[仿真]Simulation of Ion Noise in Microwave Tubes

Abstract—The ion noise in microwave tube is studied using ++&F5'?
g  
two-dimensional particle-in-cell method. The fluctuation of the ion Hkg@M?(  
amount, which is the source of ion noise of the tube, is observed in *}/xy SH3  
the simulation process. It is found that the sufficient ions amount in T"QY@#
E  
drift tube and beam envelope scalloping appear to be responsible J3:P/n&  
for ion noise after changing the gas pressure, magnetic focusing E*(Q'p9C  
field, and drift tube length. A great number ions escape radially *D AgcB  
and their amount is about half of the beam electron when ion EHzZ9zH\  
noise occurs. The number of secondary electron is less than that "VT5WFj  
of the ion and beam electron; it affects the ion noise very slightly. m9L+|r  
There are two ways can be used for depressing the ion noise. The Ne^#5T  
first is adjusting or increasing the magnetic focusing field in drift +D h=D*  
tube. The second is creating static electric field gradient to make 'Fonn  
the ion .. ,1~Zqprn  
="A[*:hC"  

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