Ultra-cold plasmas: a paradigm for strongly coupled and classical electron fluids

2009 ◽  
Vol 75 (6) ◽  
pp. 799-815 ◽  
Author(s):  
CLAUDE DEUTSCH ◽  
GUENTER ZWICKNAGEL ◽  
ANTOINE BRET
Keyword(s):  
Ion Beam ◽  
Debye Length ◽  
Cyclotron Radius ◽  
Classical Electron ◽  
Strongly Coupled ◽  
Charged Particle Beams ◽  
Slowing Down ◽  
Beam Cooling ◽  
Cold Plasmas ◽  
Atomic Rydberg

AbstractUltra-cold plasmas obtained by ionization of atomic Rydberg states are qualified as classical and strongly coupled electron fluids. They are shown to share several common trends with ultra-cold electron flows used for ion-beam cooling. They exhibit specific stopping behaviour to charged particle beams, which may be used for diagnostic purposes. Ultra-cold plasmas are easily strongly magnetized. Then, one expects a strongly anisotropic behaviour of low ion velocity slowing down when the target electron cyclotron radius becomes smaller than the corresponding Debye length.

Linearized potential of an ion moving through plasma

1990 ◽  
Vol 44 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Thomas Peter
Keyword(s):  
Ion Beam ◽  
Debye Length ◽  
Electron Plasma ◽  
Electron Velocity ◽  
Thermal Electron ◽  
Wake Field ◽  
Poisson Equations ◽  
Beam Cooling ◽  
Wide Range ◽  
New Feature

The solution of the linearized Vlasov–Poisson equations describing a projectile ion moving through a classical isotropic electron plasma is investigated analytically and numerically for a wide range of projectile velocities vp Extending the range of earlier computations considerably, our calculations were performed for velocities up to vp = 15vth, showing the wake field behind the ion for distances 0 ≤ d ≤ 200λD, where vth is the thermal electron velocity and λD the Debye length of the plasma. As a new feature, we demonstrate that the amplitude of the wake field in the region vp/vth ≤ d/λD ≤/23(vp/vth)3 is almost undamped, and only for larger distances from the ion does it take the 1/d behaviour shown in other work. Thus the wake field of a single ion persists for much longer than previously thought. The question of whether this effect could have practical consequences, for example, for ion-beam cooling, is briefly addressed.

scholarly journals Classical scattering and stopping power in dense plasmas: the effect of diffraction and dynamic screening

2016 ◽  
Vol 34 (3) ◽  
pp. 457-466 ◽  
Author(s):  
M. K. Issanova ◽  
S. K. Kodanova ◽  
T. S. Ramazanov ◽  
N. Kh. Bastykova ◽  
Zh. A. Moldabekov ◽  
...  
Keyword(s):  
Good Description ◽  
Ion Beam ◽  
Stopping Power ◽  
Diffraction Effect ◽  
Classical Electron ◽  
Plasma Ions ◽  
First Case ◽  
Dynamic Screening ◽  
Quantum Diffraction ◽  
Coulomb Logarithm

AbstractIn the present work, classical electron–ion scattering, Coulomb logarithm, and stopping power are studied taking into account the quantum mechanical diffraction effect and the dynamic screening effect separately and together. The inclusion of the quantum diffraction effect is realized at the same level as the well-known first-order gradient correction in the extended Thomas–Fermi theory. In order to take the effect of dynamic screening into account, the model suggested by Grabowski et al. in 2013 is used. Scattering as well as stopping power of the external electron (ion) beam by plasma ions (electrons) and scattering of the plasma's own electrons (ions) by plasma ions (electrons) are considered differently. In the first case, it is found that in the limit of the non-ideal plasma with a plasma parameter Γ → 1, the effects of quantum diffraction and dynamic screening partially compensate each other. In the second case, the dynamic screening enlarges scattering cross-section, Coulomb logarithm, and stopping power, whereas the quantum diffraction reduces their values. Comparisons with the results of other theoretical methods and computer simulations indicate that the model used in this work gives a good description of the stopping power for projectile velocities $v\,{\rm \lesssim}\, 1.5 v_{{\rm th}}$, where vth is the thermal velocity of the plasma electrons.

Radiofrequency Gaseous Detection Device

2000 ◽  
Vol 6 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Gerasimos D. Danilatos
Keyword(s):  
Electromagnetic Field ◽  
Ion Beam ◽  
Free Electrons ◽  
Particle Beams ◽  
Charged Particle Beams ◽  
Multiple Collisions ◽  
Electron Microscopes ◽  
Ionizing Radiations ◽  
Low Pressures ◽  
Photon Signal

A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

scholarly journals Mapping the Relative Biological Effectiveness of Proton, Helium and Carbon Ions with High-Throughput Techniques

Cancers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3658
Author(s):  
Lawrence Bronk ◽  
Fada Guan ◽  
Darshana Patel ◽  
Duo Ma ◽  
Benjamin Kroger ◽  
...  
Keyword(s):  
High Throughput ◽  
Relative Biological Effectiveness ◽  
Biological Effects ◽  
Ion Beam ◽  
Particle Beam ◽  
Clonogenic Survival ◽  
Carbon Ions ◽  
Charged Particle Beams ◽  
Biological Effectiveness ◽  
Therapy Center

Large amounts of high quality biophysical data are needed to improve current biological effects models but such data are lacking and difficult to obtain. The present study aimed to more efficiently measure the spatial distribution of relative biological effectiveness (RBE) of charged particle beams using a novel high-accuracy and high-throughput experimental platform. Clonogenic survival was selected as the biological endpoint for two lung cancer cell lines, H460 and H1437, irradiated with protons, carbon, and helium ions. Ion-specific multi-step microplate holders were fabricated such that each column of a 96-well microplate is spatially situated at a different location along a particle beam path. Dose, dose-averaged linear energy transfer (LETd), and dose-mean lineal energy (yd) were calculated using an experimentally validated Geant4-based Monte Carlo system. Cells were irradiated at the Heidelberg Ion Beam Therapy Center (HIT). The experimental results showed that the clonogenic survival curves of all tested ions were yd-dependent. Both helium and carbon ions achieved maximum RBEs within specific yd ranges before biological efficacy declined, indicating an overkill effect. For protons, no overkill was observed, but RBE increased distal to the Bragg peak. Measured RBE profiles strongly depend on the physical characteristics such as yd and are ion specific.

Radiofrequency Gaseous Detection Device

2000 ◽  
Vol 6 (1) ◽  
pp. 12-20
Author(s):  
Gerasimos D. Danilatos
Keyword(s):  
Electromagnetic Field ◽  
Ion Beam ◽  
Free Electrons ◽  
Particle Beams ◽  
Charged Particle Beams ◽  
Multiple Collisions ◽  
Electron Microscopes ◽  
Ionizing Radiations ◽  
Low Pressures ◽  
Photon Signal

Abstract A radiofrequency gaseous detection device is proposed for use with instruments employing charged particle beams, such as electron microscopes and ion beam technologies, as well as for detection of ionizing radiations as in proportional counters. An alternating (oscillating) electromagnetic field in the radiofrequency range is applied in a gaseous environment of the instrument. Both the frequency and amplitude of oscillation are adjustable. The electron or ion beam interacts with a specimen and releases free electrons in the gas. Similarly, an ionizing radiation source releases free electrons in the gas. The free electrons are acted upon by the alternating electromagnetic field and undergo an oscillatory motion resulting in multiple collisions with the gas molecules, or atoms. At sufficiently low pressures, the oscillating electrons also collide with surrounding walls. These processes result in an amplified electron signal and an amplified photon signal in a controlled discharge. The amplified signals, which are proportional to the initial number of free electrons, are collected by suitable means for further processing and analysis.

Microdosimetry in ion-beam therapy

2015 ◽  
Vol 30 (17) ◽  
pp. 1540027 ◽  
Author(s):  
Giulio Magrin ◽  
Ramona Mayer
Keyword(s):  
Biological Effects ◽  
Ion Beam ◽  
Experimental Information ◽  
Physical Parameters ◽  
Radiation Quality ◽  
Ion Beam Therapy ◽  
Slowing Down ◽  
Ion Therapy ◽  
Biological Effectiveness

The information of the dose is not sufficiently describing the biological effects of ions on tissue since it does not express the radiation quality, i.e. the heterogeneity of the processes due to the slowing-down and the fragmentation of the particles when crossing a target. Depending on different circumstances, the radiation quality can be determined using measurements, calculations, or simulations. Microdosimeters are the primary tools used to provide the experimental information of the radiation quality and their role is becoming crucial for the recent clinical developments in particular with carbon ion therapy. Microdosimetry is strongly linked to the biological effectiveness of the radiation since it provides the physical parameters which explicitly distinguish the radiation for its capability of damaging cells. In the framework of ion-beam therapy microdosimetry can be used in the preparation of the treatment to complement radiobiological experiments and to analyze the modification of the radiation quality in phantoms. A more ambitious goal is to perform the measurements during the irradiation procedure to determine the non-targeted radiation and, more importantly, to monitor the modification of the radiation quality inside the patient. These procedures provide the feedback of the treatment directly beneficial for the single patient but also for the characterization of the biological effectiveness in general with advantages for all future treatment. Traditional and innovative tools are currently under study and an outlook of present experience and future development is presented here.

scholarly journals Lorentz Scanning Electron/Ion Microscopy

Microscopy ◽  
2021 ◽  
Author(s):  
Ken Harada ◽  
Keiko Shimada ◽  
Yoshio Takahashi
Keyword(s):  
Electromagnetic Fields ◽  
Measurement Method ◽  
Ion Beam ◽  
Electron Holography ◽  
Force Model ◽  
Reconstruction Technique ◽  
Visualization Technique ◽  
Particle Beams ◽  
Charged Particle Beams ◽  
Scanning Electron

Abstract We have developed an observation and measurement method for spatial electromagnetic fields by using scanning electron/ion microscopes, combined with electron holography reconstruction technique. A cross-grating was installed below the specimen, and the specimens were observed under the infocus condition, and the grating was simultaneously observed under the defocus condition. Electromagnetic fields around the specimen were estimated from grating-image distortions. This method is effective for low and middle magnification and resolution ranges; furthermore, this method can in principle be realizable in any electron/ion beam instruments because it is based on the Lorentz force model for charged particle beams. Mini Abstract We have developed a visualization technique for spatial electromagnetic fields by using scanning electron/ion microscopes, combined with electron holography reconstruction technique. A specimen and a cross-grating installed below the specimen were observed simultaneously. The distorted grating image caused by electromagnetic fields around the specimen were quantitatively measured and visualized.

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