Comparison of experimental tests and theory for a rectangular two-channel dielectric wakefield accelerator structure

Shchelkunov, Sergey V.; Marshall, T. C.; Sotnikov, G. V.; Hirshfield, J. L.; Gai, W.; Conde, Manoel; Power, John; Mihalcea, D.; Yusof, Z.

doi:10.1103/physrevstab.15.031301

Cited by 18 publications

(10 citation statements)

References 25 publications

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“…In the simple case the collinear acceleration schemes 2 T  [1 -3]. There are several ways to increase the transformer ratio, namely: (i) using a long driver bunch with a linearly increasing current [4], (ii) using a drive bunch sequence of bunches with increasing charge (ramped bunch train) [5 -8], (iii) using the structures with spaced channels for drive and witness bunches [9,10]. In [11] it was demonstrated, that a combination of a dielectric-loaded structure and plasma gives an opportunity for the drive and test bunches to be focused.…”

Section: Introductionmentioning

confidence: 99%

Wakefield Excitation by a Ramped Electron Bunch Train in a Plasma-Dielectric Waveguide

Galaydych¹,

Sotnikov²,

Onishchenko³

2021

Problems of Atomic Science and Technology

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A linear theory of wakefield excitation by a ramped electron bunch train in a cylindrical plasma-dielectric waveguide is presented. It is shown that during an excitation process the drive bunches are in the focusing field due to the radial electric field excitation of the plasma wave. The possibility of both obtaining a high transformer ratio and focusing the drive and witness bunches is demonstrated.

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Section: Introductionmentioning

confidence: 99%

Wakefield Excitation by a Ramped Electron Bunch Train in a Plasma-Dielectric Waveguide

Galaydych¹,

Sotnikov²,

Onishchenko³

2021

Problems of Atomic Science and Technology

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“…Most of the studies on the use of dielectric structures have been carried out for cylindrical collinear configurations, but achieving both high accelerating gradient and elevated transformer ratio in this configuration appears to be impossible [5]. Attention also has been directed to dielectric-lined waveguides having rectangular configuration [6][7][8][9][10][11][12][13]. Simplicity of manufacturing, possibility of realizing a multimode regime of excitation with equally-spaced frequencies [6] resulting in a significant increase of accelerating field amplitude, easy fine tuning of working frequency, additional intrinsic focusing in an accelerating field [7], availability of low-loss, dispersion-free dielectric materials, make dielectric-lined structures in a rectangular configuration attractive for excitation of accelerating fields by a laser pulse [11] or electron bunches [6-10, 12, 13].…”

Section: Introductionmentioning

confidence: 99%

The Dielectric Resonator Wakefield Accelerator

Sotnikov

Marshall

Shchelkunov

et al. 2018

2018 IEEE Advanced Accelerator Concepts Workshop (AAC)

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We report preliminary studies of a three-channel, rectangular, high gradient dielectric wakefield accelerator element, which, unlike the collinear cylindrical dielectric wakefield device, does not suffer from low transformer ratio and may offer relief from the beam breakup instability. When configured as a resonator (DWR), it can be driven by a series of modest-charge drive bunches. This rectangular mode-locked resonator consists of three channels lined with low-loss dielectric slabs: the central wider channel is the drive bunch channel, whereas two adjacent narrow channels are used to accelerate electron and/or positron bunches; this provides a favorable transformer ratio. At the moment when, after reflecting from the resonator exit, the wakefield returns to the resonator entrance, the next bunch is injected into the resonator entrance. The length of the resonator is also chosen to be a multiple of half the desired wakefield wavelength. The rectangular geometry permits superposition of harmonics of wakefields in the resonator. The short length of the device and its planar configuration should allow management of beam breakup, and a lengthy drive bunch train can be dynamically stabilized by using a series of DWR units rotated about the z-axis in 90 increments.

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“…The dielectric wakefield accelerator (DWA) is a promising candidate for building the TeV-energy range electronpositron collider [1][2][3][4][5]. However, among the DWAs shortcomings we should mention the susceptibility of bunches to the beam breakup instability [6,7] (BBU) peculiar to electron linear accelerators [8].…”

Section: Introductionmentioning

confidence: 99%

Excitation of wakefields by relativistic electron bunches in the dielectric waveguide filled with radially inhomogeneous plasma

2017

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One of shortcomings of the dielectric wakefield accelerators (DWA) limiting the effective length of an acceleration is susceptibility of drive bunches to beam breakup (BBU) instability [1]. With the purpose to suppress this instability recently it has been proposed to fill the drift channel of dielectric structure with plasma of certain density [2]. The investigations of plasma DWA (PDWA) [2] were made for dielectric wakefield structures with homogeneous radial plasma density. Such consideration is right if plasma comes to the drift channel from external source.Other, widely way of plasma creation is capillary discharge. For this case on big times from the beginning of discharge (it is more than a half of pulse width of discharge current) steady distribution of plasma density with inhomogeneous distribution of discharge density forms [3]. At short distances from the axis a radial dependence of plasma density can be described with the parabolic dependence [3,4] 2 0 ( )where a is the inner radius of dielectric tube.Investigations on excitation of wakefield in PDWA with and inhomogeneous transverse distribution of plasma density were not carried out so far. For practical application of the proposed accelerating structure it is important to know how the accelerating gradient and focusing forces acting on test bunches will change in case when plasma in the drift channel is created as a result of the capillary discharge.Here we report the results of numerical simulation of wakefield excitation in the dielectric structure filled with plasma created in capillary discharge. Wakefield is built up at injection of electron bunch in dielectric tube with permittivity of 3.8; outside diameter of dielectric tube (is equal to the diameter of metal waveguide) is 1.2 mm, inner diameter is 1.0 mm. Energy of drive bunch electrons is 5 GeV, bunch charge is 3 nC, its length was 0.2 mm, solid bunch has diameter of 0.9 mm. For the testing the excited wakefield we used a witness bunch. Witness bunch has the same energy and sizes as drive bunch, the charge of witness bunch was less by ten times than drive bunch charge.The drift channel (internal area of dielectric tube) is filled with plasma of on-axis density n 0 = 4.41×10 14 cm -3 . Three different models of dependence of plasma density on radius were investigated: a) homogeneous radial plasma density; b) parabolic dependence of plasma density on radius according eq. (1) At numerical simulation by means of the 2.5D PIC code created by us we examined a structure of wakefield and dynamics of electron bunches at their motion in the drift camera. In Fig. 1 axial profiles of the Lorentz wakefield force acting on test electron in dielectric waveguide with plasma filling for the time t = 26.69 ps from the beginning of injection of drive bunch for different dependences of plasma density on radius are shown: a) homogeneous, b) parabolic (1) and c) the BPM dependence [3]. The grey rectangle near output end shows the location of the drive bunch electrons. Vertical arrows have noted the possible pl...

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Comparison of experimental tests and theory for a rectangular two-channel dielectric wakefield accelerator structure

Cited by 18 publications

References 25 publications

Wakefield Excitation by a Ramped Electron Bunch Train in a Plasma-Dielectric Waveguide

Wakefield Excitation by a Ramped Electron Bunch Train in a Plasma-Dielectric Waveguide

The Dielectric Resonator Wakefield Accelerator

Excitation of wakefields by relativistic electron bunches in the dielectric waveguide filled with radially inhomogeneous plasma

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