Horace Heffner wrote:
> At 9:29 AM 2/8/5, Frederick Sparber wrote:
>>Horace Heffner wrote:
>>
>>>
>>> Energetically effective fusion created using electron beams I think is
>>>or would be essentially
>>> electron catalysed fusion. This requires a minimum beam intensity of
>>> 1x10^19 electrons/(cm^2*s),
>>>
>>Commercially available Electron Beam Welders can put 3.10e-18 electrons
>>per second
>>into a weld piece with a 150 Kev - 0.4 millimeter diameter beam .
>>
>>> OK, so that's a beam intensity of (3x10^18 electrons/sec)/(Pi*(0.02cm)^2) =
>>> 2.39x10^21 electrons/(cm^2*s), which is about 2000 times the minimum
>> intensity, thus very good. The principle remaining problem is target
>> vaporization and destruction of the confinement. It might be better to
>> operate with a pulsed electron su! pply.
>>Horace Heffner wrote:
>>
>>>
>>> Energetically effective fusion created using electron beams I think is
>>>or would be essentially
>>> electron catalysed fusion. This requires a minimum beam intensity of
>>> 1x10^19 electrons/(cm^2*s),
>>>
>>Commercially available Electron Beam Welders can put 3.10e-18 electrons
>>per second
>>into a weld piece with a 150 Kev - 0.4 millimeter diameter beam .
>>
>>> OK, so that's a beam intensity of (3x10^18 electrons/sec)/(Pi*(0.02cm)^2) =
>>> 2.39x10^21 electrons/(cm^2*s), which is about 2000 times the minimum
>> intensity, thus very good. The principle remaining problem is target
>> vaporization and destruction of the confinement. It might be better to
>> operate with a pulsed electron su! pply.
>
Actually 50 times the minimum is available with a 0.4 millimeter diameter beam
from a 150 Kev beam at 0.1 amps continuous operation.
>
>>>
>>> but I think improves with increased intensity.
>>> Achieving a fast, dense, and high energy electron flux imposed on
>>> inertially confined hydrogen might best be done using x-rays, however.
>>
>
>>The problem with generating x-rays with electrons, is the low generation
>>efficiency:
>
>>X-ray yield (%) = 1.216e-7 * Z * Volts (about 1% efficiency for
>>tungsten, Z = 74)
>
> I don't understand this. If the source is 1.216x10^8 volts the efficiency
> is 740 percent? The above only applies in some range?
>>>
>>> but I think improves with increased intensity.
>>> Achieving a fast, dense, and high energy electron flux imposed on
>>> inertially confined hydrogen might best be done using x-rays, however.
>>
>
>>The problem with generating x-rays with electrons, is the low generation
>>efficiency:
>
>>X-ray yield (%) = 1.216e-7 * Z * Volts (about 1% efficiency for
>>tungsten, Z = 74)
>
> I don't understand this. If the source is 1.216x10^8 volts the efficiency
> is 740 percent? The above only applies in some range?
1.216e-7 * 74 * 150,000 volts = 1.35 % . Yes, it is an old Bragg formula range-limited.
At 6.0 Mev tungsten is about 54 % efficient .
Lithium (Z = 3) is about 0.055% efficient at 150 Kev, which is good. :-)
>
>>Also collimating them is a bit of a problem as they are finding out with
>>laser-generated x-rays.
>Yes. In a lab x-rays can be focused by refraction using lenses made out of
>pitch, etc., or by use of reflection at high incidence off the inside of
> lots of small metal tubes. Parabolic reflection might be inefficient to
> impossible depending on energy.
>
>>At these energies the x-rays undergo the Compton (Scattering) Effect
>>giving up to 1/3 their
>>energy to the electrons (about 60 Kev max.with 200 Kev x-ray photons).
>
>
> Yes, so with efficiency factors of 0.01 for x-ray generation and .33 for
> momentum exchange we get down to a net factor 0.0033, which is not
> insurmountable in pulsed mode.
>
>>Also collimating them is a bit of a problem as they are finding out with
>>laser-generated x-rays.
>Yes. In a lab x-rays can be focused by refraction using lenses made out of
>pitch, etc., or by use of reflection at high incidence off the inside of
> lots of small metal tubes. Parabolic reflection might be inefficient to
> impossible depending on energy.
>
>>At these energies the x-rays undergo the Compton (Scattering) Effect
>>giving up to 1/3 their
>>energy to the electrons (about 60 Kev max.with 200 Kev x-ray photons).
>
>
> Yes, so with efficiency factors of 0.01 for x-ray generation and .33 for
> momentum exchange we get down to a net factor 0.0033, which is not
> insurmountable in pulsed mode.
>
> So, a pulse generator is needed that is
> much more than 100 times the current and which is also about 3 times the
> voltage of the electron welder, but only briefly. Cooling pulsed x-ray
> tubes is less difficult than continuous duty tubes.
> much more than 100 times the current and which is also about 3 times the
> voltage of the electron welder, but only briefly. Cooling pulsed x-ray
> tubes is less difficult than continuous duty tubes.
>
The 150 - 200 Kev @ 1/2amp e-beam welders will run continuously the
filament and beam focusing is the the only heat energy input requirement.
Plus the vacuum pumps for differential pumping against the LiH-LiD capsule
lithium-gas leakage. At 688 C the vapor pressure of LiH is less than 50 Torr.
>
>The target could a multi-layer target, consisting of, for example, an outer
> jacket of x-ray transparent confinement material with highest Z possible,
> an LiD-LiT mixture, mixed with an x-ray reflecting/dispersing powder, a
> high-z confinement jacket, and an LiD-LiT core?
>The target could a multi-layer target, consisting of, for example, an outer
> jacket of x-ray transparent confinement material with highest Z possible,
> an LiD-LiT mixture, mixed with an x-ray reflecting/dispersing powder, a
> high-z confinement jacket, and an LiD-LiT core?
>
At 2850 Joule per gram heat of fusion of LiH at it's 688 deg C melting point,
a 250 gram capsule of LiH-LiD (~ 7.95 grams/mole) "heat-sinked" with liquid metal heat pipes
for energy extraction,should handle the required 15 Kw-thermal input and the 5 X input (75 Kw Thermal) output.
>
Snip
>
> Regards,
> Horace Heffner
>
> Regards,
> Horace Heffner
Frederick
