Patent Application
20070236300
The drawings illustrate the design and utility of preferred embodiments, in which similar elements are referred to by common reference numerals. In order to better appreciate how the above-recited and other advantages and objects are obtained, a more particular description of the embodiments will be rendered, which are illustrated in the accompanying drawings. These drawings depict only typical embodiments and are not therefore to be considered limiting of its scope.
Various embodiments are described hereinafter with reference to the figures. It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated.
In the illustrated embodiments, the first phase shifter 120 is coupled to the second port 104 via a tee 130 having a first arm 132, a second arm 134, and a third arm 136, wherein the first arm 132 is coupled to the second port 104, the second arm 134 is coupled to a first load 140, and the third arm 136 is coupled to the first phase shifter 120. In some embodiments, the arms 132, 134, 136 may be tubular structures, the respective ends of which are sized and shaped to couple to the second port 104 (or to a coupling component, e.g., a tube, that is coupled between the second port 104 and the tee 130), the first load 140 (or to a coupling component, e.g., a tube, that is coupled between the fist load 140 and the tee 130), and the first phase shifter 120 (or to a coupling component, e.g., a tube, that is coupled between the first phase shifter 120 and the tee 130), respectively.
The power regulator 18 also includes a short circuit 150 connected to the first phase shifter 120. In some embodiments, a mechanically-sliding short circuit may be used to replace devices 120,150, in which case, the short circuit may be used to adjust a phase shift. As shown in the figure, the power regulator 18 further includes a shunt reactance element 160 and a second load 170, both of which are coupled to the second phase shifter 122. The shunt reactance element 160 is sized to provide a proper magnitude of a signal to the generator 16. In some embodiments, the shunt reactance element 160 may be implemented by using a rod or a screw that penetrates a wall (e.g., a wall that is coupled to, or associated with, the second phase shifter 122). In other embodiments, the shunt reactance element 160 may be implemented by using other structure(s)/device(s) known in the art. For example, U.S. Pat. No. 3,714,592 discloses a shunt reactance element that may be used with embodiments described herein.
The phase shifter 120 can be implemented using a variety of devices known in the art. For example, in some embodiments, the phase shifter 120 can be a mechanical phase shifter, such as a ceramic element sized to be inserted into an electric field region. In other embodiments, the phase shifter 120 may be implemented electrically by using a fast ferrite tuner (FFT). The FFT is a transmission line partially filled with ferrite material, which is biased magnetically by an electromagnet. In such cases, phase control (e.g., microwave phase control) can be accomplished by changing a current to vary the magnetic field (being electromagnetically driven). Such configuration is advantageous in that it allows a relative phase be adjusted quickly, e.g., by changing the current level, and therefore the magnetic level and the corresponding RF phase-shift, within a few milliseconds, for example within an RF inter-pulse period. For example, in some embodiments, the current may be changed at every 10 milliseconds or less, and more typically, at every 2 milliseconds. In some cases, the above configuration allows adjacent RF pulses or pulse trains to be of different amplitudes. In further embodiments, the first phase shifter 120 can be implemented as other forms of a delay line. The phase shifter 120 can also be implemented using other mechanical and/or electrical components known in the art in other embodiments. Examples of phase shifter or its related components that may be used with embodiments described herein are available from Thales MESL in Scotland, UK, AFT Microwave GmbH in Germany, and The Ferrite Company in Nashua, N.H. In any of the embodiments described herein, the phase shifter 120 may be connected to a computer or a digital processor, which controls the operation of the phase shifter 120.
During use, the power generator 16 delivers power at a fixed level to the first port 102 of the circulator 100, and the power is transmitted from the first port 102 to the second port 104. At the second port 104, the power exits the circulator 100 and enters an radiofrequency circuit comprised of the first phase shifter 120, the short circuit 150, the tee 130, and the first load 140. The combination of the short circuit 150 and the phase shifter 120 provides the function of shunting the load 140 with a reactance that can vary from zero (short circuit) to infinity (open circuit), or any value therebetween, thereby reflecting, all, some, or none of the power back into the second port 104.
The power reflected back to the second port 104 (which can vary from a small amount to substantially all the power exiting the second port 104, and is changed in phase with respect to the phase of the RF out of the power generator 16) is transmitted to the third port 106, and is used by the accelerator 12 to accelerate an electron beam (e.g., to a desired energy level). Some power will be reflected from the accelerator 12 and be transmitted to the third port 106 of the circulator 100, where it is diverted to the fourth port 108.
The reflected power exiting the fourth port 108 is transmitted through a radiofrequency circuit comprised of the second phase shifter 122, the shunt reactance element 160, and the second load 170. Some of the reflected power is absorbed in the second load 170. The remaining reflected power is reflected by the reactance element 160, passes through the second phase shifter 122 again, and enters the fourth port 108. The reflected power entering the fourth port 108 is diverted to the first port 102, and is the reflected power that the power generator 16 “sees.”
As illustrated in the above embodiments, the first phase shifter 120 is configured to affect a magnitude of the power being delivered to the third port 106 (and therefore, to the accelerator 12), and to affect the relative phase of radiofrequency between the first and the third ports 102, 106. Also, the second phase shifter 122 is configured to affect the relative phase of reflected radiofrequency power between the first and the third ports 102, 106 so that the power generator 16 sees the reflected power (wave) in the phase which causes it to “lock” to the accelerator's frequency. As such, the power regulator 18 of
The first radiofrequency circuit extending from the first port 104 and/or the second radiofrequency circuit extending from the fourth port 108 may have other configurations in other embodiments. For example, in other embodiments, either (or both) of the first and the second radiofrequency circuits may be implemented using other forms of a phase-shift delay line.
It should be noted that the power regulator 18 is not limited to the example discussed previously, and that the power regulator 18 can have other configurations in other embodiments. For example, in other embodiments, the power regulator 18 needs not have all of the elements shown in
Although particular embodiments have been shown and described, it will be understood that they are not intended to limit the present inventions, and it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present inventions. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The present inventions are intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the present inventions as defined by the claims.
