Index of content:
Volume 77, Issue 12, December 2006
- PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS
77(2006); http://dx.doi.org/10.1063/1.2400021View Description Hide Description
A model predictive control (MPC) technique is proposed for the frequency stabilization of transverse Zeeman He–Ne laser. The beat frequency locking method is applied as the criterion of frequency stabilization. When heated by the voltage output of the feedback electronic circuit, the copper wire twisted around the laser tube is applied to maintain the length of the laser cavity and stabilize the frequency of the laser. Four steps for MPC design, i.e., model setup, output prediction, selection of reference path, and calculation of control quality, have been introduced. By this means, a single-chip microprocessor (80C196) generates a pulse width modulation wave that is transferred into a heating signal. The calibration result shows that the frequency stability of our proposed transverse Zeeman laser reaches by means of the MPC method.
77(2006); http://dx.doi.org/10.1063/1.2405391View Description Hide Description
Proton acceleration experiments involving a thick Ti foil target irradiation are carried out with the femtosecond Ti:sapphire laser JLITE-X. The plasma emission at is recorded employing concave multilayermirrors, which image the front- and rear-side plasmas onto the sensitive surfaces of a fast x-ray photodiode and a backside-illuminated charge coupled device. Online time-of-flight fast-particle measurements are performed simultaneously with the extreme ultraviolet (XUV) measurements. A strong correlation is observed between the energetic proton signal and the spatiotemporal behavior of the XUV plasma emission. In particular, the longer duration of the prepulse-produced XUV plasma emission indicates a lowering of the maximum proton energy. This allows using the XUV emission for the diagnostics of the high-intensity laser–solid-target interaction.
77(2006); http://dx.doi.org/10.1063/1.2405358View Description Hide Description
We have developed a new electrostatic analyzer which enables medium energy plasma particle measurements with full solid angle coverage. The design of the test model realizes the uppermost measurement energy of with applied high voltages of . Laboratory experiments with the test model analyzer show that its performance agrees with numerical simulations. The test model design is well suited for combination with a mass analysis unit, while our new design can also be applied to medium energy electron measurements. Medium energy ion/electron sensors with this new design will surely be appreciated for upcoming space missions that will observe hot/energetic plasma structures in the regions such as the inner magnetosphere or reconnection region.