A Novel Method for Testing the Inner Temperature of Helix TWT under Operation using FBG

A novel method for testing the inner temperature of the helix TWT under operation using fiber Bragg grating (FBG) is proposed, in which the high-temperature FBG keeps in close contact with the support rod, and the gold-coated fiber stretching out is welded with the tube to keep vacuum tightness. In order to verify the feasibility of the method, simulation for the power performance of the helix TWT with different number of embedded fibers is performed, showing that using only one fiber could minimize the impacts on the operating performance. The helix TWT prototype with an embedded high-temperature FBG has been successfully manufactured, and the next step is to test the temperature inside the tube.