Volume 70, Issue 9, September 1999
Index of content:
70(1999); http://dx.doi.org/10.1063/1.1149951View Description Hide Description
We demonstrate a simple calibration method of a rf magnetic probe by utilizing a two port network analysis method. The sensitivity (V/G) of the probe is determined by measuring the scattering parameters of and The magnetic field generated by the Helmholtz coil is calculated from and the probe sensitivity is obtained from The measured probe sensitivity is 0.1–0.6 V/G in the frequency range of 1–15 MHz.
Instantaneous measurement system of the effective photon energy for a single shot x-ray pulse radiation70(1999); http://dx.doi.org/10.1063/1.1149992View Description Hide Description
For a short pulse x-ray radiation with extremely broad spectrum such as Bremsstrahlung, the effective photon energy cannot be determined by conventional x-ray detectors with only a single x-ray pulse shot. An instantaneous measurement system capable of determining the energy with a single shot has been developed. The system is made of a metal–oxide–semiconductor linear array image sensor, a scintillation phospher, and an absorber material, and a control system of the sensor. The energy of a hard x-ray pulse with a short pulse duration of 500 ns is determined with this system. It is shown that the system can determine the energy more quickly and accurately than with the conventional method.
70(1999); http://dx.doi.org/10.1063/1.1149993View Description Hide Description
We describe the principle of operation and construction of an inexpensive, reliable system for the automated dispensing of liquid nitrogen from a single supply Dewar to multiple cryogenic traps. The system can be run under full computer control and in conjunction with existing designs of traps will allow unattended operation over long duty periods combined with programmed temperature cycles.
70(1999); http://dx.doi.org/10.1063/1.1149994View Description Hide Description
The necessary number of wavelength channels is investigated in incoherent Thomson scattering diagnostics. The measurement errors (σ) are evaluated for a realistic case and their lower limits are given in explicit forms. For a given number of wavelength channels, optimal channel allocation in the wavelength space is sought by minimizing the average relative errors. As a scale of the goodness of measurement, we introduce the ratio averaged over the electron temperature of interest. This quantity ranges from 0 to 1 and tends to 1 as the lowest achievable error is approached. If we conclude that is sufficient, then for a typical ruby laser system measuring 400–700 nm, seven channels is an adequate number for covering the electron temperature of 0.01–10 keV and five channels for 0.1–10 keV.