Interdigital longitudinal magnetic mode drift tube linear accelerator of separation focusing type

Abstract

The invention provides an interdigital longitudinal magnetic mode drift tube linear accelerator of a separation focusing type, and belongs to the technical field of linear accelerators. The characteristic of small size of a permanent magnet quadrupole iron is utilized, and a focusing magnet is placed in a single drift tube, so that the shunt impedance and the average acceleration gradient of the acceleration tube can be effectively improved. According to the first drift tube linear accelerator, a plurality of drift tubes are arranged in a transverse focusing section C at intervals, and a permanent-magnet quadrupole magnet is arranged in each drift tube in the axial direction. A drift tube linear accelerator of the other type provided by the invention is an improvement on a first drift tubelinear accelerator, and the synchronous phase of a drift tube gap in a transverse focusing section C is controlled, so that a 0-degree accelerating section B is formed after the transverse focusing section C, thereby saving the length of a longitudinal bunching section A and further improving the accelerating efficiency.

Description

technical field [0001] The invention belongs to the technical field of linear accelerators, and in particular relates to a linear accelerator of a split-focus interdigitated longitudinal magnetic mode drift tube. Background technique [0002] The structure of the drift tube linear accelerator is a vacuum radio frequency resonant cavity with at least two drift tubes (the main body of the drift tube is a hollow cylindrical conductor) installed on the central axis, above and below the vacuum radio frequency resonant cavity (or A pair of ridge structures are arranged symmetrically on the left and right sides, and each drift tube is fixed to the ridge structure of the cavity by a support rod. Its working principle is: feed high-power RF (Radio Frequency, radio frequency) electromagnetic waves with a set frequency into the resonant cavity, and these electromagnetic waves will generate an electric field between the drift tubes, and the hollow cylindrical area inside the drift tube ...

AI Technical Summary

Problems solved by technology

[0010] In the currently published technical information, there are two methods for preparing the drift tube containing the permanent magnet quadrupole magnet and the support rod: the first method is to install the permanent magnet quadrupole magnet in the drift tube, and then use a drift tube with a magnetic shielding device. The drift tube and the end cap are welded by electron beam to form a drift tube assembly; this processing method is characterized by the use of a magnetic shielding device, which is used to shield the influence of the magnetic field of the permanent magnet on the electron beam current and ensure the reliability of welding; but due to The use of magnetic shielding devices makes the process of electron beam welding more complicated and requires processing and installation of additional magnetic shielding tools

The second method is to install the permanent quadrupole magnet by thermal expansion and contraction. The drift tube using this processing method is mainly divided into two parts, the drift tube jacket with the support rod and the permanent magnet quadrupole magnet. The inner sleeve of the drift tube of the pole magnet, put the inner sleeve of the drift tube in a low temperature environment (in liquid nitrogen), and place the outer sleeve in room temperature or warm water. Due to thermal expansion and contraction, the dimensions of the inner sleeve of the drift tube and the outer sleeve of the drift tube are exactly the same. After the installation is completed When the drift tube assembly is placed at room temperature, the inner sleeve and the outer sleeve of the drift tube will expand and contract due to temperature changes, and they will be stuck with each other to form a tightly connected drift tube assembly. Uncontrollability, resulting in lower installation accuracy than that of the existing technology, and low temperature is involved in the processing, the preservation of the matching components is more troublesome, and the process is complicated and difficult

There are two solutions in the prior art: one is that the entire support rod is made of steel, and the surface of the support rod is plated with oxygen-free copper. The disadvantage is that the thermal conductivity is very poor; the other is that the support rod inside the acceleration cavity Oxygen-free copper is used for processing, and other support rods are processed by stainless steel materials, and the two are welded together to form a complete support rod, and then the support rod and the drift tube are welded together, and how to reduce the size of the support rod and the drift tube during the welding process The deformation of the drift tube (the welding deformation exceeds a certain range, which may cause the center of the drift tube to deviate too much from the design value, which cannot be corrected, and the entire workpiece is invalid) is difficult to implement

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