#6 FAQ: Quick fusion factoids
Posted: Fri Mar 02, 2012 10:46 am
We are besieged with questions specific to what is needed to do fusion. Here is a quick list.......
Fusion voltage needed:
Fusion, in the fusor, is achieved through supplying electrical energy in a reduced atmosphere of gas to generate a plasma. The voltage needed to achieve this depends on your detector type and sensitivity. In a fusor, fusion that can be detected begins at about 12 kilovolts (12kv) applied. No newbie without a very sensitive and expensive detector will be able to detect this. So, given the norm here, you will need about 25 kilovolts or more. At 35 kilovolts you will achieve a very easy fusion detect.
Your power supply must be a negative "hot" supply. This means that the positive high voltage lead must be connected to ground. You must have a minimum of 10-15 milliamps of available current at full potential with 20 or more milliamps being very desirable. Such supplies are very expensive if purchased new, ($2,000 - $5,000) but used supplies are often found on e-bay. Many fusioneers make up their own power supplies to avoid a major outlay of cash.
Fusion fuel:
There is only one fusion fuel that you will ever be able to obtain, and even then, with some variable degree of difficulty. That fuel is deuterium gas. Forget all other supposed fusion fuels that you may have read about in the fusion literature here or elsewhere.
Fusion reactor pressure, (environment within the fusor):
You will find that you can only do creditable fusion in a metallic, sealed vessel filled with a nearly 100% pure atmosphere of deuterium gas at a pressure of between 5 and 20 microns. (nearly 1 millionth of earth's normal atmospheric pressure). This means you will need to take your vessel down to nearly 1 billionth of an atmosphere with two tandem vacuum pump systems and back fill to one millionth of an atmosphere with deuterium gas.
Vacuum pumps consist of a foreline pump and a high vacuum pump. Both of these pumps can be found used and in good shape for a total of about $500.00. If you look about and get some good deals this cost figure can be reduced further.
Fusion Temperature:
This is a term involving total public confusion through both mis-information and lack of knowledge in what temperature really is. So, forget all about temperature until you are ready to really study and learn by digging into the literature or reading various FAQs here and the many postings related to it. Suffice it to say that the working fusor reaches outside temperatures, on the metallic shell, of over 200 degrees F which is very hot to the touch.
Fusor chamber or reactor vessel:
This must be metallic! Stainless steel is the normal vessel material used. The vessel can be almost any shape, but cylindrical and spherical fusors are the norm. The normal diameter is in the 6 to 8-inch range. You cannot do sustained fusion in a glass bell jar as it can't withstand the localized, internal heating found at detectable levels of fusion operations.
Fusion detection:
You can't claim fusion until you prove it here. The norm is to detect neutrons which are a common deuterium fusion by-product. Neutrons are the only fusion "ash" product that can be detected outside of the fusor reactor vessel. Sensitive, already made up, neutron detectors are extremely expensive with a very cheap new one being over $2,000.00. Bubble detectors that have a limited life span of about 6 months or more are avaialble for about $200.00 - $300.00.
If a fusor is operated at very high levels of easy detection, neutron induced silver activation detectable by an inexpensive geiger counter is possible. Also, special scintillation detection schemes can be fashioned by the electronically adroit fusioneer.
Radiation:
The radiation emitted from the normal stainless steel type fusor working under 25kv is very minimal both from a neutron and x-ray standpoint. However, at voltages much above 25kv, the stronger x-radiation will start to penetrate the metallic shell. (normally .060 thick). For voltages above 30kv, either remote operation, (10 feet or more operator-to-fusor distance), or some sort of thin lead shield around the fusor is advisable to reduce x-ray exposure. Above 40 kv, only a well constructed lead shield should be used. See the radiation forum for all the FAQs on this subject. Neutron radiation has never been a big issue, but at 70kv and above, a neutron absorber shield might also be in order. Thus far, no amateur operates in this upper high voltage region and no fusioneer has ever been exposed to any significant x-ray or neutron radiation.
Fusion energy out of the fusor....Power!
The average successful fusor will never demand more than about 500 watts of power from its high voltage supply as input. The absolute maximum fusion power generated from the best fusor ever made might be about 10 millionths of one watt.
Thus, the fusor demands about 50 million times more input power than it generates.
Bottom line? Forget about producing net fusion energy.....Ever!
Other stuff:
There are a myriad of fine details. Look up the requisite FAQs in the forums specific to your questions.
Richard Hull
Fusion voltage needed:
Fusion, in the fusor, is achieved through supplying electrical energy in a reduced atmosphere of gas to generate a plasma. The voltage needed to achieve this depends on your detector type and sensitivity. In a fusor, fusion that can be detected begins at about 12 kilovolts (12kv) applied. No newbie without a very sensitive and expensive detector will be able to detect this. So, given the norm here, you will need about 25 kilovolts or more. At 35 kilovolts you will achieve a very easy fusion detect.
Your power supply must be a negative "hot" supply. This means that the positive high voltage lead must be connected to ground. You must have a minimum of 10-15 milliamps of available current at full potential with 20 or more milliamps being very desirable. Such supplies are very expensive if purchased new, ($2,000 - $5,000) but used supplies are often found on e-bay. Many fusioneers make up their own power supplies to avoid a major outlay of cash.
Fusion fuel:
There is only one fusion fuel that you will ever be able to obtain, and even then, with some variable degree of difficulty. That fuel is deuterium gas. Forget all other supposed fusion fuels that you may have read about in the fusion literature here or elsewhere.
Fusion reactor pressure, (environment within the fusor):
You will find that you can only do creditable fusion in a metallic, sealed vessel filled with a nearly 100% pure atmosphere of deuterium gas at a pressure of between 5 and 20 microns. (nearly 1 millionth of earth's normal atmospheric pressure). This means you will need to take your vessel down to nearly 1 billionth of an atmosphere with two tandem vacuum pump systems and back fill to one millionth of an atmosphere with deuterium gas.
Vacuum pumps consist of a foreline pump and a high vacuum pump. Both of these pumps can be found used and in good shape for a total of about $500.00. If you look about and get some good deals this cost figure can be reduced further.
Fusion Temperature:
This is a term involving total public confusion through both mis-information and lack of knowledge in what temperature really is. So, forget all about temperature until you are ready to really study and learn by digging into the literature or reading various FAQs here and the many postings related to it. Suffice it to say that the working fusor reaches outside temperatures, on the metallic shell, of over 200 degrees F which is very hot to the touch.
Fusor chamber or reactor vessel:
This must be metallic! Stainless steel is the normal vessel material used. The vessel can be almost any shape, but cylindrical and spherical fusors are the norm. The normal diameter is in the 6 to 8-inch range. You cannot do sustained fusion in a glass bell jar as it can't withstand the localized, internal heating found at detectable levels of fusion operations.
Fusion detection:
You can't claim fusion until you prove it here. The norm is to detect neutrons which are a common deuterium fusion by-product. Neutrons are the only fusion "ash" product that can be detected outside of the fusor reactor vessel. Sensitive, already made up, neutron detectors are extremely expensive with a very cheap new one being over $2,000.00. Bubble detectors that have a limited life span of about 6 months or more are avaialble for about $200.00 - $300.00.
If a fusor is operated at very high levels of easy detection, neutron induced silver activation detectable by an inexpensive geiger counter is possible. Also, special scintillation detection schemes can be fashioned by the electronically adroit fusioneer.
Radiation:
The radiation emitted from the normal stainless steel type fusor working under 25kv is very minimal both from a neutron and x-ray standpoint. However, at voltages much above 25kv, the stronger x-radiation will start to penetrate the metallic shell. (normally .060 thick). For voltages above 30kv, either remote operation, (10 feet or more operator-to-fusor distance), or some sort of thin lead shield around the fusor is advisable to reduce x-ray exposure. Above 40 kv, only a well constructed lead shield should be used. See the radiation forum for all the FAQs on this subject. Neutron radiation has never been a big issue, but at 70kv and above, a neutron absorber shield might also be in order. Thus far, no amateur operates in this upper high voltage region and no fusioneer has ever been exposed to any significant x-ray or neutron radiation.
Fusion energy out of the fusor....Power!
The average successful fusor will never demand more than about 500 watts of power from its high voltage supply as input. The absolute maximum fusion power generated from the best fusor ever made might be about 10 millionths of one watt.
Thus, the fusor demands about 50 million times more input power than it generates.
Bottom line? Forget about producing net fusion energy.....Ever!
Other stuff:
There are a myriad of fine details. Look up the requisite FAQs in the forums specific to your questions.
Richard Hull