1. A Pyroelectric Crystal Particle Accelerator
Amanda Gehring, Rose-Hulman Institute of Technology
Rand Watson, Texas A&M Cyclotron Institute

2. Pyroelectric Crystals
1) When heated, a pyroelectric crystal produces an electric field. The atoms shift, and the dipoles of the individual crystal lattices realign, creating a uniform polarity. The faces of the crystal become oppositely charged. When the crystal cools, the polarity and electric field reverse.

3. Experimental Setup D +D  3He + n (820 KeV) (2.45 MeV) D + D  T + p
Recent experiments have shown that the electric field produced by the pyroelectric crystal can be utilized to accelerate deuterons to sufficient energies to initiate the d + d fusion reaction. This suggests the possibility of developing a pyroelectric crystal neutron generator. Upon heating, the front face of the crystal becomes positively charged, creating positive deuterium ions from field ionization of nearby gas molecules. The deuterons are accelerated toward the deuterated polyethylene target, and electrons from the target are accelerated toward the crystal where they collide with the surface producing x rays and bremsstrahlung. Spectra of this radiation are measured with a Si(Li) detector and the endpoint of the bremsstrahlung is used to determine the accelerating potential. Upon cooling, the polarity reverses.
D +D  3He n
(820 KeV) (2.45 MeV)
D + D  T p
(1.01 MeV) (3.02 MeV)

4. Goals of Experiment
Instigate d + d fusion and optimize the neutron output by varying the D2 gas pressure
Optimize parameters that determine the intensity and energy of the particle beam
Examine feasibility of using the system as a neutron generator

5. Pyroelectric Crystals
LiNbO3 and LiTaO3

6. Inner System

8. First Set of Experiments
Energy calibrated Si(Li) x-ray detector using a 241-Am source
Conducted runs under vacuum at the heating currents of 0.5 A, 1.0 A, 1.5 A, and 2.0 A
Recorded the number of x-rays in 10 s intervals
Acquired x-ray spectra

9. Temperature Change and X-ray Count Rate

10. X-ray Spectrum at Heating Cycle

11. X-ray Spectrum at Cooling Cycle
In order to determine the maximum accelerating potential, x-ray spectra were taken in order to determine the endpoint of the bremstraahlung spectrum.

12. Heating Current Effect on Energy

13. Heating Current Effect on Beam Intensity

14. Second Set of Experiments
Energy calibrated liquid scintillator neutron detector using a 252-Cf source
Conducted runs with D2 gas at pressures of 5.0, 2.5, 1.2, 0.5, and 0.1 mtorr.
Recorded the number of neutrons and x-rays in 10 s intervals
Acquired x-ray spectra

15. Temperature Change and Neutron Count Rate

16. X-ray Spectrum at Heating Cycle

17. X-ray Spectrum at Cooling Cycle
In order to determine the maximum accelerating potential, x-ray spectra were taken in order to determine the endpoint of the bremstraahlung spectrum.

18. D2 Pressure Effect on Energy

19. D2 Pressure Effect on Beam Intensity

20. Future Research Address discharges and unfocused beam
Run experiments under different deuterium gas pressures
Replicate previous results
Use of two pyroelectric crystals

21. Acknowledgements National Science Foundation Department of Energy
Texas A&M Cyclotron Institute
Dr. Rand Watson
Jon Kalodimos

22. Results Run Current (A) Max x-ray Heating Energy (keV)
Max x-ray Cooling Energy (keV)
Max Heating Count Rate (counts/s)
Avg. Max Heating Count Rate (counts/s)
Max Cooling Count Rate (counts/s)
Avg. Max Cooling Count Rate (counts/s) 2
0.5 36 -
154 3
1.0 53 43
4118
3664
117 72 4 61 30
1505
1097 5
1.5 66 65
11175
6806
441
182 8
2.0 74 76
13591
10573
1470
735 11 55 71
13220
8148
1509
493 12 88
15063
11687
1641
1066 13 80
15816
12980