Sensitivity analysis of a 140-GHz coaxial gyrotron cavity with corrugations on the inner and outer walls

Design of MW-Class Coaxial Gyrotron Cavities With Mode-Converting Corrugation Operating at the Second Cyclotron Harmonic

“…In the same figure, the eigenvalues considering corrugation only on the insert are also given, calculated by the surface impedance model (SIM) [4]. It is evident that TE 17,10 is altered and divided into two coupled branches [19], [21], TE 17,10a and TE 17,10b , in the midsection (denoted by the shaded rectangle in the figures), whereas TE 37,18 is left almost unaffected, with a "dip" in the midsection due to the presence of the outer corrugation in that region. The Q factors of these modes in the two cavities (without and with outer corrugation) are given in Table IV, where it is evident that the Q factor of TE 37,18 increases, whereas the corresponding values of the branches of TE 17,10 decrease.…”

“…It should be noted that the selection of TE 37,18 as the operating mode is to some extent arbitrary, to demonstrate the generality of the method. Our mode-selection criteria demand only: 1) an eigenvalue similar to that of TE 34, 19 , in order to be compatible with 2 MW CW operation at 170 GHz and 2) a relative caustic radius similar to that of TE 34, 19 , so that a possible future implementation of our design could be combined with an electron gun similar to that used in existing European gyrotrons.…”

“…6 (for TE 37,18 ), where it is clearly seen that the curve of TE 8, p intersects that of TE 17,10 (and therefore coupling is expected to take place there), whereas TE 37,18 is unaffected in this specific C-range. The depth of the outer corrugation D is chosen at 0.1 mm, which has been shown to provide a good balance between the diffractive Q factor and the ohmic Q factor of the operating mode [19]. The eigenvalue curves versus the axial coordinate z of the cavity, including the outer corrugation (cavity UpA), are given in Fig.…”

“…This way of suppression of the first-harmonic competitors can be achieved by introducing azimuthal corrugation on the cavity's outer wall, with geometrical characteristics chosen accordingly for the appropriate coupling to be introduced. This concept was proposed in [18], where it was used in a coaxial gyrotron cavity for enhancing the operation of a first-harmonic gyrotron and was adopted in [19]. It was also used in [20], albeit without a coaxial insert, for low-power second-harmonic operation at 300 GHz.…”

Μελέτη Φαινομένων Αλληλεπίδρασης Ηλεκτρονικής Δέσμης Και Ηλεκτρομαγνητικών Κυμάτων Σε Σύνθετες Διατάξεις Κυματοδηγών

“…Να τονιστεί ότι αζιμουθιακές αυλακώσεις έχουν χρησιμοποιηθεί στις κοιλο τητες των γυροτρονι ων, αφού έτσι βελτιώνεται η επιλεκτικο τητα του ρυθμού λειτουργίας καταπιέζοντας τους ανταγωνιστικούς ρυθμούς. Μάλιστα, οι αυλακώσεις αυτές μπορούν να υπάρξουν στον εσωτερικό αγωγό της ομοαξονικής κοιλότητας [33], [50], [117], [118], αλλά έχουν προταθεί και για την εξωτερική επιφάνεια αυτής [49], [119]. Επιπρόσθετα, τέτοιες αυλακώσεις βρίσκουν εφαρμογή και στις λυχνίες οδεύοντος κύματος (gyro-TWA) ως διατάξεις αργού κύματος (slow-wave structures) [120]- [123].…”