Electrostatic ion beam trap for electron collision studies

Abstract

We describe a system combining an ion beam trap and a low energy electron target in which the interaction between electrons and vibrationally cold molecular ions and clusters can be studied. The entire system uses only electrostatic fields for both trapping and focusing, thus being able to store particles without a mass limit. Preliminary results for the electron impact neutralization of C 2 − ions and aluminum clusters are presented.

The decay of ion bunches in the self-bunching mode

“…Collisions between the stored dc beam and the bunch are assumed to scale with the product of the two separate populations (N 0 -N (t))N (t). Since collisional losses from the trap, which are given by k c 1, occur on much longer time scales (>300 s) than the bunch duration (<12 s), the total Average parameter values with standard deviations from fitting the measured bunch decay amplitudes using equation (14) of ion bunches stored in self-bunching mode without and with RF as described in the text. The fitting parameters are defined as: the bunch amplitude B measured at twice the ion oscillation frequency, the dimensionless bunch expansion terms β and β 2 , intrabeam scattering term α and bunch loss rate k.…”

“…These traps only use electrostatic fields, functioning on a principle quite similar to that of an optical resonator. Numerous traps such as these have been built in recent years, hosting a wide variety of experiments in cluster physics [4][5][6][7][8][9][10], molecular physics [11][12][13] and electron collision studies [14]. Experiments probing larger clusters and other heavy species exploit the mass invariance of ion trajectories in these electrostatic storage devices.…”

Trapping of highly charged ions with an electrostatic ion trap

“…Using a low (< 20V ) radio frequency voltage with frequencies close to the oscillation frequency of the ions in the trap we were able to observe trapping times up to 50 ms. Running the ion trap in the so called "bunching" or synchronization mode [6] in the time domain of the pickup signal we observed a strange oscillation on the millisecond scale superposing the ion oscillation in the trap on the microsecond scale. This is shown in Fig.…”

Dissociative recombination and mutual neutralization of heavier molecular ions: C10H8+, WF5+, and CnFm+

“…1 The upper mass limit in magnetic rings, however, is approximately 100 Da, due to the fact that heavier ions have lower velocities for stable orbits and then achieving velocity-matching conditions is extremely difficult. 8 The more recent electrostatic ion storage rings 1, [9][10][11] and traps [12][13][14] can overcome the mass limit because they do not fight the velocitydependent Lorentz force, but only a handful of DR (and no MN) measurements have been taken with these relatively new apparatuses. 9,15 Additional electrostatic storage rings and a) E-mail: afrl.rvborgmailbox@kirtland.af.mil traps are currently being developed.…”