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A Wave Chaos Approach to Understanding and Mitigating Directed Energy Effects

A Wave Chaos Approach to Understanding and Mitigating Directed Energy Effects. Steven Anlage, Thomas Antonsen, Edward Ott. The Maryland Wave Chaos Group. Graduate Students Ming-Jer Lee Harita Tenneti Trystan Koch Undergraduate Student Christopher Bennett Post-Doc Dr. Gabriele Gradoni

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A Wave Chaos Approach to Understanding and Mitigating Directed Energy Effects

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  1. A Wave Chaos Approach to Understanding and Mitigating Directed Energy Effects Steven Anlage, Thomas Antonsen, Edward Ott

  2. The Maryland Wave Chaos Group Graduate Students Ming-Jer Lee Harita Tenneti Trystan Koch Undergraduate Student Christopher Bennett Post-Doc Dr. Gabriele Gradoni 2010 URSI Young Scientist Award Jen-Hao Yeh James Hart Now at Lincoln Labs Biniyam Taddese Tom Antonsen Steve Anlage Ed Ott NRL Collaborators: Tim Andreadis, Lou Pecora, Hai Tran, Sun Hong, Zach Drikas, Jesus Gil Gil Funding: AFOSR MURI 2001; AFOSR; ONR MURI 2007; ONR AppEl

  3. A Wave Chaos approach to understanding / quantifying DE Effects in electronics The model works for ‘ray-chaotic’ enclosures Two incident rays with slightly different initial directions have rapidly diverging trajectories Embrace CHAOS as the central organizing principle! Many electronic enclosures display ray chaos Computer enclosures Aircraft cockpits Ship compartments Offices etc.

  4. The Random Coupling Model A quantitative model of statistical and systematic aspects of HPM effects in enclosures Statistical aspects: The underlying classical chaos means that the wave properties are ‘universal’ and governed by Random Matrix Theory (RMT) ► The statistics of all wave properties (resonant freqs., standing wave patterns, Z, Y, S, etc.) are UNIVERSAL and governed by a single loss parameter: The non-universal aspects are captured by the radiation impedance Zrad of the coupling ‘ports’ Zrad of the ports can be determined by a number of techniques, both experimental and theoretical RCM Web Site: http://www.cnam.umd.edu/anlage/RCM/index.htm

  5. Effect of Direct Ray Paths Original Random Coupling Model (RCM) - RF energy is randomized on entering cavity - Only radiation impedance of ports, cavity volume and average Q are important In some geometries, or in narrow frequency bands specifics of internal geometry are important Modified Random Coupling Model - J. Hart et al., PHYSICAL REVIEW E 80, 041109 (2009) - Allows for systematic improvement by inclusion of geometric details if known - Can be used in conjunction with measured data Systematic aspects of HPM Effects Inclusion of ‘Short Orbits’ in the RCM

  6. Extensions of The Random Coupling Model Systematic aspects of HPM Effects Inclusion of ‘Short Orbits’ in the RCM Theory work funded by AFOSR ↔ x is a complex matrix with universal fluctuations governed by the loss parameter a = df3dB/Df ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ Survival probability in the ensemble Uniform attenuation James Hart, T. Antonsen, E. Ott, Phys. Rev. E 80, 041109 (2009)

  7. Nonuniversal Properties Captured by the Extended RCM Empty Cavity Data Data and Theory smoothed with the same 125-cm (240 MHz window) low-pass filter Experimental work funded by AFOSR, and now ONR/AppEl Theory includes all orbits to 200 cm length J.-H. Yeh, et al., Phys. Rev. E 81, 025201(R) (2010); J.-H. Yeh, et al., arXiv:1006.3040

  8. Extensions of The Random Coupling Model Realistic systems consist of many coupled enclosures Can the RCM be extended to handle these situations? J. P. Parmentier (ONERA)

  9. Extending the RCM to the case of Coupled Cavities Cavity 1 Cavity 2 Fluctuations in transmission through cavity 1 Approximations: high loss, weak transmission Mean properties of cavity 2 The statistics of coupling are dominated by the statistics of transmission through the first cavity, scaled by the mean impedance of the next cavity Generalize to an arbitrary cascade of enclosures and treat junction topology

  10. Extending the RCM to the case of Coupled Cavities Future Work: Consider networks of coupled cavities Graph topology

  11. The Statistics of Tunneling between Enclosures Work in collaboration with Lou Pecora @ NRL In some cases, two enclosures will be coupled by structures beyond cutoff Examples include metal ducts at frequencies below cutoff, intermediate rooms/compartments that are below resonance Can we use what we know about chaotic eigenfunctions to solve this problem? Does it make a difference if the enclosures are regular or chaotic? Barrier Enclosure 1 Enclosure 2 Barrier Enclosure 1 Enclosure 2 Ray Chaotic Enclosure case Regular Enclosure case

  12. The Statistics of Tunneling between Enclosures: The 1D Case Energy splitting Dk2 is proportional to the tunneling rate through the barrier

  13. Splitting Fluctuations versus Energy Numerical simulations by Lou Pecora (NRL) These splittings, and their fluctuations, are predictable in the chaotic case

  14. Results of Wave Chaos Theory The theory uses the random plane wave hypothesis to calculate the tunneling rate Sliding average of mean splitting Sliding average of splitting fluctuations Wave chaos theory in agreement with simulations Surprisingly, all three agree quite closely… Black lines (Data) – simulations by Lou Pecora (NRL)

  15. An Experiment to Test the Wave Chaos Tunneling Theory Barrier Infinite Waveguide Ray-Chaotic Enclosure The tunneling escape rate will vary from mode to mode, giving fluctuations in the quality factor of the modes. The mean and fluctuations of the 1/Q with k2 should follow the wave chaos theory predictions

  16. New Research and Transfer of RCM Knowledge Base to Naval Research Lab We are collaborating with the group of Tim Andreadis to test the RCM is more realistic scenarios, and to transfer our knowledge / know-how to DoD Experimental tests of the RCM in 3D enclosures Hai Tran and Zach Drikas New Antenna Configuration Radiation Impedance Measurement

  17. The Electromagnetic Chaotic Time-Reversal Sensor Transmitted Sona 60ns pulse with 7GHz (λ~4cm) center frequency. Work funded by ONR MURI 2007 Anlage et al. Acta Physica Polonica A 112, 569 (2007)

  18. ELECTROMAGNETIC Chaotic Time-Reversal Sensor:- Injection of time reversed Sona Sensors based on time-reversed pulse reconstruction: B. T. Taddese, et al., Appl. Phys. Lett. 95, 114103 (2009) B. T. Taddese, et al., arXiv:1008.2409

  19. Electromagnetic Time-Reversal of Enclosure with Aperture Sun Hong, Zach Drikas, Hai Tran, Jesus Gil Gil, Tim Andreadis, NRL Step 2: Step 1: Port 2 Port 1 5ns Short Monopole Inside

  20. Conclusions The Random Coupling Model is being extended and generalized in new ways Short Orbits Connected Enclosures Electrically Large Antennas Theory and Experiment work in parallel, and stimulate each other NRL Collaboration has resulted in: New experiments and new applications for the RCM and time-reversed EM Extension of the RCM Transfer of know-how to DoD Future Work: Experimental test of tunneling fluctuations Theory of multiple connected and networked enclosures Modeling and experiments of fading statistics IC Post-Doc grant: Nonlinear time-reversed electromagnetics DURIP proposal: System for Investigation of Terahertz Wave Chaos

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