Injection apparatus both for positive and negative ions

Abstract: An injection apparatus both for positive and negative ions comprising: a first (1), a third (3) and a fourth (4) bump magnets arranged in order on a circulation orbit, a second bump magnet (2) arranged on said circulation orbit between the first (1) and the third (3) bump magnets so as to maintain a given position relative to the circulation orbit and a carbon film (5) arranged between the second (2) and the third (3) bump magnets, wherein the second bump magnet (2) is afforded with both of respective functions of a bump magnet and a septum magnet, the second bump magnet (2) is operated as the bump magnet upon the injection of a negative ion beam, while the second bump magnet (2) is operated as the septum magnet upon the injection of a positive ion beam.

Description: The present invention relates to an injection apparatus both for positive and negative ions which can be applied on a proton accelerator, a various ion accelerator and the like. In conventional ion accelerators including, for instance, a synchrotron, which are used for accelerating positive ions or negative ions, the injection apparatus are in widely different forms depending upon whether the ions to be accelerated are positively or negatively charged. By way of example IEEE Trans on Magnetics July 1994, USA pages 2134-2137 Kumagai et al "The injection Septum Magnets of the SPring-8 Storage Ring" described three AC Septum magnets and a pulsed Septum magnet used for the injection apparatus of an accelerator system. For example, as for the injection apparatus used for the proton accelerator, a multi-turn injection system based on charge exchange by negative hydrogen ions, is generally adopted, as exemplified in Fig. 3. A negative ion injection apparatus as shown in Fig. 3 is formed by arranging bump magnets 11, 12, 13 and 14 in turn on a circulating orbit, intermediate ones 12 and 13 of which are arranged so as to make a determined offset against end ones 11 and 14 and further between intermediate ones 12 and 13 a carbon film 15 is fixedly disposed. As shown in Fig. 4 which indicates a crosssection A-A in Fig. 3, the bump magnet 12 is formed of a magnet 12a having a U-shaped longitudinal cross-section, inside of which conductors 12b and 12c are provided for forming single turn exciting coils which are arranged in such a way that a center of a circulation orbit and a beam injection point are positioned between these conductors 12b and 12c. In the above exemplified conventional negative ion injection apparatus, an orbit of a negative ion beam, for instance, H- ion beam which is injected into the bump magnet 12 at a determined angle is deflected, upon the injection of negative ion, that is, upon the charge conversion multiplex injection, by the bump magnetic field formed in the bump magnet 12, substantially in parallel with the circulation orbit center as shown in Fig. 3, and then, after passing through the bump magnet 12, electrons are separated from the negative ion beam by the carbon film 15, so as to be converted into a positive ion beam. This positive ion beam gets on the circulation orbit through bump magnets 13 and 14, and then, during the subsequent circulation, is injected into the bump magnet 12 along the orbit which is deflected through the bump magnet 11 as shown in Fig. 3. The orbit of this positive ion beam is deflected by the aforesaid bump magnetic field in an opposite direction to that in the case of the negative ion beam, and, as a result, flows into the negative ion beam. In this connection, according to the function of the bump magnet 11 to 14, it is arranged that the orbit is shifted in such a way as the injected ion beam is passed through the carbon film 15 only upon the negative ion injection. On the other hand, as for the injection apparatus used for the positive ion accelerator, a circulation orbit shift system is adopted in general, as exemplified in Fig. 5. A positive ion injection apparatus as shown in Fig. 5 is formed by arranging a septum magnet 21 afforded with a determined offset against the circulation orbit center together with bump magnets, not shown in Fig. 5, in both of up and down streams in the circulation orbit direction. As shown in Fig. 6 which indicates a crosssection B-B in Fig. 5, the septum magnet 21 is formed of a magnet 21a having a C-shaped longitudinal crosssection, inside of which conductors 21b and 21c are provided for forming single turn exciting coils which are arranged in such a way that a beam injection point is positioned between these conductors 21b and 21c and outside of which a center of a circulation orbit is positioned. In the above exemplified conventional positive ion injection apparatus, an orbit of a positive ion beam which is injected into the septum magnet 21 at a determined angle is deflected, upon the injection of positive ion, that is, upon the circulation orbit shift multiplex injection, substantially in parallel with the circulation orbit center as shown in Fig. 5, by the fact that the circulation orbit which is shifted by a bump magnet, not shown in Fig. 5 is temporarily passed through a septum magnetic field formed in the septum magnet 21, and then gets on the circulation orbit through the aforesaid bump magnet, not shown in Fig. 5. In the above exemplified conventional ion injection apparatus as shown in Fig. 4 which is used for the proton accelerator, the charge exchange injection system based on negative ions is adopted. In this charge exchange injection system based on negative ions, it is possible to efficiently put the ion beam into the circulation orbit. However, in the case that particles being heavier than He ion are injected, upon the charge exchange effected by making negative ions to impinge with the carbon film after the injection, the decrease of injection efficiency is caused because the ratio between the charge and the mass is not constant compared to the case of protons. So that, this charge exchange injection system based on negative ions cannot be applied to the case where heavy ions are injected. In order to facilitate the injection of positive ions being heavier than He ion in the circular accelerators including the proton accelerator, it is required to further provide an additional injection apparatus, for instance, the positive ion injection apparatus as shown in Fig. 6, which comprises the septum magnet for deflecting the orbit of the injected beam substantially in parallel with the circulation orbit, as well as the bump magnet for parallelly shifting the circulation orbit in upper and lower streams of the above septum magnet, so as to inject the beam in parallel with the circulation orbit through the septum magnet as the circulation orbit is shifted. As described above, the negative ion injection and the positive ion injection have been conventionally realized respectively by different injection apparatus. Accordingly, in the case either negative ions or positive ions are injected and accelerated through the same accelerator, it has been conventionally required to provide the aforesaid two kinds of injection apparatus, and to change these injection apparatus from each other, each time the kind of the beam to be injected is changed. For changing the injection apparatus which is set up in vacuum together with the accelerator, it is necessary to break the vacuum situation. So that, the work for this change becomes large scale and further requires a working term longer than three weeks. As a result, an enormous working cost is necessary for it, as well as the restriction is brought into the application of the accelerator. Certain embodiments of the present invention are arranged to obviate the above-mentioned difficulties. An object of certain embodiments of the present invention is to provide an injection apparatus both for positive and negative ions having both of respective functions of a positive ion injection apparatus and a negative ion injection apparatus. According to one aspect of the present invention there is provided an injection apparatus for positive and negative ions comprising a first, a third and a fourth bump magnets arranged serially on a circulation orbit, a second magnet arranged on said circulation orbit between the first and the third bump magnets so as to maintain a given position relative to the circulation orbit and a carbon film arranged between the second and the third bump magnets, wherein the second magnet is operable with both of respective functions of a bump magnet and a septum magnet, and means for operating said second magnet as a bump magnet upon the injection of a negative ion beam, and means for operating said second magnet as a septum magnet upon the injection of a positive ion beam. According to a further aspect of the present invention there is provided a method of operating an injection apparatus for positive and negative ions having a first, a third and a fourth bump magnets arranged in order on a circulation orbit, a second bump magnet arranged on said circulation orbit between the first and the third bump magnets so as to maintain a given position relative to the circulation orbit and a carbon film arranged between the second and the third bump magnets, the method comprising operating said second magnet as a bump magnet upon the injection of a negative ion beam; and operating said second magnet as a septum magnet upon the injection of a positive ion beam. In an embodiment of the invention an injection apparatus both for positive and negative ions comprises: a first, a third and a fourth bump magnets arranged in order on a circulation orbit center, a second bump magnet arranged between the first and the third bump magnets so as to maintain a given position relative to the circulation orbit center and a carbon film arranged between the second and the third bump magnets, wherein at the time of injecting a negative ion beam, said second bump magnet is functioned as a bump magnet, an orbit of the negative ion beam injected at a given angle is deflected in parallel with the circulation orbit through a bump magnetic field formed in the second bump magnet, electrons contained in the negative ion beam is stripped through the carbon film and converted into a positive ion beam, which gets on the circulation orbit through the third and the fourth bump magnets, and, at the time of the injection of a positive ion beam, the second bump magnet is functioned as a septum magnet, after an orbit of the positive ion beam injected at a given angle is deflected in parallel with said circulation orbit, the circulation orbit is shifted through the first bump magnet to temporarily pass through a septum magnetic field formed in the second bump magnet, the positive ion beam gets on the circulation orbit through the third and the fourth bump magnets. Embodiments of the present invention realize an injection apparatus both for positive and negative ions which is compacted by affording respective functions of the bump magnet and the septum magnet to the second bump magnet and further by selecting either one of these functions in response to the kind of the injected beam, wherein the second bump magnet comprises a first conductor arranged outside the circulation orbit and second and third conductors arranged inside the circulation orbit, the bump magnetic field is formed between the first and the second conductors and the septum magnetic field is formed between the second and the third conductors. Embodiments of the present invention provide an injection apparatus, wherein among the first to the fourth bump magnets arranged in order on the circulation orbit center, the second bump magnet is afforded with both of respective functions of the bump magnet and the septum magnet. So that, upon the injection of negative ion beam, the charge conversion multiplex injection system based on negative ions can be realized similarly as the conventional injection apparatus as shown in Fig. 3 by making the second bump magnet to function as a bump magnet, while, upon positive ion beam injection, the circulation orbit shift multiplex injection system based on positive ions can be realized similarly as the conventional injection apparatus as shown in Fig. 5 by making the second bump magnet to function as a septum magnet. Embodiments of the present invention provide an injection apparatus, wherein upon the injection of a negative ion beam, the second bump magnet is affording a function as a bump magnet, after an orbit of the negative ion beam injected at a given angle is deflected in parallel with the circulation orbit through a bump magnetic field formed in the second bump magnet, electrons contained in the negative ion beam is stripped through the carbon film and converted into a positive ion beam, which gets on the circulation orbit through the third and the fourth bump magnets, so that, as a result, the charge conversion multiplex injection system based on negative ions can be realized similarly as the conventional injection apparatus as shown in Fig. 3, while, upon the injection of a positive ion beam, the second bump magnet is affording a function as a septum magnet, after on orbit of the positive ion beam injected at a given angle is deflected in parallel with the circulation orbit by making the circulation orbit shifted through the first bump magnet to temporarily pass through a septum magnetic field formed in the second bump magnet, the positive ion beam gets on the circulation orbit through the third and the fourth bump magnets, so that, as a result, the circulation orbit shift multi-turn injection system based on positive ions can be realized similarly as the conventional injection apparatus as shown in Fig. 5. For better understanding of the invention, reference is made by way of example to accompanying drawings, in which: Fig. 1 is a cross-sectional view showing an example in principle of an injection apparatus embodying the present invention; Fig. 2 is a cross-sectional view along C-C of Fig. 1 showing the example as shown in Fig. 1; Fig. 3 is a cross-sectional view showing an example in principle of a conventional negative ion injection apparatus as mentioned before; Fig. 4 is a cross-sectional view along A-A of Fig. 3 showing the example as shown in Fig. 3; Fig. 5 is a cross-sectional view showing an example in principle of a conventional positive ion injection apparatus as mentioned before; and Fig. 6 is a cross-sectional view along B-B of Fig. 5 showing the example as shown in Fig. 5. Throughout different views of the drawings: 1, 2 are bump magnets, 2a is an magnetic, 2b, 2c, 2d are conductors, 3,4 are bump magnets and 5 is a carbon film. An embodiment of the present invention will be described in detail hereinafter by referring to the drawings. Fig. 1 shows an arrangement in principle of the injection apparatus both for positive and negative ions embodying the present invention. The injection apparatus as shown in Fig. 1 is formed by arranging bump magnets 1, 2, 3 and 4 in order in a circulation orbit. The bump magnet 2 is substantially lozenge-shaped such as the center thereof is somewhat diagonally situated in relation to the circulation orbit center, so as to facilitate the injection of an ion beam. On the other hand, a carbon film 5 is arranged between the bump magnets 2 and 3 and fixed therein, so as to be situated almost perpendicular to the circulation orbit. As shown in Fig. 2 indicating a crosssection along C-C of Fig. 1, three conductors 2b, 2c, 2d respectively forming single-turn exciting coils for magnet are provided inside a magnet 2 having a U-shaped transverse crosssection, the circulation orbit center and the negative ion beam injection point is situated between the conductors 2b and 2c, while the positive ion beam injection point is situated between the conductors 2c and 2d. These conductors 2b, 2c, 2d respectively form magnetic poles which have respective polarities as shown respectively in Fig. 1, wherein the conductor 2c serves as a common conductor to the conductors 2b and 2d. Accordingly, a bump magnetic field, which passes respectively downward at the conductor 2b and upward at the conductor 2c through a plane of the drawing, is generated between the conductors 2b and 2c by the excitation of the conductors 2b and 2c, while a septum magnetic field, which passes respectively downward at the conductor 2d and upward at the conductor 2c through the plane of the drawing, is generated by the excitation of the conductors 2d and 2c. The function of the above mentioned embodiment will be described hereinafter. Upon negative ion injection, that is, upon the charge conversion multiplex injection, the bump magnet 2 is operated as a bump magnet by making exciting currents flow through the conductors 2b and 2c of the magnet 2. In this situation, the orbit of the negative ion beam, for instance, the H - ion beam, which includes electrons injected into the bump magnet 2 at a given angle, is deflected substantially in parallel with the circulation orbit, as shown in Fig. 1, through the bump magnetic field formed in the bump magnet 2, and then, after passing through the bump magnet 2, electrons included in the negative ion beam are stripped by the carbon film 5, so as to be changed to the positive ion beam. This positive ion beam, the orbit of which is deflected through the bump magnets 3, 4 as shown in Fig. 1, gets on the circulation orbit. In the subsequent circulation, the circulating beam, that is, the positive ion beam on the circulation orbit, the orbit of which is deflected through the bump magnet 1 as shown in Fig. 1, is injected into the bump magnet 2. The orbit of this circulating ion beam, which is deflected through the same bump magnetic field in the direction opposite to that in the case of the negative ion beam, results to meet the injected negative ion beam within the bump magnet 2. In this connection, it is arranged that the orbit of the circulating ion beam is shifted by the function of the bump magnets 1 to 4, in such a way that the injected ion beam is passed through the carbon film 5 only in the time of the negative ion beam injection. On the other hand, upon the positive ion beam injection, that is, the circulation orbit shift multiplex injection, the conductor 2c in the bump magnet 2 is operated as a common conductor, that is, a septum conductor in relation to the conductors 2b and 2d, which common conductor 2c is supplied with an exciting current corresponding to the sum of individual exciting currents supplied between the conductors 2b and 2c and between 2c and 2d respectively, so as to operate the bump magnet 2 as a septum magnet by supplying exciting currents to all of these conductors 2b, 2c and 2d. At the same time, additional bump magnets not shown in Fig. 1, provided in upper and lower reaches thereof, is excited for shifting the circulation orbit as shown in Fig. 1, wherein the bump magnet is not excited in the time of the negative ion beam being injection. Consequently, the orbit of the positive ion beam injected into the bump magnet 2 at a given angle is deflected substantially in parallel with the circulation orbit as shown in Fig. 1, by the fact that the above shifted circulation orbit is temporarily passing through the septum magnetic field formed in the bump magnet 2, and subsequently meets the circulation orbit through the bump magnets 3, 4, 1 and 2 in order. In this connection, before the injected ion beam, which has met the circulation orbit, returns to the injection point after the one round circulation, the circulation orbit is reverted to the original state by releasing the excitation of the additional bump magnets provided in upper and lower reaches, thereby the circulation is subsequently maintained on the circulation orbit of the injected beam. As mentioned above, the injection apparatus both for positive and negative ions as shown in Fig. 1 embodying to the present invention, can be realized respectively through a compact arrangement, wherein said apparatus comprises a single set of arrangement, two quite different injection systems, that is, the charge conversion injection system for accelerating protons and the circulation orbit shift injection system for accelerating positive ions. According to this injection apparatus, it is applicable for accelerating various kinds of particles, the use of the accelerator can be expanded for a multi-purpose particle accelerator in future. The change between proton acceleration and positive ion acceleration can be attained without any large-scale change of the arrangement. It is possible in principle to change the kind of particles to be accelerated at each accelerating pulse. According to the application of this injection apparatus both positive and negative ions embodying the invention, particularly, upon KEKPS, that is, Proton Synchrotron of High Energy Physics Laboratory, it is possible to effect the acceleration of both a high intensity proton beam and a high energy ion beam, so as to realize multipurpose use of the particle accelerator. It is possible that the negative ion beam and positive ion beam can be shifted simultaneously to be over-lapping on the same circulation orbit by controlling the timing of both injections. As it is apparent from the above description, that the injection apparatus both for positive and negative ions embodying to the present invention, can be realized similarly as the conventional injection apparatus, such that among the first to the fourth bump magnets arranged in order on the circulation orbit center, the second bump magnet is afforded with both of respective functions of the bump magnet and the septum magnet, while, upon the injection of negative ion beam, the charge conversion multiplex injection system based on negative ions can be realized similarly as the conventional injection apparatus as shown in Fig. 3 by making the second bump magnet to function as a bump magnet, and further, upon the positive ion beam injection, the circulation orbit shift multiplex injection system based on positive ions can be realized similarly as the conventional injection apparatus as shown in Fig. 5 by making the second bump magnet function as a septum magnet. For the above reason, the injection apparatus for both positive ions and negative ions for which it has conventionally beer essential to have two kindsof injection apparatus, can be compacted by uniting into one system, the accelerator provides more flexibility in the applicable field by releasing the long time and large scale working necessary for mutually interchanging the injection apparatus upon the change of the kind of injection beam. Moreover, the injection apparatus both for negative and positive ions embodying the present invention can realize a charge conversion multiplex injection system based on negative ions as in the conventional injection apparatus shown in Fig. 3, such that upon the injection of a negative ion beam, the second bump magnet is affording a function as a bump magnet, after an orbit of the negative ion beam injected at a given angle is deflected in parallel with the circulation orbit through a bump magnetic field formed in the second bump agent, electrons contained in the negative ion beam are separated through the carbon film and converted into a positive ion beam, which gets on the circulation orbit through the third and the fourth bump magnets, while upon the injection of a positive ion beam, the second bump magnet is affording a function as a septum magnet, after an orbit of the positive ion beam injected at a given angle is deflected in parallel with the circulation orbit by making the circulation orbit shifted through the first bump magnet to temporarily pass through a septum magnetic field formed in the second bump magnet, the positive ion beam gets on the circulation orbit through the third and the fourth bump magnets, so that, as a result, the circulation orbit shift multiplex injection system based on positive ions can be realized similarly as the conventional injection apparatus as shown in Fig. 5. Consequently, according to embodiments of the present invention, the apparatus which conventionally necessitates two kinds of arrangements for injecting both positive and negative ion beams can be unified into a compact form and further to be released from the large-scale and long term work for changing the two kinds of arrangements from each other, each time the kind of injected ion beam is changed, so as to increase the freedom in the application of the particle accelerator.

Claims: An injection apparatus for positive and negative ions comprising a first, a third and a fourth bump magnets (1,3,4) arranged serially on a circulation orbit, a second magnet (2) arranged on said circulation orbit between the first and the third bump magnets (1,3) so as to maintain a given position relative to the circulation orbit and a carbon film (5) arranged between the second and the third bump magnets (2,3), wherein the second magnet (2) is operable with both of respective functions of a bump magnet and a septum magnet, and means for operating said second magnet (2) as a bump magnet upon the injection of a negative ion beam, and means for operating said second magnet (2) as a septum magnet upon the injection of a positive ion beam. An injection apparatus for positive and negative ions as claimed in claim 1, wherein upon the injection of a negative ion beam, the second magnet (2) is affording a function as a bump magnet, after an orbit of the negative ion beam injected at a given angle is deflected in parallel with the circulation orbit through a bump magnet field formed in the second magnet (2), electrons contained in the negative ion beam is separated through the carbon film (5) and converted into a positive ion beam, which gets on the circulation orbit through the third and the fourth bump magnets (3,4) wherein upon the injection of a positive ion beam, the second magnet (2) is affording a function as a septum magnet, after an orbit of the positive ion beam injected at a given angle is deflected in parallel with the circulation orbit by making the circulation orbit shifted through the first bump magnet (1) to temporarily pass through a septum magnetic field formed in the second magnet (2), the positive ion beam gets on the circulation orbit through the third and the fourth bump magnets (3,4). An injection apparatus for positive and negative ions as claimed in claim 1 or 2, wherein the second magnet (2) comprises a first conductor (2b) arranged outside the circulation orbit and a second and a third conductor (2c,2d) arranged outside the circulation orbit, a bump magnetic field is formed between the first and the second conductors (2b,2c) and a septum magnetic field is formed between the second and the third conductors (2c,2d). An injection apparatus for use with either positive or negative ions as claimed in any preceding claim, wherein at least one magnet is arranged on a ion circulation path, and one of said magnets is arranged to be operated as a bump magnet upon the injection of a negative ion beam and to be operated as a septum magnet on injection of a positive ion beam. A method of operating an injection apparatus for positive and negative ions having: a first, a third and a fourth bump magnets arranged in order on a circulation orbit, a second bump magnet arranged on said circulation orbit between the first and the third bump magnets so as to maintain a given position relative to the circulation orbit and a carbon film arranged between the second and the third bump magnets, the method comprising: operating said second magnet (2) as a bump magnet upon the injection of a negative ion beam; and operating said second magnet (2) as a septum magnet upon the injection of a positive ion beam. A method of operating injection apparatus for positive and negative ions as claimed in claim 5, further comprising the steps of: injecting a negative ion beam into said injection apparatus at a given angle, operating the second magnet (2) to form a bump magnetic field, deflecting the orbit of said negative ion beam by a given angle in parallel with the circulation orbit, separating electrons contained in the negative ion beam through the carbon film (5) to form a positive ion beam, and deflecting the positive ion beam onto the circulation orbit through the third and fourth bump magnets (3,4). A method of operating injection apparatus for positive and negative ions as claimed in claim 5, further comprising the steps of injecting a positive ion beam into said injection apparatus at a given angle, operating the second magnet (2) as a septum magnet, deflecting the orbit of the positive ion beam in parallel with the circulation orbit, and deflecting the positive ion beam onto the circulation orbit through the third and fourth bump magnets (3,4). A method of operating injection apparatus for positive and negative ions as claimed in any of claims 5 to 7, comprising the steps of: positioning at least one magnet on an ion circulation path, operating said at least one magnet as a bump magnet upon the injection of a negative ion beam, and operating said at least one magnet as a septum magnet on the injection of a positive ion beam.

Inventors: SAKAI IZUMI, SAKAI, IZUMI
Applicants: HIGH ENERGY ACCELERATOR RESEAR, HIGH ENERGY ACCELERATOR RESEARCH ORGANIZATION
Application year: 1995
Main classification: H05H7
IPC codes: H05H7, H05H13