Experimental demonstration of wakefield effects in a THz planar diamond accelerating structure

Abstract

We have directly measured THz wakefields induced by a subpicosecond, intense relativistic electron bunch in a diamond loaded accelerating structure via the wakefield acceleration method. We present here the beam test results from the diamond based structure. Diamond has been chosen for its high breakdown threshold and unique thermoconductive properties. Fields produced by a leading (drive) beam were used to accelerate a trailing (witness) electron bunch which followed the drive bunch at a variable distance. The energy gain of a witness bunch as a function of its separation from the drive bunch describes the time structure of the generated wakefield.

Transverse operator method for wakefields in a rectangular dielectric loaded accelerating structure

“…Let us next examine the operatorT E (14). We consider the Hilbert space H E ¼ L 2 f½Àc; c ; j"ð1 À " 2 Þjg  L 2 ð½0; w Þ, where ¼ j"ð1 À " 2 Þj is the weight function.…”

“…Wakefields in rectangular dielectric-loaded structures have been experimentally studied [14,[38][39][40], Table I. In [38,39] a wakefield measurement using a single crystal diamond-loaded rectangular accelerating structure was reported.…”

“…A THz structure was recently tested at Brookhaven National Laboratory [14], consisting of a rectangular waveguide loaded with polycrystalline chemical vapor deposition diamond plates as an accelerating structure. In this experiment, a drive (high charge) electron beam was launched through the structure exciting a wakefield following behind it.…”

“…Since 1988 when the first proof of principle experimental results were published [4], studies of cylindrical dielectric structures have been presented in numerous publications (see [5][6][7][8][9][11][12][13][14][15][16]). …”

“…A 3 nC charge and 30 m long bunch of the 23 GeV SLAC/ FACET accelerator generates 1-10 GV=m wakefields in the THz range [6,13]. These wakefields are used for accelerating a less intense but high energy electron bunch propagating behind the drive bunch at a distance corresponding to the accelerating phase of the E z field [4,5,14]. Dielectric based structures provide, in addition to the high accelerating gradient, the possibility of controlling the frequency spectrum of the structure by introducing nonlinear dielectrics (ferroelectrics) [15,16].…”