US3076116A

US3076116A - Klystron apparatus

Info

Publication number: US3076116A
Application number: US841270A
Authority: US
Inventors: Donald F Drieschman; Thomas M Lott
Original assignee: Eitel Mccullough Inc
Current assignee: Varian Medical Systems Inc
Priority date: 1959-09-21
Filing date: 1959-09-21
Publication date: 1963-01-29
Anticipated expiration: 1980-01-29
Also published as: GB923649A; DE1289920B

Description

D. F. DRIESCHMAN ETAL 3,076,116

Jan. 29, 1953 KLYSTRON APPARATUS 3 Sheets-Sheet].

Filed Sept. 21, 1959 INVENTORS DONALD E DRIESCHMAN THOMAS M. LOTT BY 'F 2- 9% F ATTORNEYS Jan. 29, 1963 D. F. DRIESCHMAN ETAL 3,076,116

KLYSTRON APPARATUS Filed Sept. 21, 1959 3 Sheets-Sheet? 4 ll lilll I ll 1- 6'4 3 111mm! mun v 13i! 3 M nu IN V EN TORS DONALD E DRIESCHMAN Y 55% M. LOTT W azzz ATTORNEYS Jan. 29, 1963 D. F. DRIESCHMAN ETAL 3,076,116

KLYSTRON APPARATUS Filed Sept. 21, 1959 3 Sheets-Sheet 5 INVENTORS DONALD E DRIESCHMAN T HOMAS M. LOTT ATTURNEYS 3,076,116 KLYSTRGN APPARATUS Donald F. Drieschman, Palos Verdes Estates, and Thomas M. Lott, an Mateo, Calif., assignors to Eitel-Mcilullough, Inc, San Bruno, (Salli, a corporation of California Filed Sept. 21, 1959, er. No. 841,279 19 (Zlaiins. (Cl. 315-535) This invention relates to klystron apparatus and more particularly to an improved arrangement of the electronic and magnetic circuitry for use with klystrons.

As is well known in the art, amplifier klystrons comprise an elongated vacuum envelope containing a drift tube, an electron gun at one end of the drift tube for projecting a beam of electrons through the drift tube, and a collector electrode at the other end of the drift tube for receiving the electron beam. The drift tube is made of metal to provide a field-free transit path for said electron beam and comprises a plurality of sections spaced from each other to form interaction gaps which are surrounded by cavity resonators. According to prior art, the resonant cavities are sometimes placed totally within the envelope and sometimes they are placed partly within and partly outside the envelope.

As is also well known in the art, a magnetic field which is axially parallel to the drift tube is used to guide the electron beam through the drift tube and to prevent the beam from spreading. The magnetic field is usually provided by a magnetic circuit comprising one or more electromagnetic coils and a pair of annular iron pole pieces, all of which are placed outside the envelope surrounding the klystron.

The pole pieces are usually located one at each end of.

the drift tube and are mechanically connected to each other by a frame made of magnetic material. The frame is located externally to the coils and provides a low-reluctance return path between the pole pieces.

The klystron apparatus which has heretofore experienced the greatest commercial success comprises a vacuum envelope which encloses the drift tube, gun, collector and only a portion of the resonant cavities; exterior cavity portions which are removably mounted on the envelope to varying degrees; and a magnetic circuitry which comprises a separate structural unit into which the klystron envelope and exterior cavity portions are assembled.

However, the assembly of a klystron envelope and its exterior cavity portions into its magnetic circuitry has presented certain difficulties. In the first place, the klystron envelope tends to be heavy and unwieldy, particularly in klystron apparatus designed for high power output at the lower end of the frequency range in which klystrons normally operate.

Furthermore, the vacuum wall between the interior cavity portions and the exterior cavity portions must be made of insulating material, such as glass or ceramic, which is comparatively weak, structurally, particularly in tension. Thus, the klystron envelope must be handled with care and is customarily handled in a vertical position, since it can be handled in a horizontal position only if it is supported throughout its entire length at all times to prevent the insulating portions of the vacuum wall from being placed in tension due to bending moments.

In general, a klystron envelope has been inserted axially and vertically into the magnetic circuitry with the pole pieces therein fitting closely around the envelope. The exterior portions of the cavities are then fitted to the envelope which is a complicated mechanical operation because of the close proximity of the magnetic frame and coils to the envelope.

Thus, according to the prior art, a space at least twice 3,.h7d,ll6 Patented Jan. 29, 1963 ire as long as the klystron envelope is required to allow its insertion into the magnetic circuitry and a substantial amount of mechanical assembly and adjustment in cramped quarters are required, once the envelope has been inserted into the magnetic circuitry, in order to prepare the apparatus for operation.

it is an object of this invention to provide improved klystron apparatus.

It is another object of this invention to provide improved klystron apparatus which is more readily assembled.

It is a further object of this invention to provide klystron apparatus which requires less space for assembly.

It is still another object of this invention to provide klystron apparatus in which the magnetic circuitry and portions of the resonant cavities external to the envelope are mounted as a unit independently of the klystron envelope.

It is yet another object of the invention to provide klystron apparatus in which the klystron envelope is inserted laterally into the magnetitc circuitry.

Accordingly to the invention, the magnetic circuitry, external cavity portions and other portions of the klystron apparatus external to the klystron envelope (hereinafter referred to collectively as hardware) are mounted asa unit mechanically independent of the klystron envelope (hereinafter called klystron). According to one feature of this invention, one of the pole pieces of the hardware is provided with a radial passageway extending between the central aperture in that pole piece and the periphery of the plate-like pole piece to allow the klystron to be inserted laterally into the hardware after the coils have been moved axially so as not to interfere with the lateral movement of the klystron. According to another feature of this invention, the exterior cavity portions of the klystron and the magnetic circuitry and pole pieces are mounted into a structural unit to enable the klystron apparatus to be readily assembled or disassembled. And according to a still further feature of this invention, all items disposed within themagnetic coils are made of nonmagnetic material so as not to interfere with the magnetic field which guides the beam on its axis.

These, and other objects and features of advantage, will become more clearly apparent from the following description of the invention when taken in conjunction with the accompanying drawings. This invention is not limited to the disclosed species, as variant embodiments thereof are contemplated and may be adopted within the scope of the claims.

Referring to the drawings:

FIGURE 1 is a perspective view of the novel hardware partially broken away to show a klystron envelope positioned therein.

FIGURE 2 is a side elevation of the hardware and klystron.

FlGURE 3 is a plan view of the hardware and klystron viewed from line 33 on FIGURE 2.

Gne embodiment of the invention as shown in FIG- URE 1 has a klystron It? installed vertically within hardware 12, with the collector 14 of the klystron disposed downward as shown in the drawing, and the electron gun in oriented upward. The hardware. 12 has a steel frame which forms a low-reluctance magnetic path and is mounted on casters 18. The frame has a ring base 20 formed from channel sections. Depending from the base 20 are two parallel cross braces 22 and extending upward from the base 20 are three coil-support posts 24- to which a top pole piece 26 in the form of a plate is fixed.

Within the circle formed by posts 24 are shown four magnetic coils 28 disposed in a temporary position on the cross braces 22. The magnetic coils '28 are shown partially broken away in order that details of the hardware 12 and klystron may be shown. Extending upward from cross braces 22 is a short tubular steel collector support 30 with a bottom pole piece 32, which is also in the form of a plate. The pole piece 32 has a center aperture 34 which encloses the collector 14 of the klystron. On pole piece 32 is fixed a smaller magnetic coil 36 to help control the electron beam in the klystron. Coil 36, pole piece 32 and the tubular support 30 are all shown partially broken away. Fixed to the bottom pole piece 32 and to the top pole piece 26, and within a cylinder as defined by the magnetic coils 28, is disposed a vertical cavity support post 38 made of a non-magnetic material such as aluminum. On the cavity support post 38 are supported semi-cylindrical cavity sections 39 which have a cut-out 40 which fits around the klystron as shown. According to the embodiment shown, there are six semi-circular cavity sections 39 which form three complete cylindrical cavities since the klystron as shown and used in this embodiment has three interaction gaps. The cavity sections 39 are mounted on support post 38 by hinges 41. The sections 39 rotate about post 38 as illustrated by the top cavity which is rotated out of the way of the klystron, and by the middle cavity which is closed around the klystron. One semi-cylindrical section 3 of the bottom cavity is removed. On each cut-out 40 of the cavity sections 39 are disposed contact fingers 42. Contact fingers 42 are standard resilient-type fingers which form a good electrical contact between cavity sections 39 and klystron 10. A long brace 44 is shown supporting the free end of the cavity sections 39. Long braces 44 are required only on the coil support posts which are opposite the hinges 41. These posts are shown as 24'. The other long braces 44 are not shown for simplicity. Short braces 46 which are on all the coil support posts 24 and 24' support the large magnetic coils 28 in their respective positions during klystron operation as will be explained hereinafter. Braces 46 are shown rotated and protruding outwardly so that coils 28 are easily moved axially up and down the frame past the braces. Of course, long braces 44 must be rotated outwardly before the coils 28 can be moved axially up and down.

Referring to FIGURE 2 of the drawing, the hardware 12 is shown in elevation with the klystron 10 installed and ready for operation. Parts of the hardware are partially broken out to show details. Braces 46 are shown supporting coils 28.

Braces

44 and 46 are held in place on the posts 24 and 24' by friction. By loosening bolts 48 on the braces 46 and 44- the friction grip which holds the braces can be released. The braces are then moved out of the way and coils 28 are lowered onto the cross braces 22.

Each cavity section 39 has a tuning mechanism 52 which is used to tune the cavities by either inductance or capacitance tuning. In the embodiment illustrated, the top cavity is the control cavity which, as is well known in the klystron art, velocity modulates the electron beam produced by the electron gun and collected by the collector. The middle cavity or intermediate cavity helps to further velocity modulate the electron beam. The bottom cavity is the output cavity from which amplified electromagnetic energy is coupled.

Referring to FIGURE 3 which shows the top plan view of the hardware 12 with the klystron 10, the top pole piece 26 of the hardware is made with a U-shaped recess or passageway 54 which extends from the periphery of the pole piece 26 inward so that the klystron 10 protrudes through the passageway 54. The passageway 54 is closed by a rectangular removable plate 56 and by a semi-circular removable plate 58. Together,

removable plates

56 and 58 form a circular aperture 60 through which extends the klystron 10. Around the klystron and upon the top pole piece 26 is placed a housing 62 which houses a small coil 64 (FIGURE 2) whose primary function is to center the electron beam in the drift tube. The hinge 41 for the top cavity sections 39 is observed below 4 the pole piece 26 through the broken-out section in the pole piece. Clips 66 on the cavity sections 39 hold the two sections together around the klystron.

To install the klystron in the hardware, the

removable plates

56 and 58 are removed from the top pole piece 26. The magnetic coils are placed on the cross brace 22 and the cavity sections 39 are opened to their open position as shown by the top cavity in FIGURE 1. The klystron, being held by a crane in the vertical position, is moved into the hardware from the side with the collector 14 clearing the bottom pole piece 32. When the collector is directly over the aperture 34 of the pole piece 32, the klystron is lowered until it bottoms. The cavity sections 39 are rotated to their operative positions around the klystron and clamped by clips 66. The magnetic coils 28 are raised and secured in their respective positions as shown in FIGURE 2 and secured in place by tightening braces 46 on posts 24. Braces 44 are rotated on posts 24- under the cavity sections 39 and tightened.

Removable plates

56 and 58, and coil 64 are replaced on the top pole piece 26 and secured by suitable means.

Every item of the hardware which is located within the cylinder defined by the coils 28 is made of a non-magnetic material so that the magnetic field is not distorted. The frame of the hardware is made of steel, a magnetic material, to decrease the permeability of the magnetic circuit by providing a low-reluctance path exterior of the coils. This low-reluctance path extends through top pole piece 26, posts 24 and 24', base 20, cross braces 26, and tubular support 28 and bottom pole piece 32.

Thus, a klystron can be easily mounted in the novel hardware. Little or no head room is required in order to remove or insert the klystron within the hardware. The klystron apparatus is a mobile unit which can be removed intact from the main circuitry and replaced by a complete spare.

Although the embodiment described shows a klystron installed in the vertical position, the hardware can be rotated so that the klystron is installed horizontally without departing from the invention.

We claim:

1. Apparatus for a klystron comprising a pair of axially spaced plate-like pole pieces having coaxial apertures spaced radially inwardly from the outer periphery of the pole pieces, at least one of said pole pieces having a passageway extending radially from the outer periphery thereof to said aperture therein and communicating therewith; and means radially spaced from said passageway mechanically connecting said pole pieces to each other to form a low reluctance magnetic path therebetween.

2. Apparatus for a klystron comprising a pair of axially spaced plate-like pole pieces having coaxial apertures therein, at least one of said pole pieces having a passageway extending radially through said plate-like pole piece to said aperture therein and communicating therewith; and a magnetic member radially spaced from said passageway and connecting said pole pieces.

3. Apparatus according to claim 2 wherein a removable section of magnetic material is provided to close said passageway.

4. Apparatus for a klystron comprising a pair of axially spaced pole pieces having apertures coaxially disposed about a longitudinal axis, a magnetic member connecting said pole pieces; a non-magnetic member disposed between said axis and said magnetic member and supported on at least one of said pole pieces; and exterior cavity portions disposed on said non-magnetic member.

5. Apparatus according to claim 4 wherein one of said pole pieces is provided with a radially extending passageway communicating with the aperture therein and a removable section of magnetic material is provided to close said passageway.

6. Apparatus for a klystron comprising a magnetic frame, and a magnetic coil disposed within said magnetic frame, said magnetic frame including a pair of spaced plate-like pole pieces having coaxial apertures therethrough, at least one of said pole pieces having a passageway extending radially through said pole piece to said aperture therein and communicating therewith, and means on said frame for removably supporting said magnetic coil within said frame and around the said klystron.

7. Apparatus according to claim 6 wherein a removable section of magnetic material is provided to close said passageway after lateral insertion of said klystron into said frame.

8. Apparatus for a klystron comprising a magnetic frame, and a magnetic coil disposed within said magnetic frame, said magnetic frame including a pair of spaced pole pieces having coaxial apertures, at least one of said pole pieces having a passageway extending radially to said aperture therein and communicating therewith, a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor, a coil support post disposed between said pole pieces, and means on said post for removably supporting said magnetic coil around said klystron.

9. Apparatus for a klystron comprising a magnetic frame, an exterior cavity portion and a magnetic coil disposed within said frame, said magnetic frame including a pair of spaced pole pieces having coaxial apertures, at least one of said pole pieces having a passageway extending radially to said aperture therein and communicating therewith, a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor, a cavity support post of non-magnetic material disposed between said two pole pieces and within said magnetic coil, said exterior cavity portion being formed from two sections and disposed in pairs on hinges on said support post, and means on said frame for removably supporting said magnetic coil around said klystron.

10. Apparatus according to claim 9 wherein said cavity support post is parallel to said axis and spaced therefrom.

11. Apparatus for a kylstron comprising a magnetic frame, a magnetic coil disposed within said magnetic frame, and an exterior cavity portion, said magnetic frame including a pair of spaced pole pieces having coaxial apertures, at least one of said pole pieces having a passageway extending radially to said aperture therein and communicating therewith, means on said frame for emovably supporting said magnetic coil around said kylstron, a non-magnetic cavity support post disposed between said pole pieces within said magnetic coil and displaced from said passageway, said exterior cavity portion formed from two sections, said sections being hingemounted on said cavity support post in pairs whereby said sections rotate about said post and enclose said kylstron to form said exterior cavity portion, and a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor.

12. Apparatus for a klystron comprising a magnetic frame, a magnetic coil disposed Within said frame, and an exterior cavity portion, said magnetic frame comprising first and second coaxially apertured plates spaced from each other said plates forming a pair of pole pieces, at least one of said pole pieces having a passageway extending radially to said aperture therein and communicating therewith, a coil mounting post made of magnetic material disposed between the pole pieces outside said magnetic coil and displaced from said passageway, at least one friction-grip brace movably mounted on said coil mounting post for removably supporting said magnetic coil around said klystron, a non-magnetic cavity support post disposed between said pole pieces and within said magnetic coil, said exterior cavity portion being formed from two sections and mounted on hinges on said cavity support post for rotational motion of said sections about said cavity support posts as a center, and a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor.

13. Klystron apparatus compri mg a klystron having a vacuum envelope, an electron gun at one end, a collector at the other end, and electron interaction means therebetween and a hardware apparatus for said klystron, said hardware apparatus comprising a magnetic frame, magnetic coil disposed within said frame, and an exterior cavity portion, said magnetic frame including a pair of spaced pole pieces having coaxial apertures, at least one of said pole pieces having a passageway extending radially to said aperture therein and communicating therewith, means on said frame for removably mounting said magnetic coil within said frame and around said klystron, said space between pole pieces being such that said klystron is installed therein with said electron gun and said collector disposed exterior of said pole pieces and with said electron interaction means disposed between said pole pieces, said klystron passing through said apertures, a non-magnetic cavity support post disposed between said pole pieces within said magnetic coil and displaced from said passageway, said exterior cavity portion formed from two sections, said sections being hinge-mounted on said post in pairs whereby said sections rotate about said post and enclose said klystron to form said exterior cavity portion, and a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor.

14. Apparatus for a klystron comprising a magnetic frame, at least one magnetic coil disposed within said frame, and at least one exterior cavity portion, said magnetic frame including a pair of spaced pole pieces having coaxial apertures, at least one of said pole pieces having a passageway extending radially to sa'd aperture therein and communicating therewith, means on said frame for storing said magnetic coil exterior of the space between said pole pieces and around the axis of said aperture, at least one magnetic coil support post displaced from said passageway and connecting both pole pieces to form a lowreluctance path exterior of said magnetic coil, coil supports disposed on said coil support post, a cavity support post of non-magnetic material disposed between said pole pieces, said exterior cavity portion formed from two sections, hinge means on said cavity support post for mounting said sections in pairs, and a section of magnetic material removably disposed within said passageway to form a magnetically permeable closure therefor.

15. Apparatus for a klystron comprising a pair of spaced pole pieces having coaxial apertures, at least one exterior cavity portion for said klystron, means supporting said exterior cavity portion apart from the klystron and between said pole pieces, and means mechanically and magnetically connecting said pole pieces to each other and disposed exterior of said exterior cavity portion and said means for mounting said exterior cavity portions.

16. Apparatus for a klystron comprising a pair of spaced pole pieces having coaxial apertures, at least one magnetic coil disposed around the axis of said apertures, at least one exterior cavity portion for said klystron, nonmagnetic means for supporting said exterior cavity portion apart from the klystron and between said pole pieces and within said magnetic coil, means for supporting said magnetic coil exterior of said non-magnetic means, and means mechanically and magnetically connecting said pole pieces to each other and disposed exterior of said magnetic coil.

17. Apparatus for a klystron comprising a pair of spaced pole pieces having coaxial apertures, at least one exterior cavity portion for said klystron, said exterior cavity portion formed from two sections, a cavity support post of non-magnetic material disposed between said pole pieces,

said sections of said exterior cavity portions mounted on said cavity support post, and at least one magnetic post disposed exterior of said exterior cavity portions and fixed to both pole pieces.

18. Apparatus according to claim 17 wherein at least one magnetic coil is disposed around the axis of said apertnres and spaced radially inwardly from said magnetic post, and means supporting said coil around said axis.

19. Apparatus according to claim 17 wherein said cavity sections are hinge-mounted in pairs on said cavity support 10 post.

References Cited in the file of this patent UNITED STATES PATENTS Samuel May 5, 1942 Norton et al Nov. 25, 1952 Eitel et al. Feb. 17, 1953 Drieschman et a1. June 3, 1958 Rogers Sept. 9, 1958 Preist Jan. 6, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. $076,116 January 29, 1963 Donald Fe Driesohman et a1,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2 line 21 for "magnetite" read magnetic column 5, line 64, after "other" insert a comma; column 6, line 10, after "frame," insert a :g line 40, for "aperture" read apertures q Signed and sealed this 27th day of August 1963,

(SEAL) Attest:

ERNEST w. SWIDER VI L- LADD Attesting Officer Commissioner of Patents

Claims

13. KLYSTRON APPARATUS COMPRISING A KLYSTRON HAVING A VACUUM ENVELOPE, AN ELECTRON GUN AT ONE END, A COLLECTOR AT THE OTHER END, AND ELECTRON INTERACTION MEANS THEREBETWEEN AND A HARDWARE APPARATUS FOR SAID KLYSTRON, SAID HARDWARE APPARATUS COMPRISING A MAGNETIC FRAME, MAGNETIC COIL DISPOSED WITHIN SAID FRAME, AND AN EXTERIOR CAVITY PORTION, SAID MAGNETIC FRAME INCLUDING A PAIR OF SPACED POLE PIECES HAVING COAXIAL APERTURES, AT LEAST ONE OF SAID POLE PIECES HAVING A PASSAGEWAY EXTENDING RADIALLY TO SAID APERTURE THEREIN AND COMMUNICATING THEREWITH, MEANS ON SAID FRAME FOR REMOVABLY MOUNTING SAID MAGNETIC COIL WITHIN SAID FRAME AND AROUND SAID KLYSTRON, SAID SPACE BETWEEN POLE PIECES BEING SUCH THAT SAID KLYSTRON IS INSTALLED THEREIN WITH SAID ELECTRON GUN AND SAID COLLECTOR DISPOSED EXTERIOR OF SAID POLE PIECES AND WITH SAID ELECTRON INTERACTION MEANS DISPOSED BETWEEN SAID POLE PIECES, SAID KLYSTRON PASSING THROUGH SAID APERTURES, A NON-MAGNETIC CAVITY SUPPORT POST DISPOSED BETWEEN SAID POLE PIECES WITHIN SAID MAGNETIC COIL AND DISPLACED FROM SAID PASSAGEWAY, SAID EXTERIOR CAVITY PORTION FORMED FROM TWO SECTIONS, SAID SECTIONS BEING HINGE-MOUNTED ON SAID POST IN PAIRS WHEREBY SAID SECTIONS ROTATE ABOUT SAID POST AND ENCLOSE SAID KLYSTRON TO FORM SAID EXTERIOR CAVITY PORTION, AND A SECTION OF MAGNETIC MATERIAL REMOVABLY DISPOSED WITHIN SAID PASSAGEWAY TO FORM A MAGNETICALLY PERMEABLE CLOSURE THEREFOR.