MOOBB2
Stanford University, Stanford, California, USA
OHEP/DOE, Germantown, MD, USA
SLAC, Menlo Park, California, USA
UCLA, Los Angeles, USA
We report the first observation of high-gradient acceleration of electrons in a lithographically fabricated micron-scale dielectric optical accelerator driven by a mode-locked Ti:sapphire laser. We have observed acceleration gradients far exceeding those of conventional microwave accelerator structures. Additionally, we have verified the dependence of the observed acceleration gradient on: the laser pulse energy, the laser-electron temporal overlap, the polarization of the laser, and the incidence angle of the laser. In all cases, we have found good agreement between the observed results, the analytical predictions, and the particle simulations.
SLAC, Menlo Park, California, USA
Stanford University, Stanford, California, USA
Rapid progress in the development of laser technology and in the sophistication of semiconductor manufacturing has enabled the realization of the first dielectric laser-driven particle accelerator (DLA) on a chip *. Since the accelerating channel in DLA structures typically have dimensions in the 1 micron range, the ability to precisely control particle position within these structures will be critical for operation. A number of beam deflection and focusing schemes have been devised, but without the ability to measure the position of the particle beam to nanometer accuracy, these schemes will be extremely difficult to implement. We present a new concept for a beam position monitor with the unique ability to map particle beam position to a measurable wavelength. Coupled with an optical spectrograph, this beam position monitor is capable of sub-nanometer resolution. We describe one possible design of this device, and present the current status of the structure fabrication and experimental demonstration.
* E. A. Peralta, et al., "High-Gradient Acceleration of Electrons in a Laser-Driven Dielectric Micro-Accelerator." Submitted to PAC'13
SLAC, Menlo Park, California, USA
Stanford University, Stanford, California, USA
Purdue University, West Lafayette, Indiana, USA
Technion, Haifa, Israel
Particle acceleration in dielectric laser-driven micro-structures, recently demonstrated at SLAC*, holds the promise of providing low-cost compact accelerators for a wide variety of uses. Laser-driven undulators based upon this concept could attain very short (mm to sub-mm) periods with multi-Tesla field strengths. And since dielectric laser accelerators (DLAs) operate optimally with optical-scale electron bunch formats, radiation production with high repetition rate (10s of MHz) attosecond-scale pulses is a natural combination. We present preliminary analysis of the harmonic field structure for a periodic undulator based on this concept.
SLAC, Menlo Park, California, USA
Stanford University, Stanford, California, USA
Purdue University, West Lafayette, Indiana, USA
Laser driven dielectric accelerators possess advantages in their greatly reduced dimensions and costs, larger breakdown threshold, and higher accelerating gradient *. Several resonant or waveguide based structures have been proposed * ** ***. Electron acceleration with 250 MV/m gradient has been demonstrated using a silica grating structure ***. We describe a new structure of silica rod array for laser driven acceleration. The structure consists of two rows of equally spaced circular or elliptical rods, with a gap between the rows as the particle channel. Similar to the grating, the periodic arrangement of the rods along the channel provides phase reset of the EM fields and thus required phase synchronicity for acceleration. Resonances among rods enhance the near E-field in the channel to achieve high gradient. The structure has been optimized dimensionally in simulations, and exhibited quite uniform net acceleration in the gap region. One advantage of this structure is that the rods are fabricated on one single substrate, therefore positioned and aligned with lithographic level precision. Prototype samples have been fabricated **** for potential laser acceleration experiments.
* T. Plettner, R. Byer., Phys. Rev. ST-AB,11:030407,2008.
** B. Cowan, Phys. Rev. ST-AB,11:011301,2008.
*** E. Peralta et al, manuscript submitted.
**** M. Qi, private communication.