Energetic ion distribution resulting from neutral beam injection in tokamaks

1976 ◽  
Vol 16 (2) ◽  
pp. 149-169 ◽  
Author(s):  
John D. Gaffey
Keyword(s):  
Ion Beam ◽  
Planck Equation ◽  
Magnetized Plasma ◽  
Injection Velocity ◽  
Parallel Electric Field ◽  
Ion Distribution ◽  
Asymptotic Expressions ◽  
Fast Ion ◽  
Infinite Sum ◽  
The Magnetic Field

The Fokker-Planck equation is studied for an energetic ion beam injected into a magnetized plasma consisting of Maxwellian ions and electrons with υthi ≪υb≪ υthe. The time evolution of the fast ion distribution is given in terms of an infinite sum of Legendre polynomials for distributions that are axisymmetric about the magnetic field. The effect of charge exchange is included. The resulting ion distribution is somewhat isotropic for velocities much less than the injection velocity, however, the distribution is sharply peaked in both energy and pitch angle for velocities near the injection velocity. Approximate asymptotic expressions are given for the distribution in the vicinity of the injected beam and for velocities greater than the injection velocity. The effect of a weak parallel electric field is also given.

scholarly journals Dependence on ion temperature of shallow-angle magnetic presheaths with adiabatic electrons

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Alessandro Geraldini ◽  
F. I. Parra ◽  
F. Militello
Keyword(s):  
Magnetic Field ◽  
Fluid Model ◽  
Boltzmann Distribution ◽  
Distribution Functions ◽  
Magnetized Plasma ◽  
Electron Mass ◽  
Ion Temperature ◽  
Ion Distribution ◽  
Ionic Charge ◽  
The Magnetic Field

The magnetic presheath is a boundary layer occurring when magnetized plasma is in contact with a wall and the angle $\unicode[STIX]{x1D6FC}$ between the wall and the magnetic field $\boldsymbol{B}$ is oblique. Here, we consider the fusion-relevant case of a shallow-angle, $\unicode[STIX]{x1D6FC}\ll 1$ , electron-repelling sheath, with the electron density given by a Boltzmann distribution, valid for $\unicode[STIX]{x1D6FC}/\sqrt{\unicode[STIX]{x1D70F}+1}\gg \sqrt{m_{\text{e}}/m_{\text{i}}}$ , where $m_{\text{e}}$ is the electron mass, $m_{\text{i}}$ is the ion mass, $\unicode[STIX]{x1D70F}=T_{\text{i}}/ZT_{\text{e}}$ , $T_{\text{e}}$ is the electron temperature, $T_{\text{i}}$ is the ion temperature and $Z$ is the ionic charge state. The thickness of the magnetic presheath is of the order of a few ion sound Larmor radii $\unicode[STIX]{x1D70C}_{\text{s}}=\sqrt{m_{\text{i}}(ZT_{\text{e}}+T_{\text{i}})}/ZeB$ , where e is the proton charge and $B=|\boldsymbol{B}|$ is the magnitude of the magnetic field. We study the dependence on $\unicode[STIX]{x1D70F}$ of the electrostatic potential and ion distribution function in the magnetic presheath by using a set of prescribed ion distribution functions at the magnetic presheath entrance, parameterized by $\unicode[STIX]{x1D70F}$ . The kinetic model is shown to be asymptotically equivalent to Chodura’s fluid model at small ion temperature, $\unicode[STIX]{x1D70F}\ll 1$ , for $|\text{ln}\,\unicode[STIX]{x1D6FC}|>3|\text{ln}\,\unicode[STIX]{x1D70F}|\gg 1$ . In this limit, despite the fact that fluid equations give a reasonable approximation to the potential, ion gyro-orbits acquire a spatial extent that occupies a large portion of the magnetic presheath. At large ion temperature, $\unicode[STIX]{x1D70F}\gg 1$ , relevant because $T_{\text{i}}$ is measured to be a few times larger than $T_{\text{e}}$ near divertor targets of fusion devices, ions reach the Debye sheath entrance (and subsequently the wall) at a shallow angle whose size is given by $\sqrt{\unicode[STIX]{x1D6FC}}$ or $1/\sqrt{\unicode[STIX]{x1D70F}}$ , depending on which is largest.

Solitons in a magnetized ion-beam plasma system

1993 ◽  
Vol 50 (3) ◽  
pp. 349-357 ◽  
Author(s):  
B. C. Kalita ◽  
M. K. Kalita ◽  
R. P. Bhatta
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Magnetized Plasma ◽  
Plasma System ◽  
Ion Density ◽  
One Dimensional ◽  
Maximum Value ◽  
The Waves ◽  
The Magnetic Field ◽  
Constant Maximum

The formation of ion-acoustic solitary waves in a magnetized plasma with stationary ions and beam ions together with inertia-less electrons is investigated. The generation of waves in a plane is assumed to be one-dimensional, in a direction inclined at an angle θ to the direction of the magnetic field, with constant drift velocity of the ion beam. Remarkably, the amplitudes of the solitons are found to attain a maximum value at a particular beam-ion velocity γ, and then decrease slightly and remain almost constant for higher γ. The width of the waves is large at small y for small beam-ion density Nb, but it attains a constant minimum value at a particular value of γ. The amplitude decreases sharply to zero with decreasing y, whereas it remains almost constantly high for larger y. It is observed that as a wave approaches the direction of the magnetic field, its amplitude increases to a constant maximum value, which is larger for higher beam-ion velocities.

Acoustic instabilities and plasma heating resulting from energetic ion beam injection

1979 ◽  
Vol 21 (2) ◽  
pp. 193-204 ◽  
Author(s):  
E. H. Da Jornada ◽  
J. D. Gaffey ◽  
M. Zales Caponi
Keyword(s):  
Ion Beam ◽  
Plasma Heating ◽  
Magnetized Plasma ◽  
Moment Equations ◽  
Plasma Properties ◽  
Electrostatic Waves ◽  
Slowing Down ◽  
Heating Mechanism ◽  
Acoustic Instabilities ◽  
The Magnetic Field

Electrostatic instabilities excited by an energetic ion beam are examined as a possible plasma heating mechanism. The dielectric properties of electrostatic waves in a uniform magnetized plasma are studied for a warm ion beam propagating at an arbitrary angle with respect to the magnetic field. The instability threshold and growth rate are calculated for the resonant ion-beam and ion- acoustic modes. The quasi-linear moment equations are used to follow the self-consistent evolution of the macroscopic plasma properties. A comparison is made with the collisional slowing-down rate of the beam. For the fastest growing modes it is found that the quasi-linear slowing-down time is significantly shorter than the coffisional slowing-down time.

scholarly journals Parametric study of hyperfine structure of Zr II even-parity levels

2016 ◽  
Vol 94 (12) ◽  
pp. 1310-1313 ◽  
Author(s):  
Safa Bouazza
Keyword(s):  
Hyperfine Structure ◽  
Ion Beam ◽  
Model Space ◽  
Laser Fluorescence ◽  
Beam Laser ◽  
Extended Space ◽  
Experimental Values ◽  
The One ◽  
Fast Ion ◽  
Laser Fluorescence Spectroscopy

Until now experimental hyperfine structure (hfs) data of 12 even-parity Zr II levels were given in the literature. Recently new hyperfine splitting measurements of 11 other Zr II levels, of the same parity are achieved, applying fast-ion-beam laser-fluorescence spectroscopy. The hfs of these 23 gathered levels has been analysed by simultaneous parametrisation of the one- and two-body interactions, first in model space (4d + 5s)3 and secondly in extended space. For the three lowest configurations, radial parameters of the magnetic dipole A and quadrupole electric B factors are deduced in their entirety for 91Zr II, compared and discussed with calculated values, available in the literature, and also with ours, computed by means of the ab initio method. For instance we give the main experimental values of the extracted single-electron hfs parameters of 4d25s: [Formula: see text] = –2701 MHz, [Formula: see text] = –122.4 MHz, and [Formula: see text] = –113.5 MHz.

Fast ion beam chopping system for neutron generators

2005 ◽  
Vol 76 (2) ◽  
pp. 023304 ◽  
Author(s):  
S. K. Hahto ◽  
S. T. Hahto ◽  
K. N. Leung ◽  
J. Reijonen ◽  
T. G. Miller ◽  
...  
Keyword(s):  
Ion Beam ◽  
Neutron Generators ◽  
Fast Ion

Measurement of the fast ion distribution using active NPA diagnostics at the Globus-M2 spherical tokamak

2021 ◽  
Author(s):  
Nikolai Nikolaevich Bakharev ◽  
I M Balachenkov ◽  
F V Chernyshev ◽  
Vasily K Gusev ◽  
Evgeniy Kiselev ◽  
...  
Keyword(s):  
Charge Exchange ◽  
Neutral Beam ◽  
Scanning System ◽  
Spatial Distributions ◽  
Spherical Tokamak ◽  
Ion Distribution ◽  
Fast Ion ◽  
Additional Charge

Abstract Active NPA measurements of the fast ion distribution using the neutral beam as an additional charge exchange target are discussed. Expressions for the calculation of the NPA signal based on the fast ion distribution and for the reconstruction of the fast ion distribution from the NPA signal are provided. Demonstration of the described approach is carried out on the Globus-M2 spherical tokamak, where a scanning system for the NPAs was recently installed. Main features of the active NPA application on Globus-M2 are considered. The energy and spatial distributions of fast deuterium ions at dedicated pitch angles are obtained and compared with the calculated ones. Key traits of the obtained distributions are considered and explained.

scholarly journals First multispacecraft ion measurements in and near the Earth’s magnetosphere with the identical Cluster ion spectrometry (CIS) experiment

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1303-1354 ◽  
Author(s):  
H. Rème ◽  
C. Aoustin ◽  
J. M. Bosqued ◽  
I. Dandouras ◽  
B. Lavraud ◽  
...  
Keyword(s):  
Solar Wind ◽  
Angular Resolution ◽  
Dynamic Range ◽  
Ion Beam ◽  
Three Dimensional ◽  
Charge Composition ◽  
Ion Distribution ◽  
Central Plasma ◽  
Cluster Ion ◽  
High Level

Abstract. On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS) experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+) from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF), giving the mass per charge composition with medium (22.5°) angular resolution, and a Hot Ion Analyser (CIS2/HIA), which does not offer mass resolution but has a better angular resolution (5.6°) that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities) were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions)

Lower hybrid turbulence excited by a fast transverse ion beam in a magnetized plasma

1998 ◽  
Vol 38 (5) ◽  
pp. 661-671 ◽  
Author(s):  
E.V Suvorov ◽  
E Holzhauer ◽  
W Kasparek ◽  
A.B Burov ◽  
Y.A Dryagin ◽  
...  
Keyword(s):  
Ion Beam ◽  
Magnetized Plasma ◽  
Lower Hybrid

scholarly journals Scattering of field-aligned beam ions upstream of Earth's bow shock

2007 ◽  
Vol 25 (3) ◽  
pp. 785-799 ◽  
Author(s):  
A. Kis ◽  
M. Scholer ◽  
B. Klecker ◽  
H. Kucharek ◽  
E. A. Lucek ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Measurements ◽  
Bow Shock ◽  
Ion Distribution ◽  
Parallel Side ◽  
Earth’S Bow Shock ◽  
High Mach ◽  
The Magnetic Field

Abstract. Field-aligned beams are known to originate from the quasi-perpendicular side of the Earth's bow shock, while the diffuse ion population consists of accelerated ions at the quasi-parallel side of the bow shock. The two distinct ion populations show typical characteristics in their velocity space distributions. By using particle and magnetic field measurements from one Cluster spacecraft we present a case study when the two ion populations are observed simultaneously in the foreshock region during a high Mach number, high solar wind velocity event. We present the spatial-temporal evolution of the field-aligned beam ion distribution in front of the Earth's bow shock, focusing on the processes in the deep foreshock region, i.e. on the quasi-parallel side. Our analysis demonstrates that the scattering of field-aligned beam (FAB) ions combined with convection by the solar wind results in the presence of lower-energy, toroidal gyrating ions at positions deeper in the foreshock region which are magnetically connected to the quasi-parallel bow shock. The gyrating ions are superposed onto a higher energy diffuse ion population. It is suggested that the toroidal gyrating ion population observed deep in the foreshock region has its origins in the FAB and that its characteristics are correlated with its distance from the FAB, but is independent on distance to the bow shock along the magnetic field.

scholarly journals TEMPERATURE MONITORING OF POLYMER FILMS UNDER IRRADIATION BY FAST ION BEAM

2017 ◽  
Author(s):  
V. N. Bondarenko ◽  
A. V. Goncharov ◽  
V. I. Sukhostavets ◽  
T. Kh. Salikhov ◽  
A. A. Abdurahmonov
Keyword(s):  
Polymer Films ◽  
Ion Beam ◽  
Temperature Monitoring ◽  
Fast Ion
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