Volume 77, Issue 1, January 2006
Index of content:
- PARTICLE SOURCES, OPTICS AND ACCELERATION; PARTICLE DETECTORS
77(2006); http://dx.doi.org/10.1063/1.2151848View Description Hide Description
A versatile timing device has been developed that permits a variety of lasers, including (yttrium aluminum garnet), excimer, and lasers, to be triggered at random times. The present application is to single-particle mass spectrometry, where the corresponding arrival times are random and signaled by a laser light-scattering apparatus. The timing circuit triggers the laser flashlamps approximately prior to the desired laser output pulse, followed by the -switch triggering pulses, which can also be used to control other lasers and/or the ion extraction optics. The flashlamps are discharged ten times per second to maintain the proper heat load on the laser flashlamps. If fewer than are detected by light-scattering apparatus, the unit sends substitute pulses to maintain the average of . When the particle flux is higher than ten per second, the circuit is designed to ignore the extra particle events. A simpler version of the circuit is also described, which accepts two timing inputs and outputs a pulse for ion extraction at a preselected time.
Conical octopole ion guide: Design, focusing, and its application to the deposition of low energetic clusters77(2006); http://dx.doi.org/10.1063/1.2162439View Description Hide Description
A design of a radio-frequency (rf) octopole ion guide with truncated conical rods arranged in a conical geometry is presented. The performance is tested in a cluster deposition apparatus used for the soft-landing of size-selected clusters on well-characterized substrates used as a model system in heterogeneous catalysis in ultrahigh vacuum. This device allows us to focus of a mass-selected clusterion beam from down to a spot size of in diameter. The transmittance is at a rf voltage of applied over an amateur radio transceiver with an interposed homemade amplifier-transformer circuit. An increase of the cluster density by a factor of 15 has been achieved. Three ion trajectories are simulated by using SIMION6, which are relevant for this focusing device: transmitted, reflected, and absorbed. The observed effects in the simulations can be successfully explained by the adiabatic approximation. The focusing behavior of the conical octopole lens is demonstrated by experiment and simulations to be a very useful technique for increasing molecule or cluster densities on a substrate and thus reducing deposition time.
Hall current layer formation in arc discharge across magnetic field and transfer of fast ions out of discharge77(2006); http://dx.doi.org/10.1063/1.2162747View Description Hide Description
In the work presented here the geometry of the Hall current layer in a plasma of the vacuum arc discharge in the transverse magnetic field are analyzed. The extraction of an intense pure flux of fast ions generated in the cathode spots with the help of the Hall layer is discussed. Experiments on the arc source of carbon fast ions are described. The anode geometry adequate to the mechanism of the arc current passage through the transverse magnetic field is found out experimentally. Up to 70% of fast ions are extracted out of the arc discharge in the arched magnetic field. In experiments, the Hall current layer formation in the vacuum arc discharge across magnetic field is confidently confirmed.