Design Formulas for Nonreactive High-Voltage Pulse Resistors

To terminate pulse equipment supplying peak voltages up to a million volts for microsecond durations requires nonreactive loads to maintain the pulse characteristics. The resistive elements must not only dissipate the pulse energy but must also maintain a low reactance for the high frequencies in the pulse waveform. The return circuit, treated as a short-circuited transmission line, forms the basis for designing nonreactive resistors with both cylindrical and fiat conductors. The distribution of voltage, current, and power is shown for the ideal design. Formulas are derived for the Chaperon double winding, the "hairpin" or loop geometry, and the coaxial form. Resistance values range from less than an ohm to several hundred thousand ohms for pulse voltages up to 1.2 million volts. Time constants vary from 10
^-6
to 10
^-10
seconds. A frequency expression is derived to aid in predicting the resistor's frequency response. Construction and measuring techniques are included. Frequency effects are analyzed to compensate for the skin effect on the resistance and inductance, and to select low-loss dielectric materials.