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???