Ionizing beam tracking in gaseous chambers for field mapping

The combination of the time-of-flight (TOF) technique with two-dimensional position-sensitive (XY) ion detection is employed for tracking projectile-gas collisions. The main goal is to determine the detailed distribution of local electric fields, which accelerate the gas ions produced in the collisions. A low-pressure target gas spectrometer for this goal is described and all necessary XY- TOF expressions concerning the ion dynamics are presented. Experimental results of a 150 keV neutral H beam colliding with a He–Ne–Ar mixture are compared with the calculations. The new method can also be used for mapping magnetic fields or in large collision gas cells, e.g., to increase resolution in mass spectrometry and to perform initial momentum measurements of the produced ions.