Robert H. Borcherts

Baseline specifications for a magnetically suspended high-speed vehicle

Baseline specifications for a magnetically suspended vehicle capable of 300 mi/h (483 km/h) operation are given. The magnetic forces (lift, drag, and lateral) on a superconducting coil moving over an aluminum guideway are shown. The basic features of the associated cryogenics are presented along with a discussion of the cryogenic refrigeration requirements. Vehicle dynamics and the resultant ride quality over roadbeds of various roughnesses are analyzed. Thrust requirements for the propulsion system are specified, and both the linear induction motor and the linear synchronous motor are considered. Several guideway configurations are suggested and the significant properties of each are noted.

Force on a Coil Moving over a Conducting Surface Including Edge and Channel Effects

The lift force FL and the drag force FD on small conducting coils placed near a large rotating conducting cylinder have been measured as functions of velocity, height, and coil geometry. These data are compared with exact calculations based upon Fourier transforms for coils moving over infinitely wide flat plates. By placing the coil near the edge of the cylinder, the effect of the edge on FL and FD and the transverse force FT were studied. A channel was then cut in the cylinder, and the properties of a U‐shaped guideway were examined. Both the edge effects and channel effects were compared with approximate calculations. Agreement was generally good, substantiating a variety of predictions for the large magnets proposed for the suspension of high‐speed ground vehicles.

High-speed transportation via magnetically supported vehicles. A study of the magnetic forces

THE PARAMETERS AFFECTING THE MAGNETIC BUOYANCY AND RESISTANCE FORCES WERE ANALYZED FOR A VEHICLE EQUIPPED WITH SUPPORTING MAGNETS WHICH IS SUSPENDED ON A CONDUCTING TRACK-BED. IN PARTICULAR THE EFFECT OF A TRACK-BED OF FINITE WIDTH WAS INVESTIGATED. THE MEASUREMENTS EXTENDED TO THE FORCES ACTING ON A PERMANENTLY EXCITED SUPERCONDUCTING COIL, THE COIL BEING SUSPENDED OVER A ROTATING ALUMINIUM WHEEL WITH PERIPHERAL SPEEDS UP TO 480 KM/H. CALCULATIONS AND MEASUREMENTS SHOWED THAT THE IMPORTANT PARAMETER IS THE REYNOLDS NUMBER LAMBA = VH (MU) (SIGMA), WHERE MU AND SIGMA REPRESENT THE PERMEABILITY AND CONDUCTIVITY OF THE TRACK-BED, V THE VELOCITY OF THE VEHICLE AND H THE OPERATIONAL HEIGHT OF THE MAGNET OF THE VEHICLE. THE EFFICIENCY OF THE SYSTEM, EXPRESSED AS THE RATIO OF THE BUOYANCY TO THE RESISTANCE, IS PROPORTIONAL TO THE SQUARE ROOT OF LAMBA. /TR/

Lift and drag forces for the attractive electromagnetic suspension systems

Experiments on small-scale magnets have been performed to determine the effects of track eddy currents on the behavior of the attractive electromagnetic suspension system. Measurements of the velocity dependence of the current and the drag force for fixed lift force have been made for velocities up to 100 m/s. A model of the magnet based upon the magnetization of the poles has been developed. Fourier techniques have been used to calculate the lift and drag forces as a function of speed and current. The field dependence of the track permeability has been accounted for in an appropriate manner by a self-consistent procedure using a multi-layer model of the track. Comparison to experiment has been made for the small magnets, and the behavior of full-scale magnets is predicted.

Superconducting paddle wheels, screws, and other propulsion units for high- speed ground transportation

High‐speed ground vehicles magnetically suspended above a continuous aluminum guideway by superconducting coils can have a clearance of 0.1–0.3 m. To take full advantage of the large clearance, a propulsion system with a comparable clearance is needed. Two such systems based upon physically moving static magnetic fields produced by superconducting coils are proposed. With the use of a prime mover such as a gas turbine or a diesel engine, these systems avoid power collection problems and should result in a lower‐weight propulsion unit. A numerical analysis of each has been made to determine the thrust, the lift force, and the efficiency as a function of various parameters. The mechanical efficiency of the paddle wheel appears to have a maximum of ∼60% at 483 km/h (300 mph), while that of the superconducting screw is (1‐slip) for an infinitely long machine. End effects will degrade the efficiency somewhat for a screw of finite length.

An investigation of two HSGT magnetic suspension systems (attraction)

Two alternate attraction magnetic suspension systems are discussed on a magnetic performance basis, as well as on their lift-to-weight ( L/W ) capabilities. On an equal current basis, the lower reluctance, flat track configuration has higher lift force and better L/W than the U-shaped track configuration with its larger leakage flux. With equal magnetization (unequal currents) and low guidance forces ( F_{G}/F_{L} \leq 0.3 ), the U-shaped track has a higher L/W ratio, but both attraction systems suffer from low L/W when all elements of the suspension system are considered.

Magnetic Forces on a Coil Moving Above a Conducting Plate

Magnetic levitation is one of the more promising methods suggested for supporting high‐speed vehicles; high‐field‐strength magnets or coils in the vehicle are to be levitated by magnetic fields resulting from eddy currents induced in the conducting roadbed or guideway. In the present study the forces on a rectangular, flat, current‐carrying coil moving above and parallel to a conducting plate of arbitrary thickness are investigated. Analytical expressions are developed for the lift and drag forces on the coil as a function of speed. Numerical calculations are carried out for a very thick plate and for a plate with thickness of the order of the skin depth. Thick plate results are compared with experimental measurements of lift and drag on a superconducting coil suspended above a rotating aluminum wheel.