Design of the Compact Linear Collider main linac accelerating structure made from two halves

Abstract

Milling on two longitudinally split halves is one method to manufacture accelerating structures. This method is simple and allows one to avoid electromagnetic fields at bonding joints, making it attractive in manufacturing high-gradient accelerating structures. An X-band structure design with strong wakefield damping based on this manufacturing approach is studied in this work as an alternative design for the Compact Linear Collider (CLIC) main linac accelerating structures. The geometry of the structure is optimized to greatly reduce the surface fields, improve the efficiency, and suppress the wakefield. This structure features the baseline design of the CLIC main linac with additional advantages. This study may serve as a reference for designing other high frequency-band corrugated structures.

A Compact, Low-Field, Broadband Matching Section for Externally Powered X-Band Dielectric-Loaded Accelerating Structures

“…This slight difference along the y axis allows the accelerating fields in the vacuum region to be almost identical and uniform. Figure 4 (b) shows that for the same DLA structure, the ratio of the peak magnetic field to the average accelerating field is 9.32 mA/V, which is much larger than that of existing metallic CLIC-G [36][37][38] structures. It is also found that strong magnetic fields are located on the metallic surface, resulting in large surface currents and hence high power loss and high pulsed surface heating temperature rise [30][31][32][33].…”

Investigations Into X-Band Dielectric Assist Accelerating Structures for Future Linear Accelerators

“…By substituting these numbers into Eq. (2), a RF-tobeam power efficiency for a DAA structure as high as rf−to−beam = 51% is reached, which is 52% higher than previously reported CLIC-G structures with an efficiency of 33.5% [7][8][9][10][11][12][13][14]. It should be pointed out that this efficiency is based on a DAA structure with an ultralow-loss tangent of 6 × 10 −6 .…”

“…Consideration of such a regular cell is used to generate a TM02-π mode, in which the periodic length 1 is equal to 1 = 0 /2, where 0 = 25 mm is the free-space wavelength for 0 . The iris aperture radius 0 is chosen as 0 = 3.15 mm which is comparable with that of CLIC-G structure [7][8][9][10][11][12][13][14] considering the DAA structure can be potentially used for CLIC main linac in the future. According to the optimization processing in Ref [48], the disk thickness 1 is chosen to be a quarter of the resonant wavelength in such a dielectric material.…”

“…VER the past few decades, conventional disk-loaded copper radiofrequency (RF) structures have been widely studied, and used to accelerate particles in a variety of applications for scientific research [1][2], medical cancer therapy [3][4], and industrial processing [5][6]. A high accelerating gradient of up to 100 MV/m has been demonstrated at room temperature for an X-band copper structure, which has been studied as the baseline accelerating structure design for the Compact Linear Collider (CLIC) main linac [7][8][9][10][11][12][13][14]. Such a structure is named 'CLIC-G', operating at 11.994 GHz in 2π/3 mode with an unloaded quality factor 0 ≈ 5600 , a shunt impedance ′ ≈ 92 MΩ/m, and a power efficiency rf−beam ≈ 28.5%.…”

Development and high-power testing of an X -band dielectric-loaded power extractor

“…In order to improve the gradient, efficiency, and cost of a TBA collider, various novel accelerating/decelerating structures have been studied: metallic two-halves structure [20,29,30], dielectric-loaded structure (DLS) [12][13][14][15]19], metameterial structure [26,31,32], photonic band gap structure [33][34][35], and many others [16,23,25,[36][37][38][39][40][41]. Among them, the DLS is a very attractive candidate for a TBA collider due of its simple geometry, low fabrication cost, high group velocity with reasonable shunt impedance, and potential to withstand GV/m gradient.…”