The Study Of Segmented Linear Ion Trap And Secular Motion Of Ions In Coulomb Crystals

Ions trapped in an ion trap can stay in a small region of space with a long time.Laser Doppler cooling ions in an ion trap to temperatures in the mK or ?K range.It is one of the frontier research directions in the field of precise measurement physics to measure basic physical constants directly by using precise spectra of cold molecular ions cooled by coulomb crystals.This thesis mainly discusses the laser Doppler cooling and sympathetic cooling of ions and the formation of coulomb crystals in a segmented linear ion trap.The geometrical parameters of ion trap were obtained by measuring the secular motion frequencies of ion coulomb crystals.The variation trends of the secular motion frequencies of ions in multi-component Coulomb crystals were obtained by studying the bicomponent coulomb crystals produced by calcium ions sympathetically cooled beryllium ions.The main content of this thesis includes the following parts:1.A linear Paul trap system was designed and constructed.The vacuum degree was 3.0×10 mbar.A set of radio frequency voltage source was developed with the output voltage vary from 0 V to 210 V and the frequency vary from 3.0 MHz to 4.2 MHz.The DC source is a 12-channel independent control source with an amplitude of-10 V-10 V and an accuracy of 1 mV.2.A set of laser system for ionizing calcium atoms and cooling calcium ions was set up.397 nm and 866 nm lasers were stabilized with long-term frequency uncertainty of 8.09E-10 and 8.21E-10,respectively.3.Trapping and laser cooling of 40Ca+ ions in a linear trap were realized.The additional micromotion of ions was effectively reduced by using structure compensation and position compensation methods.The stable 40Ca+ Coulomb crystals were obtained.4.The radial and axial geometric parameters of the ion trap were obtained by measuring the secular motion frequencies of the ions in the ion trap.The relative accuracies of radial and axial geometric parameters were 0.3%and 0.9%,respectively.Anharmonic property in the radial direction of the linear ion trap was verified by using radial geometric parameter for the first time.5.In a linear Paul trap,the laser cooled calcium ions were used to sympathetically cooled beryllium ions,and the secular motion frequencies of Ca+ and Be+ ions in Ca+Be+ bicomponent coulomb crystals were measured and studied.It revealed the strong radial motion coupling and weak axial motion coupling characteristics of the two species of ions...