The Development of a Compact
Pyroelectric X-Ray Generator
Ross McCart
HMS Sultan
Nuclear Department
Project Aims
• Build a Pryoelectric X-Ray Source.
• Test and characterise the source. (Modify design if necessary)
• Research into increasing energy of X-Rays
• Possibly couple source with X-Ray collimator.
• (Adapt the source to enable the production of Neutrons)
X-Ray Tube
Pyroelectric Materials
• Non-conducting crystals develop an electric polarisation when they are
subjected to a uniform temperature change.
• Only in crystals with a Polar axis.
• The requirements are fulfilled in about 10 out of the 32 crystal classes.
• Effect known since 314 B.C
• Pyroelectric effect found in motion detection, pollution monitors and in bones.
• Tourmaline, Sugar cane, Lithium Tantalate and Barium Niobate
Properties of Lithium Tantalate
Ferroelectric Effect – Polarising the crystal
Z+
+
LiTaO3
-Z-
Crystal
+
Ta
Z-
O O O
+
LiTaO3
Li
Properties of the Crystal
Pyroelectric Constant
 
Q
AC  T
Emission Current
I C   AC
dT
dt
The rate of polarisation per
change in temperature.
Negative as polarisation
occurs when crystal cools.
For a 100°C change over
180 seconds an emission
current of 2x10-8Amps is
predicted.
-2.3x10-4Cm-2K-1 for LiTaO3
6.25x1010 electrons per
second
Potential Difference
+
V 
Q
C

 A C - T+

AC
AG
 0   C

dC
dG

C
C
g
C




Cg
CC
X Ray Production
Heating Cycle
Cooling Cycle
Source Amptek
Setup
Advantages and Disadvantages
• Low power, approximately 1.4mW.
• Runs on a 12V battery or power supply.
• Handheld and portable.
• No Radioactive Sources.
• Solid State – no moving parts
• X-Ray Flux approximately 108 Photons per second
• Isotropic production of X-Rays
• Not a continuous flux
• Cannot be turned off instantaneously
• Limited end point energy with one crystal setup.
Potential Uses
• Security
• X-Ray fluorescence
• Radiography
• Teaching and Research
• Bomb Disposal
• Non-destructive testing
Wikipedia
Neutron Generation
2
2

4
3
1
H  H  He  He  0 n
2
2
4

3
2.45MeV
1
H  H  He  H  1 p
2
3
4
1
H  H  He  0 n
14.10MeV
The potential barrier of deuterium is 288keV, however the deuterium ions are
 able to tunnel under the barrier, lowering the energy required.

Goals
Short Term
• Complete Build
• Characterise the electric field from X Ray emission
Research Areas of Interest
• Two Crystal Setup – Increasing Tube Potential
• Stacking Crystals – Increasing Crystal Thickness
• Continuous Flux Using Multiple Crystals
Acknowledgments
• Dr Ian Giles
• Dr Kirk D Atkinson
• Miss Samantha Morris
• Sean Jarmen
• And other members of staff at the Nuclear Department.
Any Questions?