Re -discussion design methods for Pierce guns

The initial value of the convergence half angle in the iterative synthesis is discussed and a more logical function is given for assigning it. With the application of the new function, the results of normal and high -convergence Pierce guns are completely the same with the results which are obtained with the application of Vaughan's, and reasonable results are got of the low -convergence ones which can not be settled by Vaughan's method. Therefore, the new function extends the application range of the iterative synthesis from the high -convergence to the low -convergence Pierce guns．