Coherent radiation from spatiotemporally modulated gyrating electron beams.
Coherent radiation from spatiotemporally modulated gyrating electron beams.
复制标题
来自时空调制旋转电子束的相干辐射。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
Hirshfield
中科院分区：
文献类型：
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作者：
Hirshfield
回旋自激加速器中的电子束沿下锥形轴对称静磁场绝热传输时，可以作为绕轴螺旋传播。这种螺旋线以加速器的基本泵浦频率在时间上旋转，并在空间上随轴向螺距变化，该螺距取决于泵浦频率和本地回转频率之间的差值。我们证明了音调可以自由调节，以便在泵浦频率的每一次谐波处，光束与导波快波之间的频率和波数都匹配。结果，在波幅为一阶的过程中，可以发生从波束到波的功率转移。给出了基于这一概念的谐波转换器的例子，适用于94 GHz和1000 GHz的源，其磁场不超过10公斤。由于电子可以在相互作用过程中保持相干性，因此可以推测能量转移可以相当有效。与相应的腔回旋管振荡器和非低温磁体相比，这种谐波转换器在大功率应用中的实际优势可能包括缓解模式竞争、直接输出耦合、较低的壁热负荷和更简单的集束器。
An electron beam from a cyclotron autoresonant accelerator passing adiabatically along a down-tapered axisymmetric static magnetic field can propagate as an axis-encircling helix. This helix rotates temporally at the fundamental pump frequency of the accelerator, and varies spatially with an axial pitch that depends upon the difference between the pump frequency and the local gyrofrequency. We show that the pitch can thus be freely adjusted so as to allow both frequency and wave-number matching between the beam and a guided fast wave at each harmonic of the pump frequency. As a result, power transfer from beam to wave can occur in a process that is first order in the wave amplitude. Examples of a harmonic converter based on this concept are given for 94- and 1000-GHz sources employing magnetic fields no stronger than 10 kG. Since the electrons can maintain phase coherence during the interaction, one can speculate that the power transfer can be fairly efficient. Practical advantages of this harmonic converter for high-power applications may include alleviation of mode competition, direct output coupling, lower wall heat loading, and simpler beam collectors than for corresponding cavity gyrotron oscillators and noncryogenic magnets.