Analysis of a Symmetric Terahertz Dielectric-Lined Rectangular Structure for High Gradient Acceleration

Marshall²,

Phys. Rev. ST Accel. Beams

et al. 2012

Self Cite

Experimental results are reported for test beam acceleration and deflection in a two-channel, cm-scale, rectangular dielectric-lined wakefield accelerator structure energized by a 14-MeV drive beam. The dominant waveguide mode of the structure is at $30 GHz, and the structure is configured to exhibit a high transformer ratio ($12:1). Accelerated bunches in the narrow secondary channel of the structure are continuously energized via Cherenkov radiation that is emitted by a drive bunch moving in the wider primary channel. Observed energy gains and losses, transverse deflections, and changes in the test bunch charge distribution compare favorably with predictions of theory.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Marshall²,

Phys. Rev. ST Accel. Beams

et al. 2012

Self Cite

“…A charge profile that is flattened along the y-axis (see Fig.1) and extends a half-LSM 41 -period along the z-axis might be suitable. However, a small circular cross-section point-like drive bunch may also be used, in which case, if the orientation of the tall resonators along the beamline is alternated by +/ − 90 o around the z-axis, it should be possible to obtain dynamical stabilization of the drive bunch train, because it is found that when expanding the forces about a small region including the z-axis in the drive channel at the drive bunch location, there results transverse forces F x = −F y , a quadrupolelike effect [25] that obtains despite the different height and width dimensions of the resonator. Fig.7 shows how this might be implemented to obtain dynamical stability FIG.…”

Section: The Three-channel Rectangular Dielectric Wakefield Resomentioning

confidence: 99%

“…7. Showing alternating DWR units oriented by a 90 degree rotation in order to dynamically stabilize the drive bunch (in red, traversing the two units) [25]. Four accelerated witness bunches are shown in blue that can be accelerated in such a sequence of resonators.…”

Section: The Three-channel Rectangular Dielectric Wakefield Resonator...mentioning

confidence: 99%

The Dielectric Resonator Wakefield Accelerator

Marshall

2018 IEEE Advanced Accelerator Concepts Workshop (AAC)

et al. 2018

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.

“…In [21], a THz-scale dielectric-lined three-channel rectangular structure is described which can be thought of as two aforementioned quadrants combined together [see Fig (top, right)] so there are two parallel drive channels (~1 mm wide and 0.6 mm tall) and one channel for acceleration (~ 0.1 mm wide). The design mode is LSM 41 , and the design transformer ratio ~20:1.…”

Section: Multichannel Dielectric Wakefield Acceleration Schemesmentioning

confidence: 99%

High transformer ratio of multi-channel dielectric wakefield structures

Marshall²,

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2016

Dielectric wakefield (DWA) accelerator concepts are receiving attention on account of their promising performance, mechanical simplicity, and anticipated low cost. Interest in DWA physics directed toward an advanced high-gradient accelerator has been enhanced by a finding that some dielectrics can withstand very high fields (> 1 GV/m) for the short times during the passage of charged bunches along dielectric-lined channels. In a two-channel structure, a drive bunch train propagates in a first channel, and in the second adjacent channel where a high gradient wakefield develops, a witness bunch is accelerated. Compared with single-channel DWA's, a two-beam accelerator delivers a high transformer ratio, and thereby reduces the number of drive beam sections needed to achieve a given final test beam energy. An overview of multi-channel DWA structures will be given, with an emphasis on two-channel structures, presenting their advantages and drawbacks, and potential impact on the field. Studies aimed to examine charging rate and charge distribution in a thin walled dielectric wakefield accelerator from a passing charge bunch and the physics of conductivity and discharge phenomena in dielectric materials useful for such accelerator applications are presented in a separate paper in the EAAC-2015 conference proceedings.