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Electron Temperature (electron + temperature)

Distribution by Scientific Domains

Physics and Astronomy	72%

Selected Abstracts

Towards Fast Measurement of the Electron Temperature in the SOL of ASDEX Upgrade Using Swept Langmuir Probes

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 9 2010
H.W. Müller
Abstract On ASDEX Upgrade first experiments were made using single probes with a voltage sweep frequency up to 100kHz. Possibilities and limitations using fast swept probes with a standard diagnostic and analysis tools are discussed. A good agreement between the data derived from fast swept single probe characteristics and floating as well as saturation current measurements was found. In a stationary (non ELMing) plasma the data of the fast swept probe are compared to standard slow swept probes (kHz range) showing an improvement of the measurement by faster sweeping. While ELM filaments already could be resolved the access of electron temperature fluctuations in small scale turbulence still has to be improved. Further comparisons are done in ELMy H-mode with combined ball-pen probe/floating potential measurements which can deliver electron temperatures with 25 , s time resolution at reduced spatial resolution compared to pin probes. During ELMs the electron temperatures derived from the ball-pen probe and fast swept single probes agreed (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Fluid Model of a Sheath Formed in Front of an Electron Emitting Electrode Immersed in a Plasma with Two Electron Temperatures

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 2 2005
T. Gyergyek
Abstract The formation of a sheath in front of a negatively biased electrode (collector) that emits electrons is studied by a one-dimensional fluid model. Electron and ion emission coefficients are introduced in the model. It is assumed that the electrode is immersed in a plasma that contains energetic electrons. The electron velocity distribution function is assumed to be a sum of two Maxwellian distributions with two different temperatures, while the ions and the emitted electrons are assumed to be monoenergetic. The condition for zero electric field at the collector is derived. Using this equation the dependence of electron and ion critical emission coefficients on various parameters - like the ratio between the hot and cool electron density, the ratio between hot and cool electron temperature and the initial velocity of secondary electrons - is calculated for a floating collector. A modification of the Bohm criterion due to the presence of hot and emitted electrons is also given. The transition between space charge limited and temperature limited electron emission for a current-carrying collector is also analyzed. The critical potential, where this transition occurs, is calculated as a function of several parameters like the Richardson emission current, the ratio between the hot and cool electron density, the ratio between hot and cool electron temperature and the initial velocity of secondary electrons. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Ball-Pen Probe Measurements in L-Mode and H-Mode on ASDEX Upgrade

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 9 2010
J. Adamek
Abstract Experimental investigations of the plasma potential, poloidal electric field and electron temperature during L-mode and ELMy H-mode were performed on ASDEX Upgrade by means of a probe head containing four ball-pen probes and four Langmuir probes. This allows to measure simultaneously the floating and plasma potential at the same time which are related by the electron temperature. Thus a combination of ball-pen probes and Langmuir probes offers the possibility to determine the electron temperature directly with high temporal resolution. This novel temperature measurement method is compared to standard techniques. The influence of the electron temperature on the usual calculation of the poloidal electric field from the gradient of the floating potential is determined by a comparison to the poloidal electric field derived from the plasma potential (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle Generation

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2008
K. Behringer
Abstract Pulsed arc plasmas were diagnosed by means of emission spectroscopy. A capacitor was discharged through argon and hydrogen leading to a few cycles of damped current oscillation with ,120 ,s period and 5-12 kA maximum current. Spectroscopic measurements in the visible range were carried out in order to characterise the electron temperature and density in the arc channel as well as electron and gas temperatures in the afterglow plasmas. Spectra were integrated over 10 ,s time windows and shifted in time from pulse to pulse. The plasmas also contained substantial fractions of electrode material (brass), namely copper and zinc. The electron density was measured in the conventional way from the broadening of H, or from the Ar I Stark width. In the arc channel, it ranged from about 3 · 1022 to 2 · 1023 m,3. The broadening of Zn II lines could also be used. Ratios of Ar I to Ar II and of Zn I to Zn II line intensities were analysed for the electron temperature. Line pairs were found which lay conveniently close in one frame of the spectrometer allowing automatic on-line analysis without relying on reproducibility. Atomic physics models including opacity were developed for Ar II and Zn II in order to check the existence of a Boltzmann distribution of their excited states. These calculations showed that the observed levels were in fact close to thermodynamic equilibrium, in particular, if the resonance lines were optically thick. Electron temperature measurements yielded values between 14000 K and 21000 K. The gas temperature in the afterglow, where particles should have formed, was derived from the rotational and vibrational temperatures of C2 molecular bands. Ratios between Cu I line intensities yielded the electron temperatures. Both were found to be a few 1000 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Characteristics of VHF H2 Plasma Produced at High Pressure

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 4 2008
Y. Yamauchi
Abstract A VHF H2 plasma was produced with the multi rod electrode at high pressure and the plasma parameters were measured as a function of pressure for different VHF powers at 60 MHz. It was found that when the pressure is increased, the ion saturation current peaks at certain pressure and finally decreases at high pressures, while the electron temperature is around 10 eV. The wall potential at high pressure was lower than the values estimated from the electron temperature using the probe theory. Furthermore, the anomalous reduction of the electron saturation current was observed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Sheath in Front of a Negatively Biased Collector that Emits Electrons and is Immersed in a Two Electron Temperature Plasma

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2005
T. Gyergyek
Abstract An extension of a recently published [Gyergyek T., ,er,ek M. Contrib. Plasma Phys., 45, (2005), 89] one dimensional fluid model of the sheath formation in front of a floating electrode (collector) that emits secondary electrons and is immersed in a two-electron temperature nonmagnetized, collisionless plasma is presented. The electron velocity distribution function is assumed to be a two-temperature maxwellian, while the singly charged positive ions and the emitted electrons are assumed to be monoenergetic. It is assumed that the electrons in the pre-sheath potential drop obey the Boltzmann relation, so that a larger fraction of the hot than of the cool electrons can penetrate to the sheath edge. Our model predicts that the collector can in some cases have 3 and in some cases, when the emission of electrons from the collector is critical, even 5 different floating potentials at the same hot to cool electron temperature and density ratios very far away from the collector. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Fluid Model of a Sheath Formed in Front of an Electron Emitting Electrode Immersed in a Plasma with Two Electron Temperatures

A New Method of Electron Temperature Determination in Unmagnetized and Magnetized RF Plasmas without RF Compensating Circuit

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 7-8 2004
Y.-S. Choi
Abstract Collected current versus applied voltage(I-V) curve of Langmuir probe in RF plasma is severely distorted by RF fluctuations leading to overestimation of electron temperature. RF compensation circuit has been used to obtain the undistorted I-V curve, yet it produces time-averaged one. A new and simple method is proposed to get time-resolved I-V curve by picking the synchronized RF signals with digital oscilloscope and Labview program. This technique is tested in magnetized helicon plasmas and unmagnetized capacitive coupled RF plasmas [source]

Trivelpiece-Gould mode produced gas-discharges in a diffusion-controlled regime

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 3-4 2003
H. Schlüter
Abstract The study presents a numerical fluid-plasma model of waveguide discharges sustained by travelling azimuthallysymmetric Trivelpiece-Gould modes. The results describe weakly-magnetized (, , ,e) plasma production in a diffusion-controlled regime (, being the wave frequency, ,e the electron gyro-frequency). However, with respect to the influence of the external magnetic field on the transverse ambipolar-diffusion coefficient, cases of both weak and strong impact of the magnetic field are covered. In its electrodynamical part, the model involves detailed description of the behaviour of the Trivelpiece-Gould waves in radially-inhomogeneous collisional plasmas. The gas-discharge part of the model specifies plasma production in an argon gas. The results are for the self-consistent structure of the discharge composed out of the interrelated variations of wavenumber, space damping rate, plasma density, electron temperature and power absorbed on average by an electron. The analysis is in terms of influence of gas-pressure and magnetic-field changes. [source]

Flow characteristics of a cold helium arc-jet plasma along open field lines

IEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2009
Kazuyuki Yoshida Member
Abstract We experimentally study plasma parameters including ion acoustic Mach number of expanding cold helium plasma jet with an electron temperature of less than 1 eV flowing along open field lines. It is experimentally found that the ion Mach number increases from 1 to 3, and that the plasma potential decreases by about 1 V. We discuss the experimental results based on a quasi one-dimensional flow model in which the plasma is assumed to be quasi-neutral and in a state of thermodynamic equilibrium. Our model describes the ion acceleration, the axial profiles of the potential drop, and the electron temperature/density. The model also shows that the helium ions are accelerated both by the electric field and by the increasing cross-sectional area of the transonic flow. After the ion acceleration, the ion Mach number decreases and the electron temperature increases. These phenomena are discussed in terms of a shock wave. It is noted that the electron density decreases even in the shock wave. This is discussed in terms of rapid recombination because of the low electron temperature. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source]

Monoenergetic electron beam generation in a laser-driven plasma acceleration

LASER PHYSICS LETTERS, Issue 2 2006
M. Adachi
Abstract We obtained a 7-MeV monoenergetic electron beam from a plasma with the electron density ne of 1.5 × 1020 cm,3 produced by a 2-TW 50-fs laser pulse. In both higher and lower sides of the density region of 4 × 1019 ÷ 4 × 1020 cm,3, energy spectra of electrons were bi-Maxwellian distribution function whose maximum electron energy and effective electron temperature were 30 MeV and approximately MeV, respectively. Observed first Stokes satellites in the forward scattering light spectra, and the density dependences of maximum electron energy and the effective temperature suggest that electrons are first accelerated by SMLWFA and are further accelerated by direct laser acceleration (DLA) in the ne region of more than 2 × 1020 cm,3; a cascade acceleration by SMLWFA and DLA. A Stokes satellite peak observed with the monoenergetic beam suggests that the monoenergetic beam would be accelerated by SMLWFA. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Deep spectroscopy of the FUV,optical emission lines from a sample of radio galaxies at z, 2.5: metallicity and ionization,

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008
A. Humphrey
ABSTRACT We present long-slit near-infrared (NIR) spectra, obtained using the Infrared Spectrometer And Array Camera (ISAAC) instrument at the Very Large Telescope, which sample the rest-frame optical emission lines from nine radio galaxies at z, 2.5. One-dimensional spectra have been extracted and, using broad-band photometry, have been cross-calibrated with spectra from the literature to produce line spectra spanning a rest wavelength of ,1200,7000 Å. The resulting line spectra have a spectral coverage that is unprecedented for radio galaxies at any redshift. We have also produced a composite of the rest-frame ultraviolet (UV),optical line fluxes of powerful, z, 2.5 radio galaxies. We have investigated the relative strengths of Ly,, H,, H,, He ii,1640 and He ii,4687, and we find that Av can vary significantly from object to object. In addition, we have identified new line ratios to calculate electron temperature: [Ne v],1575/[Ne v],3426, [Ne iv],1602/[Ne iv],2423, O iii],1663/[O iii],5008 and [O ii],2471/[O ii],3728. We calculate an average O iii temperature of 14100+1000,600 K. We have modelled the rich emission line spectra, and we conclude that they are best explained by active galactic nucleus (AGN) photoionization with the ionization parameter U varying between objects. For shock models (with or without the precursor) to provide a satisfactory explanation for the data, an additional source of ionizing photons is required , presumably the ionizing radiation field of the AGN. Single slab photoionization models are unable to reproduce the high- and the low-ionization lines simultaneously: the higher ionization lines imply higher U than do the lower ionization lines. This problem may be alleviated either by combining two or more single slab photoionization models with different U, or by using mixed-medium models such as those of Binette, Wilson & Storchi-Bergmann. In either case, U must vary from object to object. On the basis of N v/N iv] and N iv]/C iv we argue that, while photoionization is the dominant ionization mechanism in the extended emission line regions (EELR), shocks make a fractional contribution (,10 per cent) to its ionization. The N v/N iv] and N iv]/C iv ratios in the broad-line region (BLR) of some quasars suggest that shock ionization may be important in the BLR also. We find that in the EELR of z, 2 radio galaxies the N/H abundance ratio is close to its solar value. We conclude that N/H and metallicity do not vary by more than a factor of 2 in our sample. These results are consistent with the idea that the massive ellipticals which become the hosts to powerful AGN are assembled very early in the history of the universe, and then evolve relatively passively up to the present day. [source]

Extragalactic MeV ,-ray emission from cocoons of young radio galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
M. Kino
ABSTRACT Strong ,-ray emission from cocoons of young radio galaxies is predicted for the first time. Considering the process of adiabatic injection of the shock dissipation energy and mass of the relativistic jet in active nuclei into the cocoon, while assuming thermalizing electron plasma interactions, we find that the thermal electron temperature of the cocoon is typically predicted to be of the order of , MeV, and is determined only by the bulk Lorentz factor of the relativistic jet. Together with the time-dependent dynamics of the cocoon expansion, we find that young cocoons can yield thermal bremsstrahlung emissions at energies ,MeV. [source]

On the relation between electron temperatures in the O+ and O++ zones in high-metallicity H ii regions

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2006
Leonid S. Pilyugin
ABSTRACT We suggest a new way to establish the relation between the electron temperature t3 within the [O iii] zone and the electron temperature t2 within the [O ii] zone in high-metallicity (12 + log(O/H) > 8.25) H ii regions. The t2,t3 diagram is constructed by applying our method to a sample of 372 H ii regions. We find that the correlation between t2 and t3 is tight and can be approximated by a linear expression. The new t2,t3 relation can be used to determine t2 and accurate abundances in high-metallicity H ii regions with a measured t3. It can also be used in conjunction with the ff relation for the determination of t3 and t2 and oxygen abundances in high-metallicity H ii regions, where the [O iii],4363 auroral line is not detected. The derived t2,t3 relation is independent of photoionization models of H ii regions. [source]

Effect of ion energy on structural and electrical properties of intrinsic microcrystalline silicon layer deposited in a matrix distributed electron cyclotron resonance plasma reactor

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2010
Sanjay K. Ram
Abstract Microcrystalline silicon films were deposited in a matrix distributed electron cyclotron resonance (MDECR) plasma enhanced chemical vapor deposition (PECVD) system using pure silane, under varying substrate bias conditions. Microstructural characterization of the films shows a lower void fraction and a preponderance of nanograins in films deposited at negative bias, while in positive bias a thin incubation layer is seen with a higher void fraction. Plasma emission studies reveal higher electron temperature and more atomic H at positive bias, which lead to early onset of crystallization. The microstructural properties of the films are correlated with the dark and phototransport properties. Our study demonstrates the importance of substrate bias in controlling the ion energy and properties of films deposited in the MDECR reactor. [source]

1-D Self-consistent Fluid Modelling of the Pulsed Magnetron Discharge

PLASMA PROCESSES AND POLYMERS, Issue S1 2009
Philip Thomason
Abstract A 1-D fluid code simulation of the region above the racetrack in a magnetron discharge has been developed to yield predictions for the temporal evolution of the axial plasma parameters during pulsed DC operation. To take into account anomalous cross-field diffusion transport rates, an effective magnetic field profile has been calculated based on the real experimental values, to yield ratios in the effective electron gyro and collision frequencies comparable with Bohm diffusion. Pulse frequencies from 100 to 500,kHz are considered, with gas pressures ranging from 0.25 to 0.65,Pa. The model results for the plasma potential, electron and ion densities, during the pulse cycle agree well with experimental measurements made in the Liverpool magnetron using time-resolved Langmuir and emissive probes. In the bulk plasma, the predictions for electron temperature are close to the measured values; however, in the sheath region they are artificially high due to the model assumption that only Maxwellian distributed electrons exist in all regions of the discharge. This inadequacy in the model and the methods to improve has been discussed. Results for DC magnetrons are also shown. [source]

Global Model of He/O2 and Ar/O2 Atmospheric Pressure Glow Discharges

PLASMA PROCESSES AND POLYMERS, Issue 6 2008
Ganyoung Park
Abstract Atmospheric pressure glow discharges (APGDs) have widespread applications, including sterilization, cancer cell treatment, deposition, and surface modification due to their rather simple configurations, thanks to no need for vacuum system and their great capability to generate reactive species such as radical oxygen species. Helium and argon are widely used as feeding gases, achieving stable operations for wide ranges of parameters in atmospheric pressure, and oxygen is added into these gases to generate more reactive oxygen species (ROS), which play a significant role in sterilization. As the measurements of species densities and electron temperature in APGDs are difficult, we have developed the zero-dimensional global model of He/O2 and Ar/O2 APGDs to calculate the densities of several kinds of species and electron temperature. It was shown that even though small fraction of oxygen less than 1% was added to helium or argon, electrons dissipated most of their energy through collisions with oxygen molecules rather than helium or argon atoms. The densities of electron, atomic oxygen, and ozone of Ar/O2 were higher than those of He/O2; however, the electron temperature of He/O2 was higher than that of Ar/O2. When the pulsed power is applied, the time-averaged electron temperature for the shorter pulse period and the larger duty ratio increased, and the electron density decreased as the duty ratio increased. [source]

Probe Diagnostics of Expanding Plasmas at Low Gas Pressure

PLASMA PROCESSES AND POLYMERS, Issue 2 2006
Mariya Dimitrova
Abstract Summary: Results from tandem-type probe diagnostics of a plasma source based on an inductive discharge are presented in this study. The driver region is in the classical form of a cylindrically shaped inductive discharge, with a coil positioned over a gas discharge tube, whereas a bigger metal chamber provides volume for plasma expansion. Low pressure argon discharges were studied. The axial profiles of the plasma parameters were measured in the discharge in the metal chamber. The results obtained show that decreasing electron temperature and plasma density with increasing distance from the driver characterizes the behavior of the expanding plasmas. Moreover, two regions with different rates of variation of the plasma parameters complete the plasma expansion volume: a faster drop close to the driver and slow axial changes away from it. The gas pressure and power applied for the discharge maintenance were the external parameters varied. Axial profiles of the electron concentration in the plasma expansion region of an inductive discharge. [source]

High energy emission from AGN cocoons in clusters of galaxies

ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009
M. Kino
Abstract Gamma-ray emission from cocoons of young radio galaxies is predicted. Considering the process of adiabatic injection of the shock dissipation energy and mass of the relativistic jet into the cocoon, we find that the thermal electron temperature of the cocoon is typically predicted to be of the order of ,MeV, and is determined only by the bulk Lorentz factor of the jet. Together with the time-dependent dynamics of the cocoon expansion, we find that young cocoons can yield thermal bremsstrahlung emissions at energies ,MeV. Hotter cocoons (i.e., GeV) for younger sources are also discussed (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Chandra ACIS Imaging Spectroscopy of Sgr A East

ASTRONOMISCHE NACHRICHTEN, Issue S1 2003
Y. Maeda
Abstract We report on the X-ray emission from the shell-like, non-thermal radio source Sgr A East located in the inner few parsecs of the Galaxy based on observations made with the ACIS detector on board the Chandra X-ray Observatory. The X-ray emission from Sgr A East is concentrated within the central ,2 pc of the larger radio shell. The spectrum shows strong K, lines from highly ionized ions of S, Ar, Ca, and Fe. A simple isothermal plasma model gives electron temperature ,2 keV, absorption column ,1 × 1023 H cm,2, luminosity ,8 × 1034 ergs s,1 in the 2,10 keV band, and gas mass ,2,½ M, with a filling factor ,. The plasma appears to be rich in heavy elements, over-abundant by roughly a factor of four with respect to solar abundances. Accompanied with filamentary or blob-like structures, the plasma shows a spatial gradient of elemental abundance: the spatial distribution of iron is more compact than that of the lighter elements. These Chandra results strongly support the long-standing hypothesis that Sgr A East is a supernova remnant (SNR). Since Sgr A East surrounds Sgr A* in projection, it is possible that the dust ridge compressed by the forward shock of Sgr A East hit Sgr A* in the past, and the passage of the ridge may have supplied material to accrete onto the black hole in the past, and may have removed material from the black hole vicinity, leading to its present quiescent state. [source]

Towards Fast Measurement of the Electron Temperature in the SOL of ASDEX Upgrade Using Swept Langmuir Probes

Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle Generation

Comparison of Langmuir Probe and Laser Thomson Scattering Methods in the Electron Temperature Measurement in Divertor Simulator MAP-II

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2006
A. Okamoto
Abstract In order to investigate details of anomaly in the Langmuir probe current (I)-voltage (V) characteristics, electron temperatures and densities are measured by both Langmuir probe and laser Thomson scattering methods. The electron densities measured with both methods show good agreement in hydrogen-molecular assisted recombination (H2 -MAR) plasmas. On the other hand, the electron temperatures measured with Langmuir probe are overestimated compared with that obtained from the Thomson scattering spectrum in the H2 -MAR plasmas. Histogram of electron current deviated from its average shows that fluctuation appeared in the electron current becomes large and the histogram distorted in temperature-overestimated condition, especially when the probe voltage is negatively biased. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Effective collision strengths for electron-impact excitation of transitions within the ground 1s2 2s2 2p4 manifold of O-like Fe18+

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2009
Juan A. Santana
Abstract Collision strengths have been computed for the electron impact excitations of parity and spin forbidden transitions within the ground 1s22s22p4 manifold of Fe XIX (Fe18+). The calculations were carried out using a relativistic R-matrix close-coupling method based on the effective many-body Hamiltonian. Twenty-six target states were included in the close-coupling expansion. Effective collision strengths, assuming a Maxwellian electron velocity distribution, were evaluated for all transitions within the ground configuration. Good agreement is found with previous Breit-Pauli R-matrix calculations at low electron temperatures, 5.0 , log Te , 6.0 K, for all the transitions, whereas significant differences are found for electron temperatures in the range 6.0 , log Te , 7.0 K. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source]

The ionization of the emission-line gas in young radio galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009
J. Holt
ABSTRACT This paper is the second in a series in which we present intermediate-resolution, wide-wavelength coverage spectra for a complete sample of 14 compact radio sources, taken with the aim of investigating the impact of the nuclear activity on the circumnuclear interstellar medium (ISM) in the early stages of radio source evolution. In the first paper (Holt, Tadhunter & Morganti), we presented the kinematic results from the nuclear emission-line modelling and reported fast outflows in the circumnuclear gas. In this paper, we use the line fluxes to investigate the physical conditions and dominant ionization mechanisms of the emission-line gas. We find evidence for large electron densities and high reddening in the nuclear regions, particularly in the broader, blueshifted components. These results are consistent with the idea that the young, recently triggered radio sources still reside in dense and dusty cocoons deposited by the recent activity triggering event (merger/interaction). In addition, we find that the quiescent nuclear and extended narrow components are consistent with active galactic nucleus (AGN) photoionization, split between simple-slab AGN photoionization and mixed-medium photoionization models. For the nuclear broader and shifted components, the results are less clear. Whilst there are suggestions that the broader components may be closer to shock plus precursor models on the diagnostic diagrams, and that the electron temperatures and densities are high, we are unable to unambiguously distinguish the dominant ionization mechanism using the optical emission-line ratios. This is surprising given the strong evidence for jet,cloud interactions (broad emission lines, large outflow velocities and strong radio-optical alignments), which favours the idea that the warm gas has been accelerated in shocks driven by the radio lobes expanding through a dense cocoon of gas deposited during the triggering event. [source]