高亮度注入器腔形径向电场的线性化

LINEARIZATION OF RADIAL ELECTRICAL FIELD IN THEk HIGH-BRIGHTNESS INJECTOR

讨论了驻波腔内射频场力对电子束横向运动的影响，求出了使加速腔内径向电场线性化的阳极等位线方程。并给出了使径向电场Ｅ＿ｒ线性化的加速腔鼻锥设计所应遵循的原则，以及驻波腔径向电场线性化程度的判据。

AbstractThis paper discusses how to linearize the radial electrical field in the high-brightness injectoraccelerating cavity for reducing the emittance growth caused by the radiofrequency effects.Wecan improve that the normal emittance does not grow if the electronmagnetic force is linear whenelectron beam go through the accelerating cavity.M.E. Jones and K.T. McDonald give out twokinds different metl1od to linearize redial radiofrequency field.But M.E. Jones’s method is notcompletely suitldble to st,dnding-wave cavity and K.T. McDonald’s method is only suitable tothe cavity which have not an anode nose. A new method to linearize high一brightness injectoraccelerating cavity with an anode nose is given out. From an analytical equation(19 ),which isquite un,dnimous to real electrical ficeld. An anode equipotental line for geting a linear radial electrimalfield in standing-wave acc elerating cavity. The equipotental line should be given with equation(25 ),thus discussing how to design the anode nose to linearize the radial electrical field andwhat kind shape is optimal anode nose shape.A criterion to measure the linearizing level ofradialelectrical field is given out. From the formula (25),we conclude that the magnitude of highorder hd,rmonic must be less than 12 oercent of the magnitude of first harmonic,otherwise theradial radiofregueney field is nonlinear.Fig.2 shows the distribution of redial electrical field nearthe axis,and it indicates that the linetirization of radial electrical field in standing-waveaccelerating cavity is quite well.