Views
5 years ago

Applying the pulsed ion chamber methodology to full range reactor ...

Applying the pulsed ion chamber methodology to full range reactor ...

In measuring v(t ) a

In measuring v(t ) a source of error other than instrument error was present, I , which contributes to v(t_) only minutely at: low exposure S 5 C rates, at the high exposure rates could begin to significantly contribute to the v(t ) measured. Ideally v(t ) should ba constituted of only the steady state ion density collected. The equation which describes the I current contribution is, v c ..(t) = I R (I - exp(-t/RC)), where RC is the circuit time constant. For t « RC this reduces to Note that v„.(t) can be reduced by reducing R, just as long as t

CHAPTER V CONCLUSIONS To verify the Pulsed Ion Chamber applicability to the measuring of the full range of reactor power, three basic steps were required, A computer based, solid state, dual chamber PIC system had to be designed and built. Gamma compensation for the expected mixed order ("linear and/or second order) response region had to he clearly verified. The PIC mode chamber response had to be proven to dp independent of temperature over a range of 25 to 500°C. The design and building of the computer based PIC system took con- siderable time and effort, but the end result was success. It met all the design requirements and more. Its versatility simply as a plasma diagnostic tool is apparent. One has full control over all pulsing- sampling sequences, as one can see in figure 3-3 all the timing sequence potentiometers are on the front panel. The system is free from the time jitter and position orientation problems which plagued the most advanced mercury wetted reed pulsers previously used. The impedance switching circuit has a response time on the order of 50 nsec, due to the use of the most advanced gigahertz switching transistors. This in itself is an improvement of a factor of 5 over the previous systems. Thus the system is a significant advancement of the PIC state of the art. Verifying the feasibility of gamma compensation was accomplished relatively easily using the PIC computer based system. Compensation, at