Scientific Instrumentation

 

An X-band, Traveling Wave, Deflection Mode Cavity for Ultra-Fast Beam Manipulation and Diagnosis

Cutting-edge applications in high energy electron beam-based physics, such as linear colliders, X-ray free-electron lasers, Inverse Compton scattering sources and plasma wakefield accelerators, require sub-picosecond pulses.  These beams must be precisely diagnosed in order to be used for such advanced applications.


RadiaBeam is developing a traveling-wave, X-band deflecting cavity for complete longitudinal phase space characterization of ultra-short electron bunches.  This diagnostic will be sensitive, robust, and absolute.  This proposed solution surpasses the state-of-the-art in deflecting cavities by taking advantage of the greater efficiency and compactness of X-band RF structures in concert with modern high-power X-band sources; in addition, the design approach allows application of this technique to the very high energies beams used in next generation light sources and linear colliders.


Presently, a full-power prototype of the X-band traveling wave deflector is in fabrication.  The device will be installed at the Accelerator Test Facility at Brookhaven National Laboratory and beam-tested to measure its performance.

 

Single Shot Bunch Length Monitoring, Based on Interferometer and Terahertz Sensing

With the recent development of advanced photoinjector accelerators and next generation light sources, the progression towards high-current, ultra-short beams is very important. The measurement of these short pulses, with sub-picosecond time resolution is essential for successful beam operation; the knowledge of the longitudinal profile and bunch length is necessary for performance optimization and benchmarking to computational models. This diagnostic will address an issue still remaining unresolved in ultra-short beams: measurement of the bunch in a single-shot, real time basis.

 

To address this problem, RadiaBeam developed a real time bunch length interferometer utilizing a novel beam autocorrelation technique. In the proposed scheme, the interference of the beam and itself takes place on the plane of a terahertz detector array; the spatial interference is correlated to the horizontal position along the array. The device has been successfully bench-tested in the laboratory, and is awaiting testing at Brookhaven National Lab with the ultra-short Accelerator Test Facility electron beam.

 

A High Resolution Transverse Diagnostic Based on Fiber Optics

Next generation light sources and advanced accelerator facilities create ultrashort electron bunches with complex transverse distributions. They demand high-resolution beam profile information that is currently limited to approximately 50 microns. Structures on the microscale are not resolvable, thus limiting the efficacy of diagnostics.

 

RadiaBeam is developing a novel transverse diagnostic based on fiber optics to address the demands of advanced accelerator facilities. An array of fibers is drawn to intercept the beam and generate Cernekov radiation. The radiation is collected on a linear array detector and post-processed to yield transverse profile information with a resolution on the order of 10 microns.