(2)
某回旋加速器的示意图如图1所示。磁感应强度大小为B的匀强磁场仅分布于两个相同且正对的半圆形中空金属盒D
1、D
2内,且与金属盒表面垂直。交变电源通过Ⅰ、Ⅱ分别与D
1、D
2相连,仅在D
1、D
2缝隙间的狭窄区域产生交变电场。初动能为零的带电粒子自缝隙中靠近D
2的圆心O处经缝隙间的电场加速后,以垂直磁场的速度进入D
1。
![](//tikupic.21cnjy.com/2024/06/13/6a/db/6adbd1a81f57e27906754bd23d9ec388.png)
①粒子在D
1、D
2运动过程中,洛伦兹力对粒子做功为W、冲量为I,则
A.W=0,I=0
B.W≠0,I=0
C.W≠0,I≠0
D.W=0,I≠0
②
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsubsup%3E%3Cmrow%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsubsup%3E%3Cmtext%3EH%3C%2Fmtext%3E%3C%2Fmath%3E)
核和
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsubsup%3E%3Cmrow%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsubsup%3E%3Cmtext%3EH%3C%2Fmtext%3E%3C%2Fmath%3E)
核自图中O处同时释放,I、Ⅱ间电势差绝对值始终为U,电场方向做周期性变化,
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsubsup%3E%3Cmrow%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsubsup%3E%3Cmtext%3EH%3C%2Fmtext%3E%3C%2Fmath%3E)
核在每次经过缝隙间时均被加速(假设粒子通过缝隙的时间和粒子间相互作用可忽略)。
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsubsup%3E%3Cmrow%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsubsup%3E%3Cmtext%3EH%3C%2Fmtext%3E%3C%2Fmath%3E)
核完成3次加速时的动能与此时
![](//math.21cnjy.com/MathMLToImage?mml=%3Cmath+xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F1998%2FMath%2FMathML%22%3E%3Cmsubsup%3E%3Cmrow%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E1%3C%2Fmn%3E%3C%2Fmrow%3E%3Cmrow%3E%3Cmn%3E3%3C%2Fmn%3E%3C%2Fmrow%3E%3C%2Fmsubsup%3E%3Cmtext%3EH%3C%2Fmtext%3E%3C%2Fmath%3E)
核的动能之比为
。
A.1:3
B.1:9
C.1:1
D.9:1
E.3:1