Галерея 2615129

🛑 ПОДРОБНЕЕ ЖМИТЕ ЗДЕСЬ 👈🏻👈🏻👈🏻

Галерея 2615129
Hierzu gibt es keine Street View-Bilder.
Hierzu gibt es keine Street View-Bilder.

Oct. 21, 1952 E. M. MCMILLAN sYNcHRo-CYCLOTRON 6 Sheets-Sheet 1 Filed May 16, 1947 Mdm f4 TTOR/VE K Ot. 21, 1952 E, M McMlLLAN SYNCHRO-CYCLOTRON 6 Sheets-Sheet 2 Filed May 16, 1947 N K R Z M NM. M m WM A W W E. M. MCMILLAN SYNCHRO-CYCLOTRON Oct 21, 1952 e sneetsheet 3 Filed May 16' 1947 /NVE/Vro@ N M M W M ,1W
n N m T T A Oct. 21, 1952 E, M. MOMILLAN 2,615,129
sYNcHRo-CYCLOTRON Filed May 16, 194'? 6 Sheets-Sheet 4 A rroR/VE y.
Oct. 21, 1952 E, M McMlLLAN SYNCHRo-CYCLOTRON 6 Sheets-Sheet 5 Filed May 16, 1947 /N VEA/TOR EQw//v MMcM/LLA/v Oct. 2l, 1952 E. M. MGMILLAN 2,615,129
sYNcHRo-CYCLOTRON i Filed May 16, 1947 6 Sheets-Sheet- 6 www Y www w@ w1 S1 wwww SQ w@ www www www www www charged particles.
with a method and means for accelerating terium atoms.
Patented Oct. 2l, 1952 sYNcHRo-CYCLOTRON Edwin M. McMillan, Berkeley, alif.,assignor to theV United States of America aslrepresented by the United States Atomic Energy Commission Application May 16, 1947, serial No. 748,434
This invention relates to the acceleration of It is particularly concerned charged particles to very great velocities. More specifically the invention relates to achieving the acceleration of ions to speeds approaching that of light by means of a magnetic resonance accelerator; a mechanism of the type known as a cyclotron.
A detailed description of a conventional cyclotron will be found in U. S. Patent No. 1,948,334
ygranted to E. O. Lawrence on February 20, 1934.
entitled IMethod and Apparatus for the Acceleration of Ions. The characteristics of cyclotrons lferred to as Deeswhich are coplanar radially and whose open diametrical edges are parallel and closely spaced. The particles to be accelerated are usually protons or deuterons formed by stripping the electrons from hydrogen or deu- The stripping is accomplished in an ion source at the center of the vacuum charnber and between the Dees and therein the hydrogen or deuterium gas is subjected to electron bombardment. Helium nuclei may also be accelerated in cyclotrons and are obtained by introducing helium gas in the ion source and subjecting it to electron bombardment.
A positive ion introduced between the Dees is pushed by the positive Dee and pulled by the negative one, thus being accelerated across the gap between them. Once the ion is urged into the cavity of a Dee it is no longer influenced by the electric field which has just accelerated it across the gap but is constrainedA by the magnetic field that is constantly applied, to travel in a circular' path. When the particle has progressed along the circular path about 180 it emerges into the region between the Dees where it once more is acted upon by both the magnetic and the electric fields. If the time which the ion has spent within the Dee is just half of the period of oscillation of the high-frequency circuit, then on emergence into the gap, the electric field will be reversed and the particle will once more be accelerated across the gap and into the `creases as the particle progresses.
2 electrically field-free region within the opposite Dee.` The length ofpath taken within theDees, between successive accelerations in thek gap,4v in- Thus, the particle spirals outwardly becausek as it'r gains speed, it has more, centrifugal force. l f
It 'has been demonstrated that within limits the speed of the particle increases at sucharate that the timeof travel between accelerations is constant.` Thus, it takes the same time to go around a small semicircle slowly as to go around a large semicircle rapidly. Therefore, the Dees may be energized byplus and minus alternations of constantfrequency. This becomes more lclear when one considers the motion of an ion rnathematically. For a charged particle 4nim/ing at right angles to a magnetic field one has the relation:
where H is the field intensity, e is the charge, v the velocity, and m the mass ofthe particle `and r is the radius of curvature of its path. Now
if the ion is allowed to traverse its semicircular path with an angular velocityequaltofW then:
WALIl (3) It is evident from this that the angular velocity of the ion is dependent of both its linear velocity and the radius of its path, or more precisely, of the energy of the ion. This is true only for particle velocities that are smallcompare'd'with the velocity of light. Furthermore it is evident that as the velocity of a particle increases, its energy or mass also increases.
Early in the development of the cyclotron it was recognized that the relativity increase of mass posed an obstacle in achieving very great particle energies therein. H. A. Bethe and M. E. Rose, in a letter Apublished in the December 1937 issue of The Physical Review stated that it was apparent that a cyclotron could'not be made to give much higher energies to particles than those which had been obtained at that time. The difiiculty is due to the relativistic change` of mass which has the effect of' destroying either resonance or focusing.
As is frequently the case in experimental physics it is theoretically possible to get around this 3 apparent practical limitation in several ways. The defocusing action which is inherent in a radially increasing magnetic eld required by the relativity condition can be overcome by providing suitable electrostatic focusing. Thomas has shown that an azimuthal adjustment of the niagnetic held will accomplish the same purpose. Each of these plans has inherent drawbacks and neither has been successiuly reduced to prac-- tice.
Again, Bethe has suggested that the only way to obtain higher particle energies in a cyclotron seems to be to increase the voltage on the Dees. Lawrence followed the suggestion when he built his 60" cyclotron in Crocker Laboratory to operate with about a quarter of a million volts on the Dees, to the end that when he was accelerating doubly charged helium ions to 32 million electron volts, the ions were required to circulate fewer than nity times. rhe advantage of such a scheme was that a rather large change in mass could take place without seriously impairing the synchronisin of the circulating ions. However when it is considered thatthe particle energy liniit increases only as the square root 01"' the Dee voltage, it is easy to see that even such a design as this has limitations beyond which it is not practical.
As previously stated, within limits the speed oi' a particle revolving in a uniform magnetic held and oscillating electric field increases at such a rate that the time of travel between accelerations is constant. ln other words, within liniits the particle stays in phase with the oscillator. As the particle velocity approaches that oi light, its energy increases and its mass becomes relatively greater. The increase in mass retards the particle and causes it to lag the oscillations oi the electric field. it is then out of synchronisin with the oscillator and will become increasingly out of phase until it enters a region of deceleration whereupon its energy will drop back to the original value. It is obvious then that there exists a range ci phase in which a particle will receive acceleration and beyond which it will not receive acceleration.
Pondering the prospect of completing a cyclotron larger than had ever been built before-not merely were the poles to have been three times the diameter of any previous model but the Dee potential was planned to be 1,000,000 volts and the oscillator power was set at 5000 kwhave devised a solut" n of this problem of phase stability as it applies to magnetic resonance accelerators. The term phase stability as here used refers to particles kept in phase with the oscillating electric field even after great mass increases have taken place therein. lr" one were to increase the magnetic held incrementally, or to decrease the elec 1ic reqency incrementL l 1J, the eduilibrium angular velocity ci the aiected particles would then be suihciently in excess of the value required to match their gain in energy that the instantaneous value oi the energy or the particle would oscillate 'cach and fort about the equilibrium value. e ene i the charged particles traveling in substantially orbits in a magnetic resonance accelerator would be phase stabilized about the equilibrium value.
The utilisation of the principle of phase stability or accelerating charged particles to high energy may be achieved in dilierent ways for light and heavy particles. For the acceleration of light particles, such as electrons, to high energy it is more convenient to vary the magnetic ield and hold the frequency of the electric cld constant, and this technique has been used in the synchrotron which is disclosed in the copending application of Edwin M. McMillan, Serial No. 656,908, for Method Of and Apparatus For Accelerating To High Energy Electrically Charged Particles. For the acceleration of heavy particles, suoli as protons, reuterons and particles, to high energy, it is more convenient to hold the magnetic field constant and vary the frequency of the oscillating electric field. This technique ernployed in the instant improvement in a cyclotron to meet the requirements ol fundamental researchers for an instrument which will supply charged particles at veryT much highe.` energy than has been obtainable heretofore.
It is therefore one object oi this invention to provide a method and for ,ccelerating charged particles to energies commensurate with substantial increa es in the mass of the particles.
Another object of the invention is to provide a method and nieans employing an oscillating electric iield and a magnetic field for controlling the energy of charged parti des by varying the ratio of the frequency oi oscillation to the magnetic neld strength.
Another object of the invention is to provide a method and means employing an oscillating electric held and a magnetic field for increasing the energy of charged particles by decreasing the frequency of scillaticn of the electric field.
A further object of the invention is to provide a method and means employing magnetic field and a varying oscillating electric field for accelerating charged particles along circular orbits in a cylindrical region and for directing the particles to a target in the outer portion of that region.
Other objects and advantages of the invention will become evident with reference to the following detailed description in conjunction with the accompanying drawings wherein:
Figure l is a diagrammatic plan, comparable to a cross section on a generally horizontal plane taken between the poles of the magnet.
Fig. 2 is a front elevation of a magnet structure and a forni of the invention ass ciated therewith but illustrating' primarily the envelope or tank or" the embodiment with portionsoi" various tank appurtenances omitted.
Fig. 3 is a view of the structure shown in Fig. 2, being generally a plan with portions of the magnet and tank broken away to increase the clarity oi disclosure.
Fig. 4 is a view of the structure disclosed in Fig. 3, the view being in part an elevation and the remainder a vertical cross section, and the several planes of the whole indicated by the line 1i4 of Fig. 3.
Fig. 5 is an end elevation partly in section on the line 5 5 of Fig. i showing to an enlarged scale the rotary condenser and its associated structures. with portions broken away to reduce the size of the figure and to improve the clarity of disclosure.
1Eig. 6 isa cross section on a vertical plane indicated by the line 5 5 of Fig. V, showing mechanical details of the rotary condenser with fragments broken away to increase the clarity of dis closure.
Fig. 7 is a frag.i entary View ci portions oi the rotary capacitor shaft showing, in section, details of the water cooling means.
Referring now to Fig. l there is illustrated schematically an electromagnetic accelerator enibodying the present invention and which I have y therefrom.
termed a synchro-cyclotron. The synchro-cyclotron II comprises a magnetic eld structure of which one pole I2 is shown, a tank I3 arranged `on a common vertical axis therewith, and a pair of electrodes I4 and I5 for establishing the required electric field. The electrode I4 as shown 'is a hollow, generally semipancake-shaped memtance equal to the distance between the sidewalls of electrode I4. The electrodes I4 and I5 are enclosed within the vacuum tight envelope or tank I3.
` The electrode I4 is insulated from the tank I3 being supported by stems I6 and I'I that are secured to the wall IB of electrode I4, and pass through insulators I9 and 2| which in turn are supported on a wall of the tank I3. The electrode I is electrically grounded through the pole I2, and since the poles may either support the tank I3 or be part of the tank, the electrode I5 is also electrically grounded through the tank I3.
Through a port 22 and a manifold. 23, two diffusion pumps 24 backed up by a motor driven pump 25 are used to maintain the necessary Vacuum within the tank I3.
A high frequency oscillatory electric lield is maintained between electrodes I4 and I5 by applying to electrode I4 a high frequency oscillating potential supplied from an electronic oscillator, the grounded electrode I5 being connected through the tank to one side of the oscillator. The oscillator circuit may be of any suitable type, such as the grounded grid circuit shown in Fig. l, comprising an oscillator tube 26 and suitable inductances and capacitances to produce an oscillator having a definite frequency. The input of the oscillator is -connected to a power supply which is fed from a 60 cycle line 2'I. The plate potential of about l5 kv. is fed in at the junction point 28. Grid bias is developed across the dropping resistor 29 Kand the radio frequency on the grid is by-passed to ground through capacitor 3I The phase of the excitation voltage between filament and grid is controlled by the capacitor 32 in series with the filament lines.
As a means of exciting the electrode I4 from the output of the oscillator, the filament lines are connected to a filament coupling loop 33, and the plate line is connected to a plate coupling loop 34. These loops 33 and 34 are arranged in parallel relationship adjacent the electrode stem I6 (Fig. 1) which constitutes a half-wave transmission line. It would of course be possible to use any convenient number of these transmission lines in parallel but for simplicity of illustration only two are shown in Fig. l. The filament and plate loops may be arranged adjacent any one or two of the transmission lines.
` The ends of the stems I6 and II, opposite the electrode I4, are supported by insulators 35 and 35 respectively and terminate in a rotary capacitor 31 enclosed in a vacuum tight tank 38. Secured to the stems are a number of spaced, fixed rings 39 with toothlike blades projecting inwardly Interposed between the iixed rings are rotatable disks 4I mounted on an insulator 42 which in turn is secured to a shaft 43 that is driven by an external motor 44 through a pulley 45. The disks 4I are also provided with peripheral blades, and 'their extent and spacing are substantially identical with those on, the xed ring 39. A second series of capacitor plates is located in the tank 38 and constitutes a coupling capacitor to ground. It comprises a rotating disk 46 mounted on the insulator 42 and positioned midway between two fixed rings 41 mounted on a wall of tank 38.
A positive bias of a few hundred volts is applied to the electrode I4 and the stator rings 39 through the choke 43 and the electrode stem I1. The radio-frequency potential on the electrode stem II is by-passed to ground through the'capacitor 49.
Ions may be provided in the apparatusr by any suitable means. Fig.- l illustrates ran ion source 5I positioned over the center of the` pole I2 and supported at the end of an arm 52midway between the electrodes I4 and I5. The arm 52 is sustained by an insulator 53 in the wall of the tank I3. The filament in the ion source 5I is energized through conductors 54 and a transformer 55 by a 60 cycle alternating current. Direct current is provided to the source 5I through a junction 56 by a pulsed supply 51 which can provide up to one thousand Volts.
Means are provided for sampling the ion current in any of the circulator orbits of the beam which are in a generally horizontal plane midway between the magnet poles. The supporting tube 58 is slidably arranged ina wall of the tank I3. As is common in cyclotron art the tube 58 is provided with an aperture l59 to receive the beam. Therein the beam falls on an electrode that is insulated from the shell of the tube and current fiows along an insulated conductor 6I through the current meter 62 to ground. The tube 58 may be moved axially through the several beam revolutions and therefore it may be positioned to intercept any single revolution of the beam from a point adjacent the source to the outermost revolution. Thus one may measure the ion current in the beam at any point along a radius of its circulatory orbits.
At a definite point in the circulator path of the beam means are provided for withdrawing the ions from the magnetic iield. For this purpose there are shown, for example, electrodes 63 and 64 which delimit an electric field designed toreceive ions and deiiect them outwardly. The electrode 63 is a curved metal structure mounted within and electrically grounded to the tank I3, and extending from a point of tangency to the path of the ions in the magnetic eld but ared outwardly therefrom. Concentric with electrode 63 is an electrode 64 comprising a curved metal strap that is mounted on a pair of supporting members 65fand 66. The supports 65 and 66 are in turn respectively mounted on insulators 6l and 68 which are formed as bushings, secured to a wall of the tank I3. An adjustable external source of direct current supplies a suitable potential on the order of 200 kv., as an example, to the electrode 64 through the conductors 69 which pass through bushings 61 and 68, and are connected to the respective supports 65 and 66. When positively charged particles are being operated upon, the electrode 64 is maintained at a suitable negative potential to withdraw the particles from the magnetic eld. The grounded electrode 63 serves to prevent the eld set up around the electrode 64 from having any effect on the orbits of the beam. Thus the electrodes G3 and E4 constitute a deflector system which is capable of deecting the charged particles in the outermost revolution of the beam orbit outwardly from the region of the magnetic field.
The particles thus aiiected pass through the channel 1|, between the electrodes and E4, and emerge from the outlet opening i2 into a region of diminished magnetic eld wherein their centrifugal force causes them to traverse an ever straightening path 'i3 into the electrode if*i and through a window in the wall i4 thereof.
The high speed particles emerging from the Dee along the path '13 may be utilized in any suitable manner such as operations upon atomic structures, in medical physics research, etc. To facilitate such investigations the high speed particles may be withdrawn from the apparatus through a window 'l5 provided in a wall of the tank I3. The window may be made of any suitable material which will at once maintain the vacuum tight continuity of the tank structure and yet permit the passage oi the emergent particles therethrough without appreciable velocity loss or scattering.
Cyclotrons have been widely discussed in the literature. As an example, a comprehensive paper dealing with the prior art in such matters as magnet design, ion sources, deectors, target arrangements, vacuum systems and shielding appeared in the Journal ci Applied Physics in January 1944 (vol. l5, pages 249) and in February
Скромная симпатичная блондинка
Негритянка с висячими сиськами показывает волосатую пизду
Чернокожая соблазнительница с большой грудью и большой попой