Folded Blumlein Pulser Attractive

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Folded Blumlein Transmission Lines (per Sandia
National Laboratories)
Folded Blumlein Pulser Attractive Can achieve
long (50 ns) pulse length in compact volume.
Blumlein configuration delivers charge voltage to
a matched load. Requires improved understanding
of electric field distributions, effects of
anistropies introduced in folds, liquid
breakdown, among other issues.
?
For HPM sources, impedances of interest range
from the order of Z 10 100 ?. Sandia effort
sponsored by AFRL/DEH
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What are the challenges?
Dielectric Breakdown at the Edges of the Line
Results of HFSS (Agilent/Ansoft) calculation at
UNM
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What are the challenges?
Dielectric Breakdown at the Edges of the Line
Animation of Electric Field in a Blumlein
Transmission Line Configuration
Results of HFSS (Agilent/Ansoft) calculation at
UNM
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What are the challenges?
Percolation of Propylene Carbonate Impregnant
Photograph of prebreakdown phenomenon in tap
water between a tip and plate. The gap is 100 µm,
the applied voltage 2 kV. Exposure time is 10 ns.
The first photograph shows the gap at 27 µs after
pulse application. Microbubbles are formed at the
tip and 10 µs later (lower photograph) plasma
formation is observed at the location of the air
microbubbles, and shockwaves are emitted from the
plasma centers. (Courtesy Karl Schoenbach, Old
Dominion University.) This diagnostic set-up will
be used to test propylene carbonate samples
provided by Sandia and by an independent
laboratory. (For a movie of Schlieren photography
of a water discharge, please see
http//www.eece.unm.edu/cp3/research.htm) Also,
see J. Qian, R.P. Joshi, K.H. Schoenbach, M.
Laroussi, E. Schamiloglu, and C. Christodoulou,
Percolative Model of Electric Breakdown in
Liquid Dielectrics, to appear in IEEE Trans.
Plasma Sci. Special Issue on Pulsed Power Science
and Technology, Oct. 02.
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A More Desirable, Longer Term Approach Would
Require High Energy-Store Dielectrics
?

Increasing dielectric constant leads to more
compact system with increased energy storage (no
folding necessary)
Challenge To identify such a material that has a
high breakdown strength and can survive many 104
discharges.
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Candidate CeramicsGlass Composites
Composition Tm Density r K BDS (C) (g/cc) (?
cm) (V/mil) SiO2-B2O3 1200 2.06 1016 4
1900 SiO2-B2O3 1000 2.72 1015 8.5
2060 CaO SiO2-B2O3 1100 2.18 1014 4 gt1900 C
aO, Al2O3 From W. Huebner, S.C. Zhang, B.
Gilmore, M.L. Krogh, B.C. Schultz, R.C. Pate, L.
F. Rinehart, and J. M. Lundstrom, High Breakdown
Strength, Multilayer Ceramics for Compact Pulsed
Power Applications, Proceedings 12th IEEE
International Pulsed Power Conference, pp.
1242-1245 (1999).  
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Candidate CeramicsTiO2
from W. Huebner, S.C. Zhang, B. Gilmore, M.L.
Krogh, B.C. Schultz, R.C. Pate, L. F. Rinehart,
and J. M. Lundstrom, High Breakdown Strength,
Multilayer Ceramics for Compact Pulsed Power
Applications, Proceedings 12th IEEE
International Pulsed Power Conference, pp.
1242-1245 (1999).  
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Approach

• use electromagnetic modeling tools to design
  resistively graded structure for use in Blumlein
• iterate with ceramists to develop sample matrices
• use pulsed high voltage tester to assess
  breakdown strength (available at Sandia, Jeff
  Alexander)
• iterate with ceramists

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Candidate Graded Dielectric
Analyze resistively graded structure proposed by
Missouri-Rolla in Blumlein configuration (B.L.
Gilmore, Ph.D. dissertation, U. Missouri-Rolla,
2002).
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IGBT Switching

• Marvin Roybal, UNM EECE undergraduate student,
  part of LANL team nominated for 2002 RD 100
  Award (Polyphase Converter-Modulator A Compact
  High-Voltage, High-Power System)
• Work performed as part of undergraduate
  independent study directed by Prof. Schamiloglu
• Marvins contribution was the design and
  construction of a fault detection chassis that
  will turn off the IGBT if an over-current fault,
  shoot-thru fault, and/or unconnected pick-up loop
  is present.

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IGBT Switching
Marvin will be a full time undergraduate on
campus at UNM beginning Fall 2002 and will be
supported by the MURI program as an undergraduate
RA.