.3 Solar Disc







B-1
B.4
Abacus
Reflector
Configurations
B-2
B.5 NEDO Model






B-2
B.6 JAXA Model






B-3

Appendix C
US Activities
NASA SPACE SOLAR POWER ACTIVITIES: 1995-2005
Foreword







C-1
C.1 Overview







C-1
C.2 A Brief History of US SPS and SSP Activities (1960s-1970s)


C-3
C.3 The NASA Fresh Look Study (1995-1997)



C-4
C.4
The
SSP
Concept
Definition
Study
(1998)
C-6
C.5 The SSP Exploratory Research & Technology (SERT) Program (1999-2000)
C-7
C.6 National Research Council (NRC)
Review
(2000-2001)
C-8
C.7
NASA-NSF_EPRI
Research
(2001-2003)
C-8
C.8 Recent NASA Research and Development in SSP & Related Technologies (2004-2005) C-9
C.9
Summary
and
Conclusions

C-9
C.10 List of Acronyms and Abbreviations



C-17
BIBLIOGRAPHY








C-18

Appendix D Japanese Activities (JAXA reports)
D.1 JAXA Models






D-1
D.2
Launch
and
Transportation
D-2
D.3 Solar Power Generation





D-4
D.4
Thermal
Control
Technology
D-7
D.5 Microwave Power Transmission on SPS




D-9
D.6 Rectenna and Ground Segments




D-14
D.7
Economics
of
SPS








D-18
D.8 Environmental and Safety Matters



D-21
D.9 Study of Laser-based SPS




D-22

Appendix E
European activities (ESA reports)
Solar Power from Space A Space Contribution to Options for 21
st
Century Sustainable Energy
Systems
Abstract







E-1
E.1 Introduction







E-1
E.2 Motivation and Frame






E-1
E.3 Objectives







E-3
E.4
European
Approach
---
Methodology
E-3
E.5
Reference
Systems

Terrestrial E-4
E.6
Reference
Systems

Space
E-5
E.7
Comparison
Results E-6
E.8
Conclusions
E-8



A-1
Appendix A
Microwave Power Transmission Activities in the world


This chapter introduces microwave power
transmission (MPT) technology as a base of SPS and its
applications. MPT technology was developed in the
1960s by Bill Brown
1,2
based on the prediction that
power could be transmitted by electromagnetic waves,
triggered by high power microwave generators. Peter
Glaser proposed SPS
3
in 1968 by applying this
technique to a geostationary satellite.

A.1 Early history

Fig. A.1.1 Tesla Tower.
4

Brown
1
and Matsumoto
5
review the early history of
microwave power transmission. It is recommended to
read these reviews. Nikola Tesla first conceived and
conducted an experiment based on the idea of wireless
power transmission. He used a Tesla coil that was
connected to a 60 m high mast with a 90 cm-diameter
ball (toroid). The power of 300 kW was fed to the Tesla
coil resonated at 150 kHz. The Tesla coil is introduced
on the web
6
in detail. Figure A.1.1 depicts Nikola
Tesla's historic laboratory and wireless communications
facility known as Wardenclyffe, Long Island, New York,
USA.
The distinctive 57 meter tall tower was
demolished in 1917, but the sturdy 28 meter square
building still remains standing in silent testimony to
Tesla's unfulfilled dream.
4

The rest of this section is cited from Matsumoto.
5
People were waiting for the invention of a high-power
microwave device to generate electromagnetic energy
of reasonably short wavelength, since efficient focusing
toward the power receiving destination is strongly
dependent on the use of technology of narrow-beam
formation by small-size antennas and reflectors. In the
1930's, much progress in generating high-power
microwaves was achieved by invention of the
magnetron and the klystron. Though the magnetron was
invented by A. W. Hull in 1921, the practical and
efficient magnetron tube gathered world interest only
after Kinjiro Okabe proposed the divided anode-type
magnetron in 1928. It is interesting to note that H. Yagi
and S. Uda, who are famous for their invention of
Yagi-Uda Antenna, stressed the possibility of power
transmission by radio waves in 1926, thereby
displaying profound insight into the coming microwave
tube era in Japan. Microwave generation by the
klystron was achieved by the Varian brothers in 1937
based on the first idea by the Heil brothers in Germany
in 1935. During World War II, development of radar
technology accelerated the production of high-power
microwave generators and antennas. Continuous Wave
(CW) high-power transmission over a microwave beam
was investigated in secrecy in Japan. The project, the
"Z-project," was aimed at shooting down air-bombers
by a high-power microwave beam from the ground, and
involved two Nobel prize laureates, H. Yukawa and S.
Tomonaga. The Japanese Magnetron was introduced in
"Electronics" of USA immediately after World War II.
However, the technology of the high-power microwave
tube was still not developed sufficiently for practical
continuous transmission of electric power. Further more,
no power device was available to convert a microwave
energy beam back to direct current (DC) power until
the 1960's.



Fig. A.1.2. Microwave powered helicopter.
200 W of power was supplied to the
electric motor from the rectenna that
collected and rectified power from a
microwave beam.
1


A-2

Fig. A.1.3 The first rectenna. Conceived at
Raytheon Co. in 1963, it was built and
tested by R. H. George at Purdue
University. It was composed of 28
half-wave dipoles, each terminated in a
bridge rectifier made from four 1N82G
point-contact, semiconductor diodes. A
power output of 7 W was produced at an
estimated 40 percent efficiency.
1


Fig. A.1.4 Artists view of SPS

The post-war history of research on free-space power
transmission is well documented by William C. Brown,
who was a pioneer of practical microwave power
transmission. It was he who first succeeded in
demonstrating a microwave-powered helicopter in 1964,
using 2.45 GHz in the frequency range of 2.4 - 2.5 GHz
reserved for the Industrial, Scientific and Medical
(ISM) applications of radio waves (Fig. A.1.2). A power
conversion device from microwave to DC, called a
rectenna, was invented and used for the
microwave-powered helicopter. The first rectenna (Fig.
3 in [1]) was composed of 28 half-wave dipoles
terminated in a bridge rectifier using point-contact
semiconductor diodes. Later, the point contact
semiconductor diodes were replaced by silicon
Schottky-barrier diodes which raised the
microwave-to-DC conversion efficiency from 40% to
84%, the efficiency being defined as the ratio of DC
output to microwave power absorbed by the rectenna.
The highest record of 84% efficiency was attained in a
demonstration of microwave power transmission in
1975 at the JPL Goldstone Facility.
7
Power was
successfully transferred from the transmitting large
parabolic antenna dish to the distant rectenna site over a
distance of 1.6 km. The DC output was 30 kW.
An important milestone in the history of microwave
power transmission was the three-year study program
called the DOE-NASA Satellite Power System Concept
Development and Evaluation Program, started in 1977.
This program was conducted to study the Solar Power
Satellite (SPS), which is designed to beam down
electrical power of 5 to 10 GW from one SPS toward
the rectenna site on the ground. The extensive study of
the SPS ended in 1980, producing a 670-page summary
document. The concept of the SPS was first proposed
by P. E. Glaser
3
in 1968 to meet both space-based and
Earth-based power needs. An artist's SPS concept is
shown in Fig. A.1.4. The SPS will generate electric
power of the order of several hundreds to thousands of
megawatts using photo-voltaic cells of sizable area, and
will transmit the generated power via a microwave
beam to the receiving rectenna site. Among the many
key technological issues that must be overcome before
SPS realization, microwave power transmission (MPT)
is one of the most important. The problem involves not
only the technological development of microwave
power transmission with high efficiency and high safety,
but also scientific analysis of microwave impact onto
the space plasma environment.

A.2 US Activities
After high-power microwave tubes became available,
Brown demonstrated a microwave-powered helicopter in
1964. A focusing ellipsoidal reflector is illuminated with
microwave power and a microwave beam is formed (Fig.
A.1.2). The helicopter was confined by vertical tether
wires. The rectenna (rectifier + antenna) converts
microwave directly to direct current (DC) for WPT. The
frequency was 2.45 GHz in one of the industrial, scientific
and medical (ISM) bands. Later he demonstrated an
indoor MPT experiment with 90% dc-dc conversion
efficiency.
2
Jet Propulsion Laboratory (JPL) succeeded
in transmitting 30kW in the 2.5GHz band from a 26m
parabolic antenna to a rectenna 1.6km away (Fig.
A.2.1).
7

Microwave-driven acceleration by photon reflection
has been suggested for propelling probes to very high
speeds for science missions to the outer solar system and
the nearby stars. Beam-driven probes have the advantage
that energy is expended to accelerate only the sail and
payload, not the propelling beam generator.
8


Fig. A.2.1. Microwave power transmission over 1.54km

A.3 Canadian Activities
The worlds first flight of a