

Real-time deformations of organ based on structural mechanics for surgical simulators

NASA Astrophysics Data System (ADS)

Nakaguchi, Toshiya; Tagaya, Masashi; Tamura, Nobuhiko; Tsumura, Norimichi; Miyake, Yoichi

2006-03-01

This research proposes the deformation model of organs for the development of the medical training system using Virtual Reality (VR) technology. First, the proposed model calculates the strains of coordinate axis. Secondly, the deformation is obtained by mapping the coordinate of the object to the strained coordinate. We assume the beams in the coordinate space to calculate the strain of the coordinate axis. The forces acting on the object are converted to the forces applied to the beams. The bend and the twist of the beams are calculated based on the theory of structural mechanics. The bend is derived by the finite element method. We propose two deformation methods which differ in the position of the beams in the coordinate space. One method locates the beams along the three orthogonal axes (x, y, z). Another method locates the beam in the area where the deformation is large. In addition, the strain of the coordinate axis is attenuated in proportion to the distance from the point of action to consider the attenuation of the stress which is a viscoelastic feature of the organs. The proposed model needs less computational cost compared to the conventional deformation method since our model does not need to divide the object into the elasticity element. The proposed model was implemented in the laparoscopic surgery training system, and a real-time deformation can be realized.

RC beams shear-strengthened with fabric-reinforced-cementitious-matrix (FRCM) composite

NASA Astrophysics Data System (ADS)

Loreto, Giovanni; Babaeidarabad, Saman; Leardini, Lorenzo; Nanni, Antonio

2015-12-01

The interest in retrofit/rehabilitation of existing concrete structures has increased due to degradation and/or introduction of more stringent design requirements. Among the externally-bonded strengthening systems fiber-reinforced polymers is the most widely known technology. Despite its effectiveness as a material system, the presence of an organic binder has some drawbacks that could be addressed by using in its place a cementitious binder as in fabric-reinforced cementitious matrix (FRCM) systems. The purpose of this paper is to evaluate the behavior of reinforced concrete (RC) beams strengthened in shear with U-wraps made of FRCM. An extensive experimental program was undertaken in order to understand and characterize this composite when used as a strengthening system. The laboratory results demonstrate the technical viability of FRCM for shear strengthening of RC beams. Based on the experimental and analytical results, FRCM increases shear strength but not proportionally to the number of fabric plies installed. On the other hand, FRCM failure modes are related with a high consistency to the amount of external reinforcement applied. Design considerations based on the algorithms proposed by ACI guidelines are also provided.

Ground-Based Calibration Of A Microwave Landing System

NASA Technical Reports Server (NTRS)

Kiriazes, John J.; Scott, Marshall M., Jr.; Willis, Alfred D.; Erdogan, Temel; Reyes, Rolando

1996-01-01

System of microwave instrumentation and data-processing equipment developed to enable ground-based calibration of microwave scanning-beam landing system (MSBLS) at distances of about 500 to 1,000 ft from MSBLS transmitting antenna. Ensures accuracy of MSBLS near touchdown point, without having to resort to expense and complex logistics of aircraft-based testing. Modified versions prove useful in calibrating aircraft instrument landing systems.

Electrostatic plasma lens for focusing negatively charged particle beams.

PubMed

Goncharov, A A; Dobrovolskiy, A M; Dunets, S M; Litovko, I V; Gushenets, V I; Oks, E M

2012-02-01

We describe the current status of ongoing research and development of the electrostatic plasma lens for focusing and manipulating intense negatively charged particle beams, electrons, and negative ions. The physical principle of this kind of plasma lens is based on magnetic isolation electrons providing creation of a dynamical positive space charge cloud in shortly restricted volume propagating beam. Here, the new results of experimental investigations and computer simulations of wide-aperture, intense electron beam focusing by plasma lens with positive space charge cloud produced due to the cylindrical anode layer accelerator creating a positive ion stream towards an axis system is presented.

Diagnostics of the ITER neutral beam test facility.

PubMed

Pasqualotto, R; Serianni, G; Sonato, P; Agostini, M; Brombin, M; Croci, G; Dalla Palma, M; De Muri, M; Gazza, E; Gorini, G; Pomaro, N; Rizzolo, A; Spolaore, M; Zaniol, B

2012-02-01

The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H(-)∕D(-) production is enhanced by cesium evaporation, will be monitored with thermocouples, electrostatic probes, optical emission spectroscopy, cavity ring down, and laser absorption spectroscopy. The beam is analyzed by cooling water calorimetry, a short pulse instrumented calorimeter, beam emission spectroscopy, visible tomography, and neutron imaging. Design of the diagnostic systems is presented.

Direct Reaction Measurements Using GODDESS

DOE PAGES

Pain, S. D.; Ratkiewicz, A.; Baugher, T.; ...

2017-10-26

GODDESS is a coupling of the charged-particle detection system ORRUBA to the gamma-ray detector array Gammasphere. This coupling has been developed in order to facilitate the high-resolution measurement of direct reactions in normal and inverse kinematics with stable and radioactive beams. GODDESS has been commissioned using a beam of 134Xe at 10 MeV/A, in a campaign of stable beam measurements. The measurement demonstrates the capabilities of GODDESS under radioactive beam conditions, and provides the first data on the single-neutron states in 135Xe, including previously unobserved states based on the orbitals above the N=82 shell closure.

Femtosecond Beam Sources and Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uesaka, Mitsuru

2004-12-07

Short particle beam science has been promoted by electron linac and radiation chemistry up to picoseconds. Recently, table-top TW laser enables several kinds of short particle beams and pump-and-probe analyses. 4th generation SR sources aim to generation and application of about 100 fs X-ray. Thus, femtosecond beam science has become one of the important field in advanced accelerator concepts. By using electron linac with photoinjector, about 200 fs single bunch and 3 fs multi-bunches are available. Tens femtoseconds monoenergetic electron bunch is expected by laser plasma cathode. Concerning the electron bunch diagnosis, we have seen remarkable progress in streak camera,more » coherent radiation spectroscopy, fluctuation method and E/O crystal method. Picosecond time-resolved pump-and-probe analysis by synchronizing electron linac and laser is now possible, but the timing jitter and drift due to several fluctuations in electronic devices and environment are still in picoseconds. On the other hand, the synchronization between laser and secondary beam is done passively by an optical beam-splitter in the system based on one TW laser. Therefore, the timing jitter and drift do not intrinsically exist there. The author believes that the femtosecond time-resolved pump-and-probe analysis must be initiated by the laser plasma beam sources. As to the applications, picosecond time-resolved system by electron photoinjector/linac and femtosecond laser are operating in more than 5 facilities for radiation chemistry in the world. Ti:Sapphire-laser-based repetitive pump-and-probe analysis started by time-resolved X-ray diffraction to visualize the atomic motion. Nd:Glass-laser-based single-shot analysis was performed to visualize the laser ablation via the single-shot ion imaging. The author expects that protein dynamics and ultrafast nuclear physics would be the next interesting targets. Monograph titled 'Femtosecond Beam Science' is published by Imperial College Press/World Scientific in 2004.« less

Full-beam performances of a PET detector with synchrotron therapeutic proton beams.

PubMed

Piliero, M A; Pennazio, F; Bisogni, M G; Camarlinghi, N; Cerello, P G; Del Guerra, A; Ferrero, V; Fiorina, E; Giraudo, G; Morrocchi, M; Peroni, C; Pirrone, G; Sportelli, G; Wheadon, R

2016-12-07

Treatment quality assessment is a crucial feature for both present and next-generation ion therapy facilities. Several approaches are being explored, based on prompt radiation emission or on PET signals by [Formula: see text]-decaying isotopes generated by beam interactions with the body. In-beam PET monitoring at synchrotron-based ion therapy facilities has already been performed, either based on inter-spill data only, to avoid the influence of the prompt radiation, or including both in-spill and inter-spill data. However, the PET images either suffer of poor statistics (inter-spill) or are more influenced by the background induced by prompt radiation (in-spill). Both those problems are expected to worsen for accelerators with improved duty cycle where the inter-spill interval is reduced to shorten the treatment time. With the aim of assessing the detector performance and developing techniques for background reduction, a test of an in-beam PET detector prototype was performed at the CNAO synchrotron-based ion therapy facility in full-beam acquisition modality. Data taken with proton beams impinging on PMMA phantoms showed the system acquisition capability and the resulting activity distribution, separately reconstructed for the in-spill and the inter-spill data. The coincidence time resolution for in-spill and inter-spill data shows a good agreement, with a slight deterioration during the spill. The data selection technique allows the identification and rejection of most of the background originated during the beam delivery. The activity range difference between two different proton beam energies (68 and 72 MeV) was measured and found to be in sub-millimeter agreement with the expected result. However, a slightly longer (2 mm) absolute profile length is obtained for in-spill data when compared to inter-spill data.

Concept and implementation of the Globalstar mobile satellite system

NASA Technical Reports Server (NTRS)

Schindall, Joel

1995-01-01

Globalstar is a satellite-based mobile communications system which provides quality wireless communications (voice and/or data) anywhere in the world except the polar regions. The Globalstar system concept is based upon technological advancements in Low Earth Orbit (LEO) satellite technology and in cellular telephone technology, including the commercial application of Code Division Multiple Access (CDMA) technologies. The Globalstar system uses elements of CDMA and Frequency Division Multiple Access (FDMA), combined with satellite Multiple Beam Antenna (MBA) technology and advanced variable-rate vocoder technology to arrive at one of the most efficient modulation and multiple access systems ever proposed for a satellite communications system. The technology used in Globalstar includes the following techniques in obtaining high spectral efficiency and affordable cost per channel: (1) CDMA modulation with efficient power control; (2) high efficiency vocoder with voice activity factor; (3) spot beam antenna for increased gain and frequency reuse; (4) weighted satellite antenna gain for broad geographic coverage; (5) multisatellite user links (diversity) to enhance communications reliability; and (6) soft hand-off between beams and satellites. Initial launch is scheduled in 1997 and the system is scheduled to be operational in 1998. The Globalstar system utilizes frequencies in L-, S- and C-bands which have the potential to offer worldwide availability with authorization by the appropriate regulatory agencies.

Investigation of chaos and its control in a Duffing-type nano beam model

NASA Astrophysics Data System (ADS)

Jha, Abhishek Kumar; Dasgupta, Sovan Sundar

2018-04-01

The prediction of chaos of a nano beam with harmonic excitation is investigated. Using the Galerkin method the nonlinear lumped model of a clamped-clamped nano beam with nonlinear cubic stiffness is obtained. This is a Duffing system with hardening type of nonlinearity. Based on the energy function and the phase portrait of the system, the resonator dynamics is categorized into four situations in which Using Malnikov function, an analytical criterion for homoclinic intersection in the form of inequality is written in terms of the system parameters. A numerical study including largest lyapunov exponent, Poincare diagram and phase portrait confirm the analytical prediction of chaos and effect of forcing amplitude. Subsequently, a linear velocity feedback controller is introduced into the system to successfully control the chaotic motion of the system at a faster rate at larger value of gain parameter.

Implementation of the Timepix ASIC in the Scalable Readout System

NASA Astrophysics Data System (ADS)

Lupberger, M.; Desch, K.; Kaminski, J.

2016-09-01

We report on the development of electronics hardware, FPGA firmware and software to provide a flexible multi-chip readout of the Timepix ASIC within the framework of the Scalable Readout System (SRS). The system features FPGA-based zero-suppression and the possibility to read out up to 4×8 chips with a single Front End Concentrator (FEC). By operating several FECs in parallel, in principle an arbitrary number of chips can be read out, exploiting the scaling features of SRS. Specifically, we tested the system with a setup consisting of 160 Timepix ASICs, operated as GridPix devices in a large TPC field cage in a 1 T magnetic field at a DESY test beam facility providing an electron beam of up to 6 GeV. We discuss the design choices, the dedicated hardware components, the FPGA firmware as well as the performance of the system in the test beam.

The construction of a highly transportable laser ranging station

NASA Technical Reports Server (NTRS)

1980-01-01

The technology of the transportable Laser Ranging Station (TLRS) used in crustal dynamics studies was examined. The TLRS used a single photoelectron beam of limited energy density returned from the Laser Geodynamic Satellite (LAGEOS). Calibration was accomplished by the diversion of a small portion of the outgoing beam attenuated to the same level as the satellite return. Timing for the system was based on a self calibrating Ortec TD811, 100 picosec time interval device. The system was contained in a modified, single chassis recreational vehicle that allowed rapid deployment. The TLRS system was only airmobile on the largest transport aircraft. A 30 cm simple plano/concave transfer lens telescope aided in beam direction. The TLRS system fulfills the need for an accurate method of obtaining range measurements to the LAGEOS satellite incorporated in a mobile, air transportable, and economical configuration.

Developments on a SEM-based X-ray tomography system: Stabilization scheme and performance evaluation

NASA Astrophysics Data System (ADS)

Gomes Perini, L. A.; Bleuet, P.; Filevich, J.; Parker, W.; Buijsse, B.; Kwakman, L. F. Tz.

2017-06-01

Recent improvements in a SEM-based X-ray tomography system are described. In this type of equipment, X-rays are generated through the interaction between a highly focused electron-beam and a geometrically confined anode target. Unwanted long-term drifts of the e-beam can lead to loss of X-ray flux or decrease of spatial resolution in images. To circumvent this issue, a closed-loop control using FFT-based image correlation is integrated to the acquisition routine, in order to provide an in-line drift correction. The X-ray detection system consists of a state-of-the-art scientific CMOS camera (indirect detection), featuring high quantum efficiency (˜60%) and low read-out noise (˜1.2 electrons). The system performance is evaluated in terms of resolution, detectability, and scanning times for applications covering three different scientific fields: microelectronics, technical textile, and material science.

Current Status of Study on Hydrogen Production with Space Solar Power Systems (SSPS)

NASA Astrophysics Data System (ADS)

Mori, M.; Kagawa, H.; Nagayama, H.; Saito, Y.

2004-12-01

Japan Aerospace Exploration Agency (JAXA) has been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. The microwave based SSPS are huge solar power systems that generate GW power by solar cells. The electric power is transmitted via microwave from the SSPS to the ground. In the laser based SSPS, a solar condenser equipped with lenses or mirrors and laser-generator would be put into orbit. A laser beam would be sent to Earth-based hydrogen generating device. We are proposing a roadmap that consists of a stepwise approach to achieve commercial SSPS in 20-30 years. The first step is 50kW class Technology Demonstration Satellite to demonstrate microwave power transmission. The second step is to demonstrate robotic assembly of 10MW class large scale flexible structure in space on ISS co-orbit. The third step is to build a prototype SSPS in GEO. The final step is to build commercial SSPS in GEO. We continue the study of SSPS concepts and architectures, technology flight demonstration and major technology development. System design of tens of kW class Technology Demonstration Satellite and conceptual study of 10MW class demonstration system on ISS co-orbit are also conducted. Several key technologies which are needed to be developed in appropriate R&D roadmap, such as high-voltage solar cell array, fiber type of direct solar pumping solid-state laser, high efficiency magnetron, thermal control technology and control technology of large scale flexible structure etc. are also investigated. In the study of concept design of commercial SSPS mentioned above, we have studied some configurations of both microwave based SSPS and laser based SSPS. In case of microwave based SSPS, the solar energy must be converted to electricity and then converted to a microwave beam. The on-ground rectifying antenna will collect the microwave beam and convert it to electricity to connect to commercial power grids. From the past experiences of the conceptual design of the1GW class SSPS, it is clear that system with the mirrors and modularized unit which integrated solar cells and microwave power transmitters is promising. In this type of SSPS, the solar lights are directed to the energy conversion unit integrated solar cells and microwave power transmitters using mirrors. The key factor in designing systems is feasibility of thermal system. Considering above these factors, some reference models are being considered now. FY2003 reference model is the model for formation flight without the center truss which connect to primary mirrors to energy conversion unit. Using this model as basis, we are carrying out examination from various viewpoints aiming at the cost minimum to build and maintain the systems. In case of laser based SSPS, the laser beam would be directly produced from the solar light using the direct solar pumping solid-state laser device. This laser beams would be collected on ground and used to produce hydrogen from seawater. The receiving / energy conversion station is settled on an ocean, and producing hydrogen can be stored and transported by ships to consumers. In designing laser based SSPS, conversion efficiency of the direct solar pumping solid-state laser and feasibility of thermal system are critical factors. Since magnification of solar concentrator is very high, improvement of thermal control system is important. Feasibility of its ground facilities and production technology of hydrogen using laser beams has been also studied. Both hydrogen generating systems with photo-catalyst device and electrolytic ones have been examined. From the past experiences of this study, high efficient electric power generating technology using the solar cell which suited the wavelength of laser is promising. The life cycle cost model of laser based SSPS was created and evaluated its validity. Sensitivity analysis of laser based SSPS are also continued aiming at hydrogen generating cost of around 20 cent per Nm3 . This paper presents a summary of studies on SSPS that JAXA has examined.

Dual-wavelength photothermal optical coherence tomography for blood oxygen saturation measurement

NASA Astrophysics Data System (ADS)

Yin, Biwei; Kuranov, Roman V.; McElroy, Austin B.; Milner, Thomas E.

2013-03-01

We report design and demonstration of a dual wavelength photothermal (DWP) optical coherence tomography (OCT) system for imaging of a phantom microvessel and measurement of hemoglobin oxygen saturation (SO2) level. The DWP-OCT system contains a swept-source (SS) two-beam phase-sensitive (PhS) OCT system (1060 nm) and two intensity modulated photothermal excitation lasers (770 nm and 800 nm). The PhS-OCT probe beam (1060 nm) and photothermal excitation beams are combined into one single-mode optical fiber. A galvanometer based two-dimensional achromatic scanning system is designed to provide 14 μm lateral resolution for the PhS-OCT probe beam (1060 nm) and 13 μm lateral resolution for photothermal excitation beams. DWP-OCT system's sensitivity is 102 dB, axial resolution is 13 μm in tissue and uses a real-time digital dispersion compensation algorithm. Noise floor for optical pathlength measurements is 300 pm in the signal frequency range (380-400 Hz) of photothermal modulation frequencies. Blood SO2 level is calculated from measured optical pathlength (op) signal in a 300 μm diameter microvessel phantom introduced by the two photothermal excitation beams. En-face and B-scan images of a phantom microvessel are recorded, and six blood samples' SO2 levels are measured using DWP-OCT and compared with values provided by a commercial blood oximeter. A mathematical model indicates thermal diffusion introduces a systematic artifact that over-estimates SO2 values and is consistent with measured data.

The Potential for Health Monitoring in Expandable Space Modules: The Bigelow Expandable Activity Module on the ISS

NASA Technical Reports Server (NTRS)

Wells, Nathan D.; Madaras, Eric I.

2017-01-01

Expandable modules for use in space and on the Moon or Mars offer a great opportunity for volume and mass savings in future space exploration missions. This type of module can be compressed into a relatively small shape on the ground, allowing them to fit into space vehicles with a smaller cargo/fairing size than a traditional solid, metallic structure based module would allow. In April 2016, the Bigelow Expandable Activity Module (BEAM) was berthed to the International Space Station (ISS). BEAM is the first human-rated expandable habitat/module to be deployed and crewed in space. BEAM is a NASA managed ISS payload project in partnership with Bigelow Aerospace. BEAM is intended to stay attached to ISS for an operational period of 2 years to help advance the technology readiness for future expandable modules. BEAM has been instrumented with a suite of space flight certified sensors systems which will help characterize the module's performance for thermal, radiation shielding and impact monitoring against potential Micro Meteoroid/Orbital Debris (MM/OD) providing fundamental information on the BEAM environment for potential health monitoring requirements and capabilities. This paper will provide an overview of how the sensors/instrumentation systems were developed, tested, installed and an overview of the current sensor system operations. It will also discuss how the MM/OD impact detection system referred to as the Distributed Impact Detection System (DIDS) data is being processed and reviewed on the ground by the principle investigators.

Rapid and efficient formation of propagation invariant shaped laser beams.

PubMed

Chriki, Ronen; Barach, Gilad; Tradosnky, Chene; Smartsev, Slava; Pal, Vishwa; Friesem, Asher A; Davidson, Nir

2018-02-19

A rapid and efficient all-optical method for forming propagation invariant shaped beams by exploiting the optical feedback of a laser cavity is presented. The method is based on the modified degenerate cavity laser (MDCL), which is a highly incoherent cavity laser. The MDCL has a very large number of degrees of freedom (320,000 modes in our system) that can be coupled and controlled, and allows direct access to both the real space and Fourier space of the laser beam. By inserting amplitude masks into the cavity, constraints can be imposed on the laser in order to obtain minimal loss solutions that would optimally lead to a superposition of Bessel-Gauss beams forming a desired shaped beam. The resulting beam maintains its transverse intensity distribution for relatively long propagation distances.

Issues in Acceleration of A Muon Beam for a Neutrino Factory

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Delayen; D. Douglas; L. Harwood

2001-06-01

We have developed a concept for acceleration of a large phase-space, pulsed muon beam from 190 MeV to 50 GeV as part of a collaborative study of the feasibility of a neutrino factory based on in-flight decay of muons. The muon beam's initial energy spread was {approximately}20% and each bunch has the physical size of a soccer ball. Production of the muons will be quite expensive, so prevention of loss due to scraping or decay is critical. The former drives the system to large apertures and the latter calls for high real-estate-average gradients. The solution to be presented utilizes amore » 3 GeV linac to capture the beam, a 4-pass recirculating linac to get the beam to 10 GeV, and then a 5-pass linac to get the beam to 50 GeV. Throughout the system, longitudinal dynamics issues far outweighed transverse dynamics issues. This paper focuses on the issues surrounding the choice of superconducting rf structures over copper structures.« less

Beam Instrument Development System

DOE Office of Scientific and Technical Information (OSTI.GOV)

DOOLITTLE, LAWRENCE; HUANG, GANG; DU, QIANG

Beam Instrumentation Development System (BIDS) is a collection of common support libraries and modules developed during a series of Low-Level Radio Frequency (LLRF) control and timing/synchronization projects. BIDS includes a collection of Hardware Description Language (HDL) libraries and software libraries. The BIDS can be used for the development of any FPGA-based system, such as LLRF controllers. HDL code in this library is generic and supports common Digital Signal Processing (DSP) functions, FPGA-specific drivers (high-speed serial link wrappers, clock generation, etc.), ADC/DAC drivers, Ethernet MAC implementation, etc.

Control System for the LLNL Kicker Pulse Generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, J A; Anaya, R M; Cook, E G

2002-06-18

A solid-state high voltage pulse generator with multi-pulse burst capability, very fast rise and fall times, pulse width agility, and amplitude modulation capability for use with high speed electron beam kickers has been designed and tested at LLNL. A control system calculates a desired waveform to be applied to the kicker based on measured electron beam displacement then adjusts the pulse generators to provide the desired waveform. This paper presents the design of the control system and measure performance data from operation on the ETA-11 accelerator at LLNL.

APT Blanket System Loss-of-Coolant Accident (LOCA) Based on Initial Conceptual Design - Case 2: with Beam Shutdown Only

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamm, L.L.

1998-10-07

This report is one of a series of reports that document normal operation and accident simulations for the Accelerator Production of Tritium (APT) blanket heat removal system. These simulations were performed for the Preliminary Safety Analysis Report. This report documents the results of simulations of a Loss-of-Flow Accident (LOFA) where power is lost to all of the pumps that circulate water in the blanket region, the accelerator beam is shut off and neither the residual heat removal nor cavity flood systems operate.

A home-made system for IPCE measurement of standard and dye-sensitized solar cells.

PubMed

Palma, Giuseppina; Cozzarini, Luca; Capria, Ennio; Fraleoni-Morgera, Alessandro

2015-01-01

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm the possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.

Design of charge exchange recombination spectroscopy for the joint Texas experimental tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Y.; Zhuang, G., E-mail: ge-zhuang@hust.edu.cn; Cheng, Z. F.

The old diagnostic neutral beam injector first operated at the University of Texas at Austin is ready for rejoining the joint Texas experimental tokamak (J-TEXT). A new set of high voltage power supplies has been equipped and there is no limitation for beam modulation or beam pulse duration henceforth. Based on the spectra of fully striped impurity ions induced by the diagnostic beam the design work for toroidal charge exchange recombination spectroscopy (CXRS) system is presented. The 529 nm carbon VI (n = 8 − 7 transition) line seems to be the best choice for ion temperature and plasma rotationmore » measurements and the considered hardware is listed. The design work of the toroidal CXRS system is guided by essential simulation of expected spectral results under the J-TEXT tokamak operation conditions.« less

Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System

NASA Astrophysics Data System (ADS)

Turnbull, D.; Goyon, C.; Kemp, G. E.; Pollock, B. B.; Mariscal, D.; Divol, L.; Ross, J. S.; Patankar, S.; Moody, J. D.; Michel, P.

2017-01-01

We report the first complete set of measurements of a laser-plasma optical system's refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time. The data include the first demonstration of a laser-plasma polarizer with 85 %- 87 % extinction for the particular laser and plasma parameters used in this experiment, complementing the existing suite of high-power, tunable, and ultrafast plasma-based photonic devices.

Refractive Index Seen by a Probe Beam Interacting with a Laser-Plasma System.

PubMed

Turnbull, D; Goyon, C; Kemp, G E; Pollock, B B; Mariscal, D; Divol, L; Ross, J S; Patankar, S; Moody, J D; Michel, P

2017-01-06

We report the first complete set of measurements of a laser-plasma optical system's refractive index, as seen by a second probe laser beam, as a function of the relative wavelength shift between the two laser beams. Both the imaginary and real refractive index components are found to be in good agreement with linear theory using plasma parameters measured by optical Thomson scattering and interferometry; the former is in contrast to previous work and has implications for crossed-beam energy transfer in indirect-drive inertial confinement fusion, and the latter is measured for the first time. The data include the first demonstration of a laser-plasma polarizer with 85%-87% extinction for the particular laser and plasma parameters used in this experiment, complementing the existing suite of high-power, tunable, and ultrafast plasma-based photonic devices.

Particle production of a graphite target system for the intensity frontier

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, X.; Kirk, H.; McDonald, K. T.

2015-05-03

A solid graphite target system is considered for an intense muon and/or neutrino source in support of physics at the intensity frontier. We previously optimized the geometric parameters of the beam and target to maximize particle production at low energies by incoming protons with kinetic energy of 6.75 GeV and an rms geometric emittance of 5 mm-mrad using the MARS15(2014) code. In this study, we ran MARS15 with ROOT-based geometry and also considered a mercury-jet target as an upgrade option. The optimization was extended to focused proton beams with transverse emittances from 5 to 50 mm-mrad, showing that the particlemore » production decreases slowly with increasing emittance. We also studied beam-dump configurations to suppress the rate of undesirable high-energy secondary particles in the beam.« less

Perspectives of using the 223-nm wavelength of the KrCl excimer laser for refractive surgery and for the treatment of some eye diseases

NASA Astrophysics Data System (ADS)

Bagayev, Sergei N.; Chernikh, Valery V.; Razhev, Alexander M.; Zhupikov, Andrey A.

2000-06-01

The new surgical UV ophthalmic laser system Medilex based on the KrCl (223 nm) excimer laser for refractive surgery was created. The comparative analysis of using the UV ophthalmic laser systems Medilex based on the ArF (193 nm) and the KrCl (223 nm) excimer lasers for the correction of refractive errors was performed. The system with the radiation wavelength of 223 nanometer of the KrCl excimer laser for refractive surgery was shown to have several medical and technical advantages over the system with the traditionally used radiation wavelength of 193 nanometer of the ArF excimer laser. In addition the use of the wavelength of 223 nanometer extends functional features of the system, allowing to make not only standard for this type systems surgical and therapeutic procedures but also to treat such ocular diseases as the glaucoma and herpetic keratities. For the UV ophthalmic laser systems Medilex three variations of the beam delivery system including special rotating masks and different beam homogenize systems were developed. All created beam delivery systems are able to make the correction of myopia, hyperopia, astigmatism and myopic or hyperopic astigmatism and may be used for therapeutic procedures. The results of the initial treatments of refractive error corrections using the UV ophthalmic laser systems Medilex for both photorefractive keratectomy (PRK) and LASIK procedures are presented.

Quantitative approach for optimizing e-beam condition of photoresist inspection and measurement

NASA Astrophysics Data System (ADS)

Lin, Chia-Jen; Teng, Chia-Hao; Cheng, Po-Chung; Sato, Yoshishige; Huang, Shang-Chieh; Chen, Chu-En; Maruyama, Kotaro; Yamazaki, Yuichiro

2018-03-01

Severe process margin in advanced technology node of semiconductor device is controlled by e-beam metrology system and e-beam inspection system with scanning electron microscopy (SEM) image. By using SEM, larger area image with higher image quality is required to collect massive amount of data for metrology and to detect defect in a large area for inspection. Although photoresist is the one of the critical process in semiconductor device manufacturing, observing photoresist pattern by SEM image is crucial and troublesome especially in the case of large image. The charging effect by e-beam irradiation on photoresist pattern causes deterioration of image quality, and it affect CD variation on metrology system and causes difficulties to continue defect inspection in a long time for a large area. In this study, we established a quantitative approach for optimizing e-beam condition with "Die to Database" algorithm of NGR3500 on photoresist pattern to minimize charging effect. And we enhanced the performance of measurement and inspection on photoresist pattern by using optimized e-beam condition. NGR3500 is the geometry verification system based on "Die to Database" algorithm which compares SEM image with design data [1]. By comparing SEM image and design data, key performance indicator (KPI) of SEM image such as "Sharpness", "S/N", "Gray level variation in FOV", "Image shift" can be retrieved. These KPIs were analyzed with different e-beam conditions which consist of "Landing Energy", "Probe Current", "Scanning Speed" and "Scanning Method", and the best e-beam condition could be achieved with maximum image quality, maximum scanning speed and minimum image shift. On this quantitative approach of optimizing e-beam condition, we could observe dependency of SEM condition on photoresist charging. By using optimized e-beam condition, measurement could be continued on photoresist pattern over 24 hours stably. KPIs of SEM image proved image quality during measurement and inspection was stabled enough.

High-precision positioning system of four-quadrant detector based on the database query

NASA Astrophysics Data System (ADS)

Zhang, Xin; Deng, Xiao-guo; Su, Xiu-qin; Zheng, Xiao-qiang

2015-02-01

The fine pointing mechanism of the Acquisition, Pointing and Tracking (APT) system in free space laser communication usually use four-quadrant detector (QD) to point and track the laser beam accurately. The positioning precision of QD is one of the key factors of the pointing accuracy to APT system. A positioning system is designed based on FPGA and DSP in this paper, which can realize the sampling of AD, the positioning algorithm and the control of the fast swing mirror. We analyze the positioning error of facular center calculated by universal algorithm when the facular energy obeys Gauss distribution from the working principle of QD. A database is built by calculation and simulation with MatLab software, in which the facular center calculated by universal algorithm is corresponded with the facular center of Gaussian beam, and the database is stored in two pieces of E2PROM as the external memory of DSP. The facular center of Gaussian beam is inquiry in the database on the basis of the facular center calculated by universal algorithm in DSP. The experiment results show that the positioning accuracy of the high-precision positioning system is much better than the positioning accuracy calculated by universal algorithm.

Hollow Gaussian beam generated by beam shaping with phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Nie, Yongming; Li, Xiujian; Qi, Junli; Ma, Haotong; Liao, Jiali; Yang, Jiankun; Hu, Wenhua

2012-03-01

Based on the refractive beam shaping system, the transformation of a quasi-Gaussian beam into a dark hollow Gaussian beam by a phase-only liquid crystal spatial light modulator (LC-SLM) is proposed. According to the energy conservation and constant optical path principle, the phase distribution of the aspheric lens and the phase-only LC-SLM can modulate the wave-front properly to generate the hollow beam. The numerical simulation results indicate that, the dark hollow intensity distribution of the output shaped beam can be maintained well for a certain propagation distance during which the dark region will not decrease whereas the ideal hollow Gaussian beam will do. By designing the phase modulation profile, which loaded into the LC-SLM carefully, the experimental results indicate that the dark hollow intensity distribution of the output shaped beam can be maintained well even at a distance much more than 550 mm from the LC-SLM, which agree with the numerical simulation results.

Measurement of M²-Curve for Asymmetric Beams by Self-Referencing Interferometer Wavefront Sensor.

PubMed

Du, Yongzhao

2016-11-29

For asymmetric laser beams, the values of beam quality factor M x 2 and M y 2 are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, even when analyzing the same beam. To overcome this non-uniqueness, a new beam quality characterization method named as M²-curve is developed. The M²-curve not only contains the beam quality factor M x 2 and M y 2 in the x -direction and y -direction, respectively; but also introduces a curve of M x α 2 versus rotation angle α of coordinate axis. Moreover, we also present a real-time measurement method to demonstrate beam propagation factor M²-curve with a modified self-referencing Mach-Zehnder interferometer based-wavefront sensor (henceforth SRI-WFS). The feasibility of the proposed method is demonstrated with the theoretical analysis and experiment in multimode beams. The experimental results showed that the proposed measurement method is simple, fast, and a single-shot measurement procedure without movable parts.

Measurement of M2-Curve for Asymmetric Beams by Self-Referencing Interferometer Wavefront Sensor

PubMed Central

Du, Yongzhao

2016-01-01

For asymmetric laser beams, the values of beam quality factor Mx2 and My2 are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, even when analyzing the same beam. To overcome this non-uniqueness, a new beam quality characterization method named as M2-curve is developed. The M2-curve not only contains the beam quality factor Mx2 and My2 in the x-direction and y-direction, respectively; but also introduces a curve of Mxα2 versus rotation angle α of coordinate axis. Moreover, we also present a real-time measurement method to demonstrate beam propagation factor M2-curve with a modified self-referencing Mach-Zehnder interferometer based-wavefront sensor (henceforth SRI-WFS). The feasibility of the proposed method is demonstrated with the theoretical analysis and experiment in multimode beams. The experimental results showed that the proposed measurement method is simple, fast, and a single-shot measurement procedure without movable parts. PMID:27916845

Edge roughness evaluation method for quantifying at-size beam blur in electron-beam lithography

NASA Astrophysics Data System (ADS)

Yoshizawa, Masaki; Moriya, Shigeru

2000-07-01

At-size beam blur at any given pattern size of an electron beam (EB) direct writer, HL800D, was quantified using the new edge roughness evaluation (ERE) method to optimize the electron-optical system. We characterized the two-dimensional beam-blur dependence on the electron deflection length of the EB direct writer. The results indicate that the beam blur ranged from 45 nm to 56 nm in a deflection field 2520 micrometer square. The new ERE method is based on the experimental finding that line edge roughness of a resist pattern is inversely proportional to the slope of the Gaussian-distributed quasi-beam-profile (QBP) proposed in this paper. The QBP includes effects of the beam blur, electron forward scattering, acid diffusion in chemically amplified resist (CAR), the development process, and aperture mask quality. The application the ERE method to investigating the beam-blur fluctuation demonstrates the validity of the ERE method in characterizing the electron-optical column conditions of EB projections such as SCALPEL and PREVAIL.

Advanced Energy Conversion Technologies and Architectures for Earth and Beyond

NASA Technical Reports Server (NTRS)

Howell, Joe T.; Fikes, John C.; Phillips, Dane J.; Laycock, Rustin L.; ONeill, Mark; Henley, Mark W.; Fork, Richard L.

2006-01-01

Research, development and studies of novel space-based solar power systems, technologies and architectures for Earth and beyond are needed to reduce the cost of clean electrical power for terrestrial use and to provide a stepping stone for providing an abundance of power in space, i.e., manufacturing facilities, tourist facilities, delivery of power between objects in space, and between space and surface sites. The architectures, technologies and systems needed for space to Earth applications may also be used for in-space applications. Advances in key technologies, i.e., power generation, power management and distribution, power beaming and conversion of beamed power are needed to achieve the objectives of both terrestrial and extraterrestrial applications. There is a need to produce "proof-ofconcept" validation of critical WPT technologies for both the near-term, as well as far-term applications. Investments may be harvested in near-term beam safe demonstrations of commercial WPT applications. Receiving sites (users) include ground-based stations for terrestrial electrical power, orbital sites to provide power for satellites and other platforms, future space elevator systems, space vehicle propulsion, and space surface sites. Space surface receiving sites of particular interest include the areas of permanent shadow near the moon s North and South poles, where WPT technologies could enable access to ice and other useful resources for human exploration. This paper discusses work addressing a promising approach to solar power generation and beamed power conversion. The approach is based on a unique high-power solar concentrator array called Stretched Lens Array (SLA) applied to both solar power generation and beamed power conversion. Since both versions (solar and laser) of SLA use many identical components (only the photovoltaic cells need to be different), economies of manufacturing and scale may be realized by using SLA on both ends of the laser power beaming system in a space solar power application. Near-term uses of this SLA-laser-SLA system may include terrestrial and space exploration in near Earth space. Later uses may include beamed power for bases or vehicles on Mars. Strategies for developing energy infrastructures in space which utilize this technology are presented. This dual use system produces electrical energy efficiently from either coherent light, such as from a highly coherent laser, or from conventional solar illumination. This allows, for example, supplementing solar energy with energy provided by highly coherent laser illumination during periods of low solar illumination or no illumination. This reduces the need for batteries and alternate sources of power. The capability of using laser illumination in a lowest order Gaussian laser mode provides means for transmitting power optically with maximum efficiency and precision over the long distances characteristic of space. A preliminary receiving system similar to that described here, has been produced and tested under solar and laser illumination. A summary of results is given.

Voxel-Based 3-D Tree Modeling from Lidar Images for Extracting Tree Structual Information

NASA Astrophysics Data System (ADS)

Hosoi, F.

2014-12-01

Recently, lidar (light detection and ranging) has been used to extracting tree structural information. Portable scanning lidar systems can capture the complex shape of individual trees as a 3-D point-cloud image. 3-D tree models reproduced from the lidar-derived 3-D image can be used to estimate tree structural parameters. We have proposed the voxel-based 3-D modeling for extracting tree structural parameters. One of the tree parameters derived from the voxel modeling is leaf area density (LAD). We refer to the method as the voxel-based canopy profiling (VCP) method. In this method, several measurement points surrounding the canopy and optimally inclined laser beams are adopted for full laser beam illumination of whole canopy up to the internal. From obtained lidar image, the 3-D information is reproduced as the voxel attributes in the 3-D voxel array. Based on the voxel attributes, contact frequency of laser beams on leaves is computed and LAD in each horizontal layer is obtained. This method offered accurate LAD estimation for individual trees and woody canopy trees. For more accurate LAD estimation, the voxel model was constructed by combining airborne and portable ground-based lidar data. The profiles obtained by the two types of lidar complemented each other, thus eliminating blind regions and yielding more accurate LAD profiles than could be obtained by using each type of lidar alone. Based on the estimation results, we proposed an index named laser beam coverage index, Ω, which relates to the lidar's laser beam settings and a laser beam attenuation factor. It was shown that this index can be used for adjusting measurement set-up of lidar systems and also used for explaining the LAD estimation error using different types of lidar systems. Moreover, we proposed a method to estimate woody material volume as another application of the voxel tree modeling. In this method, voxel solid model of a target tree was produced from the lidar image, which is composed of consecutive voxels that filled the outer surface and the interior of the stem and large branches. From the model, the woody material volume of any part of the target tree can be directly calculated easily by counting the number of corresponding voxels and multiplying the result by the per-voxel volume.

A new ion beam facility based on a 3 MV Tandetron™ at IFIN-HH, Romania

NASA Astrophysics Data System (ADS)

Burducea, I.; Straticiuc, M.; Ghiță, D. G.; Moșu, D. V.; Călinescu, C. I.; Podaru, N. C.; Mous, D. J. W.; Ursu, I.; Zamfir, N. V.

2015-09-01

A 3 MV Tandetron™ accelerator system has been installed and commissioned at the "Horia Hulubei" National Institute for Physics and Nuclear Engineering - IFIN-HH, Măgurele, Romania. The main purpose of this machine is to strengthen applied nuclear physics research ongoing in our institute for more than four decades. The accelerator system was developed by High Voltage Engineering Europa B.V. (HVE) and comprises three high energy beam lines. The first beam line is dedicated to ion beam analysis (IBA) techniques: Rutherford Backscattering Spectrometry - RBS, Nuclear Reaction Analysis - NRA, Particle Induced X-ray and γ-ray Emission - PIXE and PIGE and micro-beam experiments - μ-PIXE. The second beam line is dedicated to high energy ion implantation experiments and the third beam line was designed mainly for nuclear cross-sections measurements used in nuclear astrophysics. A unique feature, the first time in operation at an accelerator facility is the Na charge exchange canal (CEC), which is used to obtain high intensity beams of He- of at least 3 μA. The results of the acceptance tests demonstrate the huge potential of this new facility in various fields, from IBA to radiation hardness studies and from medical or environmental applications to astrophysics. The main features of the accelerator are presented in this paper.

Two-dimensional wavelength routing for transparent optical wireless networking

NASA Astrophysics Data System (ADS)

Shi, Haiyan; Liang, Kefei; Sheard, Stephen J.; O'Brien, Dominic C.; Faulkner, Grahame E.

2005-08-01

In this article a novel system architecture that uses a combination of wavelength and spatial diversity for indoor infrared wireless communications is presented. This configuration promises to fully exploit the available bandwidth of optics and demonstrate all-optical networking. Electronic processing is restricted to mobile terminals, with base stations potentially remaining passive, without any conversion between optics and electronics. For the downlink, multiple transmitter beams with different wavelengths are steered from the fiber infrastructure through the base station to mobile terminals located in different positions. An optimum combination of diffractive optics and reflective optics (a diffraction grating and an array of mirrors) can flexibly steer each transmitter beam and enable full control over the required coverage pattern. For the uplink, in the transmitter, another grating and an array of mirrors can direct multiple beams upward from different mobile users toward the base station. System simulation shows that the downlink has the potential to approach 10 Gbit/s, while maintaining wide-area coverage (such as in a room of 3m×4m×4m) with the help of fine optical tracking. System modeling indicates that the uplink is more susceptible to power losses than the downlink, but the utilization of dynamic beam steering in the uplink can suppress power losses to a tolerable level (e.g. below 30dB). An array of 16 mirrors has been designed to implement point-to-point beam steering in a room of 3m×1m×1m. Two-dimensional coverage patterns measured at a distance of 0.5 m and 1.5 m coincide with simulation results. Operation at 1 Gbit/s has been demonstrated successfully for tracking in two dimensions.

Characteristics of a novel treatment system for linear accelerator–based stereotactic radiosurgery

PubMed Central

Li, Haisen; Song, Kwang; Chin‐Snyder, Karen; Qin, Yujiao; Kim, Jinkoo; Bellon, Maria; Gulam, Misbah; Gardner, Stephen; Doemer, Anthony; Devpura, Suneetha; Gordon, James; Chetty, Indrin; Siddiqui, Farzan; Ajlouni, Munther; Pompa, Robert; Hammoud, Zane; Simoff, Michael; Kalkanis, Steven; Movsas, Benjamin; Siddiqui, M. Salim

2015-01-01

The purpose of this study is to characterize the dosimetric properties and accuracy of a novel treatment platform (Edge radiosurgery system) for localizing and treating patients with frameless, image‐guided stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). Initial measurements of various components of the system, such as a comprehensive assessment of the dosimetric properties of the flattening filter‐free (FFF) beams for both high definition (HD120) MLC and conical cone‐based treatment, positioning accuracy and beam attenuation of a six degree of freedom (6DoF) couch, treatment head leakage test, and integrated end‐to‐end accuracy tests, have been performed. The end‐to‐end test of the system was performed by CT imaging a phantom and registering hidden targets on the treatment couch to determine the localization accuracy of the optical surface monitoring system (OSMS), cone‐beam CT (CBCT), and MV imaging systems, as well as the radiation isocenter targeting accuracy. The deviations between the percent depth‐dose curves acquired on the new linac‐based system (Edge), and the previously published machine with FFF beams (TrueBeam) beyond Dmax were within 1.0% for both energies. The maximum deviation of output factors between the Edge and TrueBeam was 1.6%. The optimized dosimetric leaf gap values, which were fitted using Eclipse dose calculations and measurements based on representative spine radiosurgery plans, were 0.700 mm and 1.000 mm, respectively. For the conical cones, 6X FFF has sharper penumbra ranging from 1.2−1.8 mm (80%‐20%) and 1.9−3.8 mm (90%‐10%) relative to 10X FFF, which has 1.2−2.2 mm and 2.3−5.1 mm, respectively. The relative attenuation measurements of the couch for PA, PA (rails‐in), oblique, oblique (rails‐out), oblique (rails‐in) were: −2.0%, −2.5%, −15.6%, −2.5%, −5.0% for 6X FFF and −1.4%, −1.5%, −12.2%, −2.5%, −5.0% for 10X FFF, respectively, with a slight decrease in attenuation versus field size. The systematic deviation between the OSMS and CBCT was −0.4±0.2 mm, 0.1±0.3 mm, and 0.0±0.1 mm in the vertical, longitudinal, and lateral directions. The mean values and standard deviations of the average deviation and maximum deviation of the daily Winston‐Lutz tests over three months are 0.20±0.03 mm and 0.66±0.18 mm, respectively. Initial testing of this novel system demonstrates the technology to be highly accurate and suitable for frameless, linac‐based SRS and SBRT treatment. PACS number: 87.56.J‐ PMID:26218998

Performance of a Nanometer Resolution BPM System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogel, V; Hayano, H; Honda, Y

2005-10-14

International Linear Collider (ILC) interaction region beam sizes and component position stability requirements will be as small as a few nanometers. it is important to the ongoing ILC design effort to demonstrate that these tolerances can be achieved--ideally using beam-based stability measurements. It has been estimated that an RF cavity BPM with modern waveform processing could provide a position measurement resolution of less than one nanometer. Such a system could form the basis of the desired beam-based stability measurement, as well as be used for other specialized purposes. They have developed a high resolution RF cavity BPM and associated electronics.more » A triplet comprised of these BPMs has been installed in the extraction line of the KEK Accelerator Test Facility (ATF) for testing with its ultra-low emittance beam. The three BPMs are rigidly mounted inside an alignment frame on six variable-length struts which can be used to move the BPMs in position and angle. they have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, they have been able to demonstrate a resolution of approximately 20 nm over a dynamic range of {+-} 20 {micro}m. They report on the progress of these ongoing tests.« less

MEMS-based, RF-driven, compact accelerators

NASA Astrophysics Data System (ADS)

Persaud, A.; Seidl, P. A.; Ji, Q.; Breinyn, I.; Waldron, W. L.; Schenkel, T.; Vinayakumar, K. B.; Ni, D.; Lal, A.

2017-10-01

Shrinking existing accelerators in size can reduce their cost by orders of magnitude. Furthermore, by using radio frequency (RF) technology and accelerating ions in several stages, the applied voltages can be kept low paving the way to new ion beam applications. We make use of the concept of a Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) and have previously shown the implementation of its basic components using printed circuit boards, thereby reducing the size of earlier MEQALACs by an order of magnitude. We now demonstrate the combined integration of these components to form a basic accelerator structure, including an initial beam-matching section. In this presentation, we will discuss the results from the integrated multi-beam ion accelerator and also ion acceleration using RF voltages generated on-board. Furthermore, we will show results from Micro-Electro-Mechanical Systems (MEMS) fabricated focusing wafers, which can shrink the dimension of the system to the sub-mm regime and lead to cheaper fabrication. Based on these proof-of-concept results we outline a scaling path to high beam power for applications in plasma heating in magnetized target fusion and in neutral beam injectors for future Tokamaks. This work was supported by the Office of Science of the US Department of Energy through the ARPA-e ALPHA program under contracts DE-AC02-05CH11231.

TH-EF-BRB-05: 4pi Non-Coplanar IMRT Beam Angle Selection by Convex Optimization with Group Sparsity Penalty

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Connor, D; Nguyen, D; Voronenko, Y

Purpose: Integrated beam orientation and fluence map optimization is expected to be the foundation of robust automated planning but existing heuristic methods do not promise global optimality. We aim to develop a new method for beam angle selection in 4π non-coplanar IMRT systems based on solving (globally) a single convex optimization problem, and to demonstrate the effectiveness of the method by comparison with a state of the art column generation method for 4π beam angle selection. Methods: The beam angle selection problem is formulated as a large scale convex fluence map optimization problem with an additional group sparsity term thatmore » encourages most candidate beams to be inactive. The optimization problem is solved using an accelerated first-order method, the Fast Iterative Shrinkage-Thresholding Algorithm (FISTA). The beam angle selection and fluence map optimization algorithm is used to create non-coplanar 4π treatment plans for several cases (including head and neck, lung, and prostate cases) and the resulting treatment plans are compared with 4π treatment plans created using the column generation algorithm. Results: In our experiments the treatment plans created using the group sparsity method meet or exceed the dosimetric quality of plans created using the column generation algorithm, which was shown superior to clinical plans. Moreover, the group sparsity approach converges in about 3 minutes in these cases, as compared with runtimes of a few hours for the column generation method. Conclusion: This work demonstrates the first non-greedy approach to non-coplanar beam angle selection, based on convex optimization, for 4π IMRT systems. The method given here improves both treatment plan quality and runtime as compared with a state of the art column generation algorithm. When the group sparsity term is set to zero, we obtain an excellent method for fluence map optimization, useful when beam angles have already been selected. NIH R43CA183390, NIH R01CA188300, Varian Medical Systems; Part of this research took place while D. O’Connor was a summer intern at RefleXion Medical.« less

Realization of synaptic learning and memory functions in Y2O3 based memristive device fabricated by dual ion beam sputtering

NASA Astrophysics Data System (ADS)

Das, Mangal; Kumar, Amitesh; Singh, Rohit; Than Htay, Myo; Mukherjee, Shaibal

2018-02-01

Single synaptic device with inherent learning and memory functions is demonstrated based on a forming-free amorphous Y2O3 (yttria) memristor fabricated by dual ion beam sputtering system. Synaptic functions such as nonlinear transmission characteristics, long-term plasticity, short-term plasticity and ‘learning behavior (LB)’ are achieved using a single synaptic device based on cost-effective metal-insulator-semiconductor (MIS) structure. An ‘LB’ function is demonstrated, for the first time in the literature, for a yttria based memristor, which bears a resemblance to certain memory functions of biological systems. The realization of key synaptic functions in a cost-effective MIS structure would promote much cheaper synapse for artificial neural network.

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Nie, Yongming; Ma, Haotong; Li, Xiujian; Hu, Wenhua; Yang, Jiankun

2011-07-01

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230fs, which is caused by the spatial--temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged.

Proton radiography based on near-threshold Cerenkov radiation

DOEpatents

van Bibber, Karl A.; Dietrich, Frank S.

2003-01-01

A Cerenkov imaging system for charged particle radiography that determines the energy loss of the charged particle beam passing through an object. This energy loss information provides additional detail on target densities when used with traditional radiographic techniques like photon or x-ray radiography. In this invention a probe beam of 800 MeV to 50 GeV/c charged particles is passed through an object to be imaged, an imaging magnetic spectrometer, to a silicon aerogel Cerenkov radiator where the charged particles emitted Cerenkov light proportional to their velocity. At the same beam focal plane, a particle scintillator produces a light output proportional to the incident beam flux. Optical imaging systems relay the Cerenkov and scintillator information to CCD's or other measurement equipment. A ratio between the Cerenkov and scintillator is formed, which is directly proportional to the line density of the object for each pixel measured. By rotating the object, tomographic radiography may be performed. By applying pulses of beam, discrete time-step movies of dynamic objects may be made.

Dynamic Beam Solutions for Real-Time Simulation and Control Development of Flexible Rockets

NASA Technical Reports Server (NTRS)

Su, Weihua; King, Cecilia K.; Clark, Scott R.; Griffin, Edwin D.; Suhey, Jeffrey D.; Wolf, Michael G.

2016-01-01

In this study, flexible rockets are structurally represented by linear beams. Both direct and indirect solutions of beam dynamic equations are sought to facilitate real-time simulation and control development for flexible rockets. The direct solution is completed by numerically integrate the beam structural dynamic equation using an explicit Newmark-based scheme, which allows for stable and fast transient solutions to the dynamics of flexile rockets. Furthermore, in the real-time operation, the bending strain of the beam is measured by fiber optical sensors (FOS) at intermittent locations along the span, while both angular velocity and translational acceleration are measured at a single point by the inertial measurement unit (IMU). Another study in this paper is to find the analytical and numerical solutions of the beam dynamics based on the limited measurement data to facilitate the real-time control development. Numerical studies demonstrate the accuracy of these real-time solutions to the beam dynamics. Such analytical and numerical solutions, when integrated with data processing and control algorithms and mechanisms, have the potential to increase launch availability by processing flight data into the flexible launch vehicle's control system.

Modeling and simulation of a beam emission spectroscopy diagnostic for the ITER prototype neutral beam injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbisan, M., E-mail: marco.barbisan@igi.cnr.it; Zaniol, B.; Pasqualotto, R.

2014-11-15

A test facility for the development of the neutral beam injection system for ITER is under construction at Consorzio RFX. It will host two experiments: SPIDER, a 100 keV H{sup −}/D{sup −} ion RF source, and MITICA, a prototype of the full performance ITER injector (1 MV, 17 MW beam). A set of diagnostics will monitor the operation and allow to optimize the performance of the two prototypes. In particular, beam emission spectroscopy will measure the uniformity and the divergence of the fast particles beam exiting the ion source and travelling through the beam line components. This type of measurementmore » is based on the collection of the H{sub α}/D{sub α} emission resulting from the interaction of the energetic particles with the background gas. A numerical model has been developed to simulate the spectrum of the collected emissions in order to design this diagnostic and to study its performance. The paper describes the model at the base of the simulations and presents the modeled H{sub α} spectra in the case of MITICA experiment.« less

An energy harvesting solution based on the post-buckling response of non-prismatic slender beams

NASA Astrophysics Data System (ADS)

Jiao, Pengcheng; Borchani, Wassim; Hasni, Hassene; Alavi, Amir H.; Lajnef, Nizar

2017-04-01

Systems based on post-buckled structural elements have been extensively used in many applications such as actuation, remote sensing and energy harvesting thanks to their efficiency enhancement. The post-buckling snap- through behavior of bilaterally constrained beams has been used to create an efficient energy harvesting mechanism under quasi-static excitations. The conversion mechanism has been used to transform low-rate and low-frequency excitations into high-rate motions. Electric energy can be generated from such high-rate motions using piezoelectric transducers. However, lack of control over the post-buckling behavior severely limits the mechanism's efficiency. This study aims to maximize the levels of the harvestable power by controlling the location of the snapping point along the beam at different buckling transitions. Since the snap-through location cannot be controlled by tuning the geometry properties of a uniform cross-section beam, non-uniform cross sections are examined. An energy-based theoretical model is herein developed to predict the post-buckling response of non-uniform cross-section beams. The total potential energy is minimized under constraints that represent the physical confinement of the beam between the lateral boundaries. Experimentally validated results show that changing the shape and geometry dimensions of non- uniform cross-section beams allows for the accurate control of the snap-through location at different buckling transitions. A 78.59% increase in harvested energy levels is achieved by optimizing the beam's shape.

Control method and system for use when growing thin-films on semiconductor-based materials

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

2001-01-01

A process and system for use during the growth of a thin film upon the surface of a substrate by exposing the substrate surface to vaporized material in a high vacuum (HV) facility involves the directing of an electron beam generally toward the surface of the substrate as the substrate is exposed to vaporized material so that electrons are diffracted from the substrate surface by the beam and the monitoring of the pattern of electrons diffracted from the substrate surface as vaporized material settles upon the substrate surface. When the monitored pattern achieves a condition indicative of the desired condition of the thin film being grown upon the substrate, the exposure of the substrate to the vaporized materials is shut off or otherwise adjusted. To facilitate the adjustment of the crystallographic orientation of the film relative to the electron beam, the system includes a mechanism for altering the orientation of the surface of the substrate relative to the electron beam.

Design of a collective scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, W., E-mail: woochanglee@unist.ac.kr; Lee, D. J.; Park, H. K.

The design characteristics of a multi-channel collective (or coherent) scattering system for small scale turbulence study in Korea Superconducting Tokamak Advanced Research (KSTAR), which is planned to be installed in 2017, are given in this paper. A few critical issues are discussed in depth such as the Faraday and Cotton-Mouton effects on the beam polarization, radial spatial resolution, probe beam frequency, polarization, and power. A proper and feasible optics with the 300 GHz probe beam, which was designed based on these issues, provides a simultaneous measurement of electron density fluctuations at four discrete poloidal wavenumbers up to 24 cm{sup −1}.more » The upper limit corresponds to the normalized wavenumber k{sub θ}ρ{sub e} of ∼0.15 in nominal KSTAR plasmas. To detect the scattered beam power and extract phase information, a quadrature detection system consisting of four-channel antenna/detector array and electronics will be employed.« less

Design of a Prototype Positive Ion Source with Slit Aperture Type Extraction System

NASA Astrophysics Data System (ADS)

Sharma, Sanjeev K.; Vattilli, Prahlad; Choksi, Bhargav; Punyapu, Bharathi; Sidibomma, Rambabu; Bonagiri, Sridhar; Aggrawal, Deepak; Baruah, Ujjwal K.

2017-04-01

The neutral beam injector group at IPR aims at developing an experimental positive ion source capable of delivering H+ ion beam having energy of 30 - 40 keV and carrying an ion beam current of 5 A. The slit aperture based extraction system is chosen for extracting and accelerating the ions so as to achieve low divergence of the ion beam (< 0.5°). For producing H+ ions a magnetic multi-pole bucket type plasma chamber is selected. We calculated the magnetic field due to cusp magnets and trajectories (orbits) of the primary electrons to investigate the two magnetic configurations i.e. line cusp and checker board. Numerical simulation is also carried out by using OPERA-3D to study the characteristic performance of the slit aperture type extraction-acceleration system. We report here the results of the studies carried out on various aspects of the design of the slit aperture type positive ion source.

Free electron lasers for transmission of energy in space

NASA Technical Reports Server (NTRS)

Segall, S. B.; Hiddleston, H. R.; Catella, G. C.

1981-01-01

A one-dimensional resonant-particle model of a free electron laser (FEL) is used to calculate laser gain and conversion efficiency of electron energy to photon energy. The optical beam profile for a resonant optical cavity is included in the model as an axial variation of laser intensity. The electron beam profile is matched to the optical beam profile and modeled as an axial variation of current density. Effective energy spread due to beam emittance is included. Accelerators appropriate for a space-based FEL oscillator are reviewed. Constraints on the concentric optical resonator and on systems required for space operation are described. An example is given of a space-based FEL that would produce 1.7 MW of average output power at 0.5 micrometer wavelength with over 50% conversion efficiency of electrical energy to laser energy. It would utilize a 10 m-long amplifier centered in a 200 m-long optical cavity. A 3-amp, 65 meV electrostatic accelerator would provide the electron beam and recover the beam after it passes through the amplifier. Three to five shuttle flights would be needed to place the laser in orbit.

Radio-over-optical waveguide system-on-wafer for massive delivery capacity 5G MIMO access networks

NASA Astrophysics Data System (ADS)

Binh, Le N.

2017-01-01

Delivering maximum information capacity over MIMO antennae systems beam steering is critical so as to achieve the flexibility via beam steering, maximizing the number of users or community of users in Gb/s rate per user over distributed cloud-based optical-wireless access networks. This paper gives an overview of (i) demands of optical - wireless delivery with high flexibility, especially the beam steering of multi-Tbps information channels to information hungry community of users via virtualized beam steering MIMO antenna systems at the free-license mmW region; (ii) Proposing a novel photonic planar integrated waveguide systems composing several passive and active, passive and amplification photonic devices so as to generate mmW carrier and embedded baseband information channels to feed to antenna elements; (iii) Integration techniques to generate a radio over optical waveguide (RoOW) system-on-wafer (SoW) comprising MIMO planar antenna elements and associate photonic integrated circuits for both up- and down- links; (iv) Challenges encountered in the implementation of the SoW in both wireless and photonic domains; (v) Photonic modulation techniques to achieve maximum transmission capacity per wavelength per MIMO antenna system. (vi) A view on control-feedback systems for fast and accurate generation of phase pattern for MIMO beam steering via a bank of optical phase modulators to mmW carrier phases and their preservation in the converted mmW domain . (vi) The overall operational principles of the novel techniques and technologies based on the coherent mixing of two lightwave channels The entire SoW can be implemented on SOI Si-photonic technology or via hybrid integration. These technological developments and their pros- and cons- will be discussed to achieve 50Tera-bps over the extended 110 channel Cband single mode fiber with mmW centered at 58.6GHz and 7GHz free-license band.

Design and analytical modeling of magneto-electro-mechanical characteristics of a novel magneto-electro-elastic vibration-based energy harvesting system

NASA Astrophysics Data System (ADS)

Shishesaz, Mohammad; Shirbani, Meisam Moory; Sedighi, Hamid Mohammad; Hajnayeb, Ali

2018-07-01

In order to effectively design an energy harvesting system for any specific application, a model that accurately characterizes the energy harvesting parameters is needed. In the present paper a novel magneto-electro-elastic (MEE) cantilever beam has been proposed and modeled as an effective means to increase the harvested electrical power in a vibration-based energy harvesting system. The cantilever beam is composed of a linear homogeneous elastic substrate and two MEE layers with perfect bonds between their interfaces. Using the constitutive equations, Gauss's and Faraday's laws, based on the Euler-Bernoulli beam theory, the coupled magneto-electro-mechanical (MeM) differential equations are derived for a harmonic base excitation in the transversal direction with a superimposed small rotation. The resulting equations are then solved analytically to obtain the dynamic behavior as well as the harvested voltages and powers of the proposed energy harvesting system. Finally, parametric numerical studies are used to examine the effect of excitation frequency, external resistive loads, and material properties on the performance of the MEE energy harvester. The study reveals that the implementation of the coil circuit has resulted in an increase in the total useful harvested power. According to the numerical results, any increase in the Young's modulus and density of the substrate layer (across the ranges that have been studied and while the properties of the MEE layer are kept constant), increases the magnitude of the magnetoelectric harvested power in the unimorph MEE energy harvester system.

SU-F-I-06: Evaluation of Imaging Dose for Modulation Layer Based Dual Energy Cone-Beam CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ju, Eunbin; Ahn, SoHyun; Cho, Samju

Purpose: Dual energy cone beam CT system is finding a variety of promising applications in diagnostic CT, both in imaging of endogenous materials and exogenous materials across a range of body sites. Dual energy cone beam CT system to suggest in this study acquire image by rotating 360 degree with half of the X-ray window covered using copper modulation layer. In the region that covered by modulation layer absorb the low energy X-ray by modulation layer. Relative high energy X-ray passes through the layer and contributes to image reconstruction. Dose evaluation should be carried out in order to utilize suchmore » an imaging acquirement technology for clinical use. Methods: For evaluating imaging dose of modulation layer based dual energy cone beam CT system, Prototype cone beam CT that configured X-ray tube (D054SB, Toshiba, Japan) and detector (PaxScan 2520V, Varian Medical Systems, Palo Alto, CA) is used. A range of 0.5–2.0 mm thickness of modulation layer is implemented in Monte Carlo simulation (MCNPX, ver. 2.6.0, Los Alamos National Laboratory, USA) with half of X-ray window covered. In-house phantom using in this study that has 3 cylindrical phantoms configured water, Teflon air with PMMA covered for verifying the comparability the various material in human body and is implemented in Monte Carlo simulation. The actual dose with 2.0 mm copper covered half of X-ray window is measured using Gafchromic EBT3 film with 5.0 mm bolus for compared with simulative dose. Results: Dose in phantom reduced 33% by copper modulation layer of 2.0 mm. Scattering dose occurred in modulation layer by Compton scattering effect is 0.04% of overall dose. Conclusion: Modulation layer of that based dual energy cone beam CT has not influence on unnecessary scatter dose. This study was supported by the Radiation Safety Research Programs (1305033) through the Nuclear Safety and Security Commission.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palma, Giuseppina; Cozzarini, Luca; Capria, Ennio

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm themore » possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.« less

Proton beam therapy and the convoluted pathway to incorporating emerging technology into routine medical care in the United States.

PubMed

Steinberg, Michael L; Konski, Andre

2009-01-01

The pathway that emerging medical technologies take to incorporation into routine medical care in the United States is a product of the social, economic, and political milieu. Our review explores how this milieu brought the incorporation of proton beam therapy into the healthcare delivery system to its current point. We look at how new technologies are presently accepted into this system and discuss the emerging trends--such as the use of evidence-based assessment of technology, coverage with evidence policies, and comparative effectiveness analysis--that are affecting proton beam therapy's effort to finds its place in the pantheon of available medical treatments for patients with cancer.

BPM System for Electron Cooling in the Fermilab Recycler Ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joireman, Paul W.; Cai, Jerry; Chase, Brian E.

2004-11-10

We report a VXI based system used to acquire and process BPM data for the electron cooling system in the Fermilab Recycler ring. The BPM system supports acquisition of data from 19 BPM locations in five different sections of the electron cooling apparatus. Beam positions for both electrons and anti-protons can be detected simultaneously with a resolution of {+-}50 {mu}m. We calibrate the system independently for each beam type at each BPM location. We describe the system components, signal processing and modes of operation used in support of the electron-cooling project and present experimental results of system performance for themore » developmental electron cooling installation at Fermilab.« less

Geostationary payload concepts for personal satellite communications

NASA Technical Reports Server (NTRS)

Benedicto, J.; Rinous, P.; Roberts, I.; Roederer, A.; Stojkovic, I.

1993-01-01

This paper reviews candidate satellite payload architectures for systems providing world-wide communication services to mobile users equipped with hand-held terminals based on large geostationary satellites. There are a number of problems related to the payload architecture, on-board routing and beamforming, and the design of the S-band Tx and L-band Rx antenna and front ends. A number of solutions are outlined, based on trade-offs with respect to the most significant performance parameters such as capacity, G/T, flexibility of routing traffic to beams and re-configuration of the spot-beam coverage, and payload mass and power. Candidate antenna and front-end configurations were studied, in particular direct radiating arrays, arrays magnified by a reflector and active focused reflectors with overlapping feed clusters for both transmit (multimax) and receive (beam synthesis). Regarding the on-board routing and beamforming sub-systems, analog techniques based on banks of SAW filters, FET or CMOS switches and cross-bar fixed and variable beamforming are compared with a hybrid analog/digital approach based on Chirp Fourier Transform (CFT) demultiplexer combined with digital beamforming or a fully digital processor implementation, also based on CFT demultiplexing.

Development of Prior Image-Based, High-Quality, Low-Dose Kilovoltage Cone Beam CT for Use in Adaptive Radiotherapy of Prostate Cancer

DTIC Science & Technology

2011-05-01

for the research in the next year. The aims in the next year include further develop- ment of the prior image- based , narrowly collimated CBCT imaging...further investigation planned for the next year. 5 BODY 1 Research Accomplishments 1.1 Implement narrow beam collimation for CBCT ROI imaging I have...noise level to mimic different mAs used in clinical and research modes of the CBCT system. Based upon experiences with the numerical phantom, I designed

Design and characterization of electron beam focusing for X-ray generation in novel medical imaging architecturea

PubMed Central

Bogdan Neculaes, V.; Zou, Yun; Zavodszky, Peter; Inzinna, Louis; Zhang, Xi; Conway, Kenneth; Caiafa, Antonio; Frutschy, Kristopher; Waters, William; De Man, Bruno

2014-01-01

A novel electron beam focusing scheme for medical X-ray sources is described in this paper. Most vacuum based medical X-ray sources today employ a tungsten filament operated in temperature limited regime, with electrostatic focusing tabs for limited range beam optics. This paper presents the electron beam optics designed for the first distributed X-ray source in the world for Computed Tomography (CT) applications. This distributed source includes 32 electron beamlets in a common vacuum chamber, with 32 circular dispenser cathodes operated in space charge limited regime, where the initial circular beam is transformed into an elliptical beam before being collected at the anode. The electron beam optics designed and validated here are at the heart of the first Inverse Geometry CT system, with potential benefits in terms of improved image quality and dramatic X-ray dose reduction for the patient. PMID:24826066

Overview of the laser activities at Rheinmetall Waffe Munition

NASA Astrophysics Data System (ADS)

Ludewigt, Klaus; Riesbeck, Thomas; Schünemann, B.; Graf, A.; Jung, Markus; Schreiber, Th.; Eberhardt, Ramona; Tünnermann, A.

2012-11-01

The paper will give an overview over the laser weapon activities at RWM (Rheinmetall Waffe Munition) over the last years. Starting from the actual scenarios for laser weapon applications as: CRAM (Counter Rocket Artillery Mortar), Air Defence and UXO (unexploded ordnance) clearing. The basic requirements of a future laser weapon as beam diameter, beam quality, tracking capability, adaptive optics were deduced. For the UXO scenario a mobile directed energy laser demonstrator for humanitarian mine and UXO clearing based on fiber lasers is presented. Based on the parameters the system concept including the cooling system, power supply and the integration into the armoured vehicle TM 170 are explained. The contribution show first experiments of UXO and IED clearing. Different technical approaches to achieve laser power in the 100 kW regime combined with very good beam quality are discussed to fulfil the requirements of the CRAM and Air Defence scenario. Spectral coupling and the beam superimposing both are performed by Rheinmetall Waffe Munition. At the spectral coupling the basic technology parameters for the fiber laser and the dielectric grating as the latest results were put into context with the power levels reached at other groups. For the beam super imposing technology the basic experiments regarding the tracking capability and compensation of the atmosphere on the test range at Unterlüß will be explained. A generic 10 kW Laser Weapon Demonstrator based on 2 Laser Weapon Modules (LWM) from RWM each 5 kW fiber Laser with beam forming and tracking integrate by the team of RWM and RAD (Rheinmetall Air Defense) into a Ground based Air Defend system consisting of Skyguard and Millenium turret are presented. The flight path of the UAV within the valley of the life firing range at Ochsenboden Switzerland is shown. Selected results of the successful tests against UAV's are presented. It shows the capability of the generic 10 kW Laser Weapon Demonstrator to track and to destroy the target. From these results the next steps of Rheinmetall Waffe Munition for a 100 kW class laser weapon are explained.

Optically controlled waveplate at a telecom wavelength using a ladder transition in Rb atoms for all-optical switching and high speed Stokesmetric imaging.

PubMed

Krishnamurthy, Subramanian; Tu, Y; Wang, Y; Tseng, S; Shahriar, M S

2014-11-17

We demonstrate an optically controlled waveplate at ~1323 nm using the 5S(1/2)-5P(1/2)-6S(1/2) ladder transition in a Rb vapor cell. The lower leg of the transitions represents the control beam, while the upper leg represents the signal beam. We show that we can place the signal beam in any arbitrary polarization state with a suitable choice of polarization of the control beam. Specifically, we demonstrate a differential phase retardance of ~180 degrees between the two circularly polarized components of a linearly polarized signal beam. We also demonstrate that the system can act as a Quarter Wave plate. The optical activity responsible for the phase retardation process is explained in terms of selection rules involving the Zeeman sublevels. As such, the system can be used to realize a fast Stokesmetric imaging system with a speed of ~3 MHz. When implemented using a tapered nano fiber embedded in a vapor cell, this system can be used to realize an ultra-low power all-optical switch as well as a Quantum Zeno Effect based all-optical logic gate by combining it with an optically controlled polarizer, previously demonstrated by us. We present numerical simulations of the system using a comprehensive model which incorporates all the relevant Zeeman sub-levels in the system, using a novel algorithm recently developed by us for efficient computation of the evolution of an arbitrary large scale quantum system.

Pointing error analysis of Risley-prism-based beam steering system.

PubMed

Zhou, Yuan; Lu, Yafei; Hei, Mo; Liu, Guangcan; Fan, Dapeng

2014-09-01

Based on the vector form Snell's law, ray tracing is performed to quantify the pointing errors of Risley-prism-based beam steering systems, induced by component errors, prism orientation errors, and assembly errors. Case examples are given to elucidate the pointing error distributions in the field of regard and evaluate the allowances of the error sources for a given pointing accuracy. It is found that the assembly errors of the second prism will result in more remarkable pointing errors in contrast with the first one. The pointing errors induced by prism tilt depend on the tilt direction. The allowances of bearing tilt and prism tilt are almost identical if the same pointing accuracy is planned. All conclusions can provide a theoretical foundation for practical works.

Wide-angle full-vector beam propagation method based on an alternating direction implicit preconditioner

NASA Astrophysics Data System (ADS)

Chui, Siu Lit; Lu, Ya Yan

2004-03-01

Wide-angle full-vector beam propagation methods (BPMs) for three-dimensional wave-guiding structures can be derived on the basis of rational approximants of a square root operator or its exponential (i.e., the one-way propagator). While the less accurate BPM based on the slowly varying envelope approximation can be efficiently solved by the alternating direction implicit (ADI) method, the wide-angle variants involve linear systems that are more difficult to handle. We present an efficient solver for these linear systems that is based on a Krylov subspace method with an ADI preconditioner. The resulting wide-angle full-vector BPM is used to simulate the propagation of wave fields in a Y branch and a taper.

Wide-angle full-vector beam propagation method based on an alternating direction implicit preconditioner.

PubMed

Chui, Siu Lit; Lu, Ya Yan

2004-03-01

Wide-angle full-vector beam propagation methods (BPMs) for three-dimensional wave-guiding structures can be derived on the basis of rational approximants of a square root operator or its exponential (i.e., the one-way propagator). While the less accurate BPM based on the slowly varying envelope approximation can be efficiently solved by the alternating direction implicit (ADI) method, the wide-angle variants involve linear systems that are more difficult to handle. We present an efficient solver for these linear systems that is based on a Krylov subspace method with an ADI preconditioner. The resulting wide-angle full-vector BPM is used to simulate the propagation of wave fields in a Y branch and a taper.

SU-E-T-571: Newly Emerging Integrated Transmission Detector Systems Provide Online Quality Assurance of External Beam Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, D; Chung, E; Hess, C

2015-06-15

Purpose: Two newly emerging transmission detectors positioned upstream from the patient have been evaluated for online quality assurance of external beam radiotherapy. The prototype for the Integral Quality Monitor (IQM), developed by iRT Systems GmbH (Koblenz, Germany) is a large-area ion chamber mounted on the linac accessory tray to monitor photon fluence, energy, beam shape, and gantry position during treatment. The ion chamber utilizes a thickness gradient which records variable response dependent on beam position. The prototype of Delta4 Discover™, developed by ScandiDos (Uppsala, Sweden) is a linac accessory tray mounted 4040 diode array that measures photon fluence during patientmore » treatment. Both systems are employable for patient specific QA prior to treatment delivery. Methods: Our institution evaluated the reproducibility of measurements using various beam types, including VMAT treatment plans with both the IQM ion chamber and the Delta4 Discover diode array. Additionally, the IQM’s effect on photon fluence, dose response, simulated beam error detection, and the accuracy of the integrated barometer, thermometer, and inclinometer were characterized. The evaluated photon beam errors are based on the annual tolerances specified in AAPM TG-142. Results: Repeated VMAT treatments were measured with 0.16% reproducibility by the IQM and 0.55% reproducibility by the Delta4 Discover. The IQM attenuated 6, 10, and 15 MV photon beams by 5.43±0.02%, 4.60±0.02%, and 4.21±0.03% respectively. Photon beam profiles were affected <1.5% in the non-penumbra regions. The IQM’s ion chamber’s dose response was linear and the thermometer, barometer, and inclinometer agreed with other calibrated devices. The device detected variations in monitor units delivered (1%), field position (3mm), single MLC leaf positions (13mm), and photon energy. Conclusion: We have characterized two new transmissions detector systems designed to provide in-vivo like measurements upstream from the patient. Both systems demonstrate substantial utility for online treatment verification and QA of photon external beam radiotherapy.« less

SU-E-T-111: Development of Proton Dosimetry System Using Fiber-Optic Cerenkov Radiation Sensor Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Son, J; Kim, M; Shin, D

2014-06-01

Purpose: We had developed and evaluated a new dosimetric system for proton therapy using array of fiber-optic Cerenkov radiation sensor (FOCRS) which can measure a percent depth dose (PDD) instantly. In this study, the Bragg peaks and spread out Bragg peak (SOBP) of the proton beams measured by FOCRS array were compared with those measured by an ion chamber. Methods and Method: We fabricated an optical fiber array of FOCRS in a handmade phantom which is composed of poly-methyl methacrylate (PMMA). There are 75 holes of 1mm diameter inside the phantom which is designed to be exposed in direction ofmore » beam when it is emerged in water phantom. The proton beam irradiation was carried out using IBA cyclotron PROTEUS 235 at national cancer center in Korea and a commercial data acquisition system was used to digitize the analog signal. Results: The measured Bragg peak and SOBP for the proton ranges of 7∼ 20 cm were well matched with the result from ion chamber. The comparison results show that the depth of proton beam ranges and the width of SOBP measured by array of FOCRS are comparable with the measurement from multi-layer ion chamber (MLIC) although there are some uncertainty in the measurement of FOCRS array for some specific beam ranges. Conclusion: The newly developed FOCRS array based dosimetric system for proton therapy can efficiently reduce the time and effort needed for proton beam range measurement compared to the conventional method and has the potential to be used for the proton pencil beam application.« less

Evaluation of a GEM and CAT-based detector for radiation therapy beam monitoring

NASA Astrophysics Data System (ADS)

Brahme, A.; Danielsson, M.; Iacobaeus, C.; Ostling, J.; Peskov, V.; Wallmark, M.

2000-11-01

We are developing a radiation therapy beam monitor for the Karolinska Institute. This monitor will consist of two consecutive detectors confined in one gas chamber: a "keV-photon detector", which will allow diagnostic quality visualization of the patient, and a "MeV-photon detector", that will measure the absolute intensity of the therapy beam and its position with respect to the patient. Both detectors are based on highly radiation resistant gas and solid photon to electron converters, combined with GEMs and a CAT as amplification structures. We have performed systematic studies of the high-rate characteristics of the GEM and the CAT, as well as tested the electron transfer through these electron multipliers and various types of converters. The tests show that the GEM and the CAT satisfy all requirements for the beam monitoring system. As a result of these studies we successfully developed and tested a full section of the beam monitor equipped with a MeV-photon converter placed between the GEM and the CAT.

The Japanese Positron Factory

NASA Astrophysics Data System (ADS)

Okada, S.; Sunaga, H.; Kaneko, H.; Takizawa, H.; Kawasuso, A.; Yotsumoto, K.; Tanaka, R.

1999-06-01

The Positron Factory has been planned at Japan Atomic Energy Research Institute (JAERI). The factory is expected to produce linac-based monoenergetic positron beams having world-highest intensities of more than 1010e+/sec, which will be applied for R&D of materials science, biotechnology and basic physics & chemistry. In this article, results of the design studies are demonstrated for the following essential components of the facilities: 1) Conceptual design of a high-power electron linac with 100 MeV in beam energy and 100 kW in averaged beam power, 2) Performance tests of the RF window in the high-power klystron and of the electron beam window, 3) Development of a self-driven rotating electron-to-positron converter and the performance tests, 4) Proposal of multi-channel beam generation system for monoenergetic positrons, with a series of moderator assemblies based on a newly developed Monte Carlo simulation and the demonstrative experiment, 5) Proposal of highly efficient moderator structures, 6) Conceptual design of a local shield to suppress the surrounding radiation and activation levels.

Beam profile and coherence properties of synchrotron beams after reflection on modified multilayer mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rack, Alexander, E-mail: alexander.rack@esrf.fr; Vivo, Amparo; Morawe, Christian

2016-07-27

Multilayer mirrors present an attractive alternative for reflective hard X-ray monochromators due to their increased bandwidth compared with crystal-based systems. An issue remains the strong modulations in the reflected beam profile, i.e. an irregular stripe pattern. This is a major problem for micro-imaging applications, where multilayer-based monochromators are frequently employed to deliver higher photon flux density. A subject of particular interest is how to overcome beam profile modifications, namely the stripe patterns, induced by the reflection on a multilayer. For multilayer coatings in general it is known that the substrate and its surface quality significantly influence the performance of suchmore » kind of mirrors as the coating reproduces to a certain degree roughness and shape of the substrate. Our studies have shown that modified coatings can significantly change the impact of the multilayer reflection on the beam profile. We will present recent results as well as a critical review.« less

Fermilab Recycler Ring BPM Upgrade Based on Digital Receiver Technology

NASA Astrophysics Data System (ADS)

Webber, R.; Crisp, J.; Prieto, P.; Voy, D.; Briegel, C.; McClure, C.; West, R.; Pordes, S.; Mengel, M.

2004-11-01

Electronics for the 237 BPMs in the Fermilab Recycler Ring have been upgraded from a log-amplifier based system to a commercially produced digitizer-digital down converter based system. The hardware consists of a pre-amplifier connected to a split-plate BPM, an analog differential receiver-filter module and an 8-channel 80-MHz digital down converter VME board. The system produces position and intensity with a dynamic range of 30 dB and a resolution of ±10 microns. The position measurements are made on 2.5-MHz bunched beam and barrier buckets of the un-bunched beam. The digital receiver system operates in one of six different signal processing modes that include 2.5-MHz average, 2.5-MHz bunch-by-bunch, 2.5-MHz narrow band, unbunched average, un-bunched head/tail and 89-kHz narrow band. Receiver data is acquired on any of up to sixteen clock events related to Recycler beam transfers and other machine activities. Data from the digital receiver board are transferred to the front-end CPU for position and intensity computation on an on-demand basis through the VME bus. Data buffers are maintained for each of the acquisition events and support flash, closed orbit and turn-by-turn measurements. A calibration system provides evaluation of the BPM signal path and application programs.

Refractive laser beam shaping by means of a functional differential equation based design approach.

PubMed

Duerr, Fabian; Thienpont, Hugo

2014-04-07

Many laser applications require specific irradiance distributions to ensure optimal performance. Geometric optical design methods based on numerical calculation of two plano-aspheric lenses have been thoroughly studied in the past. In this work, we present an alternative new design approach based on functional differential equations that allows direct calculation of the rotational symmetric lens profiles described by two-point Taylor polynomials. The formalism is used to design a Gaussian to flat-top irradiance beam shaping system but also to generate a more complex dark-hollow Gaussian (donut-like) irradiance distribution with zero intensity in the on-axis region. The presented ray tracing results confirm the high accuracy of both calculated solutions and emphasize the potential of this design approach for refractive beam shaping applications.

Automatic low-order aberration correction based on geometrical optics for slab lasers.

PubMed

Yu, Xin; Dong, Lizhi; Lai, Boheng; Yang, Ping; Liu, Yong; Kong, Qingfeng; Yang, Kangjian; Tang, Guomao; Xu, Bing

2017-02-20

In this paper, we present a method based on geometry optics to simultaneously correct low-order aberrations and reshape the beams of slab lasers. A coaxial optical system with three lenses is adapted. The positions of the three lenses are directly calculated based on the beam parameters detected by wavefront sensors. The initial sizes of the input beams are 1.8  mm×11  mm, and peak-to-valley (PV) values of the wavefront range up to several tens of microns. After automatic correction, the dimensions may reach nearly 22  mm×22  mm as expected, and PV values of the wavefront are less than 2 μm. The effectiveness and precision of this method are verified with experiments.

ETHERNET BASED EMBEDDED SYSTEM FOR FEL DIAGNOSTICS AND CONTROLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jianxun Yan; Daniel Sexton; Steven Moore

2006-10-24

An Ethernet based embedded system has been developed to upgrade the Beam Viewer and Beam Position Monitor (BPM) systems within the free-electron laser (FEL) project at Jefferson Lab. The embedded microcontroller was mounted on the front-end I/O cards with software packages such as Experimental Physics and Industrial Control System (EPICS) and Real Time Executive for Multiprocessor System (RTEMS) running as an Input/Output Controller (IOC). By cross compiling with the EPICS, the RTEMS kernel, IOC device supports, and databases all of these can be downloaded into the microcontroller. The first version of the BPM electronics based on the embedded controller wasmore » built and is currently running in our FEL system. The new version of BPM that will use a Single Board IOC (SBIOC), which integrates with an Field Programming Gate Array (FPGA) and a ColdFire embedded microcontroller, is presently under development. The new system has the features of a low cost IOC, an open source real-time operating system, plug&play-like ease of installation and flexibility, and provides a much more localized solution.« less

RF control hardware design for CYCIAE-100 cyclotron

NASA Astrophysics Data System (ADS)

Yin, Zhiguo; Fu, Xiaoliang; Ji, Bin; Zhao, Zhenlu; Zhang, Tianjue; Li, Pengzhan; Wei, Junyi; Xing, Jiansheng; Wang, Chuan

2015-11-01

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 compact linear accelerator based on a scalable microelectromechanical-system RF-structure

DOE PAGES

Persaud, A.; Ji, Q.; Feinberg, E.; ...

2017-06-08

Here, a new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number ofmore » parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further red ucing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Finally, ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.« less

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure

NASA Astrophysics Data System (ADS)

Persaud, A.; Ji, Q.; Feinberg, E.; Seidl, P. A.; Waldron, W. L.; Schenkel, T.; Lal, A.; Vinayakumar, K. B.; Ardanuc, S.; Hammer, D. A.

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

A compact linear accelerator based on a scalable microelectromechanical-system RF-structure.

PubMed

Persaud, A; Ji, Q; Feinberg, E; Seidl, P A; Waldron, W L; Schenkel, T; Lal, A; Vinayakumar, K B; Ardanuc, S; Hammer, D A

2017-06-01

A new approach for a compact radio-frequency (RF) accelerator structure is presented. The new accelerator architecture is based on the Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) structure that was first developed in the 1980s. The MEQALAC utilized RF resonators producing the accelerating fields and providing for higher beam currents through parallel beamlets focused using arrays of electrostatic quadrupoles (ESQs). While the early work obtained ESQs with lateral dimensions on the order of a few centimeters, using a printed circuit board (PCB), we reduce the characteristic dimension to the millimeter regime, while massively scaling up the potential number of parallel beamlets. Using Microelectromechanical systems scalable fabrication approaches, we are working on further reducing the characteristic dimension to the sub-millimeter regime. The technology is based on RF-acceleration components and ESQs implemented in the PCB or silicon wafers where each beamlet passes through beam apertures in the wafer. The complete accelerator is then assembled by stacking these wafers. This approach has the potential for fast and inexpensive batch fabrication of the components and flexibility in system design for application specific beam energies and currents. For prototyping the accelerator architecture, the components have been fabricated using the PCB. In this paper, we present proof of concept results of the principal components using the PCB: RF acceleration and ESQ focusing. Ongoing developments on implementing components in silicon and scaling of the accelerator technology to high currents and beam energies are discussed.

A squid-based beam current monitor for FAIR/CRYRING

NASA Astrophysics Data System (ADS)

Geithner, Rene; Kurian, Febin; Reeg, Hansjörg; Schwickert, Marcus; Neubert, Ralf; Seidel, Paul; Stöhlker, Thomas

2015-11-01

A SQUID-based beam current monitor was developed for the upcoming FAIR-Project, providing a non-destructive online monitoring of the beam currents in the nA-range. The cryogenic current comparator (CCC) was optimized for lowest possible noise-limited current resolution together with a high system bandwidth. This CCC is foreseen to be installed in the CRYRING facility (CRYRING@ESR: A study group report www.gsi.de/fileadmin/SPARC/documents/Cryring/ReportCryring_40ESR.PDF), working as a test bench for FAIR. In this contribution we present results of the completed CCC for FAIR/CRYRING and also arrangements that have been done for the installation of the CCC at CRYRING, regarding the cryostat design.

New halo formation mechanism at the KEK compact energy recovery linac

NASA Astrophysics Data System (ADS)

Tanaka, Olga; Nakamura, Norio; Shimada, Miho; Miyajima, Tsukasa; Ueda, Akira; Obina, Takashi; Takai, Ryota

2018-02-01

The beam halo mitigation is a very important challenge for reliable and safe operation of a high-energy machine. A systematic beam halo study was conducted at the KEK compact energy recovery linac (cERL) since non-negligible beam loss was observed in the recirculation loop during a common operation. We found that the beam loss can be avoided by making use of the collimation system. Beam halo measurements have demonstrated the presence of vertical beam halos at multiple locations in the beam line (except the region near the electron gun). Based on these observations, we made a conjecture that the transverse beam halo is attributed to the longitudinal bunch tail arising at the photocathode. The transfer of particles from the longitudinal space to a transverse halo may have been observed and studied in other machines, considering nonlinear effects as their causes. However, our study demonstrates a new unique halo formation mechanism, in which a transverse beam halo can be generated by a longitudinal bunch tail due to transverse rf kicks from the accelerating (monopole) fields of the radio-frequency cavities. This halo formation occurs when nonrelativistic particles enter the cavities with a transverse offset, even if neither nonlinear optics nor nonlinear beam effects are present. A careful realignment of the injector system will mitigate the present halo. Another possible cure is to reduce the bunch tails by changing the photocathode material from the present GaAs to a multi-alkali that is known to have a shorter longitudinal tail.

Design and analysis of a sub-aperture scanning machine for the transmittance measurements of large-aperture optical system

NASA Astrophysics Data System (ADS)

He, Yingwei; Li, Ping; Feng, Guojin; Cheng, Li; Wang, Yu; Wu, Houping; Liu, Zilong; Zheng, Chundi; Sha, Dingguo

2010-11-01

For measuring large-aperture optical system transmittance, a novel sub-aperture scanning machine with double-rotating arms (SSMDA) was designed to obtain sub-aperture beam spot. Optical system full-aperture transmittance measurements can be achieved by applying sub-aperture beam spot scanning technology. The mathematical model of the SSMDA based on a homogeneous coordinate transformation matrix is established to develop a detailed methodology for analyzing the beam spot scanning errors. The error analysis methodology considers two fundamental sources of scanning errors, namely (1) the length systematic errors and (2) the rotational systematic errors. As the systematic errors of the parameters are given beforehand, computational results of scanning errors are between -0.007~0.028mm while scanning radius is not lager than 400.000mm. The results offer theoretical and data basis to the research on transmission characteristics of large optical system.

Wide steering angle microscanner based on curved surface

NASA Astrophysics Data System (ADS)

Sabry, Yasser; Khalil, Diaa; Saadany, Bassam; Bourouina, Tarik

2013-03-01

Intensive industrial and academic research is oriented towards the design and fabrication of optical beam steering systems based on MEMS technology. In most of these systems, the scanning is achieved by rotating a flat micromirror around a central axis in which the main challenge is achieving a wide mirror rotation angle. In this work, a novel method of optical beam scanning based on reflection from a curved surface is presented. The scanning occurs when the optical axis of the curved surface is displaced with respect to the optical axis of the incident beam. To overcome the possible deformation of the spot with the scanning angle, the curved surface is designed with a specific aspherical profile. Moreover, the scanning exhibits a more linearized scanning angle-displacement relation than the conventional spherical profile. The presented scanner is fabricated using DRIE technology on an SOI wafer. The curved surface (reflector) is metalized and attached to a comb-drive actuator fabricated in the same lithography step. A single-mode fiber, behaving as a Gaussian beam source, is positioned on the substrate facing the mirror. The reflected optical beam angle and spotsize in the far field is recorded versus the relative shift between the fiber and the curved mirror. The spot size is plotted versus the scanning angle and a scanning spot size uniformity of about +/-10% is obtained for optical deflection angles up to 100 degrees. As the optical beam is propagating parallel to the wafer substrate, a completely integrated laser scanner can be achieved with filters and actuators self-aligned on the same chip that allows low cost and mass production of this important product.

An analytical model for transient deformation of viscoelastically coated beams: Applications to static-mode microcantilever chemical sensors

NASA Astrophysics Data System (ADS)

Heinrich, S. M.; Wenzel, M. J.; Josse, F.; Dufour, I.

2009-06-01

The problem governing the transient deformation of an elastic cantilever beam with viscoelastic coating, subjected to a time-dependent coating eigenstrain, is mathematically formulated. An analytical solution for an exponential eigenstrain history, exact within the context of beam theory, is obtained in terms of the coating and base layer thicknesses, the elastic modulus of the base material, the initial coating modulus, the coating relaxation percentage (0%-100%), and the time constants of the coating's relaxation process and its eigenstrain history. Approximate formulas, valid for thin coatings, are derived as special cases to provide insight into system behavior. Main results include (1) the time histories of the beam curvature and the coating stresses, (2) a criterion governing the response type (monotonic or "overshoot" response), and (3) simple expressions for the overshoot ratio, defined as the peak response scaled by the steady-state response, and the time at which the peak response occurs. Applications to polymer-coated microcantilever-based chemical sensors operating in the static mode are discussed.

Process observation in fiber laser-based selective laser melting

NASA Astrophysics Data System (ADS)

Thombansen, Ulrich; Gatej, Alexander; Pereira, Milton

2015-01-01

The process observation in selective laser melting (SLM) focuses on observing the interaction point where the powder is processed. To provide process relevant information, signals have to be acquired that are resolved in both time and space. Especially in high-power SLM, where more than 1 kW of laser power is used, processing speeds of several meters per second are required for a high-quality processing results. Therefore, an implementation of a suitable process observation system has to acquire a large amount of spatially resolved data at low sampling speeds or it has to restrict the acquisition to a predefined area at a high sampling speed. In any case, it is vitally important to synchronously record the laser beam position and the acquired signal. This is a prerequisite that allows the recorded data become information. Today, most SLM systems employ f-theta lenses to focus the processing laser beam onto the powder bed. This report describes the drawbacks that result for process observation and suggests a variable retro-focus system which solves these issues. The beam quality of fiber lasers delivers the processing laser beam to the powder bed at relevant focus diameters, which is a key prerequisite for this solution to be viable. The optical train we present here couples the processing laser beam and the process observation coaxially, ensuring consistent alignment of interaction zone and observed area. With respect to signal processing, we have developed a solution that synchronously acquires signals from a pyrometer and the position of the laser beam by sampling the data with a field programmable gate array. The relevance of the acquired signals has been validated by the scanning of a sample filament. Experiments with grooved samples show a correlation between different powder thicknesses and the acquired signals at relevant processing parameters. This basic work takes a first step toward self-optimization of the manufacturing process in SLM. It enables the addition of cognitive functions to the manufacturing system to the extent that the system could track its own process. The results are based on analyzing and redesigning the optical train, in combination with a real-time signal acquisition system which provides a solution to certain technological barriers.

Generalized M-factor of hollow Gaussian beams through a hard-edge circular aperture

NASA Astrophysics Data System (ADS)

Deng, Dongmei

2005-06-01

Based on the generalized truncated second-order moments, the generalized M-factor (MG2-factor) of three-dimensional hollow Gaussian beams (HGBs) through a hard-edge circular aperture is studied in cylindrical coordinate system analytically and numerically. The closed-form expression for the MG2-factor of the truncated HGBs, which is dependent on the truncation parameter β and the beam order n, can be simplified to that of the truncated, the untruncated Gaussian beams and the untruncated HGBs. Also, the power fraction is demonstrated analytically and numerically, which shows that the area of the dark region across the HGBs increases as n increasing.

Practical layer designs for polarizing beam-splitter cubes.

PubMed

von Blanckenhagen, Bernhard

2006-03-01

Liquid-crystal-on-silicon- (LCoS-) based digital projection systems require high-performance polarizing beam splitters. The classical beam-splitter cube with an immersed interference coating can fulfill these requirements. Practical layer designs can be generated by computer optimization using the classic MacNeille polarizer layer design as the starting layer design. Multilayer structures with 100 nm bandwidth covering the blue, green, or red spectral region and one design covering the whole visible spectral region are designed. In a second step these designs are realized by using plasma-ion-assisted deposition. The performance of the practical beam-splitter cubes is compared with the theoretical performance of the layer designs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scarpelli, Andrea

Nonlinear integrable optics applied to beam dynamics may mitigate multi-particle instabilities, but proof of principle experiments have never been carried out. The Integrable Optics Test Accelerator (IOTA) is an electron and proton storage ring currently being built at Fermilab, which addresses tests of nonlinear lattice elements in a real machine in addition to experiments on optical stochastic cooling and on the single-electron wave function. These experiments require an outstanding control over the lattice parameters, achievable with fast and precise beam monitoring systems. This work describes the steps for designing and building a beam monitor for IOTA based on synchrotron radiation,more » able to measure intensity, position and transverse cross-section beam.« less

Knowledge-light adaptation approaches in case-based reasoning for radiotherapy treatment planning.

PubMed

Petrovic, Sanja; Khussainova, Gulmira; Jagannathan, Rupa

2016-03-01

Radiotherapy treatment planning aims at delivering a sufficient radiation dose to cancerous tumour cells while sparing healthy organs in the tumour-surrounding area. It is a time-consuming trial-and-error process that requires the expertise of a group of medical experts including oncologists and medical physicists and can take from 2 to 3h to a few days. Our objective is to improve the performance of our previously built case-based reasoning (CBR) system for brain tumour radiotherapy treatment planning. In this system, a treatment plan for a new patient is retrieved from a case base containing patient cases treated in the past and their treatment plans. However, this system does not perform any adaptation, which is needed to account for any difference between the new and retrieved cases. Generally, the adaptation phase is considered to be intrinsically knowledge-intensive and domain-dependent. Therefore, an adaptation often requires a large amount of domain-specific knowledge, which can be difficult to acquire and often is not readily available. In this study, we investigate approaches to adaptation that do not require much domain knowledge, referred to as knowledge-light adaptation. We developed two adaptation approaches: adaptation based on machine-learning tools and adaptation-guided retrieval. They were used to adapt the beam number and beam angles suggested in the retrieved case. Two machine-learning tools, neural networks and naive Bayes classifier, were used in the adaptation to learn how the difference in attribute values between the retrieved and new cases affects the output of these two cases. The adaptation-guided retrieval takes into consideration not only the similarity between the new and retrieved cases, but also how to adapt the retrieved case. The research was carried out in collaboration with medical physicists at the Nottingham University Hospitals NHS Trust, City Hospital Campus, UK. All experiments were performed using real-world brain cancer patient cases treated with three-dimensional (3D)-conformal radiotherapy. Neural networks-based adaptation improved the success rate of the CBR system with no adaptation by 12%. However, naive Bayes classifier did not improve the current retrieval results as it did not consider the interplay among attributes. The adaptation-guided retrieval of the case for beam number improved the success rate of the CBR system by 29%. However, it did not demonstrate good performance for the beam angle adaptation. Its success rate was 29% versus 39% when no adaptation was performed. The obtained empirical results demonstrate that the proposed adaptation methods improve the performance of the existing CBR system in recommending the number of beams to use. However, we also conclude that to be effective, the proposed adaptation of beam angles requires a large number of relevant cases in the case base. Copyright © 2016 Elsevier B.V. All rights reserved.

Optical components of adaptive systems for improving laser beam quality

NASA Astrophysics Data System (ADS)

Malakhov, Yuri I.; Atuchin, Victor V.; Kudryashov, Aleksis V.; Starikov, Fedor A.

2008-10-01

The short overview is given of optical equipment developed within the ISTC activity for adaptive systems of new generation allowing for correction of high-power laser beams carrying optical vortices onto the phase surface. They are the kinoform many-level optical elements of new generation, namely, special spiral phase plates and ordered rasters of microlenses, i.e. lenslet arrays, as well as the wide-aperture Hartmann-Shack sensors and bimorph deformable piezoceramics- based mirrors with various grids of control elements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J. L.; Singh, M.; Perry, D. L.

Here, we demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.

Reflective echo tomographic imaging using acoustic beams

DOEpatents

Kisner, Roger; Santos-Villalobos, Hector J

2014-11-25

An inspection system includes a plurality of acoustic beamformers, where each of the plurality of acoustic beamformers including a plurality of acoustic transmitter elements. The system also includes at least one controller configured for causing each of the plurality of acoustic beamformers to generate an acoustic beam directed to a point in a volume of interest during a first time. Based on a reflected wave intensity detected at a plurality of acoustic receiver elements, an image of the volume of interest can be generated.

Characterizing a pulse-resolved dosimetry system for complex radiotherapy beams using organic scintillators.

PubMed

Beierholm, Anders R; Ottosson, Rickard O; Lindvold, Lars R; Behrens, Claus F; Andersen, Claus E

2011-05-21

A fast-readout dosimetry system based on fibre-coupled organic scintillators has been developed for the purpose of conducting point measurements of absorbed dose in radiotherapy beams involving high spatial and temporal dose gradients. The system measures the dose for each linac radiation pulse with millimetre spatial resolution. To demonstrate the applicability of the system in complex radiotherapy fields, output factors and per cent depth dose measurements were performed in solid water for a 6 MV photon beam and compared with Monte Carlo simulated doses for square fields down to 0.6 cm × 0.6 cm size. No significant differences between measurements and simulations were observed. The temporal resolution of the system was demonstrated by measuring dose per pulse, beam start-up transients and the quality factor for 6 MV. The precision of dose per pulse measurements was within 2.7% (1 SD) for a 10 cm × 10 cm field at 10 cm depth. The dose per pulse behaviour compared well with linac target current measurements and accumulated dose measurements, and the system was able to resolve transient dose delivery differences between two Varian linac builds. The system therefore shows promise for reference dosimetry and quality assurance of complex radiotherapy treatments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Bin; Li, Yongbao; Liu, Bo

Purpose: CyberKnife system is initially equipped with fixed circular cones for stereotactic radiosurgery. Two dose calculation algorithms, Ray-Tracing and Monte Carlo, are available in the supplied treatment planning system. A multileaf collimator system was recently introduced in the latest generation of system, capable of arbitrarily shaped treatment field. The purpose of this study is to develop a model based dose calculation algorithm to better handle the lateral scatter in an irregularly shaped small field for the CyberKnife system. Methods: A pencil beam dose calculation algorithm widely used in linac based treatment planning system was modified. The kernel parameters and intensitymore » profile were systematically determined by fitting to the commissioning data. The model was tuned using only a subset of measured data (4 out of 12 cones) and applied to all fixed circular cones for evaluation. The root mean square (RMS) of the difference between the measured and calculated tissue-phantom-ratios (TPRs) and off-center-ratio (OCR) was compared. Three cone size correction techniques were developed to better fit the OCRs at the penumbra region, which are further evaluated by the output factors (OFs). The pencil beam model was further validated against measurement data on the variable dodecagon-shaped Iris collimators and a half-beam blocked field. Comparison with Ray-Tracing and Monte Carlo methods was also performed on a lung SBRT case. Results: The RMS between the measured and calculated TPRs is 0.7% averaged for all cones, with the descending region at 0.5%. The RMSs of OCR at infield and outfield regions are both at 0.5%. The distance to agreement (DTA) at the OCR penumbra region is 0.2 mm. All three cone size correction models achieve the same improvement in OCR agreement, with the effective source shift model (SSM) preferred, due to their ability to predict more accurately the OF variations with the source to axis distance (SAD). In noncircular field validation, the pencil beam calculated results agreed well with the film measurement of both Iris collimators and the half-beam blocked field, fared much better than the Ray-Tracing calculation. Conclusions: The authors have developed a pencil beam dose calculation model for the CyberKnife system. The dose calculation accuracy is better than the standard linac based system because the model parameters were specifically tuned to the CyberKnife system and geometry correction factors. The model handles better the lateral scatter and has the potential to be used for the irregularly shaped fields. Comprehensive validations on MLC equipped system are necessary for its clinical implementation. It is reasonably fast enough to be used during plan optimization.« less

Discrimination of ionic species from broad-beam ion sources

NASA Technical Reports Server (NTRS)

Anderson, J. R.

1993-01-01

The performance of a broad-beam, three-grid, ion extraction system incorporating radio frequency (RF) mass discrimination was investigated experimentally. This testing demonstrated that the system, based on a modified single-stage Bennett mass spectrometer, can discriminate between ionic species having about a 2-to-1 mass ratio while producing a broad-beam of ions with low kinetic energy (less than 15 eV). Testing was conducted using either argon and krypton ions or atomic and diatomic oxygen ions. A simple one-dimensional model, which ignores magnetic field and space-charge effects, was developed to predict the species separation capabilities as well as the kinetic energies of the extracted ions. The experimental results correlated well with the model predictions. This RF mass discrimination system can be used in applications where both atomic and diatomic ions are produced, but a beam of only one of the species is desired. An example of such an application is a 5 eV atomic oxygen source. This source would produce a beam of atomic oxygen with 5 eV kinetic energy, which would be directed onto a material specimen, to simulate the interaction between the surface of a satellite and the rarefied atmosphere encountered in low-Earth orbit.

Particle Accelerator Focus Automation

NASA Astrophysics Data System (ADS)

Lopes, José; Rocha, Jorge; Redondo, Luís; Cruz, João

2017-08-01

The Laboratório de Aceleradores e Tecnologias de Radiação (LATR) at the Campus Tecnológico e Nuclear, of Instituto Superior Técnico (IST) has a horizontal electrostatic particle accelerator based on the Van de Graaff machine which is used for research in the area of material characterization. This machine produces alfa (He+) and proton (H+) beams of some μA currents up to 2 MeV/q energies. Beam focusing is obtained using a cylindrical lens of the Einzel type, assembled near the high voltage terminal. This paper describes the developed system that automatically focuses the ion beam, using a personal computer running the LabVIEW software, a multifunction input/output board and signal conditioning circuits. The focusing procedure consists of a scanning method to find the lens bias voltage which maximizes the beam current measured on a beam stopper target, which is used as feedback for the scanning cycle. This system, as part of a wider start up and shut down automation system built for this particle accelerator, brings great advantages to the operation of the accelerator by turning it faster and easier to operate, requiring less human presence, and adding the possibility of total remote control in safe conditions.

Generation of Low-Energy High-Current Electron Beams in Plasma-Anode Electron Guns

NASA Astrophysics Data System (ADS)

Ozur, G. E.; Proskurovsky, D. I.

2018-01-01

This paper is a review of studies on the generation of low-energy high-current electron beams in electron guns with a plasma anode and an explosive-emission cathode. The problems related to the initiation of explosive electron emission under plasma and the formation and transport of high-current electron beams in plasma-filled systems are discussed consecutively. Considerable attention is given to the nonstationary effects that occur in the space charge layers of plasma. Emphasis is also placed on the problem of providing a uniform energy density distribution over the beam cross section, which is of critical importance in using electron beams of this type for surface treatment of materials. Examples of facilities based on low-energy high-current electron beam sources are presented and their applications in materials science and practice are discussed.

Automatic Phase Calibration for RF Cavities using Beam-Loading Signals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edelen, J. P.; Chase, B. E.

Precise calibration of the cavity phase signals is necessary for the operation of any particle accelerator. For many systems this requires human in the loop adjustments based on measurements of the beam parameters downstream. Some recent work has developed a scheme for the calibration of the cavity phase using beam measurements and beam-loading however this scheme is still a multi-step process that requires heavy automation or human in the loop. In this paper we analyze a new scheme that uses only RF signals reacting to beam-loading to calculate the phase of the beam relative to the cavity. This technique couldmore » be used in slow control loops to provide real-time adjustment of the cavity phase calibration without human intervention thereby increasing the stability and reliability of the accelerator.« less

Laser sensor system documentation.

DOT National Transportation Integrated Search

2017-03-01

Phase 1 of TxDOT Project 0-6873, True Road Surface Deflection Measuring Device, developed a : laser sensor system based on several sensors mounted on a rigid beam. : This sensor system remains with CTR currently, as the project is moving into Phase 2...

Fan-beam intensity modulated proton therapy.

PubMed

Hill, Patrick; Westerly, David; Mackie, Thomas

2013-11-01

This paper presents a concept for a proton therapy system capable of delivering intensity modulated proton therapy using a fan beam of protons. This system would allow present and future gantry-based facilities to deliver state-of-the-art proton therapy with the greater normal tissue sparing made possible by intensity modulation techniques. A method for producing a divergent fan beam of protons using a pair of electromagnetic quadrupoles is described and particle transport through the quadrupole doublet is simulated using a commercially available software package. To manipulate the fan beam of protons, a modulation device is developed. This modulator inserts or retracts acrylic leaves of varying thickness from subsections of the fan beam. Each subsection, or beam channel, creates what effectively becomes a beam spot within the fan area. Each channel is able to provide 0-255 mm of range shift for its associated beam spot, or stop the beam and act as an intensity modulator. Results of particle transport simulations through the quadrupole system are incorporated into the MCNPX Monte Carlo transport code along with a model of the range and intensity modulation device. Several design parameters were investigated and optimized, culminating in the ability to create topotherapy treatment plans using distal-edge tracking on both phantom and patient datasets. Beam transport calculations show that a pair of electromagnetic quadrupoles can be used to create a divergent fan beam of 200 MeV protons over a distance of 2.1 m. The quadrupole lengths were 30 and 48 cm, respectively, with transverse field gradients less than 20 T/m, which is within the range of water-cooled magnets for the quadrupole radii used. MCNPX simulations of topotherapy treatment plans suggest that, when using the distal edge tracking delivery method, many delivery angles are more important than insisting on narrow beam channel widths in order to obtain conformal target coverage. Overall, the sharp distal falloff of a proton depth-dose distribution was found to provide sufficient control over the dose distribution to meet objectives, even with coarse lateral resolution and channel widths as large as 2 cm. Treatment plans on both phantom and patient data show that dose conformity suffers when treatments are delivered from less than approximately ten angles. Treatment time for a sample prostate delivery is estimated to be on the order of 10 min, and neutron production is estimated to be comparable to that found for existing collimated systems. Fan beam proton therapy is a method of delivering intensity modulated proton therapy which may be employed as an alternative to magnetic scanning systems. A fan beam of protons can be created by a set of quadrupole magnets and modified by a dual-purpose range and intensity modulator. This can be used to deliver inversely planned treatments, with spot intensities optimized to meet user defined dose objectives. Additionally, the ability of a fan beam delivery system to effectively treat multiple beam spots simultaneously may provide advantages as compared to spot scanning deliveries.

Future of medical physics: Real-time MRI-guided proton therapy.

PubMed

Oborn, Bradley M; Dowdell, Stephen; Metcalfe, Peter E; Crozier, Stuart; Mohan, Radhe; Keall, Paul J

2017-08-01

With the recent clinical implementation of real-time MRI-guided x-ray beam therapy (MRXT), attention is turning to the concept of combining real-time MRI guidance with proton beam therapy; MRI-guided proton beam therapy (MRPT). MRI guidance for proton beam therapy is expected to offer a compelling improvement to the current treatment workflow which is warranted arguably more than for x-ray beam therapy. This argument is born out of the fact that proton therapy toxicity outcomes are similar to that of the most advanced IMRT treatments, despite being a fundamentally superior particle for cancer treatment. In this Future of Medical Physics article, we describe the various software and hardware aspects of potential MRPT systems and the corresponding treatment workflow. Significant software developments, particularly focused around adaptive MRI-based planning will be required. The magnetic interaction between the MRI and the proton beamline components will be a key area of focus. For example, the modeling and potential redesign of a magnetically compatible gantry to allow for beam delivery from multiple angles towards a patient located within the bore of an MRI scanner. Further to this, the accuracy of pencil beam scanning and beam monitoring in the presence of an MRI fringe field will require modeling, testing, and potential further development to ensure that the highly targeted radiotherapy is maintained. Looking forward we envisage a clear and accelerated path for hardware development, leveraging from lessons learnt from MRXT development. Within few years, simple prototype systems will likely exist, and in a decade, we could envisage coupled systems with integrated gantries. Such milestones will be key in the development of a more efficient, more accurate, and more successful form of proton beam therapy for many common cancer sites. © 2017 American Association of Physicists in Medicine.

Experiments on Ion Beam Deflection Using Ion Optics with Slit Apertures

NASA Astrophysics Data System (ADS)

Okawa, Yasushi; Hayakawa, Yukio; Kitamura, Shoji

2004-03-01

An experimental investigation on ion beam deflection by grid translation was performed. The ion beam deflection in ion optics is a desired technology for ion thrusters because thrust vector control utilizing this technique can eliminate the need for conventional gimbaling devices and thus reduce propulsion system mass. A grid translation mechanism consisting of a piezoelectric motor, a ceramic lever, and carbon-based grids with slit apertures was fabricated and high repeatability in beam deflection characteristics was obtained using this mechanism. Results showed that the beam deflection angle was proportional to the grid translation distance and independent of slit width and grid voltage. A numerical simulation successfully reproduced the beam deflection characteristics in a qualitative and quantitative sense. A maximum beam deflection angle of approximately plus or minus 6 degrees, which was comparable to that of the ordinary gimbaling devices used in space, was obtained without a severe drain current. Therefore, the beam deflection by grid translation is promising as a thrust vectoring method in ion thrusters.

Finite Element Modelling and Analysis of Damage Detection Methodology in Piezo Electric Sensor and Actuator Integrated Sandwich Cantilever Beam

NASA Astrophysics Data System (ADS)

Pradeep, K. R.; Thomas, A. M.; Basker, V. T.

2018-03-01

Structural health monitoring (SHM) is an essential component of futuristic civil, mechanical and aerospace structures. It detects the damages in system or give warning about the degradation of structure by evaluating performance parameters. This is achieved by the integration of sensors and actuators into the structure. Study of damage detection process in piezoelectric sensor and actuator integrated sandwich cantilever beam is carried out in this paper. Possible skin-core debond at the root of the cantilever beam is simulated and compared with undamaged case. The beam is actuated using piezoelectric actuators and performance differences are evaluated using Polyvinylidene fluoride (PVDF) sensors. The methodology utilized is the voltage/strain response of the damaged versus undamaged beam against transient actuation. Finite element model of piezo-beam is simulated in ANSYSTM using 8 noded coupled field element, with nodal degrees of freedoms are translations in the x, y directions and voltage. An aluminium sandwich beam with a length of 800mm, thickness of core 22.86mm and thickness of skin 0.3mm is considered. Skin-core debond is simulated in the model as unmerged nodes. Reduction in the fundamental frequency of the damaged beam is found to be negligible. But the voltage response of the PVDF sensor under transient excitation shows significantly visible change indicating the debond. Piezo electric based damage detection system is an effective tool for the damage detection of aerospace and civil structural system having inaccessible/critical locations and enables online monitoring possibilities as the power requirement is minimal.

Measurement and simulation for a complementary imaging with the neutron and X-ray beams

NASA Astrophysics Data System (ADS)

Hara, Kaoru Y.; Sato, Hirotaka; Kamiyama, Takashi; Shinohara, Takenao

2017-09-01

By using a composite source system, we measured radiographs of the thermal neutron and keV X-ray in the 45-MeV electron linear accelerator facility at Hokkaido University. The source system provides the alternative beam of neutron and X-ray by switching the production target onto the electron beam axis. In the measurement to demonstrate a complementary imaging, the detector based on a vacuum-tube type neutron color image intensifier was applied to the both beams for dual-purpose. On the other hand, for reducing background in a neutron transmission spectrum, test measurements using a gadolinium-type neutron grid were performed with a cold neutron source at Hokkaido University. In addition, the simulations of the neutron and X-ray transmissions for various substances were performed using the PHITS code. A data analysis procedure for estimating the substance of sample was investigated through the simulations.

Design and Control of Small Neutral Beam Arc Chamber for Investigations of DIII-D Neutral Beam Failure During Helium Operation

NASA Astrophysics Data System (ADS)

Fremlin, Carl; Beckers, Jasper; Crowley, Brendan; Rauch, Joseph; Scoville, Jim

2017-10-01

The Neutral Beam system on the DIII-D tokamak consists of eight ion sources using the Common Long Pulse Source (CLPS) design. During helium operation, desired for research regarding the ITER pre-nuclear phase, it has been observed that the ion source arc chamber performance steadily deteriorates, eventually failing due to electrical breakdown of the insulation. A significant investment of manpower and time is required for repairs. To study the cause of failure a small analogue of the DIII-D neutral beam arc chamber has been constructed. This poster presents the design and analysis of the arc chamber including the PLC based operational control system for the experiment, analysis of the magnetic confinement and details of the diagnostic suite. Work supported in part by US DoE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.

SU-G-JeP3-06: Lower KV Image Dose Are Expected From a Limited-Angle Intra-Fractional Verification (LIVE) System for SBRT Treatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ding, G; Yin, F; Ren, L

Purpose: In order to track the tumor movement for patient positioning verification during arc treatment delivery or in between 3D/IMRT beams for stereotactic body radiation therapy (SBRT), the limited-angle kV projections acquisition simultaneously during arc treatment delivery or in-between static treatment beams as the gantry moves to the next beam angle was proposed. The purpose of this study is to estimate additional imaging dose resulting from multiple tomosynthesis acquisitions in-between static treatment beams and to compare with that of a conventional kV-CBCT acquisition. Methods: kV imaging system integrated into Varian TrueBeam accelerators was modeled using EGSnrc Monte Carlo user code,more » BEAMnrc and DOSXYZnrc code was used in dose calculations. The simulated realistic kV beams from the Varian TrueBeam OBI 1.5 system were used to calculate dose to patient based on CT images. Organ doses were analyzed using DVHs. The imaging dose to patient resulting from realistic multiple tomosynthesis acquisitions with each 25–30 degree kV source rotation between 6 treatment beam gantry angles was studied. Results: For a typical lung SBRT treatment delivery much lower (20–50%) kV imaging doses from the sum of realistic six tomosynthesis acquisitions with each 25–30 degree x-ray source rotation between six treatment beam gantry angles were observed compared to that from a single CBCT image acquisition. Conclusion: This work indicates that the kV imaging in this proposed Limited-angle Intra-fractional Verification (LIVE) System for SBRT Treatments has a negligible imaging dose increase. It is worth to note that the MV imaging dose caused by MV projection acquisition in-between static beams in LIVE can be minimized by restricting the imaging to the target region and reducing the number of projections acquired. For arc treatments, MV imaging acquisition in LIVE does not add additional imaging dose as the MV images are acquired from treatment beams directly during the treatment.« less

Dynamic cone beam CT angiography of carotid and cerebral arteries using canine model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai Weixing; Zhao Binghui; Conover, David

2012-01-15

Purpose: This research is designed to develop and evaluate a flat-panel detector-based dynamic cone beam CT system for dynamic angiography imaging, which is able to provide both dynamic functional information and dynamic anatomic information from one multirevolution cone beam CT scan. Methods: A dynamic cone beam CT scan acquired projections over four revolutions within a time window of 40 s after contrast agent injection through a femoral vein to cover the entire wash-in and wash-out phases. A dynamic cone beam CT reconstruction algorithm was utilized and a novel recovery method was developed to correct the time-enhancement curve of contrast flow.more » From the same data set, both projection-based subtraction and reconstruction-based subtraction approaches were utilized and compared to remove the background tissues and visualize the 3D vascular structure to provide the dynamic anatomic information. Results: Through computer simulations, the new recovery algorithm for dynamic time-enhancement curves was optimized and showed excellent accuracy to recover the actual contrast flow. Canine model experiments also indicated that the recovered time-enhancement curves from dynamic cone beam CT imaging agreed well with that of an IV-digital subtraction angiography (DSA) study. The dynamic vascular structures reconstructed using both projection-based subtraction and reconstruction-based subtraction were almost identical as the differences between them were comparable to the background noise level. At the enhancement peak, all the major carotid and cerebral arteries and the Circle of Willis could be clearly observed. Conclusions: The proposed dynamic cone beam CT approach can accurately recover the actual contrast flow, and dynamic anatomic imaging can be obtained with high isotropic 3D resolution. This approach is promising for diagnosis and treatment planning of vascular diseases and strokes.« less