EP1465285B1 - Coaxial line with forced cooling - Google Patents

Description

The invention relates to a coaxial line according to the preamble of claim 1. Such a device is known from DE 101 08 843 A known.

Certain applications, e.g. In the field of plasma physics, require the supply of RF power of more than 1MW by means of coaxial cables whose diameter can not be made arbitrarily large for mechanical and / or RF technical reasons. Especially in continuous wave operation, therefore, due to ohmic losses and in the area of the insulating supports, mainly due to dielectric losses, such a large amount of heat per unit of time arises on the inner conductor that forced cooling is necessary. According to the prior art, a gaseous medium is passed through the annular space between the inner conductor and the outer conductor for forced cooling. However, the heat loss amount that can be dissipated in this way is limited, especially since the pressure and thus the flow velocity of the gaseous cooling medium can not be increased arbitrarily for a number of reasons.

For cooling of superconducting coaxial cables such as from US-A-3,946,141 As is well known, liquid helium has been used, but extensive and expensive ancillary equipment is needed.

The invention has for its object to provide a coaxial line with improved cooling ability.

This object is achieved by the features specified in the characterizing part of claim 1.

As a result, considerably higher RF powers than before can be transmitted over the line for a given line diameter both in pulse and in continuous wave mode, especially when using a liquid cooling medium.

The coaxial line is characterized in that in the tubular inner conductor, a tube of smaller diameter closed at its two ends is arranged coaxially and that the annular space between this tube and the tubular inner conductor communicates with the channels in the Isolierstoffstützen. Then, the cooling medium flows only through the annular gap or annulus between the tubular inner conductor and the enclosed by this and expediently also mounted at its ends to the relevant Innenleiterverbindungsstücken tube smaller diameter. With sufficient design of the ring cross-section, the cooling effect remains virtually unchanged, while significantly lower weight of the line and less effort required for the coolant circulation ancillaries.

The cooling of the thermally much less loaded outer conductor is not the subject of the invention. It can be done by means mounted on the outer conductor cooling fins, cooling coils or similar measures known per se.

These insulating supports can be formed as outwardly guided through the outer conductor tubes (claim 2). Depending on the radial plane, three or four insulating supports, which are offset by 120 ° or 90 °, are generally sufficient. Depending on the required coolant flow, it may be sufficient to use only a portion of these insulating supports for supplying and discharging the cooling medium. By appropriate structural design of the Isolierstoffstützen is then to ensure that no additional distortions of the RF field in the circumferential direction arise.

Alternatively, the Isolierstoffstützen may be formed as a solid discs with radial channels (claim 3), for example, to divide the line into longitudinally-tight sections.

Preferably, the channels of the Isolierstoffstützen open into a chamber in an inner conductor connector at the end of the tubular inner conductor (claim 4). The inner conductor connector also forms the bearing for the respective end of the tubular inner conductor.

Suitably, the tube is the end face closed by a formed on the inner conductor connector flange (claim 5).

Instead, the tube may be closed at the end also via flanges, which are mounted axially and radially floating on the respective inner conductor connecting piece (claim 6). In particular, the play in the axial direction avoids the emergence of axial constraining forces, either as a result of manufacturing tolerances, either because of different heat-dependent changes in length of the tube and this surrounding, tubular inner conductor.

In addition, the tube may have at its outer periphery against the inner wall of the tubular inner conductor supporting centering (claim 7). This ensures that the cross-section of the annular gap or annular space between the tubular inner conductor and the tube enclosed by it remains constant in the circumferential direction, uzw. even if the coaxial line overall describes a slight arc in the longitudinal direction.

The centering elements may be arranged along a helix, i. be arranged helically around the tube (claim 8), uzw. also as individual, spaced-apart elements.

Instead, the centering elements may consist of axially extending webs (claim 9). This is aerodynamically more favorable than the arrangement along a helix.

In all embodiments, the centering elements may be integral with the tube. (Claim 10). This is manufacturing technology particularly advantageous if the tube is not made of metal but of plastic.

Alternatively, the tubular inner conductor may have in its jacket axial channels communicating with the channels in the Isolierstoffstützen (claim 11). Such an inner conductor can be made inexpensively, for example, as an extruded aluminum profile.

At a greater length, the coaxial line consists of separately cooled, electrically and mechanically interconnected sections (claim 12).

In this case, the tubular inner conductors of adjoining sections of the line are best connected to one another via complementary plug connections (claim 13).

Such a complementary plug connection may consist of a flange plate terminating the chamber of the respective inner conductor connection with an axially extending first annular collar which engages over a second annular collar on the flange plate of the subsequent line section and in turn is contactingly overlapped by a ring of axially extending contact springs, which contacts the second Concentric annular collar surrounds (claim 14). The first ring collar forms a kind of a plug, the second annular collar together with the contact spring ring the complementary coupler.

Suitably, the free ends of the contact springs of the contact spring ring lie in a radial plane which is axially set back relative to the end face of the second annular collar containing radial plane (claim 15). As a result, pre-centering is achieved when juxtaposing two line sections, in which the first annular collar engages over the second annular collar before the end face of the first annular collar comes to rest under the contact springs. This avoids that due to alignment springs to a damage of the contact springs and therefore to a non-uniform contact over the circumference, which would lead to the formation of reflections and intermodulation products as well as in the transmitted currents of several 1000 amps overheating and possibly Burning the contact surfaces would result.

Suitably, the flange plates carrying the contacting annular collars are screwed to the associated inner conductor connecting pieces (claim 16). This facilitates the conversion of the joints of mating on domes and vice versa. Furthermore, the contact spring ring can be manufactured as a single part of the most suitable material for it. He will then be at his root with the Gland plate welded.

Since the tubular inner conductor is thermally charged despite cooling much higher than the outer conductor, the occurring thermal expansion must be taken into account. For this purpose, the Isolierstoffstützen can be passed in the axial direction floating through the outer conductor (claim 17).

One possibility for this is that the guided through the outer conductor end of the Isolierstoffstütze is enclosed by a guide flange, which is held in the axial direction floating in a recess of the outer conductor, radially elastic sealed against this and contacted with him radially elastic (claim 18). The radially elastic sealing can take place by means of O-rings and the radially elastic contacting can be realized by means of a helically wound and annularly closed contact element, a so-called worm contact.

Instead, each of the tubular insulating material supports can be tilted with its inner end in the inner conductor connector and with its outer end in the Außenleiterwandung in an axial plane tilted (claim 19). The tiltable mounting can be realized, for example, by annular beads at the respective ends of the insulating supports in conjunction with dome-shaped counter-bearings in the relevant recordings on the inner conductor connector and on a passage through the wall of the outer conductor.

Fig. 1

einen verkürzt dargestellten Leitungsabschnitt im Längsschnitt;

Fig. 2

eine teilweise im Schnitt gehaltene Stirnansicht;

Fig. 3

die zur Verbindung miteinander bestimmten Endbereiche von zwei aufeinander folgenden Leitungsabschnitten;

Fig. 4

eine Ansicht des in den Fig. 3 und 5 dargestellten Dichtungs- und Kontaktierungsrings zwischen den Verbindungsflanschen der Aussenleiter;

Fig. 5

die gleichen Endbereiche wie in Fig. 3 nach Herstellung der Verbindung;

Fig. 6

eine teilweise im Schnitt gehaltene Seitenansicht eines als 90°-Bogen ausgeführten Leitungsabschnittes;

Fig. 7

den Endbereich eines Leitungsabschnitts im Längsschnitt mit einer alternativen Ausführung der Isolierstoffstützen;

Fig. 8

die Durchführung einer Isolierstoffstütze durch den Außenleiter, überwiegend im Schnitt und in vergrößertem Maßstab als Stirnansicht;

Fig. 9

eine andere Ausführungsform der Durchführung der Isolierstoffstütze im Längsschnitt und in vergrößertem Maßstab;

Fig. 10

eine zu Fig. 9 alternative Ausführungsform;

Fig. 11

eine Stirnansicht einer anderen Ausführungsform des Innenleiterrohrs;

Fig. 12

einen Leitungsabschnitt ähnlich Fig. 1, jedoch in einer anderen Ausführungsform;

Fig. 13

einen Schnitt längs der Linie XIII-XIII in Figur 12.

In the drawing, an embodiment of a coaxial line according to the invention is shown. It shows:

Fig. 1

a shortened line section shown in Longitudinal section;

Fig. 2

a partially sectioned front view;

Fig. 3

the end portions of two consecutive pipe sections intended for connection with each other;

Fig. 4

a view of the in the Fig. 3 and 5 illustrated sealing and contacting ring between the connecting flanges of the outer conductor;

Fig. 5

the same end areas as in Fig. 3 after preparation of the compound;

Fig. 6

a partially sectioned side view of a designed as a 90 ° bend line section;

Fig. 7

the end portion of a line section in longitudinal section with an alternative embodiment of the Isolierstoffstützen;

Fig. 8

the implementation of a Isolierstoffstütze by the outer conductor, mainly in section and on an enlarged scale as an end view;

Fig. 9

another embodiment of the implementation of the Isolierstoffstütze in longitudinal section and on an enlarged scale;

Fig. 10

one too Fig. 9 alternative embodiment;

Fig. 11

an end view of another embodiment of the inner conductor tube;

Fig. 12

a line section similar Fig. 1 but in another embodiment;

Fig. 13

a section along the line XIII-XIII in FIG. 12 ,

FIG. 1 shows - shortened in the longitudinal direction - a portion of a coolable coaxial cable for transmitting very high RF power. The line comprises an outer conductor tube 1, which is equipped at its two ends with connecting flanges 2. The diameter of the outer conductor tube 1 may be in the range of 120 mm or more. The outer conductor 1 coaxially surrounds a tubular inner conductor 3, which is equipped at its two ends with inner conductor connecting pieces 4. Each of the inner conductor connecting pieces 4 is mounted on insulating supports 5 made of a suitable dielectric, preferably a ceramic material, in the corresponding connecting flanges 2, and the like. in this embodiment, four each insulating supports 5, as shown Fig. 2 evident. The Isolierstoffstützen 5 are tubular and sealed by the connecting flanges 2 led to the outside. Their inner ends are sealed (see the illustrated grooves for receiving O-rings) in recesses of the inner conductor connecting pieces 4th

Chambers 6 are formed in the inner conductor connecting pieces 4 and communicate with the channels 5.1 in the insulating supports 5 via bores such as 6.1. The inner conductor connecting pieces 4 have a first flange 4.1, which is overlapped by the respective end of the inner conductor tube 3. With this flange 4.1, the relevant end of the inner conductor tube 3 is preferably welded continuously over a circumferential seam. Alternatively, between the periphery of the flange 4.1 and the end of the inner conductor tube 3, an O-ring may be provided (not shown).

Then, in addition, an HF-technically perfect contact between the flange 4.1 and the inner conductor tube 3 is necessary. Axially spaced from the first flange 4.1, the inner conductor links 4 have a second flange 4.2 of smaller diameter. This is overlapped by the respective end of a coaxially arranged in the inner conductor tube 3 tube 7 of smaller diameter. This tube 7 is not in the field-filled space and therefore does not have to be made of metal. The coaxial annular space 8 between the tubular inner conductor 3 and the tube 7 communicates via holes 6.3 apertures 6.2 with the chamber 6 in the respective inner conductor connector 4, see also Fig. 2 ,

Via the led out terminals of the insulator supports 5, at one end of the line section, a preferably liquid cooling medium, e.g. Water, fed, which then flows through the annular space 8 and is withdrawn through the Isolierstoffstützen 5 at the other end of the line section. In this way, the tubular inner conductor 3 and the inner conductor connecting pieces 4 are cooled from the inside.

On its side facing away from the tubular inner conductor 2, each chamber 6 is closed by a flange plate 10 or 11, which is connected to the inner conductor connector 4 via screws 9. The flange plate 10 on the one (in Fig. 1 left) end of the line section has an axially oriented annular collar 10.1 with an inner diameter d1. The flange plate 11 on the other (in Fig. 1 right) end of the line section has an annular collar 11.1 with the smaller outer diameter d2 <d1. With the flange plate 11, a contact spring ring 11.2 is connected, which surrounds the annular collar 11.1 coaxial. The free ends of the contact springs lie in a radial plane extending from the radial plane, which is the end face of the annular collar 11.1 contains an axial distance a is reset.

Fig. 3 illustrates that when two such line sections A and B of the annular collar 10.1 a plug element and the collar 11.1 forms together with the contact spring ring 11.2 a coupler element for the realization of the contacting connection between the tubular inner conductors 3 of the juxtaposed line pieces A and B. For transversely sealing, contacting connection of the outer conductor 1 is between the connecting flanges 2 of in Fig. 4 shown ring 20 inserted from a feathered sheet.

In Fig. 5 the line sections A and B are shown in the interconnected state. The Außenleiterverbindungsflansche 2 are screwed together as usual via tie rods 21. The annular collars 10.1 and 11.1 together form the contact spring ring 11.2 a complementary connector for the tubular inner conductor. In order to ensure sufficient cooling even in the region of these inner conductor plug-in connections 10.1, 11.1, 11.2, they are made short in the axial direction, made of materials with good thermal conductivity and sufficient material thickness.

Directional changes in the course of the line are realized by means of bends or elbows, which in principle have the same structure as the straight line sections in Fig. 1 to have. In Fig. 6 is a 90 ° arc shown. To achieve a further degree of freedom, in this case the outer conductor connecting flanges 2 are additionally equipped with ball bearings 21 in a manner known per se. At the inner conductor connector no further action is required because the plug part (10.1) and the coupler part (11.1, 11.2) are rotatable relative to each other as desired.

If the field-filled space between the outer conductor and the inner conductor in the operation of the line with gas, for example, N ₂ , is to be depressed or must, at certain points of the line longitudinally tight connections are necessary. Then, instead of the tubular insulating supports, full disks 57 made of ceramics are used, as in FIG Fig. 7 shown. These have a sufficient number of radial channels 57.1 for inlet or outlet of the cooling medium. The channels 57.1 communicate on the outer circumference with an annular channel 57.2 and on the inner circumference with a Ringkananl 6.4 communicates via the holes 6.3 with the chamber 6 in the inner conductor connector 4.

During operation of the line, its inner conductor expands more strongly than the outer conductor despite cooling. A first way of stretching this in Fig. 1 symbolically denoted by Δ 1, is to pass the insulating supports 5 floating through the wall of the outer conductor. Fig. 8 shows such a sealed and RF-tight implementation. The tubular insulating support 5 is sealed with an axial clearance Δ 2 received via an O-ring 52 in a guide sleeve 51, which sits with a Fußflansch 53 in a recess 2.1 in the wall of Außenleiterverbindungsflansches 2. The thickness of the Fußflansches 53 is slightly smaller than the depth of the recess. In a groove of the Fußflansches 53 is a so-called worm contact 54 is added, which is elastic in the radial direction. The worm contact is in turn surrounded by an O-ring 55. There remains a gap Δ 3. The base flange 53 of the guide sleeve 51 is secured by means of a pressure plate 56 in the recess 2.1. Perpendicular to the drawing plane, ie in the longitudinal direction of the line, the recess 2.1 is formed slot-like, so that the insulating material 5 including the guide sleeve 51 heat-induced changes in length Δ 1 of the tubular inner conductor 3 can follow relative to the outer conductor 1 and no Forcing forces occur. At the same time lets. This type of implementation and heat-related changes in length of the insulating support 5 in the radial direction.

Another and simpler way to prevent the occurrence of constraining forces by heat induced length changes of the inner conductor relative to the outer conductor, illustrate the Fig. 9 and 10 , The insulating support 5 is pivotally received in the inner conductor connector 4 and in the guide sleeve 51, either by kugelkalottenförmige training of its two ends in conjunction with sufficiently large-sized recesses in the inner conductor connector 4 and in the wall of Außenleiterverbindungsflansches 2 ( Fig. 9 ) or, complementary thereto, by forming corresponding annular beads in the receptacles of the ends of the insulating support 5 on the one hand in the inner conductor connector 4 and on the other hand in the guide sleeve 51 (FIG. Fig. 10 ). In both cases, the insulating sleeve can tilt α by small angle α around the point M.

In the embodiments described so far, the relatively thin, tubular inner conductor 3 is cooled by a cooling medium which flows through the annular space 8 created by means of the tube 7 of smaller diameter (cf. Fig. 1 ). Alternatively, the inner conductor may be designed as a thick-walled tube 30 with numerous, closely spaced, axial channels 31. Fig. 11 shows the corresponding cross section. In particular, made of aluminum, such tubes can be very easily produced by the extrusion process.

In FIG. 12 is one opposite Fig. 1 modified embodiment shown. The tube 7 enclosed by the tubular inner conductor 3 is closed at its two ends by flanges 71, each of which has a central journal 71.1 with which it is connected in a recess 41.1 sitting in the inner conductor connector 41 with play in particular in the axial but also in the radial direction. The radial play is drawn exaggerated for clarity. The tube 7 is thus floating between the inner conductor links 41. The space 8 between the tubular inner conductor 3 and the tube 7 communicates with the respective chamber 6 in the inner conductor connecting piece 41 via recesses 71.2 (cf. Fig. 13 ) in the pin 71.1 and the adjoining in the radial direction circumferential gap between the respective flange 71 and the end face facing the Innenleiterverbindungsstücks 41. So that the cross section of the annular space 8 remains constant over the circumference, 3 spacers between the tube 7 and the tubular inner conductor or centering elements 72 arranged. These can be found in the Fig. 12 indicated manner, the tube 7 surrounded helically. Then the flow of the cooling medium in the space 8 is also helical or helical. If this is to be avoided, the centering elements 72 are not arranged continuously but only in the form of short sections. Instead, the centering elements can also consist of axially extending webs 72. 1, as in FIG Fig. 13 indicated so that the flow of the cooling medium remains axially directed.

Claims (19)

1. A coaxial line having a tubular inner conductor (3), an outer conductor (1), insulation material supports (5) between the inner conductor and the outer conductor, and connections for conducting a coolant through the line, characterized in that a tube (7) of smaller diameter, which is frontally closed on both ends, is coaxially situated in the tubular inner conductor (3), and the annular chamber (8) between this tube (7) and the tubular inner conductor (3) communicates with channels (5.1; 57.1) in the insulation material supports (5; 57), via which the coolant is supplied to the inner conductor (3), conducted through it, and removed therefrom.
2. The coaxial line according to Claim 1, characterized in that the insulation material supports are implemented as tubes (5) led outward through the outer conductor (1).
3. The coaxial line according to Claim 1 or 2, characterized in that the insulation material supports are implemented as solid discs (57) having radial channels (57.1).
4. The coaxial line according to one of Claims 1 through 3, characterized in that the channels (5.1; 57.1) of the insulation material supports (5; 57) open into a chamber (6) in an inner conductor connection part (4) at the end of the tubular inner conductor (3).
5. The coaxial line according to one of Claims 1 through 4, characterized in that the tube (7) is frontally closed by a flange (4.2) implemented on the inner conductor connection part (4).
6. The coaxial line according to one of Claims 1 through 5, characterized in that the tube (7) is frontally closed via flanges (71) which are mounted axially and radially floating (41.1, 71.1) on the particular inner conductor connection part.
7. The coaxial line according to one of Claims 1 through 6, characterized in that the tube (7) has centering elements (72) on its outer circumference, which support it against the inner wall of the tubular inner conductor (3).
8. The coaxial line according to one of Claims 5 through 8, characterized in that the centering elements (72) are situated along a spiral (helically) around the tube (7).
9. The coaxial line according to Claim 7, characterized in that the supporting centering elements (72) comprise axially running webs (72.1).
10. The coaxial line according to one of Claims 7 through 11, characterized in that the supporting centering elements (72) are integral with the pipe (7).
11. The coaxial line according to one of Claims 1 through 10, characterized in that the tubular inner conductor (30) has axial channels (31) in its jacket, which communicate with the channels in the insulation material supports.
12. The coaxial line according to one of Claims 1 through 11, characterized in that it comprises sections (A, B) which can be cooled separately from one another and are electrically and mechanically connected to one another.
13. The coaxial line according to Claim 12, characterized in that the tubular inner conductors (3, 30) of adjoining sections (A, B) of the line are connectable to one another via complementary plug connections.
14. The coaxial line according to Claim 13, characterized in that the complementary plug connection comprises a flange plate (10), which terminates the chamber (6) of the inner conductor connection part (4), having an axially extending first annular shoulder (10.1), which slips over a second annular shoulder (11.1) on the flange plate (11) of the adjoining line section and in turn has a collar (11.2) of axially extending contact springs, which concentrically encloses the second annular shoulder (11.1), slipped over it to form a contact.
15. The coaxial line according to Claim 14, characterized in that the free ends of the contact springs of the contact spring collar (11.2) lie in a radial plane which is axially set back in relation to the radial plane containing the front face of the second annular shoulder (11.1).
16. The coaxial line according to Claim 15, characterized in that the flange plates (10, 11) are screwed together with the inner conductor connection part (4).
17. The coaxial line according to one of Claims 1 through 16, characterized in that the insulation material supports (5) are led through the outer conductor (1) floating in the axial direction.
18. The coaxial line according to one of Claims 1 through 17, characterized in that the end of each insulation material support (5) which is led through the outer conductor (1) is enclosed by a guide flange (51), which is held floating in the axial direction in a recess of the outer conductor, is radially-elastic sealed in relation thereto, and is radially-elastic in contact therewith.
19. The coaxial line according to one of Claims 2 through 18, characterized in that each of the insulation material supports (5) is mounted, with its inner end in the inner conductor connection part (4) and with its outer end in the outer conductor wall (1), so it is tiltable in an axial plane.

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