Cock Croft Walton accelerator

In summary: There is no net energy released from the reaction. In summary, linear accelerators are not very efficient for inducing collisions between particles and proton-boron^11 fusion is not a very successful reaction.
  • #1
crx
81
0
Why in an linear accelerator, like the Cock Croft Walton accelerator, in which protons would strike a solid piece of boron wouldn't give up more energy than the input?
It seems to me that this situation have the least bremsstrahlung radiation loss and the highest cross section, for fusion interaction...
Thanks!
 
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  • #2


crx said:
Why in an linear accelerator, like the Cock Croft Walton accelerator, in which protons would strike a solid piece of boron wouldn't give up more energy than the input?
It seems to me that this situation have the least bremsstrahlung radiation loss and the highest cross section, for fusion interaction...
Thanks!
Accelerators are notoriously inefficient for inducing collisions between particles. The p-11B, like other fusion reactions, has an energy-dependent cross-section, and while one can optimize the accelerator energy to optimize that reaction, there are the issues of getting an interaction and obtaining the desired reaction upon achieving the desired interaction.

The probability of the proton colliding/interacting with a B nucleus is relatively small. The if the proton collides favorably with a B-nucleus, the probability that it will produce fusion is also relatively small, and much less than the probability that it would just scatter. This is the same problem for any fusion reaction.

Certainly the fact that the boron nuclei reside atoms, i.e. they are not fully ionized, means that one does not get the brehmsstrahlung losses of the electron/nuclei interactions. But then as the proton beam and any fusion reaction occurs, the solid B target would tend to vaporize.

At present, the two approaches to fusion are considered - magnetic confinement and inertial confinment. p-B is essentially impossible with current MC configurations due largely to brehmsstrahlung and other losses (e.g. cyclotron) and the fact the Z(B)=5, which means 5 free electrons for each B-nuclei.

Inertial confinement may be an alternative, but then there is still the complication of the B atom and its 5 electrons, and the complication of borane structures. If not borane, then the target would require some layer of B and H, and perhaps alternating layers, but that has to be at cryogenic conditions (another complication).
 
  • #3


When protons from a Cockroft-Walton strike a boron target, there is no bremsstrahlung. Only electrons produce bremsstrahlung at low energies. Protons striking a boron target are slowed down by ionization of the atoms (dE/dx). Occasionally the proton will react with a boron^11 nucleus and produce 3 alpha particles (helium nuclei). This reaction occurs at about 675 keV (proton incident energy). The reaction is exothermic, releasing a few MeV of kinetic energy. The isotopic abundance of boron^11 is about 80%.

The proton-boron^11 reaction is actually a (p,alpha) reaction, leaving a beryllium^8 nucleus which rapidly decays into two more alphas.
 

Related to Cock Croft Walton accelerator

What is a Cockcroft-Walton accelerator?

A Cockcroft-Walton accelerator is a type of particle accelerator designed to accelerate charged particles, typically protons or electrons, to high energies. It uses a series of voltage multipliers to generate high voltages for particle acceleration.

How does a Cockcroft-Walton accelerator work?

The Cockcroft-Walton accelerator works by using a series of capacitors and diodes to multiply the input voltage. The input voltage is first fed through a series of capacitors, each one increasing the voltage until the desired high voltage is achieved. The high voltage is then used to accelerate charged particles through an accelerating tube.

What are the advantages of using a Cockcroft-Walton accelerator?

One advantage of using a Cockcroft-Walton accelerator is its simplicity and low cost compared to other types of particle accelerators. It also has a high voltage output and can accelerate particles to very high energies. Additionally, it is relatively compact and can be used in a variety of applications, such as medical research and industrial processes.

What are the limitations of a Cockcroft-Walton accelerator?

One limitation of a Cockcroft-Walton accelerator is the maximum voltage it can achieve. Due to the limitations of the diodes and capacitors used, it can only reach a certain voltage before the circuit breaks down. Additionally, it is not suitable for accelerating heavy particles, such as alpha particles, as they are too heavy to be accelerated by the electric fields generated.

What are some common uses for a Cockcroft-Walton accelerator?

Cockcroft-Walton accelerators are commonly used in medical research, particularly in cancer treatment through proton therapy. They are also used in industrial processes, such as sterilization and food irradiation. In addition, they are used in particle physics research to study the properties of particles at high energies.

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