High-Speed, High-Resolution Diagnostic System for a Plasma Wakefield Accelerator

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

This project is aimed towards development of a new diagnostic that will measure the physical processes underlying an advanced particle accelerator concept, a so-called plasma wakefield accelerator (PWFA). PWFA research has the ultimate goal of reducing the footprint, energy consumption, and cost of future particle accelerators by several orders of magnitude for applications ranging from X-ray free electron lasers to high-energy particle colliders. Currently, no suitable diagnostics for the accelerator plasma source have been developed, and the problem approaches a research bottleneck for the field. The characterization of the plasma source must be non-intrusive and accurate to the few-percent level in order to avoid spoiling the quality of the accelerated electron beam. This necessitates the deployment of diagnostics capable of probing a macroscopic and transient plasma source with percent-level resolution, or better, which lies outside of the application of conventional plasma diagnostic systems. This project will lay the groundwork for the development of an advanced, integrated system of diagnostic techniques intended to non-intrusively resolve the plasma source density profile (typical density range: 10^15 to 10^18 per cm^3) at the percent level in a single shot, with a spatial resolution of ~mm and a temporal resolution of ~ps. The individual diagnostic sub-systems will be based upon known and proven techniques that are run in tandem with one another to significantly reduce the systematic errors of the full system. The three primary diagnostic sub-systems rely on the principles of Stark broadening, Thomson scattering, and optical emission ("plasma glow"), respectively. The goals of the project are 1) to build detailed models and simulations of the expected signals for each of the diagnostic systems, 2) to test and optimize each system individually using a small, well characterized test plasma source, 3) to integrate all systems and perform simultaneous measurements of the test plasma source, and 4) to develop the analysis framework that combines the data collected by all of the diagnostic systems and minimizes the systematic errors in the recovered plasma density profile. The success of this project will point the way forward for an intended future project that incorporates an imaging spectrometer to provide a single-shot, spatially resolved plasma filament density profile. This will be combined with the use of an ultra-short laser probe pulse, and a fast-gated CCD camera to provide the best possible temporal resolution and signal-to-noise ratio. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.