Optimization of self-magnetically insulated “Plasma Focus Diode” on KALIF

Self-magnetically insulated “Plasma Focus Diode” (PFD) successfully developed at Nagaoka has been installed on KALIF, where efforts were carried out to clarify basic characteristics as well as to optimize the ion beam extracted. Various combination of anode and cathode has been studied to obtain best matching of PFD with KALIF. Characteristics of PFD have been found strongly dependent on the factor of g expressed by g = (ln(r
₁
/r
₂
))
^-1
, where r
₁
and r
₂
is the radious of anode and cathode, respectively. The impedance increases with increasing 1/g. At 1/g <; 0.3, it decreases rapidly. The power delivered to PFD achieves the maximum at 1/g ~ 0.3. At 1/g >; 0.3, good focusing takes place where both divergence angle and focusing radius are small, whereas focusing becomes worse at 1/g <; 0.3. From the above studies, we have found the best performance of PFD with KALIF is obtained at 1/g = 0.3 ~ 0.35.