It operates by focusing a laser pulse in the air to create a high energy plasma ball (up to several kilometers away) at a target.

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According to Andy Mazzara, the director of the Institute for Non-Lethal Defence Technologies at Pennsylvania State University, prototypes of such devices use a laser to create an ionised channel of air through which an electromagnetic pulse is directed.

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It also found he failed to provide the patient with oxygen, and that he falsely informed the air support paramedics that he was unable to obtain a radial pulse when he never attempted to do so.

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