Field Asymmetry and Thrust Control in the GDM Fusion Propulsion System
[Abstract] One of the notable attributes of the Gasdynamic Mirror (GDM) fusion propulsion system is the fact that it lends itself readily to thrust control due to asymmetry in the magnetic field configuration. GDM is a magnetic plasma confinement device that has been proposed as a potential propulsion system. It differs from the standard “collisionless” mirror in that it operates at a much higher plasma density and is generally designed with a large aspect ratio to provide plasma stability. When a plasma is injected into such a device, the electrons tend to escape through the mirrors more readily due to their small mass, leaving behind an excess of ions and correspondingly a positive electrostatic potential. Such a potential accelerates the ions while slowing down the electrons until both species drift outward at equal rate. Of special importance to its value as a propulsion device is the effect of magnetic field asymmetry on such an electrostatic potential. Numerical simulations have been carried out to study this phenomenon and to quantify the role of asymmetry on the overall performance of the system. Experiments will be conducted in order to validate the theoretical and simulation models and to provide a basis for further assessment of GDM as a propulsion device with variable thrust capability.
Gasdynamic fusion propulsion system for space exploration
An open-ended fusion system in which a high-density plasma is confined and heated to thermonuclear temperatures is examined as a potential high specific power propulsion device that can be used for space exploration. With a collision mean free path much smaller than a characteristic dimension of the system, the plasma behaves much like a continuous medium (fluid) for which the confinement time is drastically different from that which characterizes a typical fusion power reactor. Noting that fact and using an appropriate set of balance equations we derive an expression for the length of the rocket in terms of the plasma parameters required for certain propulsive capabilities. We find that a moderately sized system can produce large values of specific impulse and thrust that would allow a massive rocket to make a round-trip to Mars in months instead of years. By carrying out a preliminary engineering design we also identify those technological areas that must be developed before such a system can become practical. Many of these technologies are surprisingly not out of reach today.
Actuating Principle of Online Automatic Balancer with Counter Weight Driven by Magnetic Force
Kinematic precept of mass block in automatic balancer is proposed following the principle of online automatic dynamic balancing.By combination of electromagnet and permanent magnet,the magnetic circuit of the balancer with ring coil and rare earth permanent magnet is designed.Actuating process of the balancer is discussed and then a step drive voltage waveform is defined.For the high-speed grinding motorized spindle 170MD12Y16,the mechanical structure and dimensions of the balancer are schemed out.The electromagnetic simulations for the designed balancer are conducted and the better coil ampere-turns and reluctance adjusting ring thickness are then determined.The validity of simulation results is verified by a balancer driving experiment and the desired voltage value and its duration time are also determined.the designed balancer has a stable operation process without out-of-step and fluctuation around balanced position when the ampere-turns are considered as 1 kA,the reluctance adjusting ring thickness 0.2 mm,the driving voltage 12.4 V and the voltage duration time 120 ms.