Jagadishwar Sirigiri, is founder of Bridge12 Technologies, Inc. and serves as its President and Chief Operating Officer. He has a M.S. and Ph.D. in Electrical Engineering and Computer Science from the Massachusetts Institute of Technology, Cambridge, MA. Dr. Sirigiri has over two decades of experience in experimental and theoretical aspects of microwave engineering, vacuum electron devices and terahertz technology. Previously, he was a Research Scientist at MIT where he was the leader of the experimental program on high power microwave and terahertz source development including gyrotrons and other types of sources for application in Dynamic Nuclear Polarization (DNP) in Nuclear Magnetic Resonance (NMR), Electron Paramagnetic Resonance (EPR), fusion plasma heating and radar. He has conducted theoretical and experimental research on Photonic Band Gap (PBG) structures and Metamaterials (MTM).
Dr. Sirigiri's research resulted in several accomplishments including the experimental demonstration of > 50% efficiency in a megawatt class gyrotron for plasma heating application; theoretical and experimental research on After Cavity Interaction (ACI) in gyrotrons and its effect on efficiency; theoretical and experimental work on the low frequency oscillations in megawatt gyrotron oscillators; development of tunable continuous wave gyrotron oscillators in the millimeter wave and terahertz range and their successful application in high field DNP-NMR spectroscopy; development of high power high frequency gyrotron traveling wave tube (gyro-TWT) amplifiers at 140 GHz for applications in radar and electron EPR. He demonstrated the first vacuum electron device with a photonic band gap (PBG) structure to suppress mode competition while operating in a higher order mode. This concept is particularly useful for design of terahertz vacuum electron devices. He initiated work on the development of a 94 GHz traveling wave tube (TWT) with an overmoded interaction structure and a 250 GHz gyro-TWT amplifier using a higher order mode in a photonic band gap (PBG) structure.
Dr. Sirigiri is a Senior Member of the IEEE, and a member of the American Physical Society and Sigma-Xi. He served as a guest editor of the Twelfth Special Issue on High Power Microwave Generation of the IEEE Transactions on Plasma Sciences in 2008. He is a member of the IEEE Electron Devices Society (EDS) Vacuum Electron Devices Technical committee and member of the executive committee of the International Vacuum Electronics Conference (IVEC).
Publications (Selected)
- Real-time, T-ray imaging using a sub-terahertz gyrotron, S. T. Han, A. Torrezan, J. R. Sirigiri, M. Shapiro, R. J. Temkin, Journal of the Korean Physical Society, vol. 60, no. 11, pp. 1857-61, 2012.
- Simplified THz Instrumentation for High-Field DNP-NMR Spectroscopy, T. Maly and J. R. Sirigiri, Applied Magnetic Resonance, DOI: 10.1007/s00723-012-0360-7, 2012.
- Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization, A. C. Torrezan, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, IEEE Trans. Electron Devices, vol. 58, no. 8, pp. 2277-2783, 2011.
- Experimental Results on a 1.5 MW, 110 GHz Gyrotron with a Smooth Mirror Mode Converter, D. S. Tax, E. M. Choi, I. Mastovsky, J. M. Neilson, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, and A. C. Torrezan, J. Infrared, Millimeter and THz Waves, Vol. 32, pp. 358-370, 2011.
- Amplification of Picosecond Pulses in a 140 GHz Gyrotron Traveling Wave Tube, H. J. Kim, E. A. Nanni, M. A. Shapiro, J. R. Sirigiri, P. P. Woskow and R. J. Temkin, Phys. Rev. Lett. 105, 135101, 2010.
- Linearly Polarized Modes of a Corrugated Metallic Waveguide, E. J. Kowalski, D. S. Tax, M. A. Shapiro, J. R. Sirigiri, J. R. J. Temkin, T. S. Bigelow and D. A. Rasmussen, vo. 58, no. 11, pp. 2772-2780, IEEE Trans. Microwave Theory and Techniques, 2010.
- Resolution and Polarization Distribution in Cryogenic DNP/MAS Experiments, A. B. Barnes, B. Corzilius, M. L. Mak-Jurkauskas, L. B. Andreas, V. S. Bajaj, Y. Matsuki, M. L. Belenky, J. Lugtenburg, J. R. Sirigiri, R. J. Temkin, J. Herzfeld and R. G. Griffin, vol. 12, pp. 5861-5867, Phys. Chem. Chem. Phys, 2010.
- Continuous-Wave Operation of a Frequency Tunable 460 GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance, A. C. Torrezan, S. T. Han, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, A. B. Barnes, and R. G. Griffin, vol. 38, no. 6, pp 1150-1159, IEEE Trans. Plasma Sci, 2010.
- Cryogenic sample exchange NMR Probe for Magic Angle Spinning Dynamic Nuclear Polarization, A. B. Barnes, M. L. Mak-Jurkauskas, Y. Matsuki, V. S. Bajaj, P. C. A. van der Wel, R. DeRocher, J. Bryant, J. R. Sirigiri, R. J. Temkin, J. Lugtenburg, J. Herzfeld, and R. G. Griffin, vol. 198, no. 2, pp. 261-70, Journal of Magnetic Resonance, June 2009.
- Demonstration of a 140-GHz 1-kW Confocal Gyro-Traveling-Wave Amplifier, C. D. Joye, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 56, no. 5, pp. 818-27, IEEE Trans. on Electron Devices, May 2009.
- High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR, A. B. Barnes, G. De Paepe, P. C. A.. van der Wel, K. N. Hu, C. G. Joo, V. S. Bajaj, M. L. Mak-Jurkauskas, J. R. Sirigiri, J. Herzfeld, R. J. Temkin and R. G. Griffin, vol. 34, no. 3-4, pp. 237-63, Applied Magnetic Resonance, Aug. 2008.
- Dynamic Nuclear Polarization at High Magnetic Fields, T. Maly, G. T. Debelouchina, V. S. Bajaj, K. N. Hu, C. G. Joo, M. L. Mak-Jurkauskas, J. R. Sirigiri, P. C. A. van der Wel, J. Herzfeld, R. J. Temkin and R. G. Griffin, vo. 128, no. 5, pp. 052211, Journal of Chemical Physics, Feb. 2008.
- Observation of Large Arrays of Plasma Filaments in Air Breakdown by 1.5-MW 110-GHz Gyrotron Pulses, Y. Hidaka, E. M. Choi, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 100, no. 3, pp. 035003, Physical Review Letters, Jan 25, 2008.
- 250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR, V. S. Bajaj, M. K. Hornstein, K. E. Kreischer, J. R. Sirigiri, P. P. Woskov, M. L. Mak-Jurkauskas, J. Herzfeld, R. J. Temkin and R. G. Griffin, vol. 189, no. 2, pp. 251-79, Journal of Magnetic Resonance, Dec. 2007.
- Experimental Observation of the Effect of Aftercavity Interaction in a Depressed Collector Gyrotron Oscillator, E. M. Choi, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 14, no. 9, pp. 093302, Physics of Plasmas, Sept. 2007.
- Efficiency Enhancement of a 1.5-MW, 110-GHz Gyrotron With a Single-Stage Depressed Collector, E. M. Choi, A. J. Cerfon, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 52, no. 2, pp. 334-9, Fusion Science and Technology, Aug. 2007.
- Spectral Characteristics of a 140-GHz Long-Pulsed Gyrotron, S. T. Han, R. G. Griffin, K. N. Hu, C. G. Joo, C. D. Joye, J. R. Sirigiri, R. J. Temkin, A. C. Torrezan, and P. P. Woskov, vol. 35, no. 3, pp. 559-64, IEEE Trans. on Plasma Science, Jun 2007.
- Spatial Dispersion in Metamaterials With Negative Dielectric Permittivity and its Effect on Surface Waves, M. A. Shapiro, G. Shvets, J. R. Sirigiri, and R. J. Temkin, vol. 31, no. 13, pp. 2051-3, Optics Letters, July 1, 2006.
- Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization, C. D. Joye, R. G. Griffin, M. K. Hornstein, K. N. Hu, K. E. Kreischer, M. Rosay, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, and P. P. Woskov, vo. 34, no. 3, pp. 518-23, IEEE Trans. on Plasma Science, Jun. 2006.
- Observation of Frequency-Locked Coherent Terahertz Smith-Purcell Radiation, S. K. Korbly, A. S. Kesar, J. R. Sirigiri, and R. J. Temkin, vol. 94, pp. 054803, Phys. Rev. Lett., Feb. 2005.
- High-Power 140-GHz Quasioptical Gyrotron Traveling-Wave Amplifier, J. R. Sirigiri, M. A. Shapiro, and R. J. Temkin, Phys. Rev. Lett., vol. 90, no. 25, pp. 258302(1- 4), June 2003.
- Photonic-Band-Gap Resonator Gyrotron, J. R. Sirigiri, K. E. Kreischer, J. Machuzak, I. Mastovsky, M. A. Shapiro, and R. J. Temkin Phys. Rev. Lett., vol. 86, no. 24, pp. 5628-2631, June 2001.
Patents
- Vacuum Electron Device with Photonic Band Gap Structure and Method of Use Thereof, Chiping Chen, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, United States Patent No. US 6,801,107 B2, Oct. 5, 2004.
- Photonic band gap structure simulator, C. Chen, M. A. Shapiro, E. I. Smirnova, and R. J. Temkin, J. R. Sirigiri, United States Patent No. US 7,117,13, 10/03/2006
Publications (Journal Articles)
- Real-time, T-ray imaging using a sub-terahertz gyrotron, S. T. Han, A. Torrezan, J. R. Sirigiri, M. Shapiro, R. J. Temkin, Journal of the Korean Physical Society, vol. 60, no. 11, pp. 1857-61, 2012.
- Simplified THz Instrumentation for High-Field DNP-NMR Spectroscopy, T. Maly and J. R. Sirigiri, Applied Magnetic Resonance, DOI: 10.1007/s00723-012-0360-7, 2012.
- Operation of a Continuously Frequency-Tunable Second-Harmonic CW 330-GHz Gyrotron for Dynamic Nuclear Polarization, A. C. Torrezan, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, IEEE Trans. Electron Devices, vol. 58, no. 8, pp. 2277-2783, 2011.
- Experimental Results on a 1.5 MW, 110 GHz Gyrotron with a Smooth Mirror Mode Converter, D. S. Tax, E. M. Choi, I. Mastovsky, J. M. Neilson, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, and A. C. Torrezan, J. Infrared, Millimeter and THz Waves, Vol. 32, pp. 358-370, 2011.
- Amplification of Picosecond Pulses in a 140 GHz Gyrotron Traveling Wave Tube, H. J. Kim, E. A. Nanni, M. A. Shapiro, J. R. Sirigiri, P. P. Woskow and R. J. Temkin, Phys. Rev. Lett. 105, 135101, 2010..
- Linearly Polarized Modes of a Corrugated Metallic Waveguide, E. J. Kowalski, D. S. Tax, M. A. Shapiro, J. R. Sirigiri, J. R. J. Temkin, T. S. Bigelow and D. A. Rasmussen, vo. 58, no. 11, pp. 2772-2780, IEEE Trans. Microwave Theory and Techniques, 2010.
- Experimental Results on a 1.5 MW, 110 GHz Gyrotron with a Smooth Mirror Mode Converter, D. S. Tax , E. M. Choi, I. Mastovsky, J. M. Neilson, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin and A. C. Torrezan, Journal of Infrared Millimeter and Terahertz Waves, DOI 10.1007/s10762-010-9720-2, 2009.
- Resolution and Polarization Distribution in Cryogenic DNP/MAS Experiments, A. B. Barnes, B. Corzilius, M. L. Mak-Jurkauskas, L. B. Andreas, V. S. Bajaj, Y. Matsuki, M. L. Belenky, J. Lugtenburg, J. R. Sirigiri, R. J. Temkin, J. Herzfeld and R. G. Griffin, vol. 12, pp. 5861-5867, Phys. Chem. Chem. Phys, 2010.
- Loss Estimate for ITER ECH Transmission Line Including Multimode Propagation, M. A. Shapiro, E. J. Kowalski, J. R. Sirigiri, D. S. Tax, and R. J. Temkin, vol. 57, no. 3, pp 196-207, Fusion Science and Technology, April 2010.
- Continuous-Wave Operation of a Frequency Tunable 460 GHz Second-Harmonic Gyrotron for Enhanced Nuclear Magnetic Resonance, A. C. Torrezan, S. T. Han, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, A. B. Barnes, and R. G. Griffin, Accepted for publication in IEEE Trans. Plasma Sci, 2010.
- Observation and Study of Low-Frequency Oscillations in a 1.5-MW 110-GHz Gyrotron, A. J. Cerfon, E. Choi, C. D. Marchewka, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 37, no. 7, pp 1219-24, IEEE Trans. Plasma Sciences, July 2009.
- Cryogenic sample exchange NMR Probe for Magic Angle Spinning Dynamic Nuclear Polarization, A. B. Barnes, M. L. Mak-Jurkauskas, Y. Matsuki, V. S. Bajaj, P. C. A. van der Wel, R. DeRocher, J. Bryant, J. R. Sirigiri, R. J. Temkin, J. Lugtenburg, J. Herzfeld, and R. G. Griffin, vol. 198, no. 2, pp. 261-70, Journal of Magnetic Resonance, June 2009.
- Demonstration of a 140-GHz 1-kW Confocal Gyro-Traveling-Wave Amplifier, C. D. Joye, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 56, no. 5, pp. 818-27, IEEE Trans. on Electron Devices, May 2009.
- Plasma Structures Observed in Gas Breakdown Using a 1.5 MW, 110 GHz Pulsed Gyrotron, Y. Hidaka, E. M. Choi, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, G. F. Edmiston, A. A. Neuber, and Y. Oda, vol. 16, no. 5, pp. 055702, Physics of Plasmas, May 2009.
- Calculation of Radiation from a Helically Cut Waveguide for a Gyrotron Mode Converter in the Quasi-Optical Approximation, E. M. Choi, M. A. Shapiro, J. R. Sirigiri and R. J. Temkin, vol. 30, no. 1, pp. 8-25, Journal of Infrared Millimeter and Terahertz Waves, Jan 2009.
- Simulation of the Bulk and Surface Modes Supported by a Diamond Lattice of Metal Wires, M. A. Shapiro, K. R. Samokhvalova, J. R. Sirigiri, R. J. Temkin, and G. Shevts, vol. 104, no. 10, pp. 103107, Journal of Applied Physics, Nov. 2008.
- Low-Power Testing of Losses in Millimeter-Wave Transmission Lines for High-Power Applications, S. T. Han, E. N. Comfoltey, M. A. Shapiro, J. R. Sirigiri, D. S. Tax, R. J. Temkin, P. P. Woskov, and D. A. Rasmussen, vol. 29, no. 11, pp. 1011-18, International Journal of Infrared and Millimeter Waves, Nov. 2008.
- High-Field Dynamic Nuclear Polarization for Solid and Solution Biological NMR, A. B. Barnes, G. De Paepe, P. C. A.. van der Wel, K. N. Hu, C. G. Joo, V. S. Bajaj, M. L. Mak-Jurkauskas, J. R. Sirigiri, J. Herzfeld, R. J. Temkin and R. G. Griffin, vol. 34, no. 3-4, pp. 237-63, Applied Magnetic Resonance, Aug. 2008.
- Imaging of Atmospheric Air Breakdown Caused by a High-Power 110-GHz Pulsed Gaussian Beam, Y. Hidaka, E. M. Choi, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 36, no. 4, pp. 936-7, IEEE Trans. on Plasma Science, Aug. 2008.
- The Twelfth Special Issue on High-Power Microwave Generation, J. Luginsland, J. Sirigiri, and J. Yater, vol. 36, no. 3, pp. 566-8, IEEE Trans. on Plasma Science, Jun 2008.
- Dynamic Nuclear Polarization at High Magnetic Fields, T. Maly, G. T. Debelouchina, V. S. Bajaj, K. N. Hu, C. G. Joo, M. L. Mak-Jurkauskas, J. R. Sirigiri, P. C. A. van der Wel, J. Herzfeld, R. J. Temkin and R. G. Griffin, vo. 128, no. 5, pp. 052211, Journal of Chemical Physics, Feb. 2008.
- Observation of Large Arrays of Plasma Filaments in Air Breakdown by 1.5-MW 110-GHz Gyrotron Pulses, Y. Hidaka, E. M. Choi, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 100, no. 3, pp. 035003, Physical Review Letters, Jan 25, 2008.
- 250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR, V. S. Bajaj, M. K. Hornstein, K. E. Kreischer, J. R. Sirigiri, P. P. Woskov, M. L. Mak-Jurkauskas, J. Herzfeld, R. J. Temkin and R. G. Griffin, vol. 189, no. 2, pp. 251-79, Journal of Magnetic Resonance, Dec. 2007.
- Experimental Observation of the Effect of Aftercavity Interaction in a Depressed Collector Gyrotron Oscillator, E. M. Choi, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 14, no. 9, pp. 093302, Physics of Plasmas, Sept. 2007.
- Efficiency Enhancement of a 1.5-MW, 110-GHz Gyrotron With a Single-Stage Depressed Collector, E. M. Choi, A. J. Cerfon, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vol. 52, no. 2, pp. 334-9, Fusion Science and Technology, Aug. 2007.
- Spectral Characteristics of a 140-GHz Long-Pulsed Gyrotron, S. T. Han, R. G. Griffin, K. N. Hu, C. G. Joo, C. D. Joye, J. R. Sirigiri, R. J. Temkin, A. C. Torrezan, and P. P. Woskov, vol. 35, no. 3, pp. 559-64, IEEE Trans. on Plasma Science, Jun 2007.
- Spatial Dispersion in Metamaterials With Negative Dielectric Permittivity and its Effect on Surface Waves, M. A. Shapiro, G. Shvets, J. R. Sirigiri, and R. J. Temkin, vol. 31, no. 13, pp. 2051-3, Optics Letters, July 1, 2006.
- Operational Characteristics of a 14-W 140-GHz Gyrotron for Dynamic Nuclear Polarization, C. D. Joye, R. G. Griffin, M. K. Hornstein, K. N. Hu, K. E. Kreischer, M. Rosay, M. A. Shapiro, J. R. Sirigiri, R. J. Temkin, and P. P. Woskov, vo. 34, no. 3, pp. 518-23, IEEE Trans. on Plasma Science, Jun. 2006.
- Experimental Results For a 1.5 MW, 110 GHz Gyrotron Oscillator With Reduced Mode Competition, E. M. Choi, C. D. Marchewka, I. Mastovsky, J. R. Sirigiri, M. A. Shapiro, and R. J. Temkin, vol. 13, no. 2, pp. 023103, Physics of Plasmas, Feb 2006.
- Observation of Frequency-Locked Coherent Terahertz Smith-Purcell Radiation, S. K. Korbly, A. S. Kesar, J. R. Sirigiri, and R. J. Temkin, vol. 94, pp. 054803, Phys. Rev. Lett., Feb. 2005.
- Megawatt Power Level 120 GHz Gyrotrons for ITER Start-Up, E. M. Choi, C. Marchewka, I. Mastovsky, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, vo. 25, no. 1, pp. 1-7, Journal of Physics, Conf. Series, 2005.
- Second Harmonic Operation at 460 GHz and Broadband Continuous Frequency Tuning of a Gyrotron Oscillator, M. K. Hornstein, V. S. Bajaj, R. G. Griffin, I. Mastovsky, M. A. Shapiro, , J. R. Sirigiri, and R. J. Temkin, vo. 52, no. 5, pp. 798-807, IEEE Trans. Electron Devices, May. 2005.
- High-Power 140-GHz Quasioptical Gyrotron Traveling-Wave Amplifier, J. R. Sirigiri, M. A. Shapiro, and R. J. Temkin, Phys. Rev. Lett., vol. 90, no. 25, pp. 258302(1- 4), June 2003.
- Simulation of Photonic Band Gaps in Metal Rod Lattices for Microwave Applications, E. I. Smirnova, C. Chen, M. A. Shapiro, J. R. Sirigiri, and R. J. Temkin, J. Appl. Phys., vol. 91, no. 3, pp. 960-968, 1 February, 2002.
- Experimental Investigation of a 140 GHz Coaxial Gyrotron Oscillator, R. Advani, J. P. Hogge, K. E. Kreischer, M. Pedrozzi, M. E. Read, J. R. Sirigiri, and R. J. Temkin, IEEE Trans. Plasma Sci., vol. 29, no. 6. pp. 943-950, December 2001.
- Photonic-Band-Gap Resonator Gyrotron, J. R. Sirigiri, K. E. Kreischer, J. Machuzak, I. Mastovsky, M. A. Shapiro, and R. J. Temkin Phys. Rev. Lett., vol. 86, no. 24, pp. 5628-2631, June 2001.
- Photonic Band Gap Cavity with Improved Input Coupling, M. A. Shapiro, W. J. Brown, I. Mastovsky, J. R. Sirigiri and R. J. Temkin, Physical Review Special Topics - Accelerators and Beams, vol. 4, p. 042001, 2001.
- Automatic Dispersion Measurements of Helical Slow-Wave Structure, S. J. Rao, S. Subramanian, S. K. Datta and R. Seshadri, Defense Science Journal, Defense Sci. Inf. & Doc. Centre, India. vol. 50, no.1, pp.83-6, Jan 2000.
- Non-Resonant Perturbation Measurements on Dispersion and Interaction Impedance Characteristics of Helical Slow-Wave Structures, S. J. Rao, S. K. Ghosh, P. K. Jain and B. N. Basu, IEEE Trans. on Microwave Theory and Tech., vol. 45, no. 9, pp 1585-1593, Sept. 1997.
- Hybrid-Mode Helix Loading Effects on Gyro-Travelling-Wave Tubes, S. J. Rao, P. K. Jain and B. N. Basu, Int. J. of Elec., vol. 82, no. 6, pp. 663-675, 1997.
- Broadbanding of a Gyro-TWT by Dielectric Loading through Dispersion Shaping, S. J. Rao, P. K. Jain and B. N. Basu, IEEE Trans. on Electron Dev., vol. 43, no. 12, pp. 2290-2299, December 1996.
- Effects of Circuit Loss and Space Charge in Gyro-Travelling-Wave Tubes, S. J. Rao, P. K. Jain and B. N. Basu,Int. J. of IRMM Waves, vol. 17, no. 9, pp. 1507-1517, September 1996.
- Two-Stage Dielectric-Loading for Broadbanding a Gyro-TWT, S. J. Rao, P. K. Jain and B. N. Basu, IEEE Elect. Dev. Lett., vol. 17, no. 6, pp 303-305, June 1996.
- Amplification in Gyro-Travelling Wave Tubes - Dispersion Relation and Gain-Bandwidth Characteristics, S. J. Rao, P. K. Jain and B. N. Basu, IETE Tech. Rev., India, vol. 13, pp. 141-150, 1996.