Project Title Progress in SuperPower's 2G HTS Wire Development by RichieMcCaw

VIEWS: 13 PAGES: 4

									                    FY2009 Superconductivity for Electric Systems Peer Review
                                   Project Summary Form



Project Title:          Progress in SuperPower’s 2G HTS Wire Development Program
Organization:           SuperPower
Presenters:             Venkat Selvamanickam, John Dackow and Yi-Yuan Xie
FY 2009 Funding:        $ 1,350 k

Overall Project Purpose and Objectives:
Over the past few years, SuperPower successfully demonstrated the scale up of 2G HTS wire
technology to manufacturing. In FY08, we reported major advances in all key metrics of pilot
manufacturing: long lengths, high critical current, high throughput, delivery of and applications
using significant wire quantities. In FY09, the purpose of SuperPower’s 2G wire program was
focused on two distinct thrusts. One was to continue excellence in manufacturing of 2G HTS
wires so that high quality product could be consistently produced in our manufacturing operations
to meet the near-term requirements of our customers. The second thrust was on developing the
next level of advancements in the following key areas: high field performance, high critical
currents, high efficiency processes and advanced wire architecture for low ac losses and enhanced
stabilization. Specifically, our objectives in FY09 were to
             demonstrate manufacturing of kilometer-lengths of 2G HTS wires with critical
             currents exceeding 200 A/cm
             develop scalable approaches to manufacture 2G wires with critical current retention
             in magnetic field two times better than that of standard wires
             improve efficiency of wire fabrication using thinner, fewer, and simpler layers in our
             wire architecture
             develop novel, scalable processes for multifilamentary 2G wires for low ac loss
             applications and for enhanced stabilization
Overall, the program is strongly tied to the DOE-OE mission through the development of 2G
HTS wires that meet all the necessary requirements (piece length, performance, cost, and
manufacturing capacity) of systems that are being constructed to modernize the electric power
grid and enhance the reliability and security of the energy infrastructure. The program has a direct
impact on OE sub program goals namely, development of prototype wire achieving
1,000,000 A-m and production of an HTS coil operating in applied magnetic fields up to 5T at
65K.

2009 Approach and Results:
SuperPower uses IBAD (ion beam assisted deposition) and MOCVD (metal organic chemical
vapor deposition) processes in the manufacture of 2G wire. One of the significant advantages of
these technologies is high throughput. In addition, these technologies have enabled 2G wires with
superior mechanical properties and low ac losses, both of which are critical for electric power
applications.
In order to effectively execute our research plan on both the manufacturing development and
technology development fronts, we have organized the effort in two distinct teams so as to enable
a strong focus on both areas, but with seamless interaction between the two.

Manufacturing Excellence :
In FY08, we demonstrated 1000+m lengths of 2G wire with a performance level of 160 A/cm and
500 m lengths with a critical current of 245 A/cm. In FY09, we exceeded this performance level
by the first-ever demonstration of critical currents above 200 A/cm in 1000+m splice-free piece
length. A new world record performance of 233,810 A-m (227 A/cm over 1,030 m) was


August 4-6, 2009                                                                Alexandria, Virginia
                    FY2009 Superconductivity for Electric Systems Peer Review
                                   Project Summary Form

achieved. Additionally, critical current above 300 A/cm was demonstrated over 630 m (longest
wire length record for Ic > 300 A/cm) and 363 A/cm over 320 m. Quality control has been a
major focus in our production operations to achieve superior performance over long lengths.
Beyond our ability to optimize manufacturing processes in every step to maximize performance
over long lengths, we focused on repeatability for high-yield manufacturing. In FY09, we began
the transition from Quality Control to Quality Assurance by implementing process controls to
minimize deviations so as to achieve high yield and drive down the wire cost.

Enhanced in-field performance :
In FY08, we demonstrated enhanced critical currents at high magnetic fields in the temperature
range of 65 to 77 K using Zr-doped precursor chemistries in our MOCVD process. BZO
nanocolumns formed by a self-assembly process were found to be responsible for the enhanced
in-field performance. In FY09, we scaled up the process to 500 m lengths in our pilot MOCVD
system and demonstrated a 6-layer double pancake coil that generated a field of 0.95 T at 77 K
and 2.39 T at 65 K, the former being 30% better than the field generated in a coil made with 2G
wire without Zr addition. During this progress we discovered a major drawback to the Zr
chemical doping approach, namely poor consistency in the enhancement of in-field critical
current in long wires made in the pilot MOCVD system. We addressed this issue by a systematic
study of the influence of Zr dopant levels in our research MOCVD system and determined the
optimum levels for a wider process window. The results were successfully transitioned to the
pilot MOCVD system and long-length wires with in-field performance up to 2.5 times that of a
standard wire were demonstrated. A new coil has been made with the enhanced 2G wire and
magnetic fields well above the overall DOE HTS program’s FY09 Joule milestone of 2 T at
65 K has been consistently achieved.

In order to further enhance the consistency of the in-field critical current performance, we have
investigated methods to direct the assembly of nanocolumnar structures rather than relying purely
on self assembly. Multiple techniques have been evaluated to direct the growth of BZO
nanocolumns from nucleation sites created on the surface of the LaMnO3 (LMO) cap layer, on
which the HTS film grows on.

Higher efficiency processes:
Apart from product performance, cost and availability are two main factors that limit the
widespread use of 2G HTS wires. While steady progress continues to be made in cost reduction
through yield improvements and in capacity increase through minimization of down time and set
up time, we are pursuing technological advancements for larger impacts. Working with NREL,
we have adopted a new copper solution chemistry for electrodeposition that has enabled a 3-fold
reduction in silver overlayer thickness and led to a 3-fold reduction in materials cost and a 3-fold
increase in production capacity. In collaboration with Los Alamos and Oak Ridge National
Laboratories, we are developing planarization as an alternative to electropolishing which enables
the use of less expensive, simpler and application-specific substrates. Concomitantly, a buffer
layer processing step is eliminated which results in reduced lead time, and increased capacity.

Advanced wire architectures:
Over the past few years, multifilamentary wires have been demonstrated by a number of groups
for ac loss reduction, but have yet to be scaled up to long lengths (even 50 m of continuous single
piece length has not been demonstrated). In FY09, we have been developing a scalable technique
to produce multifilamentary 2G wires. Additionally, this technique enables filamentization of a
thick copper stabilizer too. Another new architecture developed in FY09 has been aluminum-
stabilized 2G wire which provides advantages of light-weight and low residual resistivity ratio,
both of which are valuable in applications using large coils operating at temperatures below 65 K.


August 4-6, 2009                                                                Alexandria, Virginia
                    FY2009 Superconductivity for Electric Systems Peer Review
                                   Project Summary Form


2010 Plans and Expectations:
In 2010, SuperPower will continue its two-pronged thrusts on manufacturing development and
technology development of 2G HTS wires. A new pilot MOCVD manufacturing system equipped
with on-line XRD will be brought into operation to assure high-yield operation as well as to more
than double our manufacturing capacity. Furthermore, we expect that the performance of routine
production 2G wires will be increased by 50% to 300 A/cm over lengths of several hundred
meters. We will transition the new approaches developed for controlling the distribution of
nanocolumnar structures within the HTS film for improved consistency of in-field performance of
production 2G wires. Our goal is to achieve a consistent two-fold improvement in the retention
factor of critical current in a field of 1 T at 77 K over lengths of 500+ m. We will optimize new
techniques for consistent nanocolumnar structures to fabricate thick HTS films MOCVD with
high critical currents in high fields. One goal is to achieve a 35% retention of self-field critical
current at 77 K and 1 T, in films thicker than 2 µm. The efficiency of the MOCVD process will
be enhanced by the development of optimum reactor designs to increase the conversion of
precursor to HTS film.
We will transition the modified copper chemistry know-how to manufacturing of electroplated
copper stabilizer on thin silver overlayer. We will establish a substrate planarization process to
fabricate long lengths and optimize the buffer stack to achieve performance similar to that
obtained with electropolished substrates. Additionally, inexpensive and simple binary alloy
substrates will be evaluated as an alternative to Hastelloy, while maintaining the latter’s
advantages such as mechanical properties and high resistivity. We will transition the new method
we have developed for multifilamentary 2G wires to produce 100+m lengths of low ac loss
conductor which will be used to fabricate and test prototype coils and cables. Long lengths of
aluminum-stabilized 2G wires and prototype coils will be fabricated and tested. The pathway to
reaching all these milestones will be guided by our strong collaboration with national labs as well
as with our customers and partners with an emphasis on meeting application requirements.
Deliveries of long lengths of 2G wire will continue to be made for various device applications to
customers worldwide. We will continue to market our 2G wire worldwide to strengthen customer
base and meet delivery schedules on time.

Technology Transfer, Collaboration, Partnerships:
This program continues to enjoy a close and robust collaboration with national laboratories and
Universities. In the seventh year of our CRADA with Oak Ridge National Laboratory (ORNL),
we worked on enhancing in-field performance through Zr doping and planarization processes for
buffer layers. This effort was augmented with the research conducted at ORNL on the MOCVD
system loaned by SuperPower which involved a close cooperation with ORNL staff on our
proprietary process know-how. In the ninth year of our CRADA with Los Alamos National
Laboratory (LANL), we implemented a reel-to-reel in-field critical current measurement system
for our production wires, simplified the buffer architecture, and developed substrate planarization
processes. We continued to benefit from a strong collaboration with Argonne National
Laboratory (ANL) on coordinated characterization of our production MOCVD wires, specifically
to understand non-uniformities in film growth. In our CRADA with the National Renewable
Energy Laboratory (NREL), we were able to successfully transition laboratory technology on
alternate copper chemistry for electrodeposition to significantly decrease silver content. We have
begun work with Brookhaven National Laboratory on synchrotron radiation-based
microstructural understanding of our MOCVD tapes and a new CRADA is being established.
During this fiscal year technology development in this program has been centered at the
University of Houston in a program that involves four SuperPower scientists who are stationed in
Houston, as well as several graduate students and research staff. Other notable collaboratiosn



August 4-6, 2009                                                                Alexandria, Virginia
                   FY2009 Superconductivity for Electric Systems Peer Review
                                  Project Summary Form

included microstructural and electromagnetic studies of our conductor and coil testing with
Florida State University, mechanical property measurements and analysis with NIST, and the
Naval Research Laboratory. Industrial partnerships guided our work on conductor engineering
such as the generator program with Baldor Electric, and the fault current limiter project with the
device group at SuperPower. Most of all, we engaged our customers closely to understand their
requirements and accordingly develop modifications to meet their needs. Overall, this program
greatly benefited from basic research collaboration with Universities, applied research technology
transfer with national laboratories and application projects with our customers and industry
partners.

Several visits have been made by SuperPower employees to various national labs and universities
and vice versa. SuperPower employees closely interacted with the lab scientists by frequent e-
mail and phone communication. Many sales and marketing trips were made globally to meet
directly with our customers.

The program has been reviewed this FY on site by DOE and DOD representatives.




August 4-6, 2009                                                               Alexandria, Virginia

								
To top