Faraday cup analysis of ion beams produced by a dense plasma focus

The design and performance of a Faraday cup which is used in a time-of-flight technique to measure the energy spectrum of ions accelerated away from the anode of a plasma focus are described. The cup is located in a differentially pumped (<20 μ) chamber which is separated from the main plasma focus chamber by a 0.0457-cm diam hole positioned 16 cm above the anode. This arrangement allows a bias voltage of −400 V to be applied to the cup to stop comoving electrons and permits the observation of deuteron energies down to ∼25 keV.