Views
5 years ago

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

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

-i - i y—ttth " » »

-i - i y—ttth " » » ' rp^rnrrT] Proportional |~ Region . 01 i—L—* -i-d—i—iulL t . .-juxjlL-i—i-julL—i—t~ud_J — , 001 ,01 :0 ,tttt—* t""t ii| i / // A « • » ( Ion Chamber / s—rrr / /*C =300pf. A r ,. o:f ., nJ 1 At.m. He Chamber /A Collection Voltage ® - lOOv A - 400v ., Signal Gate at 15 microsec. ; N il, j-^-j-U REACTOR POWER (watts) Figure 2-1. Results of PIC system with 1 atm. He chamber. 1000 10001 > I

design, and the fill gas composition and pressure. For the research reported here, the ions were the species used in order that some of the problems associated with electron kinetics could be avoided. The theory derived and presented in the following paragraphs will revolve around ion collection rather than electron collection used in earlier works. There are two factors basic to the feasibility end usefulness of the PIC system for the field of radiation measurement. The first of these is that the ionization density in a ehan;b°r : , when 13 it is exposed to ionizing radiation, prows rapidly (10 to 100 milliseconds) to an asymptotic limit dependent on the source intensity. The second factor is that it must be possible to theoretically relate the measured voltage signal, due to the collection of ions, to the asymptotic ionization density, and thus the source intensity. The description of the positive ion arid electron densities growth to their asyrntotic value lies in the following gas kinetics equations ; an