Parallel Coupled Cavity Structure

Sundelin, R.; Kirchgessner, J.; Tigner, M.

doi:10.1109/tns.1977.4329052

Cited by 19 publications

(10 citation statements)

References 3 publications

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“…Using a coaxial line to feed a set of cavities has been attempted before [7,8]. These approaches have not been used since these initial publications; the use of a coaxial line is difficult for many reasons.…”

Section: Distributed Coupling Linac Theorymentioning

confidence: 99%

Design and demonstration of a distributed-coupling linear accelerator structure

Tantawi

Nasr

et al. 2020

Phys. Rev. Accel. Beams

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We present a topology for linear accelerators (linacs) in which the power is distributed to the cavities through a waveguide with periodic apertures that guarantees the correct phases and amplitudes along the structure length. Unlike conventional traveling and standing-wave linacs, the presented topology allows the cavity shapes to be designed without the constraints applied to the coupling between cells to transfer power from one cell to the next. Therefore, the topology permits more degrees of freedom for the optimization of individual cavity shapes in comparison with conventional linacs. The cavity shapes can be optimized for power consumption and efficiency, and/or the manipulation of the surface fields for high gradient operation. This topology also provides a possibility for low-temperature manufacturing techniques that prevent the annealing of the material during typical brazing processes; hence, the material could retain its original properties such as hardness. We present a design and an experimental demonstration of this linac.

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Section: Distributed Coupling Linac Theorymentioning

confidence: 99%

Design and demonstration of a distributed-coupling linear accelerator structure

Tantawi

Nasr

et al. 2020

Phys. Rev. Accel. Beams

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“…The linac design [44] is based on an invention [45] that distributes the coupling over the cells of a standing-wave accelerator structure [46]. The idea of feeding each cavity has existed for some time [47][48][49]; however, until now there has been no practical electron linac implementation that allows such a topology to exist. What this invention provides is a practical implementation of a microwave circuit that is capable of feeding individual or multiple cavities separately.…”

Section: A Rf Photoinjectormentioning

confidence: 99%

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

Graves

Bessuille²,

Brown³

et al. 2014

Phys. Rev. ST Accel. Beams

119

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A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standingwave linac and rf photoinjector powered by a single ultrastable rf transmitter at X-band rf frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire accelerator is approximately 1 meter long and produces hard x rays tunable over a wide range of photon energies. The colliding laser is a Yb∶YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is 5 × 10 11 photons=second in a 5% bandwidth and the brilliance is 2 × 10 12 photons=ðsec mm 2 mrad 2 0.1%Þ in pulses with rms pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.

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“…Extending this idea further, the waveguide can be abandoned and replaced by an array of simple single cells, say the rectangular waveguide, half wavelength resonators as illustrated in Figure 5. It is then convenient to feed input power via slots from a parallel coaxial line that is also shown, as first proposed at Cornell [12]. Short circuiting this line creates a standing wave that can be suitably phased for cavity control.…”

Section: A Far Infrared Solutionmentioning

confidence: 99%

Beam-energy replacement in a compact fel

Saxon¹

1998

Nuclear Instruments and Methods in Physics Research Section A:

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To achieve high energy extraction from a compact FEL requires a method to negate the energy loss from the electron beam. A number of proposals have been made to incorporate an accelerating system within the FEL to overcome this restriction. The present study has examined various RF structures that can be conveniently integrated with an undulator magnet and has assessed the resultant performance limitations of possible infrared FELs. The muffin-tin geometry has been shown to be feasible for longer output wavelengths, whereas a side-coupled structure looks more promising below 50 µm. Magnet design options have also been explored and solutions for practical FELs are proposed that should allow high power output despite relatively low electron energies. BACKGROUNDFree electron lasers (FELs) have now demonstrated that they can provide a unique source of radiation with a combination of very high power and wide tunability [1]. They have been operated from the millimetre wave region all the way down to the present record of 240 nm, but their greatest success so far has been in the infrared (IR) regime where many user facilities have now been established [2]. Despite the lack of a material lasing medium FELs still encounter a saturation phenomenon that is due to a desynchronisation of the energy exchange process as the electrons give up their energy to the laser field. The gain curve has a width (2N) -1 for N magnetic periods in the device so that maximun energy transfer is limited to this fraction of the initial electron energy; in practice this limits the power efficiency of an FEL to about 1 % at saturation. Attempts have been made since the early days of FEL development to overcome this limit by employing a so-called tapering of the FEL undulator magnet properties along the interaction region [3,4]. Inspection of the output wavelength equation illustrates the requirement to vary either the magnet period λ u or the field strength (or both) since:where K is the undulator parameter (~λ u B ). The magnet parameters are therefore scaled to match the changing γ (E/mc 2 ) along its length, maintaining resonance with the wavelength λ. However there are severe problems with this approach, most notably the fact that the single pass gain is significantly reduced: in fact a dynamic taper not acting before saturation is desirable. The best result so far achieved was a 4-5 % energy extraction in a Los Alamos experiment [5]. REACCELERATION SCHEMESThe alternative solution is to replace the lost electron energy and so to preserve the wave-particle synchronism. This was proposed both as a DC field scheme [6] and for use of microwaves [7], but the only active experimental project has been that of the Pantell group at Stanford. Their initial proposal [8] was to copper plate the poles of an undulator magnet to create an integrated accelerating structure. Because this was a permanent magnet structure its field strength was therefore necessarily fixed and the FEL could not be tunable, so the group adopted a novel staggered pole arra...

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Parallel Coupled Cavity Structure

Cited by 19 publications

References 3 publications

Design and demonstration of a distributed-coupling linear accelerator structure

Design and demonstration of a distributed-coupling linear accelerator structure

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

Beam-energy replacement in a compact fel

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