Time resolved spot size measurements using a self magnetic pinch diode on EROS

Summary form only given. Sandia National Laboratories is participating in an intensive research effort into high brightness, electron beam, flash radiographic X-ray sources. One of the sources being investigated is the self magnetic pinch (SMP) diode, that consists of a hollow tapered stalk as the cathode and a bremsstrahlung converter as the anode. The bremsstrahlung converter is comprised of a thin foil backed by a high Z target. Electron beam interactions with anode/cathode plasmas can greatly influence the dynamics of the beam spot on target which is a standard performance metric. Typically, the time integrated spot size is measured via a rolled edge and a detector such as X-ray film or imaging plates. However, time-dependent size measurement offers insight to the dynamics of the beam-plasma interactions occurring on few nanosecond time scales. A time resolved spot size diagnostic has been fielded on a series of SMP experiments carried out on the AWE EROS accelerator. The SMP experiments consisted of several geometric variations from the standard SMP configuration. Of particular interest is the effect of thin foils placed in front of the high-Z targets on the temporal and integrated spot size. A summary of the measurements is presented along with preliminary interpretations and modeling of the diode dynamic behavior