A possible pole problem in the formula for klystron gap fields

It is noted that a pole may be encountered, in rare cases, in a previously published solution for the fields in a klystron gap. Formulas are given which allow the critical combinations of parameters to be identified. It is found that the region of inaccuracy surrounding the pole is so small that a 1-percent change in the field shaping parameter is sufficient to avoid it, with negligible error resulting.