Accelerator based light-ion fusion. Using particle accelerators it is possible to achieve particle kinetic energies sufficient to induce many light ion fusion reactions. Accelerating light ions is relatively easy, cheap, and can be done in an efficient manner - all it takes is a vacuum tube, a pair of electrodes, and a high-voltage transformer; fusion can be observed with as little as 10 kilovolt between electrodes. The key problem with accelerator-based fusion (and with cold targets in general) is that fusion cross sections are many orders of magnitude lower than Coulomb interaction cross sections.

Therefore vast majority of ions ends up expending their energy on bremsstrahlung and ionization of atoms of the target. Devices referred to as sealed-tube neutron generators are particularly relevant to this discussion. These small devices are miniature particle accelerators filled with deuterium and tritium gas in an arrangement which allows ions of these nuclei to be accelerated against hydride targets, also containing deuterium and tritium, where fusion takes place. Hundreds of neutron generators are produced annually for use in the petroleum industry where they are used in measurement equipment for locating and mapping oil reserves. Despite periodic reports in the popular press by scientists claiming to have invented "table-top" fusion machines, neutron generators have been around for half a century. The sizes of these devices vary but the smallest instruments are often packaged in sizes smaller than a loaf of bread. These devices do not produce a net power output.

region                  radius        temperature
-------------------------------------------------------
fusion core         0.3 solar radii     15x10^6 K
radiation shell   0.3-0.6 solar radii    6x10^6 K
convection shell  0.6-1.0 solar radii    1x10^6 K
photosphere             100 km             6000 K
chromosphere           2000 km           30,000 K
corona                 10^6 km           1x10^6 K

From: Glen Wurden wurden@lanl.gov
reply-towurden@lanl.gov
To Chris Walters
chrissaidthanks2008@gmail.com
date Tue, Jan 6, 2009 at 11:23 AM
RE: Question on recent article in Popular Science

Dear Mr. Walters,

Thank you for your interest. It is a bit hard to tell what is happening in your figures. Also hard to tell which are from you, and which are from General Fusion.

As you might appreciate, just making a plasma with the desired geometry and properties is one issue, but keeping it hot (enough) for long enough, is another issue, and then doing it efficiently in a container (of some sort), is yet another issue. Finally, engineering all these things together in a fashion to make net energy at an affordable cost, is the ultimate test.

Careful analysis and experimentation is required for each of these points, for any "innovative confinement concept". a term we use routinely in fusion energy sciences areas of research.

Sincerely,Glen
Dr. Glen A. Wurden
Fusion Energy Sciences Program Manager
MFE Team Leader, P-24 Plasma Physics Group
Los Alamos National Laboratory
MS-E526
Los Alamos, NM 87545 USA
tel: 505-667-5633
fax: 505-665-3552
cel: 505-310-1886

A pebble bed power plant combines a gas-cooled core[6] and a novel packaging of the fuel that dramatically reduces complexity while improving safety.[7]

The uranium, thorium or plutonium nuclear fuels are in the form of a ceramic (usually oxides or carbides) contained within spherical pebbles a little smaller than the size of a tennis ball and made of pyrolytic graphite, which acts as the primary neutron moderator. The pebble design is relatively simple, with each sphere consisting of the nuclear fuel, fission product barrier, and moderator (which in a traditional water reactor would all be different parts). Simply piling enough pebbles together in a critical geometry will allow for criticality.

The pebbles are held in a vessel, and an inert gas (such as helium, nitrogen or carbon dioxide) circulates through the spaces between the fuel pebbles to carry heat away from the reactor. If helium is used, because it is lighter than air, air can displace the helium if the reactor wall is breached. Pebble bed reactors need fire-prevention features to keep the graphite of the pebbles from burning in the presence of air although the flammability of the pebbles is disputed. Ideally, the heated gas is run directly through a turbine. However, if the gas from the primary coolant can be made radioactive by the neutrons in the reactor, or a fuel defect could still contaminate the power production equipment, it may be brought instead to a heat exchanger where it heats another gas or produces steam. The exhaust of the turbine is quite warm and may be used to warm buildings or chemical plants, or even run another heat engine.

Much of the cost of a conventional, water-cooled nuclear power plant is due to cooling system complexity. These are part of the safety of the overall design, and thus require extensive safety systems and redundant backups. A water-cooled reactor is generally dwarfed by the cooling systems attached to it. Additional issues are that the core irradiates the water with neutrons causing the water and impurities dissolved in it to become radioactive and that the high pressure piping in the primary side becomes embrittled and requires continual inspection and eventual replacement.

In contrast, a pebble bed reactor is gas-cooled, sometimes at low pressures. The spaces between the pebbles form the "piping" in the core. Since there is no piping in the core and the coolant contains no hydrogen, embrittlement is not a failure concern. The preferred gas, helium, does not easily absorb neutrons or impurities. Therefore, compared to water, it is both more efficient and less likely to become radioactive.

A large advantage of the pebble bed reactor over a conventional light-water reactor is in operating at higher temperatures. The reactor can directly heat fluids for low pressure gas turbines. The high temperatures allow a turbine to extract more mechanical energy from the same amount of thermal energy; therefore, the power system uses less fuel per kilowatt-hour. A significant technical advantage is that some designs are throttled by temperature, not by control rods. The reactor can be simpler because it does not need to operate well at the varying neutron profiles caused by partially withdrawn control rods. For maintenance, many designs include control rods, called "absorbers" that are inserted through tubes in a neutron reflector around the reactor core. A reactor can change power quickly just by changing the coolant flow rate and can also change power more efficiently (say, for utility power) by changing the coolant density or heat capacity.

Pebble bed reactors are also capable of using fuel pebbles made from different fuels in the same basic design of reactor (though perhaps not at the same time). Proponents claim that some kinds of pebble-bed reactors should be able to use thorium, plutonium and natural unenriched uranium, as well as the customary enriched uranium. There is a project in progress to develop pebbles and reactors that use MOX fuel, that mixes uranium with plutonium from either reprocessed fuel rods or decommissioned nuclear weapons.

In most stationary pebble-bed reactor designs, fuel replacement is continuous. Instead of shutting down for weeks to replace fuel rods, pebbles are placed in a bin-shaped reactor. A pebble is recycled from the bottom to the top about ten times over a few years, and tested each time it is removed. When it is expended, it is removed to the nuclear waste area, and a new pebble inserted. The core generates less power as its temperature rises, and therefore cannot have a criticality excursion when the machinery fails, it is power-limited or inherently self controlling due to Doppler broadening. At such low power densities, the reactor can be designed to lose more heat through its walls than it would generate. In order to generate much power it has to be cooled, and then the energy is extracted from the coolant.

The LIFE development team is exploring a variety of possible fuel, target and laser configurations and energies for a prototype LIFE engine. The LIFE system is designed to operate with fusion energy gains of about 25 to 30 and fusion yields of about 35 to 50 MJ to provide about 500 megawatts (MW) of fusion power – about 80 percent of which comes in the form of 14.1 million electron-volt (MeV) neutrons with the rest of the energy in X-rays and ions.

This approach to fusion generates approximately 1019 14.1-MeV neutrons per shot (about 1020 neutrons every second). When used to drive a subcritical fission "blanket," the fusion neutrons generate an additional energy gain of four to ten depending upon the details of the fission blanket, providing overall LIFE system energy gains of 100 to 300.

The fission blanket contains either 40 metric tons (MT) of depleted uranium; un-reprocessed spent nuclear fuel (SNF); natural uranium or natural thorium; or a few MT of the plutonium-239, the minor actinides such as neptunium and americium, and the fission products separated from reprocessed SNF.

The point source of fusion neutrons acts as a catalyst to drive the fission blanket, so there is no need for a critical assembly to sustain the fission chain reaction. Starting from as little as 300 to 500 MW of fusion power, a single LIFE engine can generate 2,000 to 3,000 megawatts in steady state for periods of years to decades, depending on the nuclear fuel and engine configuration. Most "pure" inertial fusion energy plant designs require laser energies of about three MJ to achieve fusion yields of 200 MJ from NIF-like targets at about 15 shots a second to generate 3,000 MW of thermal power. In contrast, the laser energy requirements of the LIFE engine to generate the same amount of thermal energy are a factor of 2 to 2.5 lower.

The neutrons pass through the first structural steel wall and a first-wall coolant to a layer of beryllium pebbles, which generate 1.8 neutrons for every neutron they absorb. The newly generated neutrons have a significantly lower energy spectrum that is ideal for fission energy generation. The moderated neutrons strike the next layer, a one-meter-thick, subcritical fission blanket containing 40 MT of fission fuel pellets. The neutrons absorbed by the fuel pellets drive neutron capture and fission reactions, releasing tremendous amounts of heat to drive turbines.

The pellets are immersed in a molten salt called flibe (2LiF + BeF2 ) that carries away heat and also produces tritium that can be harvested to manufacture new deuterium-tritium fusion targets (see How to Make a Star). As conceived by Lawrence Livermore National Laboratory physicists and engineers, the LIFE engine's fusion targets, about one centimeter long and one-half centimeter in diameter, are injected at 10 to 15 Hz (10 to 15 times a second) into the center of the fusion chamber. The current LIFE baseline power plant (shown above) assumes targets similar to those that will be used for the ignition campaign on NIF. The first experiments to demonstrate LIFE ignition and gain will use 350-nanometer (ultraviolet) laser light with a central hot-spot ignition (HSI) target and an indirect-drive configuration.

Physicist Hui Chen sets up targets gold leaf target for at Jupiter Laser at Livemore Labs to produce billions of positrons. Could Positons be introduced into fuel to induce fusion-described as:

The cycle starts with the thermal collision of two protons (1H + 1H) to form a deuteron (2H), with the simultaneous creation of a positron (e+) and a neutrino (v). The positron very quickly encounters a free electron (e-) in the sun and both particles annihilate, their mass energy appearing as two gamma-ray photons. Once the deuteron has been produced, it quickly collides with another proton and forms a 3He nucleus and a gamma ray.

This article featured in Janurary 2009 from Popular Science Magazine reviews research being done by General Fusion Inc for creation of a thermonuclear reactor based on piston compression of helium and tritium in a spherical container. The management of General Fusion are willing to consider several possible variations including; use of ultrasonic compression to enhance fusion:

Good Morning Macrosonix:
1564 E Parham Rd
Richmond, VA 23228
(804) 262-3700
(804) 266-4627 (fax)
info@macrosonix.com

An article in Popular Science Magazine for Janurary, 2009 discusses a new method under research for creating nuclear fusion by use of a heavy piston to compress a liquid and then a gas. I had asked if the same effect could be achieved by your sonic devices such as the one attached to compress the liquid or gas? One of the researchers Dr. Michel Laberge, President explained such an approach might be possible as cited below:

"If the sonic devices couple OK with a dense fluid, that would work, still would need a very expensive electrical pulsed power system."

I am not familiar with the costs of your product or how much electrical power your device uses. I hope you do not mind my suggesting a possible mutual interest might exist between your different fields of research:

The use of high intensity sound waves to compress a liquid or gas might be a cheap and useful means to create a fusion reaction. I have attached the name and contact of the General Fusion personnel who are doing the research:

Doug Richardson, BASc, MASc, CEO
Dr. Michel Laberge, President
General Fusion Inc.
108-3680 Bonneville Place
Burnaby, BC V3N 4T5 Canada
doug@generalfusion.com,
michel@generalfusion.com

Hope your staff and the staff of General Fusion don't mind my asking a question.

Chris Walters, Author

The RMS sonic device would generate a sound field which would take helium or tritum as a gas and confine it to the center of the device. The heated helium or other dense gas would become a liquid as the sonic devices increased power and set up compression in the center of the reactor. Exactly how much compress can occur depends on the strenght of the sonic device used. Some RMS devices are able to life bowling ball of ground several feet a picture of what configuation is attached as sonic.jpg

If sonic confinement could replace magnetic confinement of tritium or other fusion materials it might be possible to simply use a series of sonic generators strong enough to create fusion by themselves.

from "michel@generalfusion.com"
michel@generalfusion.com
To chrissaidthanks2008@gmail.com
Date Dec 22, 2008 12:07 PM
Subject RE: Images of what sonic generation configuration might look like etc.

Thanks for the idea, we need a few MBar of pressure, that is a lot more than lifting a bowling ball in the air!! Can you calculate how much pressure these sonic generator can make?

From michel@generalfusion.com
To: chrissaidthanks2008@gmail.com
Date Wed, Dec 24, 2008 at 2:39 PM
Subject RE: Would a single piston compressing the tritium into the helium generate better pressure?

The fusion system we propose requires ~4 MBar of pressure, this is way pass the strenght of any solid material (piston) (max 20 KBar). In our system the pressure at the wall from the piston is 20 KBar but the acoustic wave focus in the center to 4 MBar, the liquid metal is not damage by that pressure as it is a liquid.

In your proposal, the solid piston is at the same pressure as the fusing fuel, it would be destroyed. Other proposals use very fast impact to produce the large pressure and destroy the piston during each shots. It is our opinion that a system that destroy equipment for each shot would not be economical.

From: Glen Wurden
wurden@lanl.gov
reply-towurden@lanl.gov
To NIMS2006 nims2006@gmail.com
Date Thu, Jan 15, 2009 at 12:04 PM
Subject RE: Could combining different fusion devices be worthwhile-link to your website?

In short, my answer is no. Simplicity is always better than complexity, if possible.

As for your details, probably difficulties in all cases:

1). Magnetic fields have a tough time in soaking through metals.

2). Radio sources generally don’t compress the kind of plasmas needed (they don’t have the energy density necessary)

3). Heavy radioactive metals should probably be avoided.

4). If alphas are confined during fusion, then alphas from some external radioactive material also will not be able to get into the fusion region.

1. A magnetic field trying to get through a metal case is a losing cause

2. A magnetic field would probably not work on a liquid such as Detritium

2. Radio sources only generate part of the power needed to reach reaction temperature

1. Come to think of it if a design used a radioactive metal and accidently reached a critical mass or was exposed to enough neutron flux to reach a critical mass, catch fire, or other bad events.

2. An accident or machine malfunction involving a radioactive metal would spread contamination throughout the entire working area-Thank you Dr. Wurden.

This hypothetical design asks if combining different existing research ideas into one model could more effectively create and maintain thermonuclear fusion?

1. The Detritium/Lead is heated and spun at high speed and creates hole in the center of the device for a magnetic field to hold the tritium gas in place

2. A high energy impact with the piston plate generates a sonic wave which compresses the tritium target which can be further energized by either high frequency radio waves or massive electrical charge

3. Finally the tritium/plasma is subjected to further construction by the torus magnets

4. The blue inner ring could also be a radium/berllium metal inside a cadium lining which is highly radioactive and emits alpha particles to become a neutron source

1. Could the Detritium/Lead compound work better if it was Detritium/Iron compound to interact better with the magnet?

2. Can a large torus magnet effectively compress a liquid

3. Could the detritium and tritium be electrically charged to repel each other as a result of either magnetic flux or electric charges

1. What type of gas should be used; Detritium/ Uranium/ or something else?

2. Should piston plate be powered by electic gun/steam engine/ or lite shaped explosives

Propels objects up to 7,600 MpH might create a way to collide tritium targets to create, head, pressure;...

This idea is a variation of the piston concept developed by General Fusion-except it only has 1 piston and proposes to use a magnetic torus.

This design proposes to use high energy plasma created by Klystron generators using high frequency radio waves to bombard a tritium target. It appears this concept has already been attempted without a tritium target in the The Farnsworth Hirsch Fusor on the opposite side of the page.