Experimental study from linear to chaotic regimes on a terahertz-frequency gyrotron oscillator

Journal Article · Sat Dec 15 00:00:00 EST 2012 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4769033· OSTI ID:22072657

Alberti, S; Braunmueller, F; Dubray, J; Fasel, D; Hogge, J -Ph; Silva, M da; Tran, M Q; Tran, T M; Vuillemin, Q ^[1]; Ansermet, J -Ph; Cuanillon, P ^[2]; Avramides, K A ^[3]; Macor, A; Rijk, E de ^[2]; SWISSto12 Sarl, 1015 Lausanne ^[4]

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1. Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)
2. Institute of Condensed Matter Physics, Station 3, EPFL, 1015 Lausanne (Switzerland)
3. National Technical University of Athens, Athens GR-15773 (Greece)
4. Switzerland

Basic wave-particle interaction dynamics from linear to chaotic regimes is experimentally studied on a frequency tunable gyrotron generating THz radiation in continuous mode (200 W) at 263 GHz which will be used for dynamic nuclear polarization nuclear magnetic resonance spectroscopy applications. In the studied system, the nonlinear dynamics associated to the wave-particle interaction is dominated by longitudinal mode competition of a given transverse TE{sub m,p} cavity-mode. This study covers a wide range of control parameter from gyro-traveling wave tube (gyro-TWT) to gyro-backward wave oscillator (gyro-BWO) like interactions for which extensive theoretical studies have been performed in the past on a simplified system. Besides the common route to chaos characterized by period doubling, other routes have been identified among which some are characterized by line-width frequency-broadening on the side-bands. The complex nonlinear dynamics is in good agreement with the theory and the experimental results are discussed on the basis of the prediction obtained with the nonlinear time-dependent self-consistent codes TWANG and EURIDICE both based on a slow-time scale formulation of the self-consistent equations governing the wave-particle dynamics.

• OSTI ID: 22072657
• Journal Information: Physics of Plasmas, Vol. 19, Issue 12; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CHAOS THEORY
GHZ RANGE
LINE WIDTHS
MICROWAVE AMPLIFIERS
NONLINEAR PROBLEMS
NUCLEAR MAGNETIC RESONANCE
OSCILLATORS
PARTICLE INTERACTIONS
POLARIZATION
SPECTROSCOPY
THZ RANGE
TIME DEPENDENCE
TRAVELLING WAVE TUBES