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Introduction to Pulsed Power Technology
Dr. David Wetz
Assistant Professor
Department of Electrical Engineering
University of Texas at Arlington
My Background
• BSCS and BSEE from Texas Tech University in 2003 • MSEE from Texas Tech University in 2004 • Ph.D. from Texas Tech University in 2006
– MS and PhD research focused on the dielectric breakdown strength of water and other pulsed power applications
• Postdoctoral Fellow and Research Associate at Institute for Advanced Technology (IAT) at the University of Texas at Austin from 2006 to 2010 – Research on general pulsed power systems,
electromagnetic launchers (railguns) for the Army, Navy, and Air Force
• Assistant Professor at UTA from 2010 - Present
What is Pulsed Power?
• Pulsed power is a scheme where energy is stored slowly and discharged rapidly as electrical energy into a load in a single short pulse or as short pulses with a controllable repetition rate
Up to 10’s of kV, 10’s of A, and 100’s of W
millisecond to seconds
Up to a 10’s of MV, 10’s of
MA, and 100’s of GW
picoseconds to milliseconds
Pulsed Power Systems
• Prime Power Source: Usually a DC voltage or current source (10’s of kV, 100’s of A, 10’s of kJ)
• Energy Storage: Capacitors, Inductors, Batteries, Rotating Machines, etc.
• Switching: Gas or liquid breakdown switches, explosive switches, fuses, solid state switches, etc.
• Pulse Shaping: Using transmission lines to set the rise time and pulse duration of the pulse
• Loads: Coming next
Pulsed Power Loads
Military
• Radar
• EMP Simulation and Testing
• Nuclear Fusion
• Nuclear Radiation Effects
• Electromagnetic Accelerators
• High Power Microwaves
• Compact and Explosive Flux Compression Generator Systems
Civilian • Radar • Magnetic Forming of Metals • Materials and Surface Treatment • Environment • Liquid Shock Wave Application • Medical
Pulsed Power History
Until about 1970, most pulsed power research was conducted in National Laboratories and a few industrial companies. Most results were only published in internal reports, many of which were classified (Secret). Serious University pulsed power research was started at Texas Tech University in the early 1970’s and in 1976 the first International Pulsed Power Conference was organized and hosted by TTU. This conference and its proceedings are now the main forum for information exchange in this field. This bi-annual conference now has over 600 participants from all over the world. Also the IEEE Transactions on Plasma Science became an official pulsed power journal (in addition to plasma research) The last conference was held in Chicago, Illinois on June 19-23
http://ppc.missouri.edu/ The next conference will be held in San Francisco in June 2013.
Pulse Characteristics
Capacitive Energy Store
• Store energy electrostatically in the capacitor
• Release the energy by closing the circuit
• 𝐼 = 𝐶𝑑𝑉
𝑑𝑡
Inductive Energy Store
• Store energy in the inductor by flowing current through it
• Release the energy by opening the circuit
• 𝑉 = 𝐿𝑑𝐼
𝑑𝑡
Marx Generator
• Charge capacitors in parallel, and discharge them in series to achieve voltage multiplication
• http://www.youtube.com/watch?v=AIcgdjwzgCw
• http://www.youtube.com/watch?v=IrQsghadA8A
http://image.absoluteastronomy.com/images/encyclopediaimages/m/ma/marx_generator.png, AbsoluteAstronomy.com © 2009.
High Voltage Switch Demo
• Variac – Transformer where we vary the number of secondary turns to increase the output voltage
• 120 VAC – 60 Hz is put in. By adjusting the turns, we can increase the output to as high as 15000 V. A diode rectifier converts it to DC on the output
• Spark Gap switch is used to switch high voltage from the source to the load
http://en.wikipedia.org/wiki/File:Tapped_autotransformer.svg
MRI Magnetic Resonance Imaging
• The magnets in use today in MRI systems create a magnetic field of 0.5-tesla to 2.0-tesla
• High currents passed through a superconducting magnet
Electromagnetic Launchers (Railguns)
• Interaction of high current and magnetic field results in forward propulsion
http://science.howstuffworks.com/rail-gun1.htm
http://www.youtube.com/watch?v=4OqlTXwLG40
http://www.youtube.com/watch?v=-uV1SbEuzFU
Coilguns
High Power Microwave Source
• Vircators can be used to generate high power microwaves for electronic destruction
http://www.apelc.com/index.html
http://en.wikipedia.org/wiki/Vircator
http://videos.howstuffworks.com/discovery/7102-electromagnetic-pulse-bomb-video.htm
http://www.p3e.ttu.edu/Documents/P3ECenterBrochure2011.pdf
High Power Microwave Breakdown
When high power microwave signals are transmitted out of a vacuum environment and into the atmosphere, the particles become charged and a high voltage arc is formed
http://www.p3e.ttu.edu/Documents/P3ECenterBrochure2011.pdf
Measurement Devices
High Speed Thermal Imaging Camera
High Speed Imaging Camera
High Speed Digital Oscilloscope
High Voltage Probe High Current Probe
Car Stopping
Vehicle Stopping
Active Denial
• High power microwave source used for crowd control
• 95 GHz extremely high frequency waves at a target, which corresponds to a wavelength of 3.2 mm
http://en.wikipedia.org/wiki/Active_Denial_System
http://www.youtube.com/watch?v=_gfBkXFbODQ
http://www.youtube.com/watch?v=bnzcnTM_NYk
Food Sterilization
Z-Pinch Physics
Stun Guns
http://upload.wikimedia.org/wikipedia/commons/f/fb/Taser-x26.jpg
http://electronics.howstuffworks.com/gadgets/other-gadgets/stun-gun3.htm
Sandia Z-Pinch Energy per shot sufficient to power a residential home for 4 hours ~290 TW for ~70 ns (10’s of MA and 100’s of kV)
http://www.sandia.gov/z-machine/?page_id=284
Sandia Z-Pinch
http://www.sandia.gov/z-machine/?page_id=284
EM Armor
Magneforming
http://en.wikipedia.org/wiki/Electromagnetic_forming
Camera Flash
http://electronics.howstuffworks.com/camera-flash3.htm
X-Ray Source
http://health.howstuffworks.com/medicine/tests-treatment/x-ray2.htm
Research at UTA
• Research effort focused on the use of electrochemical energy sources (batteries, supercapacitors, etc.) as prime power sources for pulsed power systems
• Research effort focused on the development of a MicroGrid testbed for the US Department of Energy
Experimental Discharge Test Stand
Springs that pull the upper plate to open the circuit after an experiment
Current viewing resistor
Cell under test
2 µH variable inductor
Sixty Semikron MOSFET switches (There are six assemblies with 10 switches each) giving 145 µΩ of resistance when all in conduction
Stainless steel chamber in which the cell is enclosed for safety
Electrically activated solenoids that allow the upper plate to spring upwards
Table top
Series and parallel connection of 100 mΩ high energy resistors in series with the output to control the C rate
Thank you!!!
???QUESTIONS???