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A transverse beam profile monitor that visualizes a two-dimensional beam-induced fluorescent image was developed. The monitor employs a sheet-shaped gas flow formed by a technique of rarefied gas dynamics. A simplified analysis method was developed to reconstruct the beam intensity profile from the obtained image. The developed profile monitor and the analysis method were applied to measure the J-PARC 3 MeV ${\mathrm{H}}^{\ensuremath{-}}$ beam profile. The root mean square values of the profiles were consistent with the ones obtained by a wire-scanning-type beam profile monitor. The beam loss due to the gas sheet injection was measured as a beam-current reduction. The amount of the beam current decreased in proportion to the gas sheet flux and the reduction ranged from 0.004 to 2.5%. The assembled system was capable of reconstructing a beam profile from a single shot beam pulse ($1.7\ifmmode\times\else\texttimes\fi{}{10}^{13}$ protons in $50\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$).

Characterization of barely visible impact damage (BVID) in polymer matrix composites (PMCs) is necessary to use slow crack growth damage tolerance models and evaluate remaining life of PMC components. Azimuthally scanned angled-beam pulse-echo ultrasound is investigated as a complimentary technique to normal incidence ultrasound inspection of BVID in PMCs to characterize delamination fields. It is found that there is a correlation between signals present in the azimuthally scanned angled-beam pulse-echo ultrasound C-scans and transverse cracks seen in X-ray computed tomography inspection. These transverse cracks are not readily identifiable as transverse cracks in normal incidence C-scan inspection.

PurposeIn advanced radiotherapy techniques such as intensity-modulated radiation therapy (IMRT), the quality assurance (QA) process is essential. The aim of the study was to assure the treatment planning dose delivered during delivery of complex treatment plans. The QA standard is to perform patient-specific comparisons between planned doses and doses measured in a phantom.Materials and methodThe Delta 4 phantom (Scandidos, Uppsala, Sweden) has been used in this study. This device consists of diode matrices in two orthogonal planes inserted in a cylindrical acrylic phantom. Each diode is sampled per beam pulse so that the dose distribution can be evaluated on segment-by-segment, beam-by-beam, or as a composite plan from a single set of measurements. Ninety-five simple and complex radiotherapy treatment plans for different pathologies, planned using a treatment planning system (TPS) were delivered to the QA device. The planned and measured dose distributions were then compared and analysed. The gamma index was determined for different pathologies.ResultsThe evaluation was performed in terms of dose deviation, distance to agreement and gamma index passing rate. The measurements were in excellent agreement between with the calculated dose of the TPS and the QA device. Overall, good agreement was observed between measured and calculated doses in most cases with gamma values above 1 in >95% of measured points. Plan results for each test met the recommended dose goals.ConclusionThe delivery of IMRT and volumetric-modulated arc therapy (VMAT) plans was verified to correspond well with calculated dose distributions for different pathologies. We found the Delta 4 device is accurate and reproducible. Although Delta4 appears to be a straightforward device for measuring dose and allows measure in real-time dosimetry QA, it is a complex device and careful quality control is required before its use.

Toward ITER, the long-pulse acceleration of MeV-class negative ion beams has been successfully demonstrated and R&Ds and the procurement of high-voltage components of 1 MV power supply system have been progressed. In the accelerator development after the production of 1 MeV beams, an extraction grid, where a water cooling is reinforced and the beam is steered by aperture offset to suppress grid heat loads, has been newly developed to extend the pulse duration of the MeV-class beams. As the result, a total grid heat load has been reduced from 20% to 10% of the total beam power. The beam pulse was successfully increased from 0.4 s to 60 s at 0.68 MeV, 100 A/m 2 and 12 s at 0.89 MeV, 156 A/m 2 beams. As for the procurement of the 1 MV power supply system, 1 MV insulating transformer as the critical component has been developed. In the mock-up, a dc 1.2 MV for 1 h with the margin of 20% was stably sustained. Through the R&Ds of the critical components, design of five power supplies procured by JAEA has been finalized, and out of which a testing power supply has been completed in June 2014.

We describe the operational experience of the JET actively cooled duct liner and compare it with the previous inertially cooled duct. The paper discusses the initial conditioning of the duct liner during restart commissioning and subsequent high power performance. The new duct was conditioned in 48 plasma pulses during its first time commissioning in only 35 plasma pulses in the following restart. The inertial duct liner conditioning typically required 100 plasma pulses. In a well conditioned beamline for a 15 MW beam pulse the duct liner temperature and pressure were observed to establish an equilibrium 5 s into the pulse and remain in a steady state to the end of the pulse. The observed behaviour is compared with the design basis predictions.

하지만 ITO 는 기계적 강도 및 안정성에 대한 제한이 존재하여 현재 다양한 곡면 및 유연 투명 전도성 소재에 대한 적용에는 문제가 있다. 이러한 응용품의 요구에 따라 유연한 표면에 박막Key Words: Pulsed Laser(펄스레이저), Silver(은), Nanowire(나노와이어), Micro Fabricatio(미세가공) 초록: 펄스 레이저를 적용한 실버나노와이어의 접합 영향이 연구되었다. 조사된 레이저 펄스 에너지는 실버나노와이어 네트워크에서 실버나노와이어간에 접합을 유도하였으며 이로 인해 투명 기저위의 실버나노와이어 네트워크 박막에 전기 저항값을 조절할 수 있었다. 특히 이러한 나노네트워크에서의 접합은 개별 나노와이어의 접촉점의 형태로 발생되었고 접합의 효과는 전체 실버나노와이어 네트워크의 전기저항 변화 측정으로 평가하였다. 또한 레이저 빔 펄스폭 및 레이저 평균 출력이 나노와이어 접합 비율 평가에 적용되어 연구되었다. 실버나노와이어 네트워크의 광학 특성도 관찰되었으며 이에 레이저 공정 요소 대비 효과도 연구되었다. 최적화된 레이저빔 적용 재료처리는 특화된 국부 재료 특성 개선에 장점을 보였다. 펄스 레이저를 이용한 실버나노와이어의 재료처리의 적용과 그 효과에 대해서도 논의한다. Abstract: A direct pulsed laser process for welding and networking silver nanowires was developed. The welded nanowire network demonstrated modified electrical properties in a transparent substance. In particular, the welding points on the nanowires were investigated to measure the resistance at the connections. The level of networking in nanowires was explored with respect to various laser pulse widths and average power densities. In particular, the influence of laser beam density was investigated in detail. Selective laser treatment can be advantageous in imparting customized local property changes in transparent conducting materials. Various applications of the process are also discussed in this paper.

The ultracold neutron (UCN) source at the Paul Scherrer Institute (PSI), Switzerland has started full beam operation in mid 2011. Since then, continuous improvements have led to an UCN intensity increase by about a factor of 80 in comparison to first beam on target. UCN delivery to two beam ports is now operating on a regular basis, with e.g. about 17 million UCN delivered to one experiment over the first 200 s with every 4 s long beam pulse operated in a 480 s interval.

Long pulse operation of high power ion source is the requirement of fusion science research on neutral beam injector. A breakdown of accelerator column is drastically increased when operating with high beam energy and long beam duration. To extend the pulse length, which was stopped with every breakdown so far, the beam re-starting technology was developed and utilized. As a result, the voltage drop of every power supply due to breakdown was recovered within a time of 90 ms and beam pulse length was extended much longer than the case before this improvement. The details of the beam re-starting technology and the preliminary results were presented in this manuscript.

The experiment described in this paper is the first study of the response of a static tungsten powder sample to an impinging high energy proton beam pulse. The experiment was carried out at the HiRadMat facility at CERN. Observations include high speed videos of a proton beam induced perturbation of the powder sample as well as data from a laser Doppler vibrometer measuring the oscillations of the powder container. A comparison with a previous analogous experiment which studied a proton beam interaction with mercury is made. The experiment described in this paper is the first study of the response of a static tungsten powder sample to an impinging high energy proton beam pulse. The experiment was carried out at the HiRadMat facility at CERN. Observations include high speed videos of a proton beam induced perturbation of the powder sample as well as data from a laser Doppler vibrometer measuring the oscillations of the powder container. A comparison with a previous analogous experiment which studied a proton beam interaction with mercury is made

Recent upgrade of the neutral beam system has resulted in considerable improvement of the plasma parameters in the gas dynamic trap experiment. With injection of 5 ms, 20 keV, 4.5 MW neutral beams the electron temperature approaching 250 eV was obtained. At the same time maximal plasma beta attained about 60%. Further progress in plasma temperature and pressure could only be possible with considerable increase of the magnetic field in the central solenoid and re-optimization of its profile to improve stability of highbeta plasma, as well as with extension of the neutral beam pulse. Possible steps in this direction are considered in this paper.

Results of experiments on injection of a sequence of several electron beam pulses (80–90 keV, 20–75 A, ∼30 μs) into 1019–1021 m−3 deuterium plasma are presented. The first beam pulse was injected into deuterium gas, the following pulses propagated through residual plasma that survived the inter-pulse periods. A typical pulse duration was of the order of 106 ω p − 1 that is much longer than most of the interaction-related processes. However, we noticed significant differences in plasma processes between the first pulse and the rest ones. A suggested physical factor behind those differences is longitudinal plasma current that develops during the first beam pulse.

Because the nearspace slow-moving platform borne synthetic aperture radar (SAR) can realize high resolution imaging using low pulse repetition frequency (PRF), a full-aperture ScanSAR (FA-ScanSAR) operation, which switches the range beam pulse by pulse, was proposed for wide swath imaging. This operation separates the wide swath into several sub-swaths, and each of which can be illuminated by a narrow range beam. The SAR antenna switches the range beam to point at each of the sub-swaths in turn, transmits pulses and receives echoes pulse by pulse. The design method of main system parameters and the calculating expressions of the performance indexes are addressed in the paper. A design example is given to compare the performance of the conventional strip operation, ScanSAR and FA- ScanSAR operation. The results show that FA-ScanSAR operation can obtain high resolution by full aperture accumulation in wide swath and improve the signal-to-noise ratio of SAR images for the nearspace slow-moving platform borne SAR.

While an intense electron beam passes through the accelerating gaps of a linear induction accelerator, a strong wake field will be excited. In this paper a relatively simple model is established based on the interaction between the transverse magnetic wake field and the electron beam, and the numerical calculation in succession generates a magnetic wake field distribution along the accelerator and along the beam pulse as well. The axial electric wake field is derived based on the relation between field components of a resonant mode. According to some principles in existence, the influence of this field on the high voltage properties of the induction gap is analyzed. The Dragon-I accelerator is taken as an example, and its maximum electric wake field is about 17 kV/cm, which means the effect of the wake field is noticeable.

Control of the time-dependent characteristics of the beam pulse, beginning when it is born from the source, is important for obtaining adequate beam intensity on a target. Recent experimental measurements combined with the new mesh-refinement capability in WARP have improved the understanding of time-dependent beam characteristics beginning at the source, as well as the predictive ability of the simulation codes. The University of Maryland Electron Ring (UMER), because of its ease of operation and flexible diagnostics has proved particularly useful for benchmarking WARP by comparing simulation to measurement. One source of significant agreement has been in the ability of three-dimensional WARP simulations to predict the onset of virtual cathode oscillations in the vicinity of the cathode grid in the UMER gun, and the subsequent measurement of the predicted oscillations.

The Gun Test Facility (GTF) was built to test high-brightness sources for the proposed Linac Coherent Light Source (LCLS) at SLAC. The longitudinal emittance has been determined by measuring the energy spectrum after the linac as a function of the linac phase. The phase-space parameters defining the beam pulse width, correlated energy spread, and slice energy spread at the linac entrance (∼5 MeV beam energy) are fit to the measured energy spectra. A large, linear energy–time correlation is observed for bunch charges from 15 to 300 pC. Preliminary Parmela calculations show this correlation results from the strong longitudinal space charge forces in this short 2-ps long bunch.

The energy loss for an accelerated electron beam passing through a laser-driven RF gun has been studied. An analytical formula of the energy loss has been obtained using the time-dependent resonant modes of a cylindrical pill-box cavity. As an approximation, this formalism assumes a rigid beam pulse so the change of pulse shape dealing with space-charge force and wake field force is ignored.

Near-threshold photodissociation of ${\mathrm{Br}}_{2}$ from a supersonic beam produces slow bromine atoms that are trapped in the magnetic-field minimum formed between two opposing permanent magnets. Here we quantify the dominant trap-loss rate due to collisions with two sources of residual gas: the background limited by the vacuum chamber base pressure and the carrier gas during the supersonic gas pulse. The loss rate due to collisions with residual Ar in the background follows pseudo-first-order kinetics and the bimolecular rate coefficient for collisional loss from the trap is determined by measurement of this rate as a function of the background Ar pressure. This rate coefficient is smaller than the total elastic collision rate coefficient, as it only samples those collisions that lead to trap loss, and is determined to be $\ensuremath{\langle}\ensuremath{\nu}\ensuremath{\sigma}\ensuremath{\rangle}=(1.12\ifmmode\pm\else\textpm\fi{}0.09)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{3}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$. The calculated differential cross section can be used with this value to estimate a trap depth of $293\ifmmode\pm\else\textpm\fi{}24\phantom{\rule{0.28em}{0ex}}\mathrm{mK}$. Carrier-gas collisions occur only during the tail of the supersonic beam pulse. Using the differential cross section verified by the background-gas collision measurements provides an estimate of the peak molecular-beam density of $(3.0\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{13}\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$, in good agreement with the prediction of a simple supersonic expansion model. Finally, we estimate the trap-loss rate due to Majorana transitions to be negligible, owing to the relatively large trapped-atom phase-space volume.

A new type of beam-position monitor (BPM) has been developed in the KEKB accelerator. The BPM employs an I/Q (In-phase and Quadrature phase) demodulator operating at an acceleration frequency of 509 MHz without down converting. The peak value of a demodulated beam pulse is sampled every revolution period. Not only horizontal and vertical positions, but also the longitudinal position can be detected turn by turn. The performance of this four-dimensional BPM is described in detail. A monitor is indispensable for tuning a beam injected into the KEKB.

We outline the design concept for low-inductance high-current spark modules at a voltage level of 100 kV and a current of 1 MA. We present the results of an investigation of the switching and operating characteristics of multichannel, multigap spark modules as a function of the design and the shape and amplitude of the beam pulse. We give a description of the designs and parameters of the developed types of spark modules.

The design of a electronic beam pulse generator for industrial applications is described. The parameters of the electron beam are 700 kV, 25 kA, and 1 µsec. The design features of the magnetic circuits and the test bench used to test and inspect them are described.

The Australian Synchrotron AS is moving towards a continuous injection mode called top-up. During top-up the linac and booster synchrotron injection system will be in continuous operation rather than usedevery eight hours the way they are used at present. In order to monitor the performance of the injection system areal-time injection efficiency monitoring system has been developed. The system consists of several Fast CurrentTransformers [1] and matching digitisers [2] and is designed to count every beam pulse and measure the transmission efficiency through the whole accelerator complex. After calibrating the system using a properly matchedFaraday Cup at the electron gun, a transmission efficiency is then calculated at each stage of transferring the beamfrom 90 keV out of the gun to 3 GeV in the storage ring. The system is used to optimise the injection process inorder to maximise the injection efficiency and as an early warning system when equipment starts to fail and theinjection efficiency decreases.

With the methods of time-division multiplexing in Frontend and angle detuning in FOA, each beam pulse on SG-III prototype facility is controlled independently and so the systematic variations of power imbalance are eliminated entirely.

Some major system features are not stated but can be inferred. For example this is probably an engineering test facility, not a power plant driver, because the standoff from target to final magnet is only 5.0 m. The fusion target takes two-sided illumination with indirect drive using a total of 60 beam pulses: 10 pre-pulses (3.0 GeV) + 20 main pulses (4.0 GeV) from each side. On page 12 it's stated that the charge per beam pulse is 26.8 {micro}C, so we calculate pre-pulse: 20 x 3 GeV x 26.8 {micro}C = 1.608MJ, main pulse: 40 x 4 GeV x 26.8 {micro}C = 4.288MJ, total beam energy 5.896MJ. The beam ion mass ks 200 amu, so the species is Hg{sup +}. Therefore the mid-pulse velocities are: pre-pulse v = .1773c = 5.316 x 10{sup 7} m/s, main pulse v = .2040c = 6.114 x 10{sup 7} m/s, On page 12 it is stated that the pre-compression pulse length is L{sub 0} = 10.0m, and compression is by a 'factor of order 20'. They infer a final pulse length of about .5 m and final durations pre-pulse {tau} {approx} .5/5.316 x 10{sup 7} = 9.4 ns; main pulse {tau} {approx} .5/6.114more » x 10{sup 7} = 8.2 ms. The magnetic rigidity of the beam ions is [B{rho}] = {gamma}m v/e = {l_brace} 112.0 T-m - prepulse/129.5 T-m - mainpulse{r_brace}.« less

Electron induction linacs have been used for over four decades for a variety of applications. As discussed in Chap. 8, these include basic studies in magnetically confined fusion, transport of intense electron beams in various gases, the generation of electromagnetic radiation from free electron lasers, radiation processing of materials and food, and flash X-ray radiography sources.

We have performed a determination of magnetic structures of metamagnetic PrCo 2 Si 2 in pulsed high magnetic fields up to 16 T with a spallation neutron source at The National Laboratory for High Energy Physics in Japan. The timing of field generation was synchronized with the beam pulse every 2.5 s and the time of flight method was used to observed Bragg peaks. It has been confirmed that the complicated magnetic structures in high fields determined by this experiment are identical with those suggested by high field magnetization measurements.

The SNS will be one of the the most prolific sources of neutrinos in the world in the next few years. It will enable experiments to make significant advances in neutrino science. The SNS will have significant advantages over the old standard, the LAMPF at Los Alamos, owing to the time‐compressed beam pulse relative to LAMPF. The 500 ns long pulse will be over 1000 times shorter than the old LAMPF beam pulse of 700 μs. This article describes some of the possibilities for measurements in neutrino physics made possible by the SNS facility.

Selective suppression of high order axial modes of the gyrotron backward-wave oscillator (gyro-BWO) is investigated in theory and in experiment. The gyro-BWO interaction is much more efficient in a down-tapered interaction structure, while it is also more susceptible to the problem of axial mode competition in such a structure. Because higher order axial modes (at a higher oscillation frequency) penetrate deeper into the interaction structure, application of distributed wall loss at the downstream end of the interaction structure is shown in theory to be effective for selective suppression of these modes without degrading the efficiency of the desired fundamental axial mode. A stable gyro-BWO operating in a single mode throughout the entire beam pulse is demonstrated on the basis of this principle. Theoretical and experimental results are found to be in good agreement.

A 10MW L-band Multi-Beam Klystron (MBK) has been developed and tested by Toshiba, Japan for the European XFEL and a future linear collider projects. The Toshiba MBK has six low-perveance beams operated at low voltage of 115 kV (for 10MW) and six ring-shaped cavities to enable a higher efficiency than a single-beam klystron for a similar power. After the successful acceptance testing at the Toshiba Nasu factory in March 2006, attended by a DESY stuff, the final acceptance test was done at DESY laboratory in June 2006. In these tests, the output power of 10.2MW, more than the design goal (10MW), has been demonstrated at the standard beam voltage of 115 kV at the RF pulse length of 1.5 ms and the beam pulse of 1.7 ms at 10 Hz. The efficiency was 66%. The robustness of the tube was also demonstrated by being operated continuously more than 24 hours above 10MW. Total time of operation on the test stand at DESY already exceeds 750 hours (up to date February 4, 2007). A horizontal version of the Toshiba MBK is now under construction.