Fermilab, Batavia, Illinois, USA
The University of Texas at Austin, Austin, Texas, USA
HZDR, Dresden, Germany
Private Address, Silver Spring, USA
A significant advance in laser-driven plasma accelerator (LPA) electron-beam diagnostics has recently been demonstrated based on coherent optical transition radiation (COTR) imaging*. We find COTR signal strengths from a microbunched subset of beam exiting the LPA to be several orders of magnitude higher than that of incoherent optical transition radiation (OTR). The transverse sizes are only a few microns as deduced from the point-spread-function-related lobe structure. In addition, the far-field COTR interferometric images obtained on the same shot provide beam-size limits plus divergence and pointing information at the sub-mrad level when compared to an analytical model** with a recent revision. The integrated image intensities can be used to estimate the microbunching fraction and relatable to the LPA process. Initial results in a collaborative experiment at the Helmholtz-Zentrum Dresden-Rossendorf LPA will be reported for electron beam energies of about 215 MeV.
* A.H. Lumpkin, M. LaBerge, D.W. Rule et al., "Interferometric Optical Signature.", subm. to Phys. Rev.Lett.(2019).
** D.W. Rule, A.H. Lumpkin, Proc. of PAC2001, Vol. 2, pp. 1288-1290 (IEEE 2001).
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