Solar-pumped laser power transmission, a way to dramatically decrease launch costs?
in [Physics]
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From: William Mook on 14 Feb 2010 12:48 On Feb 12, 5:16 pm, "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > "William Mook" <mokmedi...(a)gmail.com> wrote in message > > news:fbbddf2d-60ea-4ed3-a183-23e920219728(a)k41g2000yqm.googlegroups.com... > On Dec 18 2009, 4:43 am, "Androcles" <Headmas...(a)Hogwarts.physics_q> > wrote: > > > "Jonathan" <H...(a)Again.net> wrote in message > > >news:p5SdndXFAKoISrfWnZ2dnUVZ_vWdnZ2d(a)giganews.com... > > > >I like this idea, Relatively small mirrors would power > > > the lasers, not huge solar cell arrays. The lasers would > > > transmit their beams to other satellites that convert it to, and > > > beam it down, as microwaves. No need for mile-size > > > collectors in orbit. > > > What are you babbling about? > > 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. > ============================================= > It won't be in Earth orbit then. That is absolutely correct. It will be on solar orbit. The orbital period will be 24 hours at 3 million km radius. A satellite in the same orbital plane as the Earth, will see the Earth for all but 54 minutes out of every 24 hours per day. A satellite inclined from the Earth's orbit 0.3 degrees (20 minutes of arc) will never lose sight of Earth. A satellite that is launched into Earth orbit and uses its solar collector as a solar sail to navigate to within 3 million km of the sun is capable of changing its orbital inclination and in causing the orbit to precess at a rate one degree per day so as to always be visible to Earth. A receiver and reforming satellite will take the laser energy in GEO and distribute it to users throughout cislunar space using holographic techniques developed for SDI and used in laser welding equipment today.
From: William Mook on 14 Feb 2010 12:49 On Feb 13, 2:48 am, "Androcles" <Headmas...(a)Hogwarts.physics_u> wrote: > "Pat Flannery" <flan...(a)daktel.com> 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.
From: William Mook on 14 Feb 2010 13:00 On Feb 13, 1:43 pm, Pat Flannery <flan...(a)daktel.com> wrote: > Androcles wrote: > > > When usenet posts get interrupted by gmail users, in this case Mook, > > it prevents Microsoft's Outlook Express from automatically inserting > > the indent markers, so I separate what I write with a line of: "=====". > > Then you come along and snip (only you know why) and misattribute > > who said what. The part I wrote was "It won't be in Earth orbit then", > > so your target should have been Mook, not Androcles. The safe > > thing to do is not snip. Snipping requires effort on your part and saving > > Google even a kilobyte of storage space is a raindrop in the ocean. > > This is not 1979 when 16 Kbytes of RAM and a 50 Megabyte hard > > drive was state-of-the-art, 30 years have past since then and terabytes > > are cheaper than dirt. > > Terabytes may be cheaper than dirt, but my time isn't, and having to > read through a whole messed up posting to get to one original sentence > at the bottom of it is a waste of it. > So you came up with the ==================================== bit all on > your own, and expect everyone to understand what that's supposed to mean? > The "It won't be in Earth orbit then." part could be your .sig for all > anyone seeing it would know. > You could have just copied and pasted a quote arrow > on it, and it would have ended up looking like this: > > "William Mook" <mokmedi...(a)gmail.com> wrote in message: > > > 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. > > It won't be in Earth orbit then. > > See how much more comprehensible that is for the readers who already > know what the discussion is about, having already read parts of it four > times over? > Besides, anything that both Jonathan and William Mook are discussing is > bound to be pretty comprehension-challenged right from the word go, > without putting extra hurdles in its way. :-D > > Pat The only one comprehension challenged is you Pat and your idiotic false-choice regarding Earth orbit.
From: William Mook on 14 Feb 2010 13:24 On Feb 13, 12:36 pm, David Spain <nos...(a)127.0.0.1> 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/Mook-Patent-Solar-Energy-Spectral-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/White-Paper-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
From: William Mook on 14 Feb 2010 13:27
On Feb 13, 3:03 pm, Pat Flannery <flan...(a)daktel.com> 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. |