“…In this Letter, we present the first experimental evidence for such magnetic collimation inside laser-compressed matter. Our major finding, supported by numerical simulations, is that the efficiency of this mechanism critically depends on the transient resistivity profile experienced by the REB during the compression.The experiment, detailed in Ref.[8], was conceived within the HiPER project experimental road map [9], and carried out on the VULCAN TAW laser facility of the Rutherford Appleton Laboratory. As illustrated in Fig.…”