A multi-channel, optically coupled spark gap monitor system
A spark gap monitor system has been installed on FRX-C Large Source Modification, a theta pinch experiment which forms field-reversed configuration (FRC) compact toroids. The field reversing theta pinch produces a vacuum magnetic field of 10kG inside the single turn, 2-m-long straight 0.7-id coil by discharging in series two 50kV, 200..mu..F capacitor banks with a total of 140 2.8..mu..F capacitors each with a start spark-gap switch and a ''piggy-back'' crowbar spark-gap switch. Efficient operation of the bank requires information on the timing and function of each capacitor-spark gap unit. Diagnosing the capacitor-spark-gap unit load cable current (approximately 3kA per cable) is complicated by the fact that the ground return for the capacitor is of a relatively high impedance. Units that are allowed to prefire or postfire not only degrade the performance of the bank but will self destruct or destroy their neighbors. To provide this information without introducing high voltage transients into the data acquisition and control system as optically coupled, 140 channel gap monitor system has been installed. Simplicity and reliability were key requirements in the design of the system. A resistor made of thin wall stainless steel tubing replaces a short section of the braid on one load cable on each capacitor. The voltage developed across the resistor provides the current source to drive an LED. The relatively linear output from the LED is transmitted through approximately 30m of fiber optic cable to the FRX-C control room. The signal is received by a photo diode and simple amplifier circuit that feeds the signal into a 12 channel charge integrating ADC CAMAC module for processing by the computer. The information provided by this system informs the operator as to when and how each gap fired. 2 refs., 8 figs.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6012182
- Report Number(s):
- LA-UR-87-3323; CONF-871007-15; ON: DE88001851
- Resource Relation:
- Conference: 12. symposium on fusion engineering, Monterey, CA, USA, 12 Oct 1987; Other Information: Paper copy only, copy does not permit microfiche production
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SPARK GAPS
MONITORS
CAMAC SYSTEM
CAPACITORS
FIBER OPTICS
MULTI-CHANNEL ANALYZERS
REVERSE-FIELD PINCH
WAVE FORMS
ELECTRICAL EQUIPMENT
ELECTRONIC EQUIPMENT
EQUIPMENT
MEASURING INSTRUMENTS
PINCH EFFECT
PULSE ANALYZERS
700209* - Fusion Power Plant Technology- Component Development & Materials Testing