IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 31, NO. 6, DECEMBER 2003 1337 Pulsed Power Transmission Line Transformer Based on Modern Cable Technology Adam Lindblom, Patrik Appelgren, Anders Larsson, Sten E Nyholm, Jan Isberg, and Hans Bernhoff Abstract—A high-voltage transmission-line pulse transformer has been constructed based on modern cable technology. The trans- former has been successfully tested for output powers of 0.5 GW. The high-voltage cable is equipped with a resistive layer (semicon) on the inner conductor and on the inside of the outer conductor. Semicon cables are commonly used in high-voltage transmission of electrical power. The pulse transformer was built using a coaxial semicon cable, with the inner conductor used as secondary winding and the screen as primary winding. Such a transmission-line trans- former works in the same way as an ordinary transformer. The input is transformed to the desired output using a step-up or a step-down configuration. An output voltage of 85 kV with 1- s duration was achieved into a 15 load. Because the windings are coaxial the magnetic leakage is kept low and, therefore, the coupling coefficient is high. This type of transformer is useful in applications where weight is an impor- tant factor. Another advantage is the simple design and that it can be manufactured at a low cost. Index Terms—High voltage, pulsed power, transformer, trans- mission line. I. INTRODUCTION T HE PULSED-POWER conditioning system is a key com- ponent in compact systems for generation of high-power microwaves. In normal operation, the system converts a slow high-current impulse to a fast high-voltage impulse and an intermediate energy storage device for electric energy is required for operation. The operating principle for such a system is illustrated in Fig. 1. The primary energy storage is, by closing the first switch, discharged through the storage inductor. When the second switch is opened, preferably at current maximum, the current is abruptly interrupted and the magnetically stored energy in the inductor is discharged into the load. A pulse-conditioning system based on this principle exists at Swedish Defence Research Agency (FOI) Grindsjön Research Center. The development of this system started at Texas Tech University, Lubbock, with support from FOI [1], and it is further developed at FOI [2]. In order to enhance its Manuscript received March 12, 2003; revised August 21, 2003.This work was supported by the Swedish Armed Forces and the Carl Tryggers Fund for Scien- tific Research. A. Lindblom was with the Grindsjön Research Center, Swedish Defence Re- search Agency, FOI, SE-14725 Tumba, Sweden. He is now with the Division for Electricity and Lightning Research, Ångströmlaboratoriet, Uppsala Univer- sity, SE-75121 Uppsala, Sweden (e-mail: Adam.Lindblom@hvi.uu.se). P. Appelgren, A. Larsson, and S. E. Nyholm are with the Grindsjön Research Center, Swedish Defence Research Agency, FOI, SE-14725 Tumba, Sweden (e-mail: Anders.Larsson@foi.se). H. Bernhoff and J. Isberg are with the Division for Electricity and Light- ning Research, Ångströmlaboratoriet, Uppsala University, S-75121 Uppsala, Sweden (e-mail: Hans.Bernhoff@hvi.uu.se). Digital Object Identifier 10.1109/TPS.2003.821358 Fig. 1. Pulsed-power conditioning system with inductive intermediate storage of electric energy. Fig. 2. Pulsed-power conditioning system with inductive intermediate storage of electric energy in the pulse transformer. performance, the inductance may be replaced by a step-up pulse transformer according to Fig. 2. This paper reports the design and analysis of such a step-up pulse transformer which is realized as a transmission line transformer (TLT) based on modern high-voltage cable technology. Recent development has proven that semicon cables perform well as windings in elec- trical machines such as the Powerformer [3]. In 1965, Gaaze and Schneerson (referred by Altgilbers et al. [4]) proposed a design of an impedance-matched pulsed-power conditioning system based on a transmission-line transformer. However, the design of the cable transformer has improved substantially with the introduction of modern polyethylene (XLPE) insulation. The basis of the present design originates from Bernhoff at the Electricity and Lightning Research Department, Uppsala University. High-voltage cable applications are of great interest for several usages such as power transformers [5], generators and high-power devices. This type of transformer is useful in applications where weight and size are important factors. Another advantage is the simple design and that it can be made at a low cost. There are mainly two types of transmission line transformers: the one described here and another that uses magnetic cores. 0093-3813/03$17.00 © 2003 IEEE