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Theory And Numerical Simulation Of A Compact Low Field High Frequency Gyrotron
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Book Synopsis Theory and Numerical Simulation of a Compact, Low Field, High Frequency Gyrotron by : P. Vitello
Download or read book Theory and Numerical Simulation of a Compact, Low Field, High Frequency Gyrotron written by P. Vitello and published by . This book was released on 1984 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research in Progress written by and published by . This book was released on 1982 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Journal of Infrared and Millimeter Waves by :
Download or read book International Journal of Infrared and Millimeter Waves written by and published by . This book was released on 1984 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :Machavaram V. Kartikeyan Publisher :Springer Science & Business Media ISBN 13 :3662076373 Total Pages :234 pages Book Rating :4.6/5 (62 download)
Book Synopsis Gyrotrons by : Machavaram V. Kartikeyan
Download or read book Gyrotrons written by Machavaram V. Kartikeyan and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drawing on the author's wide experience, this book gives a comprehensive review of the state of the art in gyrotron technology, covering the theory, design and applications. The book includes an extensive references list which provides an excellent guide to the related literature.
Book Synopsis Numerical Study of Nonstationary Phenomena in Gyro-Oscillators by : Alexej Grudiev
Download or read book Numerical Study of Nonstationary Phenomena in Gyro-Oscillators written by Alexej Grudiev and published by Cuvillier Verlag. This book was released on 2003-02-03 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The possible applications of gyro-oscillators span a wide range of technologies [61 – 63]. In the field of magnetic confinement fusion studies, such applications as lower hybrid current drive, electron cyclotron resonance heating (ECRH) and current drive, plasma production for different processes, and active plasma diagnostic measurements have been demonstrated. For these applications, it is necessary to develop CW gyromonotrons that operate at both higher frequencies and higher output power. Hence single-mode 110-170 GHz CW gyromonotrons with a conventional cylindrical cavity, capable of high average power (0.5-1 MW per tube), and 2 MW coaxial cavity gyromonotrons are currently under development. Gyromonotrons are also successfully used in materials processing (e.g. in advanced ceramic sintering, surface hardening, or dielectric coating of metals and alloys) as well as in plasma chemistry. The use of gyromonotrons for such technological applications appears to be of interest if one can realize a relatively simple, low cost device which is easy in service. Hence gyromonotrons with low magnetic field (operating at the 2nd harmonic of the electron cyclotron frequency), low anode voltage, high efficiency, and long lifetime are under development. Potential applications of gyro-BWOs as a tunable millimeter-wave source including position-selective heating of fusion plasma, spectroscopy, materials processing, and drivers for ultra-high power amplifiers also motivate further theoretical and experimental investigations. In many cases, the time dependence of the electromagnetic field in gyro-oscillators shows nonharmonic or multi-frequency behavior. This can be a transient process during a start-up phase (which generally causes th operating frequency to change with time), during a short-pulse operation, or during mode competition. In the latter case, the modes interacting at different cyclotron harmonics and/or in different regimes (gyromonotron or gyro-BWO) at the same time often show quite different operating frequencies. This can also be a nonstationary regime caused by operating the device at parameters significantly exceeding the start oscillation condition. Such operation regime can occur not only when increasing one of the operating parameters, for example, the beam current, but also when keeping the operating parameters constant and decreasing the start oscillation condition parameters, for example, by introducing reflections of the output power back from the load into the interaction space. Hence, in order to accurately simulate nonstationary phenomena in gyro-oscillators, a time-dependent multimode code which is capable to self-consistently model the electromagnetic field within broad spectral bandwidth is necessary. In this work, the development of a self-consistent time-dependent analysis for gyro-oscillator simulation, which is believed to be as rigorous as the PIC code approach, but which is much more efficient especially in the case of an azimuthally non-homogeneous electromagnetic field has been presented. An accurate representation of the electromagnetic field is obtained by expanding the field components in terms of the solenoidal and the irrotational eigenfunctions of the equivalent completely closed cavity. The use of the eigenfunction expansion method reduces the boundary value problem for the field components to that of solving a linear system of ordinary differential equations (ODE) for the expansion coefficients. A convolution technique together with time domain analytic expressions for the characteristic admittances of the waveguide modes and for the reflection coefficients at the apertures of the cavity are applied to accurately formulate the time-dependent boundary conditions. The presented formulation is valid for describing a field having a broad frequency spectrum. The electron beam is represented by an ensemble of particles. The relativistic equations of motion associated with the particles are solved self-consistently with the ODE for the expansion coefficients by means of a multi-step integration scheme. After code validation, it has been used to attack a number of problems. First, it has been demonstrated that the developed time-dependent self-consistent multimode code is capable to model the interaction between the modes operating at the fundamental and/or at higher harmonics of the cyclotron frequency. The numerical results for the fundamental modes agree well with the experimental results published in [144]. Moreover, it is shown that the use of the surface impedance model [132] for the calculation of modes operating at harmonics higher than the fundamental leads to wrong results in high-power coaxial cavity gyromonotrons. Hence the use of this model must always be checked if the radiation wavelength is less than about 5 times the width of the corrugation grooves. The influence of reflections on the operation of an 1 MW, 140 GHz, TE22,6 mode gyromonotron developed at Forschungszentrum Karlsruhe has been studied by means of the described self-consistent time-dependent multimode analysis. It has been found that for the gyromonotron with operating parameters close to their optimum, the onset of an unstable operation regime occurs for reflection coefficients R ≥ 0.4, and the relative width of the spectrum of the output radiation increases up to 12%. The results of the numerical investigation on output power variation and frequency pulling due to a variation of the reflection parameters agree well with the available experimental data and demonstrate a strong dependence on the reflections. Moreover, our analysis of the gyromonotron operating in the presence of reflections has shown several new features of ist nonstationary behavior. First, it has been shown that the traditionally accepted scenario of the transition from the single-frequency stationary operation regime to the chaotic nonstationary regime when increasing the reflection coefficient is not correct. In contrast, an increase of the reflection coefficient above a certain threshold value (R ≥ 0.4) leads to the sequential excitation of a number of modes of the mismatched gyromonotron cavity. Then the gyromonotron shows a very complicated periodic or quasiperiodic behavior of a regular nature. No signs of chaotic behavior have been found. Second, for higher reflection coefficients (R ≥ 0.85), the main mode as well as most of the other modes of the mismatched cavity are suppressed by that mode which shows the highest eigenfrequency, and whose field profile shows its maximum in the vicinity of the left aperture. The eigenfrequency of this mode lies next to the cutoff frequency of the left aperture and limits the achievable bandwidth of the gyromonotron output radiation when one tries to increase it by means of reflections. Third, decreasing the distance to the reflecting load increases the frequency separation between the modes, what correspondingly reduces the number of excited modes and makes the spectrum of the gyromonotron output radiation less dense. Furthermore, the obtained results reveal important details of the saturated behavior of the gyro-BWO which have not been shown in the nonstationary analysis performed before. Although on one side, they agree with results obtained by using a stationary code [50] which employs a similar outgoing-wave boundary condition, and which also uses a self-consistent beam-field interaction model, on the other side, the results demonstrate the importance of timedependent calculations for a gyro-BWO stability analysis. Moreover, the results are in good agreement with recently available results obtained by another nonstationary code [51] as well as with the experiments [10]. Furthermore, it has been shown that tuning the external magnetic field leads to the excitation of the undesired taper mode which reduces the magnetic tuning bandwidth. Moreover, in an injection-locked gyro-BWO, significant modifications of the locking bandwidth curve have been observed when the magnetic field is tuned. The locking bandwidth curve which has been found in the simulations as well as its asymmetry agree well with the experiments [108].
Download or read book Space Power written by and published by . This book was released on 1988 with total page 966 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigations of After Cavity Interaction in Gyrotrons Including the Effect of Non-uniform Magnetic Field by : Roy Choudhury, Amitavo
Download or read book Investigations of After Cavity Interaction in Gyrotrons Including the Effect of Non-uniform Magnetic Field written by Roy Choudhury, Amitavo and published by KIT Scientific Publishing. This book was released on 2014-02-05 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamic after-cavity interaction (ACI) in megawatt-class gyrotrons is investigated that could lead to lower output mode purity and increased level of internal stray radiation. The self-consistent KIT-IHM multi-mode-code SELFT has been modified to extend the simulation domain into the radius up-taper section of the gyrotron cavity where the probability of ACI exists. Studies on four different gyrotron configurations confirm that undesired interactions in the up-taper region can result in additional parasitic oscillations with relative power in the 1%-range.
Book Synopsis Journal of Current Laser Abstracts by :
Download or read book Journal of Current Laser Abstracts written by and published by . This book was released on 1984 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1990 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government reports annual index by :
Download or read book Government reports annual index written by and published by . This book was released on 199? with total page 1082 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index: Keyword A-L by :
Download or read book Government Reports Annual Index: Keyword A-L written by and published by . This book was released on 1984 with total page 1092 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Referativnyĭ zhurnal written by and published by . This book was released on 1985 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Design and Operation of a Harmonic Gyrotron Based on a Cusp Electron Gun by : Fengping Li
Download or read book Design and Operation of a Harmonic Gyrotron Based on a Cusp Electron Gun written by Fengping Li and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the results of successful operation of a 2nd harmonic gyrotron based on a cusp electron gun. The numerical and experimental results agreed well with the gyrotron design parameters. Two gyrotrons based on a cusp electron gun were designed: the first gyrotron operated at the 2nd harmonic and the second gyrotron was studied to look at the scaling of this concept for operation at the 7th harmonic at a frequency of 390 GHz. The cusp electron gun was used to produce the electron beam in the gyrotron which was annular in shape. The electron beam had a voltage of 40 kV, a current of 1.5A and a velocity ratio (perpendicular component to horizontal component) of 1.5. The experimental results from the first cusp electron gun and measurements of the high quality electron beam with ~8% velocity spread and ~10% alpha spread are presented. Analytical, numerical and experimental results of a DC harmonic gyrotron are presented. The 3D PIC code MAGIC was used to simulate the interaction of the harmonic gyrotron such as the TE71 mode at the 7th cyclotron harmonic with the large orbit electron beam with the beam thickness and beam spread introduced into the simulation. The interaction cavity of both gyrotrons was in the form of a smooth cylindrical waveguide. The relationship between the cavity dimensions and cavity Q values has been studied for optimized output at the design mode with the aim of suppressing other competing modes. A linear output taper was designed with low mode conversion at the gyrotron output. A Vector Network Analyzer with high frequency millmetre wave heads was used to measure the millimeter wave properties of the gyrotron cavity. Experiments were conducted using the electron gun for the harmonic gyrotron. The gyrotron and electron gun were built as well as the interlock and safety system, pulsed power supply and magnet, the cooling and vacuum system. Millimetre wave radiation was measured for the 2.6 mm diameter cavity gyrotron operating at the 2nd harmonic at a magnetic field of 2.08 T. Experiments demonstrated that the harmonic gyrotron was sensitive to the magnetic field and electron beam parameters. Millimetre wave radiation from 108GHz to 110GHz was measured with the use of a W-band rectifying crystal detector and high pass cut off filters. The frequency of the measured millimeter wave radiation agreed very well with the design and predictions of theory.