DE1283405B - High performance broadband electron beam amplifier tubes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

HOIj

H03f

German class: 21g-13/17

Number: 1283 405

File number: P 12 83 405.8-35 (V 17701)

Filing date: December 8, 1959

Opening day: November 21, 1968

The present invention relates to high power broadband electron beam amplifier tubes in which the electron beam first an input cavity resonator, in which it is connected to the signal to be amplified (Input signal) is modulated in the speed, then further cavity resonators for amplification the modulation and finally passes through an unloaded output cavity resonator, from which the amplified signal (output signal) is coupled via one to the output cavity resonator Auxiliary cavity is removed.

In order to be able to amplify high-frequency energy in the microwave region with a high bandwidth, it is known To use running field tubes, as running field tubes are characterized by a particularly high bandwidth. However, if you want to generate high-frequency energy with high powers, for example pulse powers of several megawatts and continuous wave power of several kilowatts, then one can run-wave tubes operate only in a very narrow frequency band, ao there are also difficulties with the heat dissipation, since tubes for very high frequencies have to be built very small.

On the other hand, it is known that klystrons, for example, result in very high high-frequency energies range or let reinforce. The difficulty with klystrons, however, is to have a wide range achieve. It is known to increase the bandwidth of klystrons (see e.g. British patent specification 804 463), to design the individual cavity resonators as band filters, namely that an a further auxiliary cavity resonator is coupled to each cavity resonator transversely to the beam direction, whose respective natural frequency differs from the frequency of the cavity resonator to which it is coupled is. However, these well-known klystrons fell short of expectations in terms of their performance. In particular, difficulties arose when decoupling the power from the output resonator a.

The aim of the invention is therefore a broadband electron beam amplifier tube, the performance and bandwidth of the previous broadband electron beam amplifier tubes is superior for high performance.

A broadband electron beam amplifier tube of the type mentioned at the outset is characterized according to the invention in that the output cavity resonator and the auxiliary cavity resonator are tuned to the same frequency in the middle of the desired operating frequency range of the tube and are critically coupled to one another and that, furthermore, the auxiliary cavity resonator is loaded in such a way that its High quality broadband electron beam amplifier tube
high performance

Applicant:

Varian Associates, Palo Alto, Calif. (V. St. A.)

Representative:

Dr.-Ing. Wilhelm Reichel, patent attorney,

6000 Frankfurt

Named as inventor:

Robert Lawrence Jepsen, Los Altos;

Richard Lambert Walter,

Palo Alto, Calif. (V. St. A.)

Claimed priority:

V. St. v. America January 2, 1959 (784 494)

factor about 05 to 0.8 times the quality factor of the output cavity resonator for maximum power output if the output cavity were present alone.

In the broadband electron beam amplifier tube of the present invention the product of gain and bandwidth is much larger than with the known ones Tubes of a comparable type.

It is beneficial if the modulating cavity resonators are tuned to frequencies that are above are distributed over the operating frequency range of the tube, possibly even slightly beyond it.

An expedient development is characterized in that the auxiliary cavity resonator of an evacuated waveguide piece is formed, which is limited by two diaphragms, one of which the Coupling aperture to the output cavity resonator and the other the coupling aperture to connect to the auxiliary cavity resonator represents subsequent output waveguide.

It is also advantageous if the output cavity resonator has an inductive tuning device and the auxiliary cavity is provided with a capacitive tuning device.

Finally, it is also useful that the vacuum-tight closure of the output arrangement by a wave-permeable dielectric window takes place, which at a distance from the lead to the output waveguide

«09 638/1341

3 4

the coupling diaphragm in the output waveguide so that the return of the electrical

is. nen the peak high frequency voltage at the gap

In the following, the invention is limited to an output of the output cavity resonator and at

example in connection with the drawings lower the values transferred to the load

will be described in detail. 5 performance is significantly reduced in that

F i g. Fig. 1 schematically shows a high frequency tube, the load current is substantially constant. Of the

where a common cavity resonator can be used as the optimal output value of Rl by the following equation

circle is used; can be expressed as follows:

F i g. 2 shows a diagram which - depending on

speed of the frequency - the performance of a high fre- io r _l -. _. _s

frequency tube with a 2 η ^ίΙΒ K ¹¹⁵ P ¹ ' ⁵ ' designed according to the invention

Output circuit with the power of a corresponding being

High frequency tube with an output circuit with only _{A the ratio of the} peak high frequency voltage

a cavity resonator to be compared; _{on the load (which was}

^F JTI ^1S iJ j ^CHT is constructed ^{in elne} Klystronrohre tronenrückkehreffekts 15) is ⁱⁿ f ^{Top View} to the beam according to the invention and accelerating voltage ^1;

F1 g. 4 is a section through part of the tubes of the ^b * ^ö

F i g. 3, which is the output circuit V ^{according to the invention d} . ^he energy conversion efficiency of

shows. Direct current in high frequency in the middle of the band;

The high-frequency tubes according to the invention can ao χ j _s t the perveance of the electron beam, and their mode of operation divided into two sections. _TT,.

are divided according to F i g. 1 along the electron ^{P is the} high frequency peak output power.

The bandwidth of a klystron amplifier with a

drive part, the task of which is to modulate the simple output beam current formed in the usual way and secondly, a cavity resonator is therefore fundamentally restricted.

Output cavity resonator, the task of which is, In typical operating conditions, the above-

to extract energy from the modulated beam. In the sizes mentioned, approximately the following values:

In the case of a klystron, the drive part contains a "_ _{1 (} ,"",

Input cavity resonator and multiple cavity ° ~ ^m>

resonators to amplify the beam modulation. It 30 ^ ⁼ * ■ '* ■ *'

however, there are also other versions of the drive η = 35%>

partly possible. A modulation of the beam current can be K = 1, S- 10 ~ ⁶ amps / volt ³ ' ^a ,

z. B. by an interaction of the electron - P = 14 · 10 * watt

Beam with an electromagnetic wave- "_, l ™",

be called which occur on a delay line 35 ^L ~ '

long runs, as is the case with traveling wave tubes. so that an optimal value for Q = Q ₀ of 33 and

In the case of the klystron tubes, it is possible to produce a half-power bandwidth of around 3 ° / ₀ . The relatively constant beam modulation over an output power of an optimally loaded individual wide frequency range in the drive part thereby causes the cavity resonator as a function of the frequency that a staggered tuning is efficient by the dashed curve in FIG. 2 is used, ie by making each individual cavity reso.

nator of the drive part to one of a group of It has been found that the bandwidth, based on

Frequencies is tuned that over a frequency r times the power when using an optimal band are distributed equal to the desired Fre-loaded single cavity resonator (i.e. the frequency band of the tube or something larger. So can 45 bandwidth at which the performance of the invention z. B. with moderate reinforcements in the order of magnitude tube is always greater than a given fraction r of of 40 to 50 db and with a number of approximately the maximum available power in the middle of the band five or six cavities in the drive part the wear and tear of an optimally loaded individual hollow tuning be staggered in such a way that the entire band space resonator), approximately by a factor of 2 compared to width of the tube by the bandwidth of the output 50 which is possible with a single cavity resonator is limited. the same value can be increased by adding a second,

The half power bandwidth of an output circuit synchronously tuned cavity resonator with the with a single cavity resonator can be coupled to the output cavity resonator and the Neglecting the losses of the cavity resonance load on the second cavity resonator contors and the radiation exposure is centered by the following slide 55. In more specific terms, it can be said equation for the reciprocal of "g", d. H. the quality factor that in a range of r-values from about 0.5 to 0.8 of the output cavity resonator: an improvement in the optimal bandwidth - related

gen to r times the maximum performance of the execution

b _w = —- = -, with only one cavity resonator - by a factor

Q Rl 60 of the order of

where JR _{0 is} the characteristic impedance of the cavity and Rl is the load impedance.

The value R ₀ is generally for reasons of
Electron interaction in the design of the column 65 can be obtained by the fact that a second hollow

the running pipe is fixed and is the same as the capacitive reaction space resonator (auxiliary cavity resonator) is used,

dance of the gap. For maximum efficiency, the critically generated with the output cavity resonator

an optimal value of the load impedance Rl, is coupled and which is loaded in such a way that the quality

5 6

factor Q _{2 of} the coupled cavity resonator in space resonator 27 passes through. Which lies in the cavity of the order of Q ₂ = rQ _0. The "critical" resonator 27 induced by the modulated beam coupling between the cavity resonators is (into electromagnetic energy with the help of a waveguide 43 divided in accordance with the usual terminology) (which is defined in detail below by the fact that the coupling is signed by one is) coupled out via a vacuum-tight window 43 'critical value (weak coupling) via a kri- and transferred to an outer waveguide (non-table value to a supercritical value (strong shown) which increases at the flange 44 on coupling) when the Impedance of the excluded.

transition circle from a monovalent to a two-valued In F i g. 4 is that made according to the invention

Function of frequency changes. io decoupling arrangement shown. The one in general

The frequency response for an output circuit with two rectangular output cavity resonators 27

_TT ,,. ... 1 . . . j. , is at one end through a cover 51

Cavity resonators for r = - = - is strongly off-, ,,,,, ·. . _n , « _TT ..

2 completed, the vacuum-tight, z. B. by hard drawn curve in F i g. 2 shown. In this case solder with the wall 52 of the cavity resonator

■ j j- TT lui · *. · ,, .. / 1 \ j 15 is connected. The opposite end of the hollow

wu-d the half-power bandwidth (r = _y ) around the _{space resonator} £ & _through * an _{inner bend53}

Factor 2 compared to the bandwidth when used. The cavity resonator 27 is coupled via the bees of a single cavity resonator (dashed curve) the opening 53 'of the inner diaphragm 53 with an auxiliary cavity resonator 54 with the same capacitance of the interaction gap, which increases between the cavity resonator 54 when the two cavity resonators are critically ao inner diaphragm 53 and an outer one Aperture 55 are coupled and the quality factor Q _{2 of} the coupled is arranged, which forms a discontinuity in the course of the right-hand cavity resonator equal to half of the quality-square output waveguide. The output factor Q _{0 of} an optimally loaded individual waveguide is set in the adjoining waveguide space resonator. section 57 continued, which on the outer panel 55 leg F i g. 3 is a multi-chamber klystron amplifier as is solidified and shown in the curved waveguide tube of high power. The beam generation 58 passes over. The auxiliary cavity resonator 54 is according to system 11 is heated via a heating connection 12 and externally loaded by the diaphragm 55, the diaphragm of which supplies an electron beam, which the tube in the longitudinal opening is denoted by 55 '. Interspersed on the waveguide direction. The jet is accelerated with the aid of a section 57, followed by a suction nozzle 59, of the earthed ring-shaped anode 14, in that a high negative potential can have melted at the cathode connection after the evacuation process is complete. The capacity of the cavity-13 is placed. The cathode connection 13 is opposite resonator 27 is isolated by the formation of the changeover the grounded body 16 by an insulating cylinder 15 effective gap 17 for the purpose of maximum utilization of the. The beam then passes through a number of beam modulations determined in a conventional manner. The cylindrical running tubes 15 'which have a number of 35 frequencies of the cavity resonator 27 can be inductively tuned to generally rectangular cavity resonators 21 by connecting a tuning piston 61 in to 27; between the running tubes are which the cover 51 is displaced, the vacuum interaction gap 17 being arranged. The beam is secured by a bellows 62, which is then captured by an electrode 28 between them. The electric piston and the cover are melted. A thin electron beam is generated by the action of an outer 40 tuning diaphragm 64, e.g. B. made of a copper-clad Mo magnet system (not shown), which is arranged between ring metal, is arranged on the membrane plate 63 of the piston 61, shaped magnetic pole pieces 29 and 31, fastened, for example, by rivets, and the ends of the membrane are guided in bundles. The resonance frequency of the resonance 64 is ζ. B. beguile by brazing in slots 21 to 27 is fastened with the help of a number of tuning rods 32 set on opposite sides, which are cut on the pole piece 31 45 of the wall 52 so that the meme are mounted and with the tuning assemblies 33 bran 64 ends close to the side surfaces, which are connected in parallel to the setting from Ab- to the plane of the drawing.

Voicing diaphragms 64 within each cavity - The tuning of the auxiliary cavity resonator 54

to be able to vary resonators. The tube is fluid- is made by making the distance between a solid

keitsgekühlt, the liquid via connections 35, 50 tuning part 65 and a movable tuning part 66

Pipes 35 'and an output line 36 is guided. is changed. The movement of the tuning part 66

The alignment and the rigid construction of the tube can be done with the aid of a tuning piston 67, the

through a number of stiffening plates 37 into the interior of the cavity resonator 54 in a similar manner

as well as by a number of stiffening rods 38 is inserted vacuum-tight like the above

ensures the transversely through the plates 37 55 piston 61. The tuning effect of the part 66 can

walk. For shielding from X-rays, which are improved by the fact that a thin tuning

run out of the tube, shields, e.g. B. membrane 68 between the part 66 and the wall

Lead screens 39 may be provided. 56 of the cavity resonator is attached. A little

The electromagnetic energy that will be amplified through passage 69 is provided in the part 66 in order to

is to avoid the input cavity resonator 21 over 60 that on both sides of the thin membrane

a coaxial cable 41 and, via a coupling branch 68, undesired pressure differences arise,

The parameters of the cavity resonators 27 and 54

lation of the electron beam at the gap 17 of the Re- are adjusted so that the above-mentioned property

sonators 21 is caused. The beam is obtained in the shaft of the large bandwidth. In addition

Cavity resonators 22, 23, 24, 25, 26 continue to play 65 before assembling the diaphragm

speed-modulated, so that a strong module opening 55 'into the plate forming the diaphragm 55

tion of the beam current is caused before the cut, until the state of maximum loading

Ray the interaction gap in the output cavity with respect to the auxiliary cavity resonator 54

results. Then, the aperture 53 'is cut in the plate forming the aperture 53 until a state the critical coupling between the cavity resonators 27 and 54 is achieved. It should be noted that in the illustrated preferred embodiment of the invention the auxiliary cavity resonator 54 is coupled to the output cavity resonator 27 via a relatively thin-walled diaphragm 53, without the need for a vacuum-tight window between these parts. This arrangement has the advantage that the dangerous cracking of the window is avoided and the effects of X-rays are suppressed which can occur when a window is placed near the high energy beam. In addition, unwanted transformation effects that can occur can be avoided. if the distance between the coupled cavity resonators is too great.

As an example of a tube designed according to the invention, a klystron amplifier with an Im- ao pulse power of 1 MW, which is operated on the band S (1700 to 5000 MHz) and in which the auxiliary cavity resonator 54 has a load

Has value ß ₂ - -y ßo. The cavity resonators 27 and 54 were tuned to the center frequency of the desired frequency range. The cavity resonators of the drive part were tuned staggered in relation to the center frequency in the following way: cavity resonator 21 minus 1.8 ° / ₀ ; Cavity 22 plus 1.8%; Cavity 23 plus 3%; Cavity resonator 24 minus 2.1%; Cavity 25 plus 2.1%; Cavity 26 plus 2.8%. Under typical operating conditions, such a tube had a half-power bandwidth of about 5 ° / ₀ as compared to a bandwidth of only 2.8 ° / o by using only one Ausgangshohlraumresonators under similar operating conditions. Significantly greater improvements in bandwidth can be achieved at higher powers and lower frequencies.

Claims (5)

Patent claims: 1. High power broadband electron beam amplifier tube in which the electron beam is initially an input cavity resonator in which it is connected to the signal to be amplified (input signal) in the speed is modulated, then further cavity resonators to amplify the modulation and finally passes through an unloaded output cavity from which the amplified Signal (output signal) through an auxiliary cavity resonator coupled to the output cavity is taken, characterized in that the output cavity resonator (27) and the auxiliary cavity resonator (54) on the same frequency in the middle range tuned to the desired operating frequency range of the tube and critically coupled to one another are and that furthermore the auxiliary cavity resonator (54) is loaded so that its quality factor about 0.5 to 0.8 times the quality factor of the output cavity resonator (27) for maximum power output if the output cavity resonator (27) were present alone. 2. Amplifier tube according to claim 1 in the manner of a multi-chamber klystron, characterized in that that the modulating cavity resonators (21 to 26) are tuned to frequencies that Distributed over the operating frequency range of the tube, possibly even a little further are. 3. amplifier tube according to claim 1 or 2, characterized in that the auxiliary cavity resonator (54) is formed by an evacuated waveguide section (56) which is bounded by two diaphragms (53, 55) of which one (53) is the coupling diaphragm to the output cavity resonator (27) and the other (55) the coupling diaphragm to the output waveguide connected to the auxiliary cavity resonator (54) (57, 58) represents. 4. amplifier tube according to claim 3, characterized in that the output cavity resonator (27) with an inductive tuning device (61, 63, 64) and the auxiliary cavity resonator (54) with a capacitive tuning device (66, 67) is provided. 5. amplifier tube according to claim 3 or 4, characterized in that the vacuum-tight closure the output arrangement takes place through a wave-permeable dielectric window (43 '), that at a distance from the coupling diaphragm (55) leading to the output waveguide (57, 58) in the output waveguide (57, 58) is arranged. References considered: British Patent No. 804,463; U.S. Patent Nos. 2,789,250, 2,798,184. 1 sheet of drawings 809 638/1341 11.63 © Bundesdruckerei Berlin