Coiled transmission line pulse generators
Methods and apparatus are provided for fabricating and constructing solid dielectric “Coiled Transmission Line” pulse generators in radial or axial coiled geometries. The pour and cure fabrication process enables a wide variety of geometries and form factors. The volume between the conductors is filled with liquid blends of monomers, polymers, oligomers, and/or cross-linkers and dielectric powders; and then cured to form high field strength and high dielectric constant solid dielectric transmission lines that intrinsically produce ideal rectangular high voltage pulses when charged and switched into matched impedance loads. Voltage levels may be increased by Marx and/or Blumlein principles incorporating spark gap or, preferentially, solid state switches (such as optically triggered thyristors) which produce reliable, high repetition rate operation. Moreover, these Marxed pulse generators can be DC charged and do not require additional pulse forming circuitry, pulse forming lines, transformers, or an a high voltage spark gap output switch. The apparatus accommodates a wide range of voltages, impedances, pulse durations, pulse repetition rates, and duty cycles. The resulting mobile or flight platform friendly cylindrical geometric configuration is much more compact, light-weight, and robust than conventional linear geometries, or pulse generators constructed from conventional components. Installing additional circuitry may accommodate optional pulse shape improvements. The Coiled Transmission Lines can also be connected in parallel to decrease the impedance, or in series to increase the pulse length.
1. A high voltage pulse generator comprised of:
a plurality of discrete energy storage and discharge pulse shaping transmission lines comprised of;
a plurality of electrical conductors that are charged positive, and/or negative, and/or neutral; and
a solid, or flexible plastic, high dielectric constant media separating the electrical conductors;
a high voltage charging source comprised of a plurality of power supplies and charge/isolation elements;
a plurality of switches to discharge the plurality of charged transmission lines into the load;
a plurality of fault protection elements;
a plurality of voltage and current diagnostic elements;
a vessel to contain the pulse generator; and
mechanical apparatus to support the pulse generator.
2. The pulse generator of claim 1 , wherein the transmission line dielectric media is comprised of high dielectric constant powder and liquid monomer, polymer, oligomer, and/or cross-linker blends that fill all or part of the volume between the electrical conductors and are cured in one or more layers to form a solid, or flexible plastic media with a relative dielectric constant greater than ten.
3. The pulse generator of claim 2 , wherein the cure rate of the high dielectric constant transmission line media is thermally controlled.
4. The pulse generator of claim 1 , wherein the transmission line electrical conductors are constructed in various shapes and geometries, including, but not limited to: thin, wide strips configured as continuous parallel or tri-plate conductors.
5. The pulse generator of claim 1 , wherein the transmission line electrical conductors are constructed in various shapes and geometries, including, but not limited to: circular cross-section inner conductor and a plurality of planer outer conductors, including two parallel plates or a rectangular cross-section.
6. The pulse generator of claim 1 , wherein the transmission line electrical conductors are constructed in various shapes and geometries, including, but not limited to: a co-axial configuration with both inner and outer conductors of circular cross-section.
7. The pulse generator of claim 1 , wherein the transmission line co-axial geometric configuration is linear.
8. The pulse generator of claim 1 , wherein the transmission line geometric configuration is a radial coil or “spiral”.
9. The pulse generator of claim 1 , wherein the transmission line geometric configuration is designed to be an axial coil such as the spool of a cable wench, or other coiled geometries such as a helix.
10. The pulse generator of claim 1 , wherein the plurality of transmission lines are connected in Marx, Blumlein, or Marxed-Blumlein circuit configurations to increase the output voltage without increasing the charge voltage.
11. The pulse generator of claim 10 , wherein the plurality of transmission lines are connected in a Marx or Blumlein configuration by means of a plurality of spark gap switches.
12. The pulse generator of claim 10 , wherein the plurality of transmission lines are connected in a Marx or Blumlein configuration by means of a plurality of electrically triggered solid-state switches.
13. The pulse generator of claim 10 wherein the individual transmission lines are connected in a Marx or Blumlein configuration by means of a plurality of optically controlled or optically triggered solid state switches.
14. The pulse generator of claim 10 , wherein the plurality of transmission lines are mounted inside a conducting vessel filled with an insulating media such as a gas, oil, or solid potting material; and the high voltage pulse is extracted from the vessel by means of a high voltage bushing.
15. The pulse generator of claim 1 , wherein the transmission line inner and/or outer conductors, and/or solid dielectric media are modified to reduce and grade the electric fields near the regions where the inner conductors exit from, and extend beyond the outer conductors to minimize the probability of electrical breakdown or flashover.
16. The pulse generator of claim 1 , wherein the transmission line inner electrical conductor is constructed of a tubular braid surrounding a circular elastic core, thus allowing the conductor to move with the dielectric media during the dielectric cure cycle to alleviate thermal and shrinkage induced mechanical stresses.
17. The pulse generator of claim 1 , wherein either mold release or a non-stick mold material is used to allow the dielectric media to move within the mold during the cure cycle, thus alleviating thermal and shrinkage induced mechanical stresses.
18. The pulse generator of claim 1 , wherein the outer surface of the transmission line solid dielectric media is coated with an electrical conductive media such as electroplate, flame-spray, or conductive paste after removal of the mold.
19. The pulse generator of claim 1 , wherein an electrical conductor is installed in contact with the outer surface of the electrically coated solid dielectric media to form the outer conductor of the transmission line pulse generator.
20. The device of claim 10 , wherein said charging is accomplished through a plurality of charge/isolation elements comprised of:
Coupled pairs of inductors in the positive and negative charge/isolation legs that are configured to cancel the magnetic fields during the charge cycle to minimize the inductance in series with the power supply, and to add the magnetic fields during the discharge cycle to minimize Marx circuit losses; anel
a plurality of diodes in the positive charge/isolation leg and sets of either electrically or optically triggered switches or inductors in the negative charge/isolation leg.