Schematic of the plasma lens experiment beam line starting with the vacuum isolation window. The positions of the three optical transition radiation screens (OTR1–OTR3) and the integrating current transformer are shown along with the beam optics elements and the layout of the plasma interaction region.
Measured plasma lens density profiles shown with Gaussian fits to the data, . Measurements were taken along the beam axis with several different positions of the density mask.
Images of the unfocused (a) and focused (b) electron beam OTR displayed with the same scaled-to-intensity color map and a constant pixel aspect ratio of 1:1. In order to provide sufficient contrast, the unfocused image (a) is the integration of five beam pulses. The projected intensity of the focused and unfocused beams (normalized to 1 pulse) in the axis (c) and axis (d) is also shown.
Measurements of underdense plasma lens focusing in the axis (a) and axis (b) of a round beam shown with solutions to the envelope equation (solid lines and shaded regions). The shaded regions indicate the shift in focal length caused by the variation in plasma lens parameters.
Comparison of focusing data with MAGIC simulation results. The width of the colored bands represents the range of values possible with the state uncertainty of the emittance measurement.
Simulation results for the average inward momentum imparted by the plasma lens to high energy test particles placed in the middle of the electron beam. A linear extrapolation from the region is also shown for comparison.
Correlation between beam charge and the focused beam spot size. Each point represents the mean of shots that fall within a 1 nC wide bin.
Correlation between beam charge and the aspect ratio of the focused beam. Each point represents the mean of shots that fall within a 1 nC wide bin.
Representative streak camera images of the unfocused (a) and plasma focused beam (b). Average time slice dependence of the beam intensity (c) and transverse FWHM (d) for unfocused and plasma focused beams over 15 shots. Note that the streak images exhibit obvious clipping in the radial direction.
Detailed quadrupole scan taken during the commissioning phase of the experiment (a). The normalized horizontal emittance found from the curve fit is . Example of the daily quadrupole scans taken during the plasma lens experiment (b). This one was taken on the same day as the focusing data reported in Sec. III. The normalized horizontal emittance calculated from this plot is .
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