Solar-pumped laser power transmission, a way to dramatically decrease launch costs?

David Spain wrote:
Pat Flannery writes:

To get this up to the point where all the effort is justified due to the
increased solar flux, you are probably going to have to get the solar
collector into something like the distance of Mercury's orbit of the Sun, and
a microwave beam is going to spread all over the place from that distance on
its way to Earth.

I thought we were talking about L1, not Mercury. We're crossing into
Mookopia at this point, never mind....

I just pointed out that the only place closer to the Sun where it's
going to stay in the same relative position with Earth is at L-1.
That's only 1% closer to the Sun than putting it in Earth orbit, so it's
not going to net you all that great of increase in solar illumination,
while introducing a lot of problems with power transmission over that
distance (1.5 million kilometers). The only advantage you really get is
not having to worry about it going into shadow at some point during the
day or year. On the flip side Earth is rotating under it, so it can't be
focused on a single surface rectenna like something in GEO can.

Pat

David Spain wrote:
"Androcles" writes:

I do have a use for a bridge, actually. A gentleman by the name of
Wheatstone gave me one.

I'd be more interested to know how you are still alive...

Given his posting address, probably via mandrake root extract.

Pat

"Pat Flannery" wrote in message
dakotatelephone...
David Spain wrote:
"Androcles" writes:

I do have a use for a bridge, actually. A gentleman by the name of
Wheatstone gave me one.

I'd be more interested to know how you are still alive...

Given his posting address, probably via mandrake root extract.

Pat

Why don't you children go play on twitter?
*plonk*

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David Spain wrote:

Well since I'm *plonk*'ed anyway,

*yawn*

Keep an eye on your toilet, there may be a basilisk showing up in it
shortly.
On second thought, keep an eye on your toilet using a remote camera to
be on the safe side, and pay particular note to any spiders fleeing the
bathroom. :-)

Betelgeuse Black

On Feb 13, 2:48*am, "Androcles" wrote:
"Pat Flannery" wrote

I can't be certain, but I will say that if you move a solar collector
array closer to the sun it will gather more energy for a given size.

You should be certain before you give us your stupid opinion, Pat Flannery.

My opinions are not stupid. You on the other hand, are exceedingly
stupid Pat.

On Feb 13, 12:36*pm, David Spain wrote:
Frankly all this seems academic, I haven't seen anything posted that shows
a practical way to convert a laser beam to electricity, unlike a microwave
beam.

?

Dave

Dave, there is the photo-electric effect and it can be quite efficient
with lasers. Nearly perfect in fact.

That's because photovoltaic cells have a specific bandgap energy.
That energy is associated with a specific wavelength.

For example, silicon has a bandgap energy of 1.11 electron-volts and
the Planck relation says 1,100 nm is the wavelength associated with
that energy. Germanium 0.67 electron volts and the Planck relation
says that photon energy is associated with 1,830 nm is associated with
that energy.

The reason silicon and germanium are only marginally efficient as
solar collectors is because sunlight is a sum of many wavelengths.
Those wavelengths bluer or shorter than the bandgap energy contribute
only the bandgap energy to the operation of the cell. Those redder or
longer than the bandgap energy contribute no energy to the operation
of the cell. Then, on top of it, you have what is known as dark
current subtract from the operation of the cell.

How efficient can these junctions be when illuminated by appropriate
band-gap matched wavelengths?

Nearly perfect! 98% or more at room temperature at solar
intensities. 99.9% efficient at room temperatures at many times solar
intensity.

I have patents on aspects of this.

http://www.scribd.com/doc/21832226/M...ectral-Cooling

By efficiently sorting photons by color, using an improved diffraction
technique, and causing photons of appropriate colors to fall on
appropriate semi-conductors, and then connecting the junctions in a
way that allows the electrons to efficiently flow, efficiencies of 60%
and more are achievable using sunlight.

I have conducted research in this area as well.

http://www.scribd.com/doc/20024019/W...to-Mok-FINAL-1

With an efficient power source we next need an efficient laser. Free
electron lasers, operating very much like microwave klystron tubes,
except at higher energies, allow the creation of tunable lasers with
greater than 80% efficiencies.

Silicon bandgaps are very interesting because 1,100 nm is near one of
the infra-red windows in Earth's atmosphere - making it convenient to
beam energy to Earth from space.

Silicon receivers collect the 1,100 nm photons and convert them with
over 90% efficiency to electricity.

Sun -- Electrons --- Laser --- Electrons
Low 60% 80% 90% overall 43.2%
High 65% 85% 95% overall 52.4%

Just as phased array techniques may be used to direct multiple
microwave beams anywhere reliably, so too can holographic techniques
be used to direct multiple laser beams anywhere reliably. I have even
pioneered a technique to use 4-wave mixing to allow satellites or
other emitters connect to any number of users at the same time

http://www.youtube.com/watch?v=2QAUkt2VPHI

On Feb 13, 3:03*pm, Pat Flannery wrote:
David Spain wrote:
Frankly all this seems academic, I haven't seen anything posted that shows
a practical way to convert a laser beam to electricity, unlike a microwave
beam.

Focus it and use it to heat some sort of working fluid for a boiler and
turbine?
This would be pretty clunky due to the fairly low efficiency of the
laser converting electrical energy into a beam, although lasers have
been built that convert sunlight straight into a laser beam with no
intermediary electrical step:http://www.technologyreview.com/Energy/19402/

Pat

Photoelectric effect is quite efficient when the bandgap energy is
matched to photon energy and load is matched to light intensity so
that it maintains peak power loading.

On Feb 14, 2:18*am, David Spain wrote:
Pat Flannery writes:
To get this up to the point where all the effort is justified due to the
increased solar flux, you are probably going to have to get the solar
collector into something like the distance of Mercury's orbit of the Sun, and
a microwave beam is going to spread all over the place from that distance on
its way to Earth.

I thought we were talking about L1, not Mercury. We're crossing into
Mookopia at this point, never mind....

Dave

Actually Dave, if you weren't such a ****ing moron you'd know how to
use the Rayleigh Criterion to calculate angular resolution of an
emitter from any distance you like.

For a circular apeture you have the Airy disc equal to;

sin(theta) = 1.22 * lambda/Diameter

So, a 1 km diameter emitter operating at 1 micron wavelength has an
angular resolution of 1.22e-9 radians while the same 1 km diameter
emitter operating at 10 cm wavelength has an angular resolution 10,000
lager - 1.22e-5 radians.

Applying trigonometry we can see that at 150 million kilometers from
the emitter the spread for the 1 micron wavelength is 183 meters and
the spread for the 10 cm wavelength is 1,830 km.

So, two 300 m dishes - about the size of Arecibo - can efficiently
send a beam of 1,000 nm wavelength IR laser energy 150 million km. A
300 m dish cannot send 10 cm wavelength beam efficiently over 150
million km.

A 300 m solar collector at 3 million km from the sun intercepts 243.8
GW of energy. At 50% overall transmission efficiency this represents
121.9 GW on Earth. About equal to all the nuclear power plants in
America.

Six satellites of this size, three in GEO and three in a solar orbit,
could displace over half the coal fired power plants in the US.

On Feb 14, 7:28*am, Pat Flannery wrote:
David Spain wrote:
Pat Flannery writes:

To get this up to the point where all the effort is justified due to the
increased solar flux, you are probably going to have to get the solar
collector into something like the distance of Mercury's orbit of the Sun, and
a microwave beam is going to spread all over the place from that distance on
its way to Earth.

I thought we were talking about L1, not Mercury. We're crossing into
Mookopia at this point, never mind....

I just pointed out that the only place closer to the Sun where it's
going to stay in the same relative position with Earth is at L-1.
That's only 1% closer to the Sun than putting it in Earth orbit, so it's
not going to net you all that great of increase in solar illumination,
while introducing a lot of problems with power transmission over that
distance (1.5 million kilometers). The only advantage you really get is
not having to worry about it going into shadow at some point during the
day or year. On the flip side Earth is rotating under it, so it can't be
focused on a single surface rectenna like something in GEO can.

Pat

One of the great advantages of using holographic techniques to steer
laser beams is that an optical connection may be maintained even when
the two end points are moving relative to one another. So, one
satellite in GEO to receive and redirect laser energy combined with
one satellite in an orbit 3 million km from the solar surface provides
just such a link. The satellite in GEO then redirects laser energy
holographically to any number of users within Cislunar space.

On Jan 2, 12:37*pm, William Mook wrote:
You start with

Laser Power Transmissionhttp://www.youtube.com/watch?v=2QAUkt2VPHI

And use it to expand the energy markets

Solar Power - Entering the Market - alkanes - protons - photonshttp://www..youtube.com/watch?v=iWiXDu64c0g

Initially Put Up with Chemical Powered Spacecrafthttp://www.scribd.com/doc/24390383/mokaerospace-3

transitioning to

Laser Powered Spacecrafthttp://www.youtube.com/watch?v=LAdj6vpYppA

Made from Propulsive Skinshttp://www.youtube.com/watch?v=mzXwctPXT4chttp://www.youtube.com/watch?v=XxV2FCUESh0http://www.youtube.com/watch?v=nzG4PEureFg

Which create a diaspora of the human race across the solar system

Your research and subsequent arguments are entirely worth considering,
but it seems few if anyone cares, other than to topic/author stalk and
bash for all they can muster.

My Google Groups weekly average following is currently "4964 views of
your messages", and that obviously doesn't include outside readers
that are likely worth 90+% of what this greater global Usenet/
newsgroup audience has to offer.

btw, Selene L1 is worthy of being solar illuminated roughly 97% of the
time, and a tethered dipole element could extend a substantial
platform of laser cannons and/or microwave transmitters safely to
within 2r of Earth (closer if you'd dare). Of course there should
also be a substantial tether anchoring this Selene L1 array of solar
collectors to the lunar surface, exactly as I'd specified years ago
for my LSE-CM/ISS that you and others opposed at every turn and on
every possible grounds.

Is there any chance we can work together on behalf of any of this?

~ BG