Method for manufacturing an accelerating tube

Abstract: The disclosure relates to a particle accelerator comprising one or more accelerating tubes and a method for manufacturing same, which accelerating tube comprises spatially separated electrodes, whereby each electrode is surrounded by a corona ring. The electrodes and corona rings are preferably formed of one and the same material and of the same plate of material. Spark gaps, passages and/or connections for a network of resistors may be formed at the same time, if desired. An element formed in this manner, to which insulators disposed between the electrodes are connected, contribute towards realising a simplified production and assembly of accelerating tubes.

Description: The present invention relates to a method for manufacturing an accelerating tube, wherein the accelerating tube is built up of a plurality of electrodes which are spatially separated and a plurality of corona rings, wherein each electrode is surrounded by a respective corona ring. Such a method for manufacturing an accelerating tube is generally known, for instance from US 5 463 268. Known particle accelerators include an accelerating tube, in which electrodes which are spatially and electrically separated from each other both by means of successive insulators are arranged in substantially equally spaced-apart relationship. The electrodes are maintained at predetermined potentials, whereby the respective potential jumps between two adjacent electrodes are usually substantially the same. Each metal electrode of the accelerating tube is connected to a resistance voltage divider, as a result of which the potential of said electrode is maintained. Charged particles are accelerated in the accelerating tube by means of the electric field in the accelerating tube, in which a vacuum is usually maintained. In order to increase the breakdown strength in the accelerating tube a corona ring is mounted round nearly every electrode. Furthermore spark gaps are present, usually between adjacent electrodes, which function to protect the insulators and resistors against excessive voltages. The accelerated particles are for example used for scientific, industrial or educative purposes. The assembly of such a known particle accelerator and the accelerating tube or accelerating tubes used therein takes place in such a manner that the respective corona rings are arranged in precisely spaced-apart relationship, at precisely determined positions with respect to the electrodes, by means of several spacers, which are usually adjustable for distance, and bolts and nuts, which are mounted and adjusted between each electrode and its associated corona ring. The drawback of such a known particle accelerator, accelerating tube and the associated method for manufacturing same is that it comprises a great many separate parts which must necessarily be precisely positioned relative to each other and be mounted by skilled personnel, who need to be specially trained. The object of the present invention is to provide a method for manufacturing said accelerating tube, which comprises fewer parts and whose assembly requires fewer manipulations by personnel who do not require special qualifications and special training, and wherein a considerable cost reduction as well as a reduction of the assembly time is realized. The method according to the invention is to that end characterized in that said accelerating tube is built up of prefabricated elements, wherein each element comprises at least an electrode fixedly interconnected to its respective corona ring. The advantage of the present invention is the fact that the number of components to be assembled on site is limited, whilst the accuracy with which the positioning of each electrode and its associated corona ring takes place is retained. This also leads to a reduction of the time required for assembling a particle accelerator and an accelerating tube, whilst also the number of connections to be made on site is reduced, as a result of which assembly can take place more simply and more quickly. Moreover, no additional supporting structures are required for positioning the electrode and the corona ring with respect to each other and interconnecting them, because said electrode and said corona ring have already been fixedly interconnected in advance before being transported to the assembly site, where a quicker assembly with the other components can take place. It is advantageous to provide the electrode of the thus prefabricated element with at least one spark gap already, prior to the assembly of the particle accelerator. This may for example take place by pressing or deep-drawing of the material of which the element is made. In this manner it is prevented that a spark gap must be formed on site as yet. Said spark gap is particularly provided with a connection for connecting one side of a resistor. Said connection preferably is a clamped connection or a clip-on connection. Preferably, said electrode, said coronaring and said spark gap are made of one plate of the same material particularly aluminium, titanium or stainless steel. In particular, said electrode, said coronaring and/or any insulator of the prefabricated element are welded, soldered pressed or glued together. The present invention will be explained in more detail hereafter with reference to the appended drawing. In the drawing like numbers indicate like parts of the accelerating tube. Figures 1 - 5 show longitudinal and sectional views of parts of one embodiment of an accelerating tube forming part of a known particle accelerator, in connection with which the present invention may be used; Figure 6 shows another embodiment of the accelerating tube according to the invention; Figures 7 - 9 show details of a possible spark gap, of a possible configuration of the electrode, and of a possible connection of a resistor to successive electrodes; and Figures 10 - 11 are cross-sectional views of further embodiments of a part of the accelerating tube according to the invention, which part comprises elements. Figure 1 shows in cross-section and in longitudinal section an accelerating tube 1, in which a series of parallel and at least substantially equally spaced-apart metal electrodes 2 are provided, which are separated from each other by means of insulators 3. Said insulators 3 are annular in Figure 1, whilst said insulators 3 form spacers between the electrodes 2 in the embodiment of Figure 2. Upon assembly of the embodiment shown in Figures 1 and 2 the successive components, that is insulator 3, electrode 2, insulator 3, electrode 2, etc., can be placed one on top of the other and be fixedly interconnected in a manner which is known per se. It is advantageous to form an assembly of this type in such a manner that, as being proposed, elements are used prior to the eventual assembly of accelerating tube 1. In that case the successive elements, between which the insulators 3 are positioned, can be stacked together upon assembly, which can take place more quickly and accurately, because electrode 2 and an associated corona ring 4, which surrounds electrode 2, have already been fixed with respect to each other. The insulating material will contain glass, porcelain or a suitable ceramic material, for example, which is not the same material as the material of electrode 2, which usually contains aluminium, titanium or stainless steel. Insulators 3 and electrodes 2 are usually glued, soldered and/or pressed together. Figures 3 - 5 are cross-sectional and a longitudinal views of successive embodiments of accelerating tube 1. Positioned round the electrode 2 is corona ring 4, which is supported on accelerating tube 1 by means of corona ring mounting supports 5. Said supports 5 comprise adjusting means for accurately positioning corona ring 4 with respect to accelerating tube 1. It is advantageous to use the same material for the electrode 2 and the corona ring 4, whereby it is especially preferred to form one-piece elements, whereby the electrode and the corona ring associated therewith are made as one unit from one plate of material, usually in one operation or in a series of operations. After such an element has been formed, the eventual assembly of accelerating tube 1 may take place by stacking said elements alternately, whereby the bond between the elements and the insulators 3 is effected by glueing, soldering or pressing. In the embodiment of Figure 3 an electrode 2 comprises one or more spark gaps 6. Said spark gaps 6 may comprise connections for a ladder network of resistors 7. The connecting of a resistor 7 may preferably take place by means of a screwed connection, a clamped connection or a clip-on connection. It is preferred to form the spark gap 6 integrally with the element, and it is in particular preferred to form said element from one plate of material. In the embodiment of Figure 3 the electrode and the corona ring are located concentrically with respect to each other and with respect to the accelerating tube 1. Figure 4 shows an embodiment wherein the centres of the accelerating tube 1 and the corona ring 4 are shifted with respect to each other. In this embodiment an equipotential section 8 is located within corona ring 4 in an equipotential surface, in which also the electrode 2 and the corona ring 4 are placed. In this case resistor 7 is mounted between adjacent equipotential sections 8. A conductor 11, which will usually consist of a spring or a connecting wire between equipotential section 8 and electrode 2. It is advantageous to form elements, of which also equipotential section 8 forms part, prior to assembly. Eventually elements can be formed together upon assembly, whereby each element consists of electrode 2, corona ring 4 and a mounting support 5 forming an integral part of said two parts, whilst insulator 3 and equipotential section 8 may already form part of said element. Furthermore the spark gaps 6 will already have been formed at the desired places in electrode 2. Figure 5 shows yet another embodiment of accelerating tube 1, wherein corona ring 4 is made in two parts, which parts are held together by insulating plates 12 which are premounted therein, which plates are mounted along the accelerating tube. Because the corona ring is made of two parts, the configuration of element, which consists at least of electrode 2 and corona ring 4, which are preferably formed in one piece from a plate, will be slightly different, although the accelerating tube will be built up of elements. Figure 6 shows a possible embodiment wherein passages have been formed in the material between corona ring 4 and electrode 2, substantially in the longitudinal direction of accelerating tube 1. An insulated gas pipe may pass through said passages, for example, or it may function as a mechanical lead-through. The shape of corona rings 4 may vary, depending on the use of the particle accelerator and the manner in which the element is machined, formed or pressed. The passages 9 may be cut out or blanked out, whilst the spark gaps 6, one possible embodiment of which is shown in detail in Figure 7, may for example be formed by pressing, as is shown in this Figure. Figure 8 shows an embodiment of the thus pre-formed electrode-corona element, in which also spark gap 6 is pre-formed. The element is curved and substantially dish-shaped. Figure 9 shows in detail the manner in which resistors 7 can be connected between the various spark gaps 6. Figure 10 shows a similar dish-shaped embodiment of the part made in the form of a plate element, which includes corona ring 4, electrode 2, spark gap 6 and also a radiation-reducing magnet section 10. Figure 11 shows an embodiment wherein the element comprising corona ring 4, electrode 2, spark gap 6 are flat. Radiation-reducing magnet sections 10 may be used, if desired. The spark gaps in the various embodiments described above may be formed by blanking, dishing, deep-drawing or bending operations. In those cases where the various parts of an element must be interconnected prior to assembly, said connecting may take place by welding, soldering, pressing, screwing or for example glueing, if desired.

Claims: A method for manufacturing an accelerating tube (1), wherein the accelerating tube (1) is built up of a plurality of electrodes (2) which are spatially separated and a plurality of corona rings (4), wherein each electrode (2) is surrounded by a respective corona ring (4), characterized in that said accelerating tube (1) is built up of prefabricated elements, wherein each element comprises at least an electrode (2) fixedly interconnected to its respective corona ring (4). A method according to claim 1, wherein the electrode (2) of said prefabricated element is provided with at least one partially pre-formed spark gap (6). A method according to claim 2, wherein said spark gap (6) is provided with a connection for connecting one side of a resistor (7). A method according to claim 1, 2 or 3, wherein said element is made of aluminium, titanium or stainless steel. A method according to claim 2, 3 or 4, wherein said electrode (2), said corona ring (4) and said spark gap (6) are made of one plate of the same material.

Inventors: KOUDIJS REIJER, KOUDIJS, REIJER
Applicants: HIGH VOLTAGE ENG EUROP, HIGH VOLTAGE ENGINEERING EUROPA B.V.
Application year: 1996
Main classification: H05H5
IPC codes: H05H5