Efficiency Enhancement of the Axial VIRCATOR

Biswas, Debabrata; Kumar, Raghwendra

doi:10.1109/tps.2007.891623

Cited by 19 publications

(4 citation statements)

References 26 publications

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“…A fallout of this theory is the existence of a limit for the electromagnetic power emanating from a given open drift tube geometry and injections energy. This can be profitably used in the design of devices used for the extraction of electromagnetic power [12].…”

Section: Discussionmentioning

confidence: 99%

Relation between space charge limited current and power loss in open drift tubes

Biswas

Kumar

2006

Physics of Plasmas

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Drift space is a region free from externally applied fields. It is an important part of many devices involving charged particle beams. The space charge effect imposes a limit on the current that can be transported through a drift space. A reasonable estimate of the space charge limited current density (J c SCL ) in closed drift tubes can be obtained from electrostatic considerations despite the fact that charge particle transport results in electromagnetic radiation. We deal here with the situation where the drift tube is open to electromagnetic radiation, for instance due to the presence of a dielectric window. In such cases, electromagnetic radiation leaks out of the window which results in a decrease in the average kinetic energy of electrons. If the injected current density is much lower than J c SCL , power loss does not result in a change in the transmitted current. As the injected current density is increased, power loss increases and at a critical value lower than J c SCL , reflection of electrons begins to occur. We also show that the lowering of the space charge limited current on account of power loss can be incorporated in the standard electrostatic picture by introducing an effective voltage for the collection plate.

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Section: Discussionmentioning

confidence: 99%

Relation between space charge limited current and power loss in open drift tubes

Biswas

Kumar

2006

Physics of Plasmas

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“…The anode-foil transparency has been made energy dependent [10] for this simulation by modifying the code XOOPIC appropriately. For particles with energy smaller than 50 keV, transparency is set to zero, while for energies between 50 and 150 keV, transparency is set to 0.5.…”

Section: Simulations Detailsmentioning

confidence: 99%

Microwave Power Enhancement in the Simulation of a Resonant Coaxial Vircator

Biswas

Kumar

2010

IEEE Trans. Plasma Sci.

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Cavity resonance effect is a useful concept in beam-wave interaction for enhancing the conversion efficiency. It is shown that an interplay between the growth of field energy inside the cavity and its extraction can be used judiciously to extract a larger power after the initial transients. Cavity parameters in a coaxial virtual-cathode oscillator have thus been optimized to allow field energy inside the cavity to grow initially. This growth is limited by the energy that leaves the cavity through the extraction region so that the field strength inside the cavity saturates optimally at a maximum value. The energy lost by the beam to the field can then be directly extracted at a high conversion efficiency. The peak cycle-averaged power efficiency obtained thus in particle-in-cell simulation exceeds 9%, while the efficiency over several cycles is found to be 7.5%.

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“…Despite the fact that a VCO has many advantages, it is less efficient. In experiments, the conversion of IREB energy to electromagnetic radiation energy remained lower than 20% [20][21][22]. As a result, the improvement of VCO efficiency has remained an ongoing and open research area.…”

Section: Introductionmentioning

confidence: 99%

The Characteristics of the Second and Third Virtual Cathodes in an Axial Vircator for the Generation of High-Power Microwaves

Mumtaz

Choi

2022

Electronics

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A virtual cathode oscillator or vircator is a vacuum tube for producing high-power microwaves (HPM). The efficiency of the vircator has been a difficult task for decades. The main reasons for low efficiency are intense relativistic electron beam (IREB) loss and few or no interactions between IREB and HPM. In this case, forming multiple virtual cathodes may be beneficial in overcoming these constraints. By reusing the axially propagating leaked electrons (LE), we could confine them and form multiple virtual cathodes (VCs). This article discussed the characteristics of newly formed VCs based on simulation results. The formation time of new VCs was discovered to be highly dependent on the reflector position and the density of LE approaching their surfaces. Furthermore, multiple VC formation in the waveguide region does not affect conventional VCs’ position or forming time. The emission mode of the generated HPM was TM01 with single and multiple VCs and remained unaffected. The formation of multiple VCs positively influenced the axial and radial electric fields. When compared to a single VC, the axial and radial electric field increased 25.5 and 18 times with multiple VCs. The findings suggested that forming multiple VCs could be a future hope for achieving high vircator efficiency.

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Efficiency Enhancement of the Axial VIRCATOR

Cited by 19 publications

References 26 publications

Relation between space charge limited current and power loss in open drift tubes

Relation between space charge limited current and power loss in open drift tubes

Microwave Power Enhancement in the Simulation of a Resonant Coaxial Vircator

The Characteristics of the Second and Third Virtual Cathodes in an Axial Vircator for the Generation of High-Power Microwaves

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