131 research outputs found
Mach numbers for gases and plasmas in a convergent-divergent cascaded arc
For a plasma, flowing through a cascaded arc channel with a varying cross-section, and flowing from a subsonic to a supersonic state, the sonic condition moves downstream and the plasma Mach number at the smallest cross section is less than one, although in case of a transonic isentropic gas flow the sonic condition is found at the smallest cross section. This shift in sonic condition is due to the lack of isentropic behavior of the plasma flow. Sources causing the anisentropy are viscosity, heat and ionization, of which ionization is vital for a plasma. It is found that the plasma Mach number is always lower than the corresponding gas Mach number. A quasi one-dimensional analysis and simulations with a two-dimensional plasma model, which support the analysis, are presented. Β© 1999 American Institute of Physics. Β© 1999 American Institute of Physic
Ionisation efficiency in a pinched cascaded arc channel
In the present study, we will focus on the improvement of the ion density at the arc outlet. Efficiency increases are necessary to obtain effective remote deposition, in which the plasma source and target area are decomposed. Remote deposition is easier to control than non-remote deposition and therefore preferable. The increase in the ionisation outflow will be obtained by creating a nozzle shaped cylindrical arc channel. Simulations were used to obtain the results. The arc plasma expands supersonically into a low pressure vessel. To simulate the existence of the expansion, a Ma=0.9 boundary condition is implemented at the arc outle
Ionisation efficiency in a pinched cascaded arc channel
In the present study, we will focus on the improvement of the ion density at the arc outlet. Efficiency increases are necessary to obtain effective remote deposition, in which the plasma source and target area are decomposed. Remote deposition is easier to control than non-remote deposition and therefore preferable. The increase in the ionisation outflow will be obtained by creating a nozzle shaped cylindrical arc channel. Simulations were used to obtain the results. The arc plasma expands supersonically into a low pressure vessel. To simulate the existence of the expansion, a Ma=0.9 boundary condition is implemented at the arc outle
RF discharge in argon with cylindrical dust particles
Kinetic computer simulations of the low pressure RF discharge in argon with cylindrical and spherical dust particles are carried out using PIC/MCC method. The Monte Carlo technique is used to describe electron and ion collisions with neutral atoms, ions, and dust particles. Obtained results show the remarkable influence of the dust particle shape on spatial distributions of RF discharge parameters including the ion density and the dust particle charge. Possible reasons of the influence can be a difference of the collection effective cross-section between spherical and cylindrical dust particles with equal surfaces as well as the balance of charged particles in dusty RF discharges.ΠΡΠ½Π΅ΡΠΈΡΠ½Π΅ ΠΊΠΎΠΌΠΏβΡΡΠ΅ΡΠ½Π΅ ΠΌΠΎΠ΄Π΅Π»ΡΠ²Π°Π½Π½Ρ ΡΠ°Π΄ΡΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ·ΡΡΠ΄Ρ Π² Π°ΡΠ³ΠΎΠ½Ρ Π· ΡΠΈΠ»ΡΠ½Π΄ΡΠΈΡΠ½ΠΈΠΌΠΈ Ρ ΡΡΠ΅ΡΠΈΡΠ½ΠΈΠΌΠΈ ΠΏΠΈΠ»ΠΎΠ²ΠΈΠΌΠΈ ΡΠ°ΡΡΠΈΠ½ΠΊΠ°ΠΌΠΈ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΎΡΡ Π· Π²ΠΈΠΊΠΎΡΠΈΡΡΠ°Π½Π½ΡΠΌ PIC/MCC ΠΌΠ΅ΡΠΎΠ΄Ρ. Π’Π΅Ρ
Π½ΡΠΊΠ° ΠΠΎΠ½ΡΠ΅-ΠΠ°ΡΠ»ΠΎ Π²ΠΈΠΊΠΎΡΠΈΡΡΠΎΠ²ΡΠ²Π°Π»Π°ΡΡ Π΄Π»Ρ ΠΎΠΏΠΈΡΡ Π΅Π»Π΅ΠΊΡΡΠΎΠ½Π½ΠΈΡ
Ρ ΡΠΎΠ½Π½ΠΈΡ
Π·ΡΡΠΊΠ½Π΅Π½Ρ Π· Π½Π΅ΠΉΡΡΠ°Π»ΡΠ½ΠΈΠΌΠΈ Π°ΡΠΎΠΌΠ°ΠΌΠΈ Ρ ΠΏΠΈΠ»ΠΎΠ²ΠΈΠΌΠΈ ΡΠ°ΡΡΠΈΠ½ΠΊΠ°ΠΌΠΈ. ΠΡΡΠΈΠΌΠ°Π½Ρ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΈ ΠΏΠΎΠΊΠ°Π·ΡΡΡΡ, ΡΠΎ ΡΠΎΡΠΌΠ° ΠΏΠΈΠ»ΠΎΠ²ΠΈΡ
ΡΠ°ΡΡΠΈΠ½ΠΎΠΊ ΠΏΠΎΠΌΡΡΠ½ΠΎ Π²ΠΏΠ»ΠΈΠ²Π°Ρ Π½Π° ΠΏΡΠΎΡΡΠΎΡΠΎΠ²Ρ ΡΠΎΠ·ΠΏΠΎΠ΄ΡΠ»ΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡΠ² ΡΠ°Π΄ΡΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ·ΡΡΠ΄Ρ, Π² ΡΠΎΠΌΡ ΡΠΈΡΠ»Ρ Π½Π° ΡΠΎΠ·ΠΏΠΎΠ΄ΡΠ»ΠΈ Π³ΡΡΡΠΈΠ½ΠΈ ΡΠΎΠ½ΡΠ² Ρ Π·Π°ΡΡΠ΄Ρ ΠΏΠΈΠ»ΠΎΠ²ΠΈΡ
ΡΠ°ΡΡΠΈΠ½ΠΎΠΊ. ΠΠΎΠΆΠ»ΠΈΠ²ΠΈΠΌΠΈ ΠΏΡΠΈΡΠΈΠ½Π°ΠΌΠΈ ΡΡΠΎΠ³ΠΎ Π²ΠΏΠ»ΠΈΠ²Ρ ΠΌΠΎΠΆΠ΅ Π±ΡΡΠΈ ΡΡΠ·Π½ΠΈΡΡ Π΅ΡΠ΅ΠΊΡΠΈΠ²Π½ΠΈΡ
ΠΏΠ΅ΡΠ΅ΡΠΈΠ½ΡΠ² ΡΡΠ΅ΡΠΈΡΠ½ΠΈΡ
Ρ ΡΠΈΠ»ΡΠ½Π΄ΡΠΈΡΠ½ΠΈΡ
ΠΏΠΈΠ»ΠΎΠ²ΠΈΡ
ΡΠ°ΡΡΠΈΠ½ΠΎΠΊ ΠΎΠ΄Π½Π°ΠΊΠΎΠ²ΠΎΡ ΠΏΠΎΠ²Π΅ΡΡ
Π½Ρ, Π° ΡΠ°ΠΊΠΎΠΆ Π±Π°Π»Π°Π½Ρ Π·Π°ΡΡΠ΄ΠΆΠ΅Π½ΠΈΡ
ΡΠ°ΡΡΠΈΠ½ΠΎΠΊ Π² Π·Π°ΠΏΠΎΡΠΎΡΠ΅Π½ΠΈΡ
ΡΠ°Π΄ΡΠΎΡΠ°ΡΡΠΎΡΠ½ΠΈΡ
ΡΠΎΠ·ΡΡΠ΄Π°Ρ
.ΠΠΈΠ½Π΅ΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΊΠΎΠΌΠΏΡΡΡΠ΅ΡΠ½ΠΎΠ΅ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠ°Π΄ΠΈΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π·ΡΡΠ΄Π° Π² Π°ΡΠ³ΠΎΠ½Π΅ Ρ ΡΠΈΠ»ΠΈΠ½Π΄ΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΈ ΡΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΏΡΠ»Π΅Π²ΡΠΌΠΈ ΡΠ°ΡΡΠΈΡΠ°ΠΌΠΈ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΡΡ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ PIC/MCC ΠΌΠ΅ΡΠΎΠ΄Π°. Π’Π΅Ρ
Π½ΠΈΠΊΠ° ΠΠΎΠ½ΡΠ΅-ΠΠ°ΡΠ»ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»Π°ΡΡ Π΄Π»Ρ ΠΎΠΏΠΈΡΠ°Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π½ΡΡ
ΠΈ ΠΈΠΎΠ½Π½ΡΡ
ΡΠΎΡΠ΄Π°ΡΠ΅Π½ΠΈΠΉ Ρ Π½Π΅ΠΉΡΡΠ°Π»ΡΠ½ΡΠΌΠΈ Π°ΡΠΎΠΌΠ°ΠΌΠΈ ΠΈ ΠΏΡΠ»Π΅Π²ΡΠΌΠΈ ΡΠ°ΡΡΠΈΡΠ°ΠΌΠΈ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΏΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡ, ΡΡΠΎ ΡΠΎΡΠΌΠ° ΠΏΡΠ»Π΅Π²ΡΡ
ΡΠ°ΡΡΠΈΡ Π·Π°ΠΌΠ΅ΡΠ½ΠΎ Π²Π»ΠΈΡΠ΅Ρ Π½Π° ΠΏΡΠΎΡΡΡΠ°Π½ΡΡΠ²Π΅Π½Π½ΡΠ΅ ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΠ°Π΄ΠΈΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠ³ΠΎ ΡΠ°Π·ΡΡΠ΄Π°, Π² ΡΠΎΠΌ ΡΠΈΡΠ»Π΅ Π½Π° ΡΠ°ΡΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΡ ΠΊΠΎΠ½ΡΠ΅Π½ΡΡΠ°ΡΠΈΠΈ ΠΈΠΎΠ½ΠΎΠ² ΠΈ Π·Π°ΡΡΠ΄Π° ΠΏΡΠ»Π΅Π²ΡΡ
ΡΠ°ΡΡΠΈΡ. ΠΠΎΠ·ΠΌΠΎΠΆΠ½ΡΠΌΠΈ ΠΏΡΠΈΡΠΈΠ½Π°ΠΌΠΈ ΡΡΠΎΠ³ΠΎ Π²Π»ΠΈΡΠ½ΠΈΡ ΠΌΠΎΠΆΠ΅Ρ Π±ΡΡΡ ΡΠ°Π·Π½ΠΈΡΠ° ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
ΡΠ΅ΡΠ΅Π½ΠΈΠΉ ΡΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈ ΡΠΈΠ»ΠΈΠ½Π΄ΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΡΠ»Π΅Π²ΡΡ
ΡΠ°ΡΡΠΈΡ Ρ ΠΎΠ΄ΠΈΠ½Π°ΠΊΠΎΠ²ΠΎΠΉ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΡΡ, Π° ΡΠ°ΠΊΠΆΠ΅ Π±Π°Π»Π°Π½Ρ Π·Π°ΡΡΠΆΠ΅Π½Π½ΡΡ
ΡΠ°ΡΡΠΈΡ Π² Π·Π°ΠΏΡΠ»Π΅Π½Π½ΡΡ
ΡΠ°Π΄ΠΈΠΎΡΠ°ΡΡΠΎΡΠ½ΡΡ
ΡΠ°Π·ΡΡΠ΄Π°Ρ
Extreme hydrogen plasma densities achieved in a linear plasma generator
A magnetized hydrogen plasma beam was generated with a cascaded arc, expanding in a vacuum vessel at an axial magnetic field of up to 1.6 T. Its characteristics were measured at a distance of 4 cm from the nozzle: up to a 2 cm beam diameter, 7.5Γ1020 m-3 electron density, ~2 eV electron and ion temperatures, and 3.5 km/s axial plasma velocity. This gives a 2.6Γ1024 H+ m-2 s-1 peak ion flux density, which is unprecedented in linear plasma generators. The high efficiency of the source is obtained by the combined action of the magnetic field and an optimized nozzle geometry. This is interpreted as a cross-field return current that leads to power dissipation in the beam just outside the source
Transport of high fluxes of hydrogen plasma in a linear plasma generator
A study was made to quantify the losses during the convective hydrogen plasma transport in the linear plasma generator Pilot-PSI due to volume recombination. A transport efficiency of 35% was achieved at neutral background pressures below ~7 Pa in a magnetic field of 1.2 T. This efficiency decreased to essentially zero at higher pressures. At 1.6 T, the measured downstream plasma density was up to double the upstream density. Apparently plasma pumping and recycling at the target start to play a role under these increased confinement conditions. Feeding the plasma column at this field strength with a net current did not change the downstream density. This indicates that recycling sets the local plasma conditions
- β¦