Influence of the breakdown mechanism to the left of the Paschen minimum on the breakdown temperature of the free electron gas Maxwell spectrum

• Dc breakdown of helium in the range to the left of the Paschen minimum is examined.
• Breakdown temperature expression of the free electron gas Maxwell spectrum is derived.
• Breakdown temperature was determined by fitting the expression to experimental results.
• Different breakdown mechanisms were applied.

Dc breakdown of helium in the range to the left of the Paschen minimum is examined. An expression relating breakdown voltage to the pd product (pressure × inter-electrode distance) and the breakdown temperature of the free electron gas Maxwell spectrum is derived. The type of breakdown mechanism is deduced by submitting the measured values of breakdown voltage in the range to the left of the minimum to a statistical analysis that treats the dc breakdown voltage as a random variable. Fitting the derived expression to experimental results allows breakdown temperatures to be determined, along with ways of applying them under different breakdown mechanisms.