Design of a multistage depressed collector system for 1-MW CW gyrotrons. I. Trajectory control of primary and secondary electrons in a two-stage depressed collector

Singh, Amarjit; Rajapatirana, S.; Men, Ye; Granatstein, V.L.; Ives, R. Lawrence; Antolak, Arlyn J.

doi:10.1109/27.772278

Cited by 56 publications

(18 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1,2 In theory, multistage depressed collectors are possible, but have not yet been demonstrated experimentally in gyrotrons. [3][4][5] Depressed collectors cannot only enhance the overall efficiency greatly but also reduce the power loading on the collector, which facilitates longpulse operation of gyrotrons and reduces the possibility of collector failure due to metal fatigue. By reducing the voltage on the collector with respect to the body, the electrons are decelerated and the deposited thermal energy on the collector is also reduced.…”

Section: Introductionmentioning

confidence: 99%

Experimental observation of the effect of aftercavity interaction in a depressed collector gyrotron oscillator

et al. 2007

View full text Add to dashboard Cite

This paper presents the experimental observation of the effect of an aftercavity interaction ͑ACI͒ in a depressed collector gyrotron oscillator. The gyrotron generates an output power of 1.5 MW at 110 GHz in 3 s pulses with a 96 kV and 40 A electron beam and has a single-stage depressed collector. The ACI arises from an unintended cyclotron resonant interaction between the microwave beam traveling out from the cavity and the gyrating electron beam. The interaction occurs in the uptaper of the launcher, immediately downstream from the cavity, where the magnetic field is slightly lower than its value in the cavity region. The ACI results in a reduction in efficiency since the electron beam tends to extract power from the wave. There is also a broadening of the spent beam energy profile, which reduces the effectiveness of the depressed collector and in turn limits the overall efficiency of a gyrotron. Measurements of the maximum depression voltage of the collector vs beam current at 96 kV are compared with simulations from the MAGY code ͓M. Botton et al., IEEE Trans. Plasma Sci. 26, 882 ͑1998͔͒. Excellent agreement is obtained between theory and experiment but only if the ACI is included. In the present experiment, it is estimated that the observed efficiency of 50% would have been about 60% in the absence of the ACI. These results verify the role of the ACI in reducing the efficiency of the gyrotron interaction.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental observation of the effect of aftercavity interaction in a depressed collector gyrotron oscillator

et al. 2007

View full text Add to dashboard Cite

show abstract

“…An intuitive solution to the issue with strong gyrotron magnetic field is to unwind it from 100 mT until a low value, typically around 10 mT [1]. If this process is adiabatic, a huge part of the electron transversal motion can be converted to the longitudinal one, however an adiabatic demagnetization will take place in a long distance, hence the collector geometry will be extremely long.…”

Section: Concept I: Non-adiabatic Demagnetizationmentioning

confidence: 99%

“…Nevertheless, there are still two concepts for gyrotron MDCs. In the first one, the gyrotron magnetic field is unwound in a special way utilizing well-controlled non-adiabatic transitions [1], whereas in the second concept, the electrons are sorted by the plasma E×B drift [2]. In the present work, these two concepts will be discussed and compared with each other.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Comparison between controlled non-adiabatic and E×B concepts for gyrotron multistage depressed collectors

Pagonakis

Illy

et al. 2017

EPJ Web Conf.

View full text Add to dashboard Cite

IntroductionGyrotrons are used as RF sources for ECH systems in nuclear fusion experiments. To obtain sufficient energy-gain factor, the future DEMOnstration fusion power plant demands highly efficient gyrotrons. The interaction between electron beam and microwave in a fusion gyrotron may have in the optimal case approximately 35 % efficiency (ηint). A large fraction of the input energy still remains in the spent electron beam. Up to ηcol ≈ 60 % of the spent beam energy can be recovered by a Single-stage Depressed Collector (SDC), which leads to an overall gyrotron efficiency of about 50 % according towhere ηRF ≈ 90 % is assumed to be the ratio between the output and the generated RF power. To achieve 60 % of gyrotron overall efficiency, the collector efficiency ηcol is required to be higher than 74 %. For this purpose, Multistage Depressed Collectors (MDC) should be introduced. In an MDC the spent electron beam will be sorted. Proper deceleration voltages (depression voltages) will be applied to each energy stage. Moreover, in order to reduce the thermal loading on the electrodes, the electron beam have to be eventually spread or swept on a large area. Designing an MDC for fusion gyrotrons is nontrivial. Three major reasons are listed here. Firstly, fusion gyrotrons works under high magnetic field, which has a dependence on the cyclotron frequency as ߱ ୡ = ݁ ‫ܤ‬ ߛ ݉ , with ߛ =

show abstract

“…A steep gradient in applied magnetic field near the voltage gap before the depressed collector-electrode, together with space charge, impart transverse deflection to beam electrons and provide trapping of electrons against leaving the collector [2]. While the known best practices in designing of depressed collectors [3][4][5][6][7][8][9][10] are used, the aforementioned key features set this collector aside from its predecessors, and are the core of the proposed collector novelty.…”

Section: Introductionmentioning

confidence: 99%

Partially–grounded depressed beam collector for the O-MBK and beyond

Jiang¹,

Teryaev²,

Shchelkunov³

et al. 2017

AIP Conference Proceedings

View full text Add to dashboard Cite

Abstract. To address RF source inefficiency, we present a design of an L-band multi-beam klystron with a new type of depressed collector. It comprises a grounded element, a magnetic lens, and an electrode held at negative potential. This collector allows recovery of a larger portion of energy in the spent electron beams than could a conventional depressed collector, and will increase the tube efficiency towards 80 % in a single stage.

show abstract

Design of a multistage depressed collector system for 1-MW CW gyrotrons. I. Trajectory control of primary and secondary electrons in a two-stage depressed collector

Cited by 56 publications

References 20 publications

Experimental observation of the effect of aftercavity interaction in a depressed collector gyrotron oscillator

Experimental observation of the effect of aftercavity interaction in a depressed collector gyrotron oscillator

Comparison between controlled non-adiabatic and E×B concepts for gyrotron multistage depressed collectors

Partially–grounded depressed beam collector for the O-MBK and beyond

Contact Info

Product

Resources

About