Photoassociative ionization of cold Na atoms: repulsive levels effects on the ion production rate

2009 ◽  
Vol 6 (2) ◽  
pp. 163-167 ◽  
Author(s):  
R.R. Paiva ◽  
R. Muhammad ◽  
R.F. Shiozaki ◽  
A.L. de Oliveira ◽  
D.V. Magalhães ◽  
...  
Keyword(s):  
Production Rate ◽  
Ion Production ◽  
Photoassociative Ionization

scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (4) ◽  
pp. 3947-3973 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Radiation Energy ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest are studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produce reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 cm−3s−1 and based on external radiation and radon measurements 4.5 cm−3s−1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3 nm, so the sink of small ions during the nucleation events was underestimated. Another reason is that the possible fogs, which caused an extra sink of small ions are not taken into account in the calculations. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. A fourth possible reason for the discrepancy is the nucleation mechanism itself. If the ions were somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days. On the other hand, not all the radiation energy is converted to ions and the possible effect of alpha recoil is also omitted.

Effects of ionisation on cloud behaviour in planetary atmospheres

2021 ◽  
Author(s):  
Martin Airey ◽  
Giles Harrison ◽  
Karen Aplin ◽  
Christian Pfrang
Keyword(s):  
Production Rate ◽  
Evaporation Rate ◽  
Cosmic Ray ◽  
Planetary Atmospheres ◽  
Direct Result ◽  
Droplet Growth ◽  
Atmospheric Density ◽  
Charged Drop ◽  
Ion Production ◽  
Cloud Particles

<p>Cosmic rays cause ionisation in all planetary atmospheres. As they collide with particles in the atmosphere, secondary charged particles are produced that lead to the formation of cluster ions. The incident cosmic ray flux and atmospheric density of the atmosphere in question determine a profile of ion production rate. From the top of the atmosphere to the planetary surface, this rate increases with atmospheric density to a point where the flux becomes attenuated such that the rate then decreases, resulting in a peak ion production rate at some height known as the Pfotzer-Regener maximum. When these ions interact with aerosols and cloud particles, a net charge results on those particles and this is known to affect their microphysical attributes and behaviour. For example, charging may enable the activation of droplets at lower saturation ratios and also enhance collision efficiency and droplet growth. This becomes important when clouds occur at a height where ionisation is sufficient to have a substantive charging effect on the cloud particles. This has very little direct effect on Earth as peak ion production occurs high above the clouds at 15-20 km; however, on Venus for example the Pfotzer-Regener maximum occurs at ~63 km, coinciding with the main sulphuric acid cloud deck. In situations such as this, the direct result of cloud charging due to cosmic ray induced ionisation may strongly influence cloud processes, their occurrence, and behaviour.</p><p>This work uses laboratory experiments to explore the effects of charging on cloud droplets. Individual droplets are levitated in a vertical acoustic standing wave and then monitored using a CCD camera with a high magnification objective lens to determine the droplet lifetime and evaporation rate. Experiments were conducted using both the droplets’ naturally occurring charge as well as some where the region around the drop was initially flooded with ions from an external corona source. The polarity and charge magnitude of the droplets was determined by applying a 10 kV/m electric field horizontally across the drop and observing its deflection towards one of the electrodes. Theory predicts that the more highly charged a droplet is, the more resistant to evaporation it becomes. Experimental data collected during this study agrees with this, with more highly charged droplets observed to have slower evaporation rates. However, highly charged drops were also observed to periodically become unstable during evaporation and undergo Rayleigh explosions. This occurs when the droplet evaporates until its diameter becomes such that its fissility reaches the threshold at which the instability occurs. Each instability of a highly charged drop removes mass, reducing the overall droplet lifetime regardless of the slower evaporation rate. Therefore, where enhanced ionisation occurs in the presence of clouds the end result may be to reduce droplet stability.</p>

scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (7) ◽  
pp. 1933-1943 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Ion Pairs ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest were studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produced reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 ion pairs cm-3s-1, and based on external radiation and radon measurements, 4.5 ion pairs cm-3s-1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3nm, so the sink of small ions during the nucleation events was underestimated. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. Another reason for the discrepancy is the nucleation mechanism itself. If the ions are somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days.

scholarly journals Proposal for enhancement of antihydrogen ion production in the GBAR experiment

2018 ◽  
Vol 181 ◽  
pp. 01002 ◽  
Author(s):  
D.A. Cooke ◽  
A. Husson ◽  
D. Lunney ◽  
P. Crivelli
Keyword(s):  
Production Rate ◽  
Charge Exchange ◽  
Exchange Process ◽  
Paul Trap ◽  
Energy Spread ◽  
Second Step ◽  
Charge Exchange Process ◽  
Ion Production ◽  
Order Of Magnitude

The production of antihydrogen ions (H̅+) in the GBAR experiment will occur via a two step charge exchange process. In a first reaction, the antiprotons(P̅) from the ELENA ring will capture a positron from a positronium(Ps) target producing antihydrogen (H̅) atoms. Those interacting in the same Ps target will produce in a second step H̅+. This results in a dependence for the H̅+ production rate which is roughly proportional to the Ps density squared. Wepresent a scheme to increase the anti-ion production rate in the GBAR experiment by tailoring the antiproton to the positron pulse in order to maximise thetemporal overlap of Ps and p̅. Detailed simulations show that an order of magnitude could be gained by bunching the antiprotons from ELENA. In order to avoid losses in their capture in the Paul trap due to the energy spread introducedby the bunching, debunching with a symmetrical inverted pulse can be appliedto the H̅+ ions.

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