17. What is the state of the superconducting magnet technology used in the VASIMR® engine?
One good source to stay abreast of the general state of superconducting magnet technology is published by Superconductor Week, active since 1986. You can find them at http://www.superconductorweek.com/
The superconducting magnet technology we have used for our experiments from 2009 to date uses niobium titanium alloy embedded in a copper matrix, a technology dating from the 1980s and widely used for applications like MRI imaging. A unique feature of our test magnet is that is uses conduction cooling directly to the cold heads of the cryocoolers, which eliminates liquid cryogens from the design. Our test magnet operates at a temperature of approximately 6 degrees Kelvin and has operated for about 10,000 hours with no problems.
The thermodynamic efficiency gained by using newer high-temperature superconducting materials will be well worth the cost and effort for space applications. Our flight designs are based on YBCO superconductors. A good source of information about these materials can be found at the University of Houston at http://www.tcsuh.com/ Manufacturers of the magnet wire include companies like SuperPower,www.superpower-inc.com.