Diagnostic Methods for Plasma and Charged Particle Beams at Karsruhe Institute of Technology

Several original methods for measuring the parameters of plasma and charged particle beams. These methods cover a wide range of non-perturbing diagnostics, specially developed for pulsed systems with poor temporal and spatial pulse to pulse reproducibility. Research items are dense plasma in streamer channels in liquid dielectrics, electron and ion diodes [1], [3] for generating high-power charged particle beams with power densities ranging from
$\text{MW}/\text{cm}^{2}$
to some
$\text{TW}/\text{cm}^2$
and dense surface plasmas on metals formed under irradiation with such charged particle beams. Measurement methods applied are based on spectroscopy of the own emission of plasma, laser induced spectroscopy and X-ray diagnostics of electron beams. Range of measured parameters covers both, low-temperature rarefied emission plasma,
$< 10^{12}\text{cm}^{-3}$
, in plasma-cathodes of electron accelerators and dense plasma,
$> 10^{18}\text{cm}^{-3}$
, in streamer channels [2], as well as measurement of megavolt electric fields in accelerating gaps of ion diodes and weak fields,
$< 1\text{kV}/\text{cm}$
, in the plasma of electron emission sources. In addition to an overview, emphasis will be given to recently developed diagnostic based on LIF-Dip spectroscopy of Rydberg transitions for measuring weak electric fields at the boundary of a rarefied low-temperature plasma [3]. The method allows to determine the full spectrum of the Stark shift in one measurement step, only, along with high temporal (5 ns) and spatial
$(< 50\mu \mathrm{m})$
resolution.