Experimental validation of CHRISTINE, a 1-D, multi-frequency helix TWT code: drive curves, phase, distortion products, and intermodulation

Summary form only given, as follows. Experimental measurements of a Hughes 8537H 80 W CW helix TWTA operated from 1.4 to 1.75 GHz are compared with predictions made by CHRISTINE, a 1-D multifrequency helix TWT simulation code. The simulations utilize a recently implemented tape helix model. Extensive experimental measurements were carried out to validate the code in both linear and saturated regimes using both single and multiple driven tones. In general, the model has shown excellent agreement with experimental measurements over a broad range of frequencies. Predicted TWT gain versus frequency characteristics agree to better than 3% of measured data with deviations in agreement explained by strong reflections at the output window that are not modeled by the code. Single tone experimental and predicted drive curves agree to better than 3% in the linear regime and to better than 1% near saturation; phase shift and AM-PM conversion predictions agree to within experimental measurement accuracies. Two-tone experimental and predicted data exhibit similarly good agreement, including third- and fifth-order intermodulation product data. Second harmonic measurements were also carried out and compared to CHRISTINE simulations with good agreement.