Quasi-neutral plasma generation of radioisotopes
Methods and apparatus for synthesizing radiochemical compounds are provided. The methods include generating a quasi-neutral plasma jet, and directing the plasma jet onto a radionuclide precursor to provide one or more radionuclides. The radionuclides can be used to prepare radiolabeled compounds, such as radiolabeled biomarkers.
1. A method for production of radioisotopes, the method comprising:
directing a light pulse along an optical axis to generate a quasi-neutral plasma jet in the absence of an electromagnetic accelerator; and
directing, in the absence of an electromagnetic accelerator, the quasi-neutral plasma jet in a direction collinear with the optical axis onto a radionuclide precursor.
2. The method of claim 1 , where the quasi-neutral plasma jet is produced by impinging a light pulse less than about 10 −11 seconds in duration onto a target material;
wherein the dimensionless vector potential of the light pulse, α o, =0.6λ √I, is greater than about one, where λ is the wavelength in μm and I is the intensity in units of 10 18 W/cm 2 .
3. The method of claim 2 , where the target material is a solid film or particle; or the target material is a liquid film, jet, or droplet.
4. The method of claim 2 , where the target material is a gas jet whose number density in the focal region of the light pulse is greater than about 10 20 nuclei per cubic centimeter.
5. The method of claim 2 , where the light pulse is preceded by one or more pre-pulses whose dimensionless vector potential α o <10 −4 .
6. The method of claim 2 , where the light pulse is produced by a laser having a wavelength of about 0.4 μm to about 20 μm.
7. The method of claim 2 , where the light pulse is preceded by one or more pre-pulses whose dimensionless vector potential α o <10 −10 .
8. The method for production of radioisotopes, comprising:
generating a quasi-neutral plasma jet; and
directing the quasi-neutral plasma jet onto a radionuclide precursor,
where the quasi neutral plasma jet passes from an evacuated region through a window to interact with the radionuclide precursor at a region of higher pressure.
9. The method of claim 8 , wherein
the evacuated region is at a pressure of 37 Pascal (Pa) or less; and
the region of higher pressure is at a pressure of about 100 kPa to about 10 MPa.
10. The method of claim 8 , wherein the region of higher pressure is at a pressure of about 100 kPa.
11. The method of claim 8 , where the window material has an average atomic number less than about 14 and thickness small enough to ensure >90% transparency to the plasma jet.
12. The method of claim 8 , wherein the window has a thickness of about 0.1 millimeter to about 0.5 mm.
13. The method of claim 8 , where the window material has an elastic modulus of greater than 1 GPa.
14. The method of claim 8 , wherein the window material supports the pressure of the high pressure region with less than about 1% strain.
15. The method of claim 8 , where the window material comprises poly-paraphenylene terephthalamide (Kevlar) or poly-p-phenylene benzo-bis-oxazole (Zylon).
16. The method of claim 8 , where the radionuclide precursor is a liquid contained in a channel or capillary of a microfluidic reactor.
17. The method for production of radioisotopes, comprising:
generating a quasi-neutral plasma jet; and
directing the quasi-neutral plasma jet onto a radionuclide precursor,
where the energy distribution of the ions in the quasi-neutral plasma jet, f(E), is chosen to maximize the rate of radioisotope production for a process with a cross-section Q(E) according to the formula:
ⅆ
[
RN
]
ⅆ
t
=
[
Precursor
]
*
∫
Q
(
E
)
*
f
(
E
)
*
v
(
E
)
ⅆ
E
where [RN] is the concentration of radionuclide, [Precursor] is the concentration of precursor, and ν(E) is the center-of-mass velocity for the nuclear reaction that converts Precursor to RN.
18. The method of claim 17 , wherein the energy distribution f(E) is a monotonically decreasing function of energy.
19. The method of claim 17 , wherein the concentration of precursor is 10 20 cm −3 or greater.