Second Generation (2G) HTS Wire

AMSC's High Temperature Superconductor (HTS) YBCO wire offers high power density and high efficiency compared to conventional copper wire, opening up a broad range of applications in the military and commercial sectors. Military applications include ship propulsion motors, air-borne generators and magnets for microwave power sources, while commercial applications include power transmission cables, electric motors and generators, transformers, synchronous condensers and fault current limiters.

It is also a “smart” material in that it switches rapidly to a resistive state when the current exceeds a critical level; this enables fault current limiters, which are surge protectors for the grid.  Electrical systems that incorporate second generation (2G) HTS wire are expected to be dramatically smaller, lighter and more cost effective than systems based on copper wire because HTS wire conducts more than 150 times the electrical current of copper wires of the same size.

AMSC's HTS Wire Manufacturing Technology

AMSC’s wire is manufactured in the world’s first commercial volume HTS manufacturing plant located in Devens, Massachusetts.

By optimizing the electrical and mechanical properties of HTS wire, AMSC is able to customize its wire products to suit a broad range of HTS applications.

Today, AMSC's 2G YBCO HTS wire manufacturing technology is based on very long, 4-cm wide strips of superconductor material that are produced in a high-speed, continuous reel-to-reel deposition process -- a process that is similar to the low-cost production of motion picture film in which celluloid strips are coated with a liquid emulsion -- and subsequently slit and laminated into eight, industry-standard 0.44-cm-wide tape-shaped wires.

The wires are laminated on both sides with copper, stainless-steel, or brass metals to provide strength, durability and certain electrical characteristics needed in applications. These new three-ply, 4.4 mm wide second generation HTS wires are called 344 superconductors.

• 344 superconductors - Type 344C — 2G HTS wire for coils, and other applications requiring the highest engineering current density
• 344 superconductors - Type 344S — stainless steel-stabilized second generation HTS wire providing a high resistance stabilizer for applications such as fault current limiters
• 344 superconductors - Type 344B — brass-reinforced and stabilized second generation HTS wire for high-current cable applications.

Second generation wire has a significantly different architecture compared to 1G wire.  The architecture of 2G YBCO HTS wire, which comprises multiple coatings on a base material, or substrate, is designed to achieve the highest degree of alignment possible of the atoms in the superconductor material. 

The objective is to achieve the highest possible electrical current carrying capacity.  While the high degree of alignment of the atoms in an HTS material can be achieved by many different laboratory techniques, the business challenge is to achieve this alignment with a high volume, low cost manufacturing methodology. The wire’s “three-ply” architecture — consisting of slit 2G tape sandwiched between thin copper or stainless steel strips — is similar to that of AMSC’s commercial 1G HTS wire.

Since 1995, AMSC has invested in R&D to develop the optimum manufacturing methodologies for each of the multiple coatings in the 2G HTS wire architecture.  Having investigated many possibilities, AMSC has selected the “MOD/RABiTS” methodology, which results in the 2G wire architecture shown in the following graphic. 

A key to success of AMSC’s 2G wire is the utilization of nanotechnology processing methods.

A nanotech surface treatment is utilized to maintain a high degree of atomic alignment during the coating process – the result of which is very high electrical current carrying capability in 2G wire produced in volume manufacturing operations.

AMSC also utilizes nanotechnology to greatly enhance the electric current performance of its 2G HTS wires by forming a dispersion of nanodots throughout the superconductor coating that are very efficient in pinning, or immobilizing, magnetic vortices.

AMSC has been reporting compelling new technical results for its 2G HTS wire technology and substantial advances in the manufacturing scale-up of the Company's 4- centimeter (cm) technology since August of 2005.  These results included the introduction of 4.4-millimeter wide 2G HTS wire branded as 344 superconductors.  The company also has demonstrated electromagnetic coils utilizing this new superconductor wire, and the achievement of commercial performance levels in 2G wire and coils.

AMSC's 344 superconductors have been developed as a replacement for the customers in 20 countries who are already using the company's industry-leading 1G HTS wire as well as customers who are utilizing 1G HTS wire made by others.  This means that customers can simply utilize 344 superconductors to make the next HTS power cable, motor, coil etc. without costly re-design or re-tooling.

AMSC’s in-depth knowledge of customer specifications for a wide range of applications – all based on meeting customers’ needs with 1G HTS wire – continues to provide us with a strong platform for developing our proprietary 2G HTS wire as a replacement for 1G wire. We believe our proprietary 2G manufacturing methodology will enable us to produce this wire at up to five times lower manufacturing cost than our 1G HTS wire. We also believe, based on our evaluations of competing 2G HTS wire manufacturing methodologies, that our commercial 2G HTS wire will have higher electrical performance at lower manufacturing costs than any competing approach.