DE2138799A1 - Process for the stable operation of a pipe with delay lines from coupled cavities and pipes suitable for this - Google Patents

Description

are aligned with a line generally parallel to the beam axis. This was flush out protection arrangement allows for higher interaction impedance in the range of 1.5T to 1 _T 8T rad phase shift per cavity period without band edge instability.

Starting point of the invention:

Attempts have already been made with delay lines from coupled cavities the higher-frequency slot mode and the lower-frequency cavity mode at the upper band

* to coalesce the edge of the cavity mode in order to significantly increase the cold bandwidth of the composite delay line. In this line of coupled cavities, however, the coupling slots in successive end walls of the cavities were offset from one another, so that the waves traveling through the delay line cross the interaction gaps meandering like a folded waveguide »The problem with this form is» that although the cold bandwidth of the line is considerably increased by the coalition of the slot and cavity modes, the backward wave branch of the ο -β diagram is in the part of the reveal 2.T phase shift has a considerable Veehsel effect impedance per period and the line tends to break out into backward wave oscillations at the ZT- * point of the cavity mode. Despite the koalitiaa of the slot and space modes in the line with offset coupled cavities, the usable bandwidth of the warm tube is considerably smaller than the cold bandwidth of the line. Lines made of coupled cavities with offset coalesced slot and cavity ilodi are therefore not used in micro-cone tubes

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made available from coupled cavities and microwave tubes provided with them

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According to a ³ special Austoild ^ mg d @ ^ I ^ fiadMag, the beam is cumislatively in the range of I ₉ OiT ^ Is 2 _B OT rad phase shift per cavity of the Y @ rz8gerwnggl @ itrag from the coupled cavities The interactions in the line ensure that the alternating impedance of the line is increased.

The invention is to be explained based on ά®τ geietensg siiJiar; show it

1 shows a schematic, partly as a block diagram _9, partly as a schematic drawing and partly as a schematic section through an older® Mkrbwellenröhre;

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-BAD ORIGINAL

FIG. 2 shows, in perspective, a coupled cavity of the line according to FIG. 1; FIG.

3 shows a section through another embodiment the parts enclosed by a circular line in FIG. 1 with features of the invention;

FIG. 4 is a schematic perspective view of a coupled hollow section of the line according to FIG.

Fig. 5 is a -β diagram to illustrate the

Burehlaßbandes a line for the hollow ridge Slot mode and co-formed cavity and slot modes?

Fig «β the normalized frequency plotted against the -» 0 middle ^; Phase shift per cavity to visualize the dispersion characteristic of a line composed of offset coupled cavities and delay lines with flattened, coalesced cavities after the expansion.

di © Wecläselffektirngsspaltimpedanz plotted against the normalized phase shift per cavity &% w Veranseheiulichung the characteristics of a successful line with aligned coalesced cavities and with offset coalesced cavities aj and

FIg ₉ 6 shows the relationship between the input power in kilowatts, plotted against the frequency in

ztH · Veransehaulichiang of the output characteristic © iasr ¥ other field tube with features of the invention.

The tube shown in Fig. 1 comprises an electron gun 2 on * which is arranged so that an electron beam 3 via an elongated beam path to a collector

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BATH ORIGINAL

is projected where the ray is captured and its energy is discharged. A delay line 5 of coupled cavities is along the beam path 3 for cumulative arranged electromagnetic interaction with the beam. The line 5 is in one embodiment for operation that part of the O- (J- »diagram that separates successive Interaction columns of the line result in a phase shift of 1. OT to 2.01 "· With others Words, the line is operated in the second space harmonic of the u - β diagram in order to use an input coupler, For example, an input coupling diaphragm 6 to amplify vibrational energy coupled to the line 5. the Vibration energy enters into cumulative interaction with the beam to produce an amplified output vibration, which is coupled from the downstream end of the line via a decoupling diaphragm 7 in a waveguide 8, which with a load, not shown, is in connection, for example an antenna.

The illustrated coupled cavity delay line has an elongated array of cavity resonators on j which are coupled via a series of coupling slots 11 staggered along the conduit in opposite end walls of each of the cavities. More precisely, the coupling slots 11 alternate from one side of the beam to the other, like the oscillation energy in main direction of the beam moves through the line. This is hereinafter referred to as "offset" coupling and is in Fig. 2 shown.

This offset-coupled delay line 5 has the Q-F1 diagram shown in FIG. 5 with curves 12 and 13. Curve 12 represents the ω- / 2 diagram for the first or low-frequency passband of the cavity mode, and curve 13 the ω- / ^ diagram of the higher passband of the "slot mode of the offset-coupled line 5. Through ent"

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Speaking dimensioning of the cavities 9 and tuning of the resonance frequency of the slots 11 to a frequency clearly This line is to be coalesced under the upper passband edge of the cavity mode. If the two modes, namely the slot mode and the cavity mode are coalesced «results in the c * -0 diagram according to curves 14 and 15 in Fig. 5 for the line with staggered slots. So the cold bandwidth for the coalized »staggered line is significantly higher compared to the leadership before the Coalition of Modi. However, as can be seen in FIG. 7, the interaction impedance increases for the uncoalized, offset line to very high impedances for phase shifts per Cavity between 1.6T and 2.01 "while the impedance for the coalesced line becomes constant at a relatively high value.

This means that for reasonable ratios of the slot inductance to the slot capacitance, i.e. significantly greater than zero, the beam velocity for the interaction must generally be set below 1 _t 5T phase shift per cavity, or an interaction due to the high interaction impedance in the vicinity of 2.0ir phase shift per cavity is obtained so that the tube vibrates.

Switching on must therefore be carried out very carefully, to achieve that the beam is switched on in such a way that the beam voltage is not caused by a lower beam voltage runs as they operate between 1.0iT and 1.51Γ Phase shift per cavity is required, or the line starts to vibrate.

Another disadvantage for operation in the 1 »0f to 1.5T range rad phase shift per cavity is that at

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effective gap impedance of the co-formed, aligned line tends to phase out in the vicinity of the point 2Trad The shift per cavity falls significantly, while the array of curves for the mutual action gap impedance according to FIG. 1 and 2 tends towards infinity at operating point 2T.

In the case of the aligned coalesced line according to FIGS. 3 and 4, can the beam voltage run through the operating point 2T? without instabilities occurring in the tube and without causing backward wave oscillations "The line according to FIGS. 3 and 4 can thus be operated in the range of 1" 5T to 1.8T rad phase shift per cavity without instabilities occurring ". As a result, the period of the line can be increased considerably for a certain operating frequency, which results in a higher interaction gap impedance for the line or, if instead more emphasis is placed on wall thickness than on mutual effect gap impedance, the heat capacity of the line can be considerably higher than that of the offset line according to FIGS. 1 and 2 be enlarged. _:

In particular, the coalesced, aligned line according to FIGS. 3 and 4 can be operated with a normalized phase shift per cavity between 1.6T and 1.8TT rad per cavity. This represents about a 25 % greater period length for the coalesced, aligned pipe compared to the coagulated staggered pipe. This additional length can either be placed in the cavity height , especially to increase the interaction impedance, or can be used to increase the wall thickness between cavities 9 gu. For example, if the initial wall thickness represents 25 % of the period and a cavity height of 75% is provided, a 25 # increase in the period results in the same cavity height being used in conjunction with twice the wall thickness between cavities 9

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can. This practically doubles the ability of the line to absorb energy.

Another important feature of the co-ordinated aligned line 19 is its immunity to band edge instabilities. For the delay lines ₈ described above with a more common phase characteristic 8 such as curves 25 and 26 in Fig. 7 and curves 27 and 28 in Fig. 6, the slope in the phase diagram approximates the band edges zero and ensures a high interaction impedance at these frequencies. Since the line matches are also generally poor at these frequencies, monotronous resonance oscillations often occur unless special construction techniques are used to suppress these oscillations. Again due to the unique properties of the coalesced, aligned lines 19, the cavity mode which creates the interaction fields in the cavity gaps is not routed at the 2T point in the line. This is basically due to the fact that in the coalesced, aligned construction, the slots resonate at this frequency, while the slot resonance frequency in a coalesced offset line is always below this point in frequency. The cavity gap mode does not receive any noticeable excitation in the aligned coalesced line under conditions where the slots are of high impedance. In a certain sense, this is analogous to the attempt to excite a half-wave section of an idle transmission line by generating a voltage maximum in the middle instead of at the ends of the line. The almost complete suppression of the gap interaction impedance associated with the line in alignment at the 2'fc point has been observed in working tubes

The total gap exchange action impedance V "of a Leitutsg

zP

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of coupled cabbage spaces is mainly determined by the ratio R of the cavity and the slope of the phase curve

set. The interaction impedance is always there relatively high, v / o the group velocity of the line low 1st · The effective beam interaction impedance also depends on the gap coupling coefficient "so that a figure of merit ₂ for lines of coupled cavities shows the value (gj (ij_J 7, the entire Spaltwechselwirkungsimpeaanz the set of lines presented in Fig. 6. All lines are R.

calculated for * ts 50. The one with the staggered line after Figures 1 and 2 obtained impedances lie between the limits of curves A and B. The coalesced aligned * Line tends to "produce higher impedances at low values of / 3_" because of the low group speed "associated with the line under such conditions.

Measured impedance data agree well with the calculated equivalent circuit diagram data, with the exception of the Prediction of the interaction impedance zero »the experimented, at point 2T in the case of the coalesced aligned Line is observed.

In a micro-wave tube of the type shown in FIGS. 3 and 4, which was designed for operation in the Ku band, the Fhaeenkurve corresponded to the curve “which has a ratio of 1000 in FIGS. 6 and 7. Such a tube was operated with a perveance of 0.8 10 and a beam voltage of 20 >> 7 kV with a beam current of 2.35 amperes. FIG. 6 shows the output power as a function of the frequency. The measured maximum power was 8.4 kV continuous wave with a 1 dB bandwidth of Z ^CA and a modulation gain of 34.7 dB. The tube was built without a jet modulator electrode. The line was also built

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Claims (1)

V1 P 298 D Claims 1 »Method for stably operating a tube with einer'Verzögerungsleitung of coupled cavities *, the cumulative electromagnetic interaction with the beam in the, range from 1.0 to 2 ^ ₉ 0iTr && phase shift; per Psricds the delay line operates by gekea _s η". ζ e --ich η et ρ - that the coupling slits between beaasKbar · th cavity resonators of the line are tuned to a slot; · = ^ as © "nance mode" which is essentially the frequency of the upper band edge of the cavity. of the delay line is _e to the low frequency edge of the Durchlsßbandes the slot mode having the Durchlaßbandkante-frequency of the cavity mode. ko so that the width of the passband of the composite delay line is considerably increased and the blocking "frequency band between the cavity" and seat-seat modes is eliminated 2 ο A method according to claim 1, characterized gekenaze leans _s da3 the Soppelsehlitze in opposite 3 Indwäade- ^ edes werdsn set of coupled cavities such _p which they lie on one side of the beam Wages and fall substantially in a plane dc through the axis. -j ray and the geometric centers of the coupling committee de «» finiert £ st _o 3. The method according to claim 2, characterized gekeß & z «i level t that the loppalsehlitze substantially in straight lines Line lie «. 20981 1/1111 BATH ORIGINAL (4. Microwave tube for carrying out the method according to claim 1, 2 or 3 »with a beam generating device, a delay line consisting of a series of cavity resonators, which are arranged along the beam path and are coupled to a series of vibration energy coupling slots» which are in the common end walls are disposed of cavity resonators, so that a delay line with a Hohlraumraodus-pass frequency band and a slot mode is formed »pass frequency band, characterized _s in that the slots are dimensioned relative to the dimensions of the cavity resonators so that its resonant frequency substantially at the upper band edge frequency of the cavity mode is to coalesce the high frequency band edge of the cavity mode with the low frequency baad edge of the slot mode to increase the width of the pass band for the composite delay line » 5. Tube according to claim 4, characterized in that that the geometric centers of the coupling slots in opposite end walls of each of the cavities, respectively lie on one side of the beam path and essentially lie in a plane which is defined by the axis of the beam path and the centers of the coupling slots. 6. Tube according to claim 4 or 5 _9, characterized in that the delay line of coupled cavities is a backward wave line for the fundamental space harmonic. 209811/1111 Blank page