1B34 — Series Spark Gap

The 1B34 is a gas-filled, two-electrode series spark gap designed for high-power switching and protective applications. Utilizing an ionizable gaseous medium, the device is engineered to handle high peak currents and peak power levels under low duty cycle conditions across a specified operating frequency range.

Construction and Physical Dimensions

The 1B34 features an asymmetrical physical construction with distinct top and bottom terminals. The mechanical specifications of the device are as follows:

• Cathode Terminal (Top): Located at the top of the device, with a diameter of 0.890 inches (+0.025" / -0.015") and a length ranging from 5/8 inches minimum to 11/16 inches maximum.
• Anode Terminal (Bottom): Located at the bottom of the device, with a diameter of 0.566 inches (±0.007") and a length ranging from 17/32 inches minimum to 19/32 inches maximum.
• Body Dimensions: The maximum body diameter is 1-3/8 inches, and the overall length ranges from a minimum of 4-11/16 inches to a maximum of 4-15/16 inches.

To ensure proper operation and thermal stability, the mounting position is restricted. The 1B34 must be mounted with the cathode end up and oriented within 60° of the vertical axis.

Electrical Characteristics

The electrical behavior of the 1B34 is defined by its breakdown thresholds, post-breakdown conduction characteristics, and internal capacitance:

• Frequency Range: The device is rated for operation from 120 to 2000 Cycles/Second.
• Instantaneous Breakdown Voltage: To initiate conduction, the initial peak breakdown voltage is 6.5 Kilovolts. Once recurrent operation is established, the recurrent peak breakdown voltage is 6.0 Kilovolts.
• Voltage Drop: Following the initiation of the spark, the voltage across the gap drops rapidly. The voltage drop is 80 Volts, measured 0.5 microseconds after breakdown.
• Interelectrode Capacitance: The capacitance between the two electrodes is 6 micro-microfarads (6 pF).

Maximum Ratings

The 1B34 is designed for pulsed service, as reflected in its maximum ratings and duty cycle limitations. Operating outside these limits may cause permanent damage or failure of the ionizable medium.

The relationship between the peak and average ratings is strictly governed by the duty cycle. For example, a calculation of average power based on peak power and duty cycle yields:

$\text{Average Power} = \text{Peak Power} \times \text{Duty Cycle} = 25,000\text{ W} \times 0.001 = 25\text{ W}$

Similarly, a calculation of average current from peak current yields:

$\text{Average Current} = \text{Peak Current} \times \text{Duty Cycle} = 120\text{ A} \times 0.001 = 0.12\text{ A} = 120\text{ mA}$

These calculations demonstrate that the average ratings represent the absolute continuous limits under the maximum rated duty cycle of 0.001.

Technical Summary

The 1B34 is a series spark gap featuring a two-electrode, gas-filled construction. It is engineered for high-voltage, high-peak-power switching applications within a frequency range of 120 to 2000 Cycles/Second. With an initial peak breakdown voltage of 6.5 Kilovolts and a post-breakdown voltage drop of 80 Volts (at 0.5 microseconds), it provides rapid transition to a conducting state. The device supports peak currents up to 120 Amperes and peak power up to 25 Kilowatts, constrained by a strict 0.001 duty cycle that limits average power dissipation to 25 Watts and average current to 120 Milliamperes. It must be operated within an ambient temperature range of -50 to +100°C and mounted within 60° of vertical with the cathode end up.