Farnsworth Fusor and Multipactor

[tak22]

http://www.scribd.com/doc/39121161/Secondary-Electron-Emission-by-Bruce-Darrow-Gaither

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In this era of energy shortages we have all daydreamed about owning a device which would take the energy that we have and multiply it. Imagine how happy we would be if you could simply plug in a device which would double your electricity. Numerous researchers, writers and inventors have sought to do just that.

But scientists have cautioned that the law of conservation of energy dictates that energy is never created nor destroyed, only converted from one form to another. None of these schemes, they say, would ever work. They are just perpetual motion machines.

The purpose of this book is to discuss advances in electronics and materials science which have made things possible which were not contemplated when the laws of Thermodynamics were postulated decades ago.

Secondary electron emission is a well-known process. It is that effect which causes additional electrons to be emitted when a substance is bombarded by a stream of electrons. This secondary emission effect was discovered a century ago, and it has found application in a variety of devices which are in use today.

Advances in electronics and the development of new materials have revealed new methods and substances which make this secondary electron emission even more effective. In fact, today the impossible is possibleâ€"one electron at a time.

If a beam of electrons is aimed at a target electrode coated with a given substance then electrons are emitted from that target. The number of electrons emitted from the target which has been bombarded is compared to the number of primary electrons in the original electron beam. The electrons emitted after bombardment by primary electrons are called secondary electrons.

The material’s propensity to emit electrons after bombardment is called the “secondary electron emission coefficient”. That is expressed as the number of secondary electrons divided by the number of primary electrons.

A secondary electron coefficient of less than 1 means that the substance does not emit as many electrons as it is bombarded with. A coefficient of greater than 1.0 means that the substance emits more secondary electrons than bombarded it

We are interested in this book in those materials which exhibit a high coefficient of secondary electron emission. The goal is to perfect a device which will emit more electrons than you started out with. Some devices have been invented to minimize or eliminate secondary electron emission, but those are not within the scope of this book.

Years of testing and research have resulted in well-known coefficients of secondary electron emission for scores of materials. Research first focused upon basic substances such as copper, steel, silver, gold and other metals. Then more exotic combinations and alloys were tested, such as oxides and alkalai metal combinations. Some metals and some combination coatings worked much better than others.

In recent years miniaturization and nanotechnology as well as chemical vapor deposition of thin films have come up with even more effective secondary electron multipliers.

In fact today’s plasma televisions and LED lights are examples of such substances and processes.

A reference to various charts is now possible to determine at a glance exactly what the secondary electron emission coefficient is for these materials.

But the devil is still in the details.

Two variables are of importance as to the materials. One variable is the angle at which the primary electrons impact the target. In general it has been found that a better result is obtained when the primary electrons graze the target material at an angle rather than hitting straight-on. But the physics of the secondary emission process and the atomic and molecular structure of the target materials mean that the optimum angle is different for different materials. The second main variable is the voltage of the beam of primary electrons. Some substances max out their secondary emission coefficient at very low
voltages and some materials reach their highest secondary emission only at much higher voltages. This is believed to be due to the depth to which the primary electrons impinges the material and the amount of tunneling into the substance.

Therefore care must be be paid to the research of the variables in the individual research papers and patents and there is no magical formula which will work for all materials. The configuration of the device used in the secondary emission process will need to vary to meet the characteristics of the target material.

Once the primary electrons have impacted the target material and secondary electrons are released, then the secondary electrons do not form a focused beam. Instead they tend to just sit there in a cloud of electrons. Meanwhile the primary electrons will usually bounce off the target at an angle equal to the angle with which they make incidence to the target. This means that the kinetic energy of the primary electrons is greater than that of the secondary electrons after impact. In other words the secondary electrons are indeed a larger number of electronsâ€"but they are of low voltage.

However numerous methods exist to increase the voltage or kinetic energy of the secondary electrons.

One process which is common in devices which employ secondary electron emission is that of multiple impacts upon this emissive target material. The great inventor, Philo Farnsworth, was the first to devise methods to facilitate these multiple impacts upon emissive materials. He called his devices “multipactors” because of the multiple impacts they made with secondary electron emissive material. Thus, if a target electrode had a
secondary electron emission coefficient of 2 then the number of primary electrons would double when they hit the target electrode. If there were two successive impacts then the primary electrons would double, and then that total would double againâ€"or be four times the original primary electrons put into the device.

If the primary electrons were somehow sent through a series of 8 target electrodes then the multiplication factor would become astronomical, and each of the impacts would result in an exponential increase of electrons based upon the coefficient of secondary electron emission from that material.

So various devices were designed and perfected to make the primary electrons impact numerous electrodes one after another. One branch of these devices is employed by photomultiplier tubes. Many of these devices are capable of multiplying the primary electrons one hundred million times. Thus minute electric currents can be sensed and multiplied so that they can register on scientific equipment. But numerous other configurations and devices are in use today.

One method is to bounce the electrons off of two opposing electrodes over and over again, like a game of ping pong. Another configuration would be to have the electrons strike electrodes arranged inside a circular tube so that they impact coated electrodes over and over again. A third method is that of forming a cascade of specially-coated electrodes and having the primary electrons bounce off off each successive electrode until they all come
out the end.

Another genre of devices are called “channel” devices. In these designs the primary electrons are sent down a waveguide or tunnel of some sort and the entire length of the device is coated with the emissive materials. The electrons keep bouncing off the walls of these guides until they reach the end and the repeated impacts result in a high multiplication of the primary electrons.

One of the axioms of electricity is that current will not conduct very well when exposed to the atmosphere because the gas acts as an insulator. Therefore most secondary electron emission devices were made in the form of vacuum tubes. The electricity goes through the vacuum without loss and then the impacts upon emissive material have the desired result.

However secondary emission and multipactors have been made into semiconductors and chips. These use the process of “avalanche” multiplication in many instances, where the electrons hit the emissive substance and are then multiplied and pass through a solid state stack of materials. Sometimes the semiconductors include a tiny vacuum space and they act in the same way as a vacuum tube.

However there is a snag or two for the use of secondary emission in chips. The first problem is “space charge”. That is the effect of completely filling up a given space with electrons. One you saturate the evacuated space with space charge then an equilibrium state is achieved and the primary electrons will no longer multiply as desired. As you might guess, the greater the area the more electrons will fit into the space before the space charge saturates the area. The space charge, then, has been found to diminish as to the 4/3 power of the area of the evacuated space. This means that, for instance, if you triple the size of vacuum space then that would result in 3x 4/3 power= 12/3 power (or the 4th power). Then a tripling of space would end up in shrinking the space charge by the 4th power. The bottom line is that bigger is better.

The second drawback to micro multipactors is that the vacuums must be higher than in vacuum tubes, and this is hard to achieve. Also many devices use sharp points as electrodes because more electrodes will emit from sharp points than from blunt shapes. In the micro world though the sharpness of the sharp point has to be correspondingly sharper. The finer the point on the electrode the harder it is to fabricate and fit into the layered semiconductor devices.

What this book hopes to achieve is not the simple multiplication of electrons to provide light or brightness but to generate electricity on a larger scale. The aim is not to build a generator station for thousands of people but to scale the multipactor devices to work with individual appliances and vehicles. Thus the size and rated capacities of the components in the proposed multipactors must be designed to be in the range of home current up to the amount of voltage and current required to power an electric car.

At this point the discussion of secondary electron emission must include some of the math and physics. Don’t let your eyes glaze over. Everybody knows a little bit about electricityâ€"and it is pretty simple. But there is a hazy horizon on the amount of knowledge of the basics of electricity. The terms are VOLTAGE, AMPERAGE and
POWER. The easy rule of thumb is that VOLTAGE x AMPS = POWER.

You need to throw in the RESISTANCE into this formulaâ€"but for now we will stick with VOLTSxAMPS=POWER.

OKâ€"so we will calculate one AMP. An Ampere involves the amount of “charge”, which is calculated in terms of a COULOMB. A Coulomb is -6.24151 × 1018 electrons. So the process of secondary electron emission results in a lot of electrons. The secondary electrons are not moving very much after they are multiplied. So they have low voltageâ€"but they DO have AMPERAGE because of the presence of lots of electrons.

The purpose of this analysis is to point out that we have low volts and high amps from secondary emission. When you remember volts x amps = power then you can see that we have to have just a high enough voltage to meet the requirements of modern electrical devices.

There are numerous well-known devices which can act as VOLTAGE MULTIPLIERS. These devices will increase the voltage, but only at the expense of a proportional decrease in the amperage.

The end product of these multipactors can be made usable, therefore, by running these high amperage currents through a voltage multiplier. You just fine-tune the voltage multiplier to give the right mix of volts and amps.

In short, secondary electron emission creates NEW electrons. We put the new electrons to use by stepping up the voltage to required levels.

In this way the laws of conservation of energy are negotiated. The multipactor creates new electrons and THEN the energy is converted from one form into another. But there is indeed a creation of new electrons in multipactors.

I will leave it to the scientists and inventors in their respective papers and patents to describe the manner in which the secondary electrons are created and how the multipactor devices are designed.

The point of my analysis is simply that the multipactors will create new electrons and the new electrons can be made usable through voltage multipliers.

One of these voltage multipliers is a Cockroft-Walton circuit. Modern electronics has manufactured numerous cheap transistor devices that you could get at Radio Shack or electric supply houses. A Cockroft-Walton circuit is simply a ladder of diodes and capacitors (pennies apiece) which double the voltage at each step of the ladder. So a multi-step ladder creates a multiple doubling of the original voltage. Some of the older designs apply a step-up transformer to do the same thing.

So we see that there is a problem with voltage in secondary electron emission. The inventors have figured out a method to use voltage to their advantage in the multipactor devices. They apply the rule that opposite charges attract. This accelerates the cloud of secondary electrons so that they will impact the next target with it’s emissive coating. The electron is a negative charge. So the inventors manipulate the sluggish cloud of negative charge by providing a positive electrode to put it into motion.

Some designs will make the next electrode one with a positive charge, so when the primary electrons strike the first target and are multiplied then the cloud of secondary electrons is accelerated right up to the second electrode coated with emissive materials. hen they make a long chain or cascade of these target electrodes then they give each of them a successively higher positive charge so that the ever-increasing cloud of secondary electrons is accelerated one step at a time in the desired direction.

Other designs use an electrode which is positioned between the first impact target and the second and they give that intermediate electrode a positive charge to accelerate the cloud of secondary electrons in the desired direction. This intermediate electrode might be in the form of a screen or grid or a tube. The positive charge, in every instance, attracts the opposite charge on the electrons and they are suddenly accelerated through the holes in these intermediate electrodes and then the electrons continue with their increased voltage until they impact the coated electrode. This step may be repeated again and again.

The positive charge on these attracting electrodes is often provided by using Cockroft-Walton circuits. So either a single or a multi-step CW circuit may be used to multiply an initial small current to give a charge bias of increasing strength to a series of attracting electrodes. Oftentimes the CW circuit contains “taps” which tap the current at a certain step in that multiplying step ladder. The step would then have one voltage level to apply to the attracting electrode, and then the next step would have a higher voltage which could be tapped at that level and applied to the next attracting electrode, and so on.

Going back the purpose of this analysis again: we are trying to get as many electrons as possible out of the multipactor. So the gameplan is to select the coating material for electrodes which has the highest secondary electron emission coefficient. Then the voltage at which the primary electrons must be accelerated to achieve the optimal secondary emission must be applied. The spatial requirements are important too because we want the right angle and the right depth for the impact zone. So we get the highest electron multiplication at each step. Then we take that level of electron multiplication and exponentially multiply it by the number of impacts in the multipactor device.

Some devices, as aforestated, simply bounce the electrons back and forth between two opposed electrodes. In these designs the electrons are moving at the speed of light, so they hit the opposite electrode in a known length of time. Then they bounce back to the original electrode. The desired effect is to have but one cloud of secondary electrons bouncing back and forth, and not a lot of different clouds. Therefore the two electrodes are given opposite charges, positive and negative, and these charges are sequentially reversed so that the electron cloud always moves away from the first electrode after they have been multiplied and then toward the target electrode for more multiplication. Since we know the distance between the two electrodes and because the speed of light is known, then we can determine the FREQUENCY at which the electric charge is reversed on these electrodes. So, take the speed of light and divide it by the distance between the electrodes. Say, 186,000 miles per second divided by 6 inches.

The resulting frequency is in the range of billions of cycles per second. There are modern oscillator chips which cost pennies which can do that.

The point here is that we take the secondary electron coefficient, and let’s say that this is 2 for the sake of argument. Then we apply the frequency of the impacts on these emissive electrodesâ€"and that is perhaps one billion times per second. In this example we would then obtain 2 to the one billionth power!

Are you beginning to get the picture?

If we make the device the right size so that the space charge does not saturate the vacuum then we can generate sufficient electrons so that we can step up the voltage and step down the amperes to achieve the desired power characteristics for our electric appliance or motor.

For the purposes of our last example we have a secondary emission coefficient of 2, or a doubling of the primary electrons at each impact with the electrode with the emissive coating. But what if the secondary emission coefficient were 10…or 100…or even 1000? Just apply the math and you can see the possibilities of these multipactors.

Attached to this anthology is one of the latest research papers from Korea where scientists have obtained a new record for the secondary emission coefficient: 22,000!

Thus reason dictates that the proper coating must be selected for the electrodes. Then the rest of the components must be selected and positioned so that the size, frequency and angle of impact are optimal.

I think I heard somebody say, “Hey, Einsteinâ€"it still has to be hooked up to electricity to start up and to power the attracting electrodes. What about that?”

The answer lies in the principle of feedback and self-oscillation. We know that many oscillators are known to exhibit the characteristic of self-oscillation. Once you get them going then they tend to keep on oscillating on their own. This process works in multipactor-oscillators. It just takes a little electricity to get them started and then the
internal processes take over and they self-oscillate, producing electrons without the input of outside electricity.

Many electronic devices apply the principle of feedback, especially in audio devices. We can remember Jimi Hendrix hitting a note on his guitar and then holding the guitar in front of his amplifier. The amp’s sound creates a feedback loop with the guitar and a sound is created which is self-sustaining without the additional input of playing another note. Numerous transistors work with feedback loops to take the electrical output of the device and split that output and send part of it back to the original input where it is again amplified. So the coupling of the output to the input wires is what is required. So using either feedback or self-oscillation or both a multipactor device can be fabricated so that it will have self-sustaining output of electrons.

That still leaves us the positive bias charge that is placed upon the attracting electrodes to accelerate those sluggish clouds of secondary electrons.

Again, we simply split the output signal and loop part of it back to the accelerating electrodes, and this is the positive charge remember. So the negative charge goes back to feedback the input and the other loop goes to the voltage multiplier. A Cockroft-Walton multiplier can be either positive or negative in chargeâ€"you simply reverse the connection between the diodes and capacitors and it multiplies the positive charge.

Therefore, we could use batteries to start up the multipactor and then apply common electronics components and devices to split the output and loop it back to the input and bias the positive electrodes. Then the battery can be shut off, and even recharged while the multipactor runs on self-sustaining current.

That guy who used Einstein’s name like a dirty word again wants to voice his opinion, “Hey, genius, this stuff is a bunch of hooey! How do we know this would work?”

How do we know?
Because of TELEVISION.
These multipactor devices were invented by Philo Farnsworth when he invented television. Just one glance at this super-egghead fellow should give you the answer. This guy was a super-brain and he just NEEDED to have special vacuum tubes to strengthen the broadcast signal of television from remote locations to make the picture tubes bright enough to seeâ€"so he simply invented multipactors to multiply that weak input signal.

If these multipactors work then why didn’t Farnsworth take over the whole world?
The reason is related to the laws of business and not the laws of physics. Philo Farnsworth saw the value of television and his multipactors but he had an independent streak which caused him to form his own Farnsworth Television company with which he intended to put RCA and GE out of business. Instead they put Farnsworth out of business by using monopoly tactics. But Philo Farnsworth applied his principles based upon secondary electron emission to the point that he invented a nuclear fusion reactor before he was through.

The heyday of vacuum tubes was filled with imitators of every sort. There is even an International Patent classification which contains only “Farnsworth Tubes”.

Since Farnsworth’s day the vacuum tube was supplanted by the Japanese transistor and then the Silicon Valley semiconductor chip. Nobody makes vacuum tubes anymore and the vacuum tube multipactor concepts have been lost in the world of microelectronics.
But even today secondary electron emission is applied in the plasma television sets where scores of little holes and dots are brightened by electron multiplication. Other areas such as scintillation counters and electron detectors and night vision goggles use the process, often in the solid-state configuration. There exists an offshoot applying vacuum tubesâ€" the sector called PHOTONICS which use vacuum tubes to multiply light into electronic signals.

As stated above, there are several basic methods of achieving multiple impacts of electrons.

These graphs and excerpts were developed over a period of time. The more ancient the research the lower the coefficients. As newer and newer materials were invented and tested there is a general trend toward higher and higher coefficients. I would respectfully call your attention to the source material in the following sections for detailed analyis of the methodology and results of individual studies and devices with various emissive materials.

Attention should be paid to the voltage required to obtain a certain coefficient of secondary electron multiplication. The graphs are not in parallel so they are slightly different pictures. But they should give a general idea of how much electron multiplication could be obtained by a particular substance.

The following chapters will discuss individual studies and patents. Some of these resource documents contain excellent discussion of historical development of the secondary electron emission devices. It is of note that secondary electron emission was first discovered about a century ago, and the first patent for a vacuum tube as applied for in 1919.

The discussion also includes mention of “work factor” as an indicator of secondary emission coefficient. The lower the work factor the higher the coefficient.

Another area of interest is that of “negative electron affinity” as an explanation for secondary electron emission. In short, the term affinity implies that a particular substance either likes or rejects electrons. The materials with negative electron affinity then are predisposed to not like negatively-charged particles and thus reject them when bombarded.

Treatises on vacuum tubes have been consulted and quoted in pertinent part. Patents are inserted to this anthology to examine their significance at particular points in time. Various studies on the individual materials exhibiting secondary emission.

Finally, I include several of my own designs for multipactor devices to power electrical appliances and motors.

tak

[ramset]

Tak
A snippet from your above Doc

"For the purposes of our last example we have a secondary emission coefficient of 2, or a doubling of the primary electrons at each impact with the electrode with the emissive coating. But what if the secondary emission coefficient were 10…or 100…or even 1000? Just apply the math and you can see the possibilities of these multipactors.

Attached to this anthology is one of the latest research papers from Korea where scientists have obtained a new record for the secondary emission coefficient: 22,000!
"
--------------
Tak is this what William Barbat is doing?

Holy Cow!
Chet

[tak22]

Chet,

Interesting, I hadn't thought about Barbat when I skimmed it, just had multipactor
on my mind. Does sound most familiar though ...

tak

[Terbo]

patent to recovery energy from multipactor effect:

http://www.google.com/patents?id=lkACAAAAEBAJ&printsec=abstract&zoom=4&source=gbs_overview_r&cad=0#v=onepage&q=&f=false

Wings --

The multipactor patent you reference is very interesting since it uses over-pressure instead of a hard vacuum in its envelope.  Specifically, this device uses 10^13 to 10^15 Torr pressures.  By comparison, 1 Atmosphere pressure = 760 Torr, so we are talking EXTREME pressures exceeding 1 billion normal Atmospheres.  I don't believe these pressures are achievable.  What am I missing? 

[wings]

Wings --

The multipactor patent you reference is very interesting since it uses over-pressure instead of a hard vacuum in its envelope.  Specifically, this device uses 10^13 to 10^15 Torr pressures.  By comparison, 1 Atmosphere pressure = 760 Torr, so we are talking EXTREME pressures exceeding 1 billion normal Atmospheres.  I don't believe these pressures are achievable.  What am I missing? 

the effect also at medium low pressure ?

http://www.google.com/patents?id=IG8BAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false

http://www.overunity.com/index.php?topic=1965.msg23706#msg23706