A flexible, multi-fiber framing diagnostic for multi-GHz frame rate imaging of pulsed power plasmas

A platform for multi-GHz frame rate imaging using a single intensified gating camera that relies on staggered optical delays in high-resolution optical fibers is introduced. The diagnostic consists of a beam splitter assembly that partitions the image, varying-length high-resolution optical fibers that stagger the image in time, and a gated camera that simultaneously images the fiber outputs. The time delay of the fibers is calibrated using a laser pulser and a fast photodiode. Individual channels are rotated due to the orientation of their respective fibers and may be flipped in the beam splitter assembly, so a simple post-processing technique is used to extract the frames. An eight-channel, 4 GHz frame rate version of this diagnostic was constructed using an intensified charge-coupled device (ICCD) with 3 ns gate times and was fielded to image visible light emission from a developing high voltage vacuum flashover event. Potential improvements or variations in this diagnostic to achieve a range of imaging capabilities for pulsed power plasmas are discussed.