Related Experiment Video
Updated: Jun 12, 2026
16:20
Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
Note: Leaf undulator to realize polarization control with low on-axis heat load
1Department of Physics, Laboratory of Advanced Materials, and Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, People's Republic of China.
The Review of Scientific Instruments
|June 3, 2010
Summary
A novel leaf undulator offers tunable polarization and significantly reduces on-axis power density. This electromagnetic device achieves lower fundamental energy and comparable photon flux, outperforming existing undulator designs.
Area of Science:
- Physics
- Electromagnetism
- Accelerator Physics
Background:
- Electromagnetic undulators are crucial for generating synchrotron radiation.
- Existing undulator designs face challenges in controlling polarization and managing on-axis power density.
Purpose of the Study:
- To introduce and analyze a new operational mode for electromagnetic elliptical undulators, termed the leaf undulator.
- To investigate the leaf undulator's capability for tunable linear polarization and its performance in reducing on-axis power density.
Main Methods:
- Theoretical study and simulation of the leaf undulator's electromagnetic properties.
- Comparison of the leaf undulator's performance metrics (polarization, power density, photon flux) with existing undulator designs like Knot and Figure-8.
Main Results:
- The leaf undulator enables linearly polarized radiation with arbitrary polarization direction, controlled by magnetic field adjustments.
- It achieves a 45-degree polarization direction when horizontal and vertical magnetic fields are equal.
- On-axis power density is suppressed by an order of magnitude compared to Knot and Figure-8 undulators, with comparable fundamental harmonic photon flux.
- Lower fundamental energy is achievable in linear mode than with other designs at similar magnetic field strengths.
Conclusions:
- The leaf undulator presents a significant advancement in undulator technology.
- It offers enhanced control over radiation polarization and improved power density management.
- This new design holds potential for optimizing synchrotron radiation sources.
Related Concept Videos
01:31Dielectric Polarization in a Capacitor
The presence of a dielectric medium in a capacitor not only changes the voltage and capacitance but also affects the electric field. In general, dielectrics can be of two types: polar and nonpolar. In a polar dielectric, the positive and negative charges in the molecules are separated by a distance and hence have a permanent dipole moment. In contrast, no such charge separation exists in a nonpolar dielectric, however the nonpolar molecules get polarized in the presence of an external electric...
01:16Biasing of P-N Junction
The operation of a p-n junction diode involves various biasing conditions, including forward bias, reverse bias, and equilibrium.
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
In equilibrium, no external voltage is applied across the p-n junction. The depletion region is formed at the junction interface due to the diffusion of carriers, which leaves behind charged dopants, acceptors on the p-side, and donors on the n-side. These immobile charges create an electric field that prevents further diffusion of carriers. The related energy band...
01:28Induced Electric Dipoles
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
01:29Potential Due to a Polarized Object
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...