Computed Tomography Density Diagnostic for Plasma Wakefield Acceleration

Plasma Wakefield Accelerators (PWFA) can produce accelerating gradients orders of magnitude greater than conventional metallic accelerators and thus are attractive for next-generation lepton colliders. The plasma source density profile determines the total energy gained in the accelerator as well as the degree of beam emittance growth throughout the acceleration process. Density diagnostics for PWFAs are a challenge due to the low density (~10¹⁶ cm^-3) and unique geometry of the plasma, with thickness of less than one millimeter and a length of roughly 20-50 cm. This requires diagnostics capable of detecting small density fluctuations and/or curvature over a relatively long region of interest. Computed tomography (CT) from direct optical imaging of the plasma glow provides a large-scale density diagnostic for reconstructing the plasma density profile over a large region of interest, limited only by the camera’s field of view. Direct imaging of the plasma filament at varying background gas densities will be analyzed using the developed CT algorithm to produce 3D profiles of intensity contours. This data will be compared with the density profile from laser ionization simulations and the reconstructed plasma profile will be used in PWFA simulations to test its performance capability.