Mircea D. Driga

Advanced compulsator design

The compulsator or compensated pulsed alternator is the name for a large family of high-energy pulsed-power rotation machinery. It covers an extensive range of currents, voltages, pulse shapes, and also frequency in the case of multipulse generators. The compulsator embodies the single-element philosophy, combining in one element the energy storage, electromechanical energy conversion, and power conditioning. However, inside the machine such functions are done in a staged manner. Two examples are given to illustrate this design philosophy: the flat pulse air-core compulsator, and the high-voltage two stage uncompensated machine (uncompulsator), which is capable of reaching voltages above 100 kV. >

Advanced compulsators for railguns

In order to maximize the penetration of a projectile into a target, the acceleration on the projectile during the launch must be minimized. Low accelerations permit the design of long and slender projectiles which have better penetration capability. From this standpoint, power supplies for electromagnetic launchers must be able to provide rectangular current pulses with a high average to peak acceleration ratio. The authors discuss efforts to obtain the desired pulse shape from a compensated pulsed alternator (compulsator) when it is used as a power supply for railguns. A general theory of the pulse shaping technique is presented first. This is followed by a discussion on the tradeoffs between various equivalent generator configurations. Finally, the electromagnetic design of the compensated pulsed alternator being developed for task C of the Electromagnetic Gun Weapons System Program is presented. >

Future trends for compulsators driving railguns

Design options for compulsators are discussed wire special emphasis on making them light-weight. Techniques of shaping the current pulse from the compulsator in order to drive railguns more effectively and efficiently are also discussed. Benefits of air-cored compulsators over iron-cored compulsators are presented.

Electrothermal accelerators: the power conditioning point of view

The authors advance the concept of a single-element power supply for ET (electrothermal) guns, showing that compulsator-type machines with waveform flexibility (pulse-shaping capability) can satisfy all the ET gun power supply and conditioning requirements while maintaining a high efficiency and low mass. Specifically, it is shown that such a compulsator is an optimal power supply for an ET accelerator due to its capability to conform to the load requirements while still performing the energy storage and electromechanical energy conversion functions in one element. Compulsators also have the highest power density reported for an electrical machine and have demonstrated repetitive rate operation at 60 Hz. A simulation of an existing laboratory-based 60-MJ HPG (homopolar generator) power supply driving an ET gun is also presented. >

Physical scale modeling to predict current diffusion in solid armatures

Scaling laws relating current diffusion in a high-conductivity material at low velocity to current diffusion in a lower conductivity material are derived. The design of an experiment to determine the validity of the scaling relationships is described. If the scaling is shown to be valid, then information for predicting thermal and mechanical loading in a solid armature (for a railgun) at high velocity will be available by measuring the current distribution at low velocity. >

Electromechanical analysis of the technology demonstrator for the IGNITEX fusion device

The Texas Ignition Experiment (IGNITEX) device is a single turn coil tokamak designed to produce and control an ignited plasma using ohmic heating alone. The proposed high strength magnet system operates at a magnetic field on-axis of 20 T, using homopolar generators (HPGs), which meet the power supply requirements (150 MA, 10 V) inexpensively. In this paper, the electromechanical analysis of a scaled down prototype (1/10 scale in linear dimensions) of the IGNITEX toroidal field (TF) magnet is presented. The primary goal of the IGNITEX Technology Demonstrator (ITD) is to prove the operation of a single turn, 20 T, toroidal field coil powered by a homopolar generator power supply system of 60 MJ, 9 MA, current operating at the Center for Electromechanics. The University of Texas at Austin (CEM-UT). In order to simulate the actual operating conditions of the full-scale device, the ITD coil will be precooled at liquid nitrogen temperature and driven by the six homopolar generators in parallel. Scaling relationships have shown that electromagnetic loading mechanical and thermal loading of the coil and their relative distribution will approximate well predicted levels of the full-scale IGNITEX device.