I Calculating t for H Ions on W Target @2.5 MeV & 100µA F=10^16

[Kostiantyn]

Hi everyone,

How to calculate time of irradiation (t) if you know:
Type of ions: H
Target material: W
Ion energy: 2.5 MeV
Ion current: 100 µA
Ion fluence: 10^16 ions/cm^2

Thank you!

 

[gleem]

We need more information. What is the purpose of the irradiation? What effect are you attempting to produce?

 

[Kostiantyn]

We need more information. What is the purpose of the irradiation? What effect are you attempting to produce?

1. The purpose of the irradiation is to study cross-sectional (along the ion pass) radiation damage in terms of in-plane stress, strain and interplanar distances.
2. Radiation damage effect, the effect of trapped helium from the point of view described above.

 

[gleem]

In your OP you indicated a hydrogen ion but you meant He? How thick is your tungsten target? For a 2.5 Mev
He⁺⁺ ion mean depth of penetration in tungsten, is estimated to be about 3 x 10 ^-4 cm.
2.5 MeV He ions have only a 1.3 cm range in air.

Your irradiation time depends on how much He you want to implant.

Also, I do not expect the energy deposition or the He concentration to be uniform vs depth.

 

[Vanadium 50]

Your irradiation time depends on how much He you want to implant.

This. (Or hydrogen if that's what you are implanting)

 

[Kostiantyn]

In your OP you indicated a hydrogen ion but you meant He? How thick is your tungsten target? For a 2.5 Mev
He⁺⁺ ion mean depth of penetration in tungsten, is estimated to be about 3 x 10 ^-4 cm.
2.5 MeV He ions have only a 1.3 cm range in air.

Your irradiation time depends on how much He you want to implant.

Also, I do not expect the energy deposition or the He concentration to be uniform vs depth.

Thanks for replay!
Sorry, my bad. Its Helium.
About first questions: all information you can get from SRIM code.

Simulation was done according to task (He ions in W target). First pic destributions of ions in target, second pic ions pass(red) stopped ions(white).

"Your irradiation time depends on how much He you want to implant." Up to the fluence of 10^16 ions/cm^2

 

[Kostiantyn]

This. (Or hydrogen if that's what you are implanting)

Up to the fluence of 10^16 ions/cm^2

 

[mfb]

Reaching a given ion fluence is easy. The beam current gives you ions per time, you just need to find the area that is irradiated. Assuming you use some scanning procedure to get a uniform fluence in the target area you will lose some of the helium ions outside the target area, how much depends on the beam profile and the scanning procedure. If you don't have a scanning procedure then you won't get a uniform fluence and you have to specify what exactly you aim for. Either way, you'll need to find out how wide your beam relative to your sample.

 

[gleem]

So the goal is to implant 10¹⁶ He ions/cm². For 100 uamp of current assuming He++ ions then the rate of deposition of He ions is

(100 x10^-6 C/sec) x ((1.6x10¹⁹)/2 ions/C ) = 8 x10¹⁴ ions/sec
where C is coulombs

Then proceed as @mfb states. It looks like you need to convolve the ion range distribution with the beam scanning pattern to obtain the desired deposition distribution assuming the beam diameter is negligible.

 

[mfb]

OP asks for ions/cm², the range of the beam in the material doesn't matter.