Subpicosecond Bunch Train Production for a Tunable mJ Level THz Source

Abstract

A strong energy modulation in an electron bunch passing through a dielectric-lined waveguide was recently demonstrated in Antipov et al., Phys. Rev. Lett. 108, 144801 (2012). In this Letter, we demonstrate a successful conversion of this energy modulation into a beam density modulation, and the formation of a series of microbunches with a subpicosecond periodicity by means of magnetic optics (chicane). A strong coherent transition radiation signal produced by the microbunches is obtained and the tunability of its carrier frequency in the 0.68-0.9 THz range by regulating the energy chirp in the incoming electron bunch is demonstrated using infrared interferometry. A tabletop, compact, tunable, and narrowband source of intense THz radiation based on this technology is proposed.

Non-destructive measurement and monitoring of separation of charged particle micro-bunches

“…[18][19][20][21][22][23][24] In both examples and in other applications driven by such beams, the development of a non-invasive, a single-shot system capable of monitoring the distance between micro-bunches is important, and in many cases, non-destructive, single-shot evaluation of the bunch-to-bunch distance is still an unresolved challenge. At present, the most popular techniques used to study micro-bunch separations are via measurements of autocorrelation functions 2,18,19 and use of a transverse deflection cavity. The first requires multi-shot measurements while the latter is a single-shot but the destructive method.…”

“…"Pre-bunched" or "micro-bunched" charged particle beams have attracted significant interest during the last decade. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Potential applications of such beams include the development of the next generation of light sources 1-5 and particle accelerators. [6][7][8][9][10][11][12] These research activities are driven by the continuous interest and demand for both high-power source of terahertz (THz) radiation [15][16][17][18] and compact particle accelerators.…”

Terahertz radiation source based on self-wake beam bunching

“…This method is simple, but yields wide band THz radiation. This method in fact is used in CTR (coherent transition radiation) interferometry to determine the bunch spacing in the train [12,14,17]. Alternatively one can use an undulator, creating a THz free electron laser (FEL).…”

“…The length of the THz extraction structure controls the resulting bandwidth (less than 1% is attainable). We will present a detailed study of the CCR approach in a systematic design to be published in an upcoming paper [14]. This approach allows a THz source with high peak power (tens of megawatts), narrow bandwidth, and sub-mJ energy per beam pulse with a tuning range approaching 100%.…”

“…We propose to use the beam's self-wake action along with compression in a chicane to introduce THz content into the beam. This approach is based on our recent successful experiments at the ATF facility of Brookhaven National Laboratory [13,14]. FIGURE 2.…”