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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 $50\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$).

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.

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 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.

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.

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.

3 pp. (2005)., ophisticated beam-based alignment is essential in future linear colliders to preserve the beam emittance during the transport through the main linac. One such method is dispersion free steering. In this paper different options to implement this method are discussed, based on the use of different accelerating gradients, RF phases and bunch particle types during a beam pulse.

As it was shown in recent papers [1, 2, 3] both spatial and temporal structure of a beam pulse are subject to generalized reciprocity inequalities:1 a product of characteristic pulse duration on its frequency bandwidth grows proportionally to effective number of modes in this pulse $$\Delta \omega \Delta t\alpha {N_{eff}}$$ (1a) The relation between width of angular spectrum of a beam and its cross-section width behaves in just the same manner $$ {{(\Delta \theta \Delta r)}^{2}}\alpha {{N}_{{eff.}}} $$ (1b)

The phenomenon of beam pulse shortening phenomenon associated with the RF electron gun is reported. The author believes that the beam loading effect plays an important role. The interaction between the electron beam and the deflecting mode is another important factor. >

The great attention in tokamak research is paid to study of the magnetic field structure now. The MSE method is used for q measurements on most large tokamaks. Numerical analysis and a series of preliminary experiments have demonstrated that for T-10 conditions — vertical beam and short (1 ms ) duration of the diagnostic beam pulse — use of the MSE is inefficient. We consider a charge exchange technique described below as an alternative method.

It has been observed that H- current could be improved by adding Ar to H2 plasma. But due to a slower pumping speed for Ar with the existing pumping scheme, the tank pressure will increase quickly during the length of a beam pulse. Since H- stripping loss depends on the tank pressure and gas species, part of the H- beam can be converted to H0 and then H0 can be converted into H+ with background H2 and Ar gas thickness. Therefore, the H- beam current, measured by a Faraday cup, situated at a distance L from GG (ground grid), will decrease because it will be converted into a H+ current. This gives a ratio of the Faraday cup net current to the H- beam current before stripping at background partial pressure of Ar.

Improvement in focusing the proton beam onto the antiproton production target necessitates the development of a higher resolution beam profile monitor. Two designs for the construction of a multiwire profile monitor grid are presented. The first is a conventional strung and tensioned Ti wire design. The second is a photo etched Ti grid of wires bonded to a ceramic substrate. Both have a central wire spacing of 125 /spl mu/m. The completed beam profile monitors are designed to operate in a 120 GeV beam pulse of 5/spl times/10/sup 12/ protons with a 1.5 /spl mu/s duration and will be installed in late 1993. >

Summary form only given. A 1-MV accelerator column composed of aperture lenses that focus and accelerate K/sup +/ ions from a hot-plate is being studied experimentally at Lawrence Berkeley Laboratory. The source must provide adequate current with a sufficiently low temperature so that the beam can be focused to the required small spot at the target. Time-independent codes provide design insight but fail to give any information about beam transients. HIF applications require careful control of the entire beam pulse. Continued refinement of the time-dependent code GYMNOS now allows detailed comparison with experiment and provides guidance for the evolution of the column design.

Two-stage autoacceleration was experimentally realized by passing an annular electron beam through a two-stage passive cavity structure. The kinetic energies of the last quarter part in the beam pulse were increased. Possibility of compression of an intense beam using multistage autoacceleration is discussed.

The effect of beam intensity and beam pulse repetition rate on the transport efficiency of 104 Ag recoils [from the 103 Rh(α, 3n) reaction] in a He jet recoil transport system has been measured. Transport was effected by using the gas doped with benzene or diethyl sulphide. The effect of concentration for these two substances has been established and the maximum transport efficiencies were about 100% for benzene (22 ppm) and about 80% for diethyl sulphide (12 ppm).

An analysis of errors connected with beam pulse width variation and instrument noise characteristics has been carried out for charge monitoring of a pulsed accelerator beam traversing an experimental target. The formulae necessary for the selection of optimum monitor and preamplifier parameters for a given range and required accuracy are presented.

A system for the reduction of the beam pulse repetition rate of the energy-variable Hamburg Isochronous Cyclotron comprising beam pulse supression in the cyclotron center and in the external beam is described.

A beam position and size monitor is described for use with pulsed beams with an intensity above 105 particles/(pulse cm2). It uses a standard multiwire chamber, but the current on each wire is integrated, digitized, and stored for each beam pulse. For optimum determination of beam size, the wire spacing in the chamber should be small compared to the beam size; the present system has 2-mm wire spacing.

A r.f. beam pulse stretcher has been applied successfully to the Carnegie Institute of Technology 450 MeV synchrocyclotron. The beam pulses are stretched completely. The duty factors are almost unity for the long time scale and less than two for the nanosecond time scale due to the phase bunch. The beam loss is 30–40 percent of the bunched beam.

The distribution of the charges contained in the individual beam pulse of the external beam of the Hamburg Isochronous Cyclotron has been studied.

An accelerator timing signal and a logic signal derived from an accelerator-produced nuclear event are used to gate on and off, respectively, a train of crystal-controlled oscillator pulses. The frequency distribution of the number of gated oscillator pulses yields detailed information about the accelerator beam pulse shape.

A debuncher with half stochastic and half resonance acceleration has been applied to the INS 160 cm. synchro-cyclotron. The resulting beam intensity has been found to be almost unchangeable with time. The average beam current is 35% as large as it had been before the debuncher was installed.