Low / Sub-Atmospheric Pressure
- Novel method of harmonic detection using RF Dual-Directional Couplers
- J.E probe for power density measurement in RF discharges
- Radio frequency atmospheric plasmas using co-planar multi-structured electrodes
- Coaxial and Planar DC Discharge Systems
- Characterization of nonlinear effects in dc discharges
Slow-wave microwave coupling structures: Slow wave structures (slotted line antenna, slotted and wire helices) were investigated theoretically. These were used for plasma production using CW microwaves were coupled at 2.45 GHz, 100 – 3kW power achieving for higher plasma production efficiency.
(LHS) A Schematic of the Slotted Line Antenna [SLA] (RHS) Typical numerical results for variation of Er, Ez and ZoHz at the antenna midplane as a function of the radius r.
(LHS) The sketch illustrates the geometry and the coordinate system where the helical curve represents one edge of the slot of the slotted helix. Note that this edge intersects the z = 0 plane at φ = 0; (RHS) Schematic of the slotted helix.
- A. Ganguli and P. Appala Naidu, “Dominant electromagnetic modes of a tape helix loaded in a conducting cylindrical waveguide”, Journal of Physics D: Applied Physics, 19 (12), 2265, (1986); DOI: 1088/0022-3727/19/12/006
- A. Ganguli and R. Baskaran, “Slow wave radiation fields of a slotted line antenna”, Journal of Applied Physics, 67 (1), 501, (1990); DOI: 10.1063/1.345233
- A. Ganguli and P. Appala Naidu, “Analysis of the dominant modes of a slotted‐helix‐loaded cylindrical waveguide for use in plasma production”, Journal of Applied Physics, 68 (7), 3679, (1990); DOI: 1063/1.346331
Theory of high frequency waves in plasma-loaded waveguides: High frequency waves in magnetized, warm, non-uniform plasma, loaded inside conducting waveguides were investigated theoretically using kinetic theory. Among other features the waves exhibit polarization reversal along the radius: a RHP wave near the plasma-waveguide axis becomes LHP away from the axis and vice-versa. Propagation characteristics, electric field, polarization profiles and wave absorption by cyclotron and Landau damping were determined.
(Top) Schematic of a plasma column loaded coaxially inside a cylindrical waveguide; (Middle) Dispersion diagrams for the m = -1, slow (a), (b) and fast-wave (c) modes; (Bottom, LHS) Radial profiles for polarization index (S) for the m= +1 and -1 (i. e. RCP and LCP) resonant modes near ECR (Bottom, RHS) Total absorption [cyclotron + Landau] and fractional contribution of Landau damping term are plotted for m= +1 and −1 resonating modes in the presence of warm electrons with a fractional population of 10% and Tw of 50 eV.
- A. Ganguli, M. K. Akhtar and R. D. Tarey, “Theory of high-frequency guided waves in a plasma-loaded waveguide”, Physics of Plasmas 5 (4), 1178, (1998); DOI: 10.1063/1.872647
- A. Ganguli, K. Akhtar and R. D. Tarey, “Absorption of high-frequency guided waves in a plasma-loaded waveguide”, Physics of Plasmas 14 (10), 102107, (2007); DOI: 10.1063/1.2799161
Modes of cold magnetized plasma in waveguides & sheath helices: Propagation characteristics, field structures and polarization details of slow and fast waves supported by cold, uniform magnetized plasma inside waveguides and sheath helices were investigated in detail.
Geometry of a plasma column loaded inside an infinitely long cylindrical sheath helix situated in free space. Region I is plasma & region II is vacuum; Cold uniform plasma modes in this configuration were studied in detail.
- P. Appala Naidu “Studies on microwave induced plasmas loaded within helical slow wave structures”, Ph.D. thesis, degree awarded by Indian Institute of Technology Delhi (1989)
Plasma production experiments using slow wave structures: Slow wave structures (slotted line antenna, slotted and wire helices) were used for plasma production in a magnetic mirror field configuration for improving plasma production efficiency and confinement. Plasma was initiated using 2.45 GHz microwaves at electron cyclotron resonance.
(LHS) Profiles of the axial magnetic field (Bo) for various coil currents, and relative positions of the helical slotted antenna, horn antenna, and vacuum window. (RHS, Top) Schematic of the slotted helical antenna (SHA), the exciting horn, etc. Note the presence of the mica screen which prevents the plasma from flowing into the horn region (RHS, Middle) Variation of the plasma density with microwave power for both resonant and non-resonant discharges (RHS, Bottom) Variation of the plasma density with radius for both resonant and non-resonant discharges
- A. Ganguli, R. Baskaran and H. D. Pandey, “Feed Optimization For the Slotted Line Antenna For High-Density Plasma Production”, IEEE Transactions on Plasma Science, 18 (1), 134, (1990); DOI: 10.1109/27.45516
- A. Ganguli, P. Appala Naidu and D. P. Tewari, “Studies on Microwave-Induced Plasma Production Using Helical Slow-Wave Structures”, IEEE Transactions on Plasma Science, 19 (2), 433, (1991); DOI: 1109/27.106843
- A. Ganguli, R. K. Jarwal, R. D. Tarey and M. K. Akhtar, “Characterization of microwave discharges produced by a slotted helical antenna in a mirror machine”, IEEE Transactions on Plasma Science, 25 (5), 1086, (1997); DOI: 10.1109/27.649630
- R. D. Tarey, R. K. Jarwal, A. Ganguli and M. K. Akhtar, “High-density plasma production using a slotted helical antenna at high microwave power”, Plasma Sources Science and Technology, 6 (2), 189, (1997); DOI: 10.1088/0963-0252/6/2/013
Plasma production using polarization control: RHP and LHP waves were used for plasma production giving novel insights into guided wave modes. Also, O-mode polarization was also used to excite the plasma.
(Top) Schematic of the experimental system showing the microwave coupling arrangement using the circular polarizer; (Bottom) Typical plot of the on-axis bulk plasma density (n0) as a function of microwave power for (Bottom, LHS) resonant discharges using linear polarization, for two pressures. (Bottom, Middle) non-resonant discharges using linear polarization. (Bottom, RHS) non-resonant and non-resonant discharges using right-hand circular polarization.
- R. D. Tarey, R. K. Jarwal, A. Ganguli and M. K. Akhtar, “High-density plasma production using a slotted helical antenna at high microwave power”, Plasma Sources Science and Technology, 6 (2), 189 (1997); DOI: 10.1088/0963-0252/6/2/013
- A. Ganguli, M. K. Akhtar, R. D. Tarey and R. K. Jarwal, “Absorption of left-polarized microwaves in electron cyclotron resonance plasmas”, Physics Letters A, 250 (1-3), 137, (1998); DOI: 10.1016/S0375-9601(98)00833-0
- A. Ganguli, M. K. Akhtar and R. D. Tarey, “Investigation of microwave plasmas produced in a mirror machine using ordinary-mode polarization”, Plasma Sources Science and Technology, 8 (4), 519, (1999); DOI: 10.1088/0963-0252/8/4/301
Theory of helicon waves: Propagation characteristics of helicon waves coupled to Trivelpiece-Gold (TG) waves along with collisional and Landau absorption was investigated in detail. Absorption is accounted for exactly, which brings about drastic changes in field patterns of the modes.
(Top, LHS) Plasma column loaded inside a cylindrical waveguide; (RHS) Typical radial profiles of normalized |Hφ| displaying prominent changes in profiles with the damping term |Im(γ1rp)| for higher-γ1 mode. (Bottom, LHS) Typical mode diagram (k vs γ1, γ2) for H and TG waves in lossless plasma at 13.56 MHz. Dotted lines refer to discrete modes of plasma-loaded conducting waveguide (rp =6 cm and rw =7.35 cm), showing the coupling between the H and TG branches. 1−1: lowest- γ1 mode; m−m: intermediate- γ1 mode; n−n: higher- γ1 mode.
- A. Ganguli, B. B. Sahu and R. D. Tarey, “Helicon wave modes, their damping and absorption in lossy plasma loaded conducting waveguide”, Physics of Plasmas, 14 (11), 113503 (2007); DOI: 10.1063/1.2804702
Investigation of absorption mechanisms in helicon plasmas: Absorption mechanisms of helicon waves and the associated TG waves in helicon discharges in conducting chamber were investigated experimentally. At low pressures Landau damping is the absorption mechanism, while at high pressures it is collisional absorption. The results are compared with the theory.
(Upper LHS) Schematic diagram of the experimental system showing location of the loop antennas and chamber ports in relation to the axial magnetic field (B0) profiles at various coil currents (Upper RHS) Orientation of the two loop antennas for excitation of the m = −1 azimuthal mode (RCP); loop 1 is in the y–z plane and loop 2 is in the x–y plane; the separation is such that the IPS is π/2 (Lower LHS) On-axis plots of the plasma density (n0), bulk electron temperature (Te), warm electron density (nw), warm electron temperature (Tw) and plasma potential (Vp) at ≈ 0.2–0.3mTorr of argon, rf power ≈ 945W and average magnetic field B0 ≈ 20G (plateau region). (Lower RHS) On-axis phase and amplitude plots for a low-pressure discharge. The discharge conditions for the present data were pressure ≈ 0.3mTorr, rf power ≈ 940W, B0 ≈ 17 G.
- A. Ganguli, B. B. Sahu and R. D. Tarey, “Investigation of absorption mechanisms in helicon discharges in conducting waveguides”, Plasma Sources Science and Technology, 20 (1), 015021, (2011); DOI: 1088/0963-0252/20/1/015021
- R. D. Tarey, B. B. Sahu and A. Ganguli, “Understanding helicon plasmas”, Physics of Plasmas, 19 (7), 073520, (2012); DOI: 10.1063/1.4739779
- B. B. Sahu, A. Ganguli and R. D. Tarey, “Warm electrons are responsible for helicon plasma production”, Plasma Sources Science and Technology, 23 (6), 065050, (2014); DOI: 10.1088/0963-0252/23/6/065050
Potential structures and double layers: Different types of potential jumps (multiple) were observed along the system length at different pressures. These are investigated and analyzed in detail in a series of papers.
Axial profiles of the various plasma parameters for typical helicon waves launched using plasma-loaded waveguides which shows three distinguished double layers (DLs).
- A. Ganguli, B. B. Sahu and R. D. Tarey, “Evidence of current free double layer in high density helicon discharge”, Physics of Plasmas, 20 (1), 013510, (2013); DOI: 10.1063/1.4789455
- B. B. Sahu, A. Ganguli and R. D. Tarey, “Observation of multiple current free helicon double layers”, Applied Physics Letters, 103 (18), 184105, (2013); DOI: 10.1063/1.4828559
- B. B. Sahu, R. D. Tarey and A. Ganguli, “Experimental investigation of current free double layers in helicon plasmas”, Physics of Plasmas, 21 (2), 023504, (2014); DOI: 10.1063/1.4864651
Compact ECR Plasma Source (CEPS)
The CEPS was conceived and developed (1995) as an ECR based compact source for high-density plasma, which can be attached to any suitable port of a chamber for filling it with plasma. Its total weight including the ring magnets is @ 14 kg and its length is about 60 cm.
A schematic of the Compact ECR Plasma Source (CEPS)
A photograph of the Compact ECR Plasma Source (CEPS) 60 cm long and weighing only 14 kgs that can be easily mounted to any system at any orientation.
Typical Argon plasma results from a CEPS source attached to an expansion chamber of 50 cm diameter and 75 cm long (a) bulk electron density (ne); (b) warm electron density (nw); (c) bulk electron temperature (Te); (d) warm lectron temperature (Tw); (e) plasma potential (Vp).
A patent has been granted for this development. The highlight of this development has been in its utility for various research activities of the lab which are of national importance, which include
- Developing a scalable, large volume plasma system (1000 - 1600 lts) for generating high density unifrom plasma. It would be especially useful for plasma processing industry.
- Developing a CEPS based electrodeless ECR plasma thruster that could be used for deep-space propulsion. Discussion on with ISRO for direct thrust measurements.
- Developing a large area (0.5 m dia), high current (few Amperes), hydrogen plasma source for fusion devices in the country. This is being developed under an MoU with IPR Gandhinagar.
- Initiating studies for developing high pressure discharges using CEPS for environment and biomedical applications beneficial to society.
- A. Ganguli and R. D. Tarey, ‘Permanent magnet compact electron cyclotron resonance plasma generator’ (Indian Patent # 301583 [Filing #: 66/DEL/2006] Patentee: IIT Delhi, 2006); URL: https://ipindiaservices.gov.in/publicsearch
- A. Ganguli, R. D. Tarey, R. Narayanan, A. Verma, D. Sahu and N. Arora, A Compact ECR Plasma Source Developed at IIT Delhi – Physics and Applications, An Invited Paper in Special Issue for commemorating 89th birthday of Prof MS Sodha, Asian Journal of Physics, 30 (1), 119, (2021); URL: http://demo050307.hostgator.co.in/content2/vol-30-2021/vol-30-no-1
- A. Ganguli, R. D. Tarey, N. Arora and R. Narayanan, “Development and studies on a compact electron cyclotron resonance plasma source”, Plasma Sources Science and Technology, 25 (2), 025026, (2016); DOI: 10.1088/0963-0252/25/2/025026
Characterization of the CEPS: Plasma flowing from the CEPS into small and medium sized chambers attached to it was characterized in detail. These studies have revealed some interesting and novel features of the plasma ejected from the CEPS.
(LHS) A schematic of the small volume plasma system setup, wherein a CEPS source is attached to an expansion system of dia. 15 cm and length 37.5 cm; The on-axis axial magnetic field profile in the expansion chamber is also shown. (RHS) Axial profiles of normalized quantities at 500W power and three different pressures in the SVPS: (a) 10 mTorr, (b) 5 mTorr and (c) 0.5 mTorr. The four profiles in each subplot are as follows: (i) and (ii) normalized bulk density, no(black solid line, solid square) and normalized warm density, nw (blue open circle) with respective normalizing factor (nF), given in brackets; (iii) An exponential fit on the density profile ñ0 = n0(z)/nF = exp[-(z−z0)/λn] (dashed– dotted blue line) with values of ñ0 and λn given in legend; z0 = 4.25 cm (iv) fit of the Boltzmann factor, exp(Vp(z) / Te) (red dotted line, open square) with value of the constant average axial Te given in the legend.
(Top LHS) Schematic of experimental setup and the contours (thick solid lines) of constant magnetic field with the field lines are shown inside a medium volume plasma system [MVPS] wherein the expansion chamber diameter being 50 cm and length 75 cm. Black (solid) lines are originating from inside the CEPS while red dashed lines are originating from outside the CEPS. (Top RHS) On axis magnetic field strength with fitted profile [B = B0 exp(−z/λM), λM = 9.2 cm] in expansion chamber. Expansion chamber starts at z = 0. (Bottom LHS) Normalized argon plasma density profile at different argon pressures. All the profiles are normalized with respect to their corresponding maxima. On axis magnetic field normalized with respect to peak value at z = 2.5 cm is also shown for reference. (Bottom RHS) Normalized hydrogen plasma density profile at different hydrogen pressures. All the profiles are normalized with respect to their corresponding maxima. On axis magnetic field normalized with respect to peak value at z=2.5 cm is also shown for reference.
- A. Ganguli, R. D. Tarey, R. Narayanan and A. Verma, “Evaluation of Compact ECR Plasma Source for thruster applications”, Plasma Sources Science and Technology, 28 (3), 035014, (2019); DOI: 10.1088/1361-6595/ab0969
- A. Verma, P. Singh, R. Narayanan, D. Sahu, S. Kar, A. Ganguli and R. D. Tarey, “Investigations on argon and hydrogen plasmas produced by Compact ECR Plasma Source”, Plasma Research Express, 1 (3), 035012, (2019); DOI: 10.1088/2516-1067/ab3f90
By combining multiple CEPS in a suitable manner it is possible to produce high density, uniform plasma over very large volume and large area, for industrial scale applications like, nitriding, carburizing, PIII, semiconductor processing for shallow junctions, ion beam source for ion implantation, etc. LVPS specifications: Chamber dia.: @ 1 m, Height: @1 m, Volume: @ 1600 lts., Number of CEPS: 18. A patent has been granted for this development.
A LVPS using 12 compact ECR Plasma Sources for producing uniform, large volume, high density plasma (~ 1000 to 1500 lts)
Typical radial plasma parameters with an input power of 400 W per source, 1 mTorr pressure using the LVPS configuration of 4 (blue, dotted line, filled up-triangle), 6 (red, dashed line, open circle) and 12 (black, solid line, filled square) CEPS Sources. respectively (a) Bulk plasma density n, (b) warm electron density nw, (c) bulk electron temperature Te, (d) warm electron temperature Tw, and (e) plasma potential Vp.
Apart from its potential for use in the plasma processing industry, the LVPS has been modified to be developed in to a large area hydrogen ion beam source for using in auxiliary heating or as a diagnostic source for the National Fusion Programme under an MoU with Institute for Plasma Research, Gandhinagar.
A. Ganguli and R. D. Tarey, ‘Systems for production of large volume high density plasmas for industrial applications using compact ECR plasma sources’ (Indian Patent # 345453 [Filing #: 992/DEL/2006], Patentee: IIT Delhi, 2006); URL: https://ipindiaservices.gov.in/publicsearch
- R. D. Tarey, A. Ganguli, D. Sahu, R. Narayanan and N. Arora, “Studies on plasma production in a large volume system using multiple compact ECR plasma sources”, Plasma Sources Science and Technology, 26 (1), 015009, (2017); DOI: 10.1088/0963-0252/26/1/ 015009
- R. D. Tarey, N. Arora, A. Ganguli and R. Narayanan, “Plasma production in large volume plasma system by compact electron cyclotron resonance sources”, 19th IEEE Pulsed Power Conference, June 2013; DOI: 10.1109/PPC.2013.6627515
In another recent study using a CEPS connected to large expansion chamber, it was shown that the CEPS has very good thruster properties. In argon gas it can produce a thrust of @50 mN at a pressure of @5 mTorr and @600 W of microwave power. These values are highly encouraging and have been vetted by theoretical calculations.
The CEPS is mounted to a larger expansion chamber (50 cm dia., 75 cm long) with the plasma expanding from the source into the expansion chamber along the diverging magnetic field lines.
The ion energy distribution function f (E) with respect to ion energy, E derived from a typical RFEA characteristics.
Simulated plots of (a) Bulk plasma density n; (b) bulk electron temperature Te; (c) plasma potential Vp; (d) thrust Fth [mN] as a function of pressures for Argon [black solid line, open circle] and Xenon [red dashed-dotted line, open square].
The highlight of this work has been that the plasma thruster developed uses an electrodeless scheme, enhancing the longevity of the source. Further, these results have paved the way for initiating discussion with the LPSC, team of ISRO for direct thrust measurements at their facility. The modifications required for undertaking such measurements is in process.
- A. Verma, A. Ganguli, D. Sahu, R. Narayanan and R. D. Tarey, "Thrust evaluation of compact ECR plasma source using 2-zone global model and plasma measurements", Plasma Sources Science and Technology, 29 (8), 085007 (17 pp), (2020); doi: 1088/1361-6595/ab97a5
- A. Ganguli, R. D. Tarey, R. Narayanan, A. Verma, "Evaluation of Compact ECR Plasma Source for thruster applications", Plasma Sources Science and Technology, 28 (3), 035014 (8 pp), (2019); doi: 1088/1361-6595/ab0969.
CEPS Studies on Hydrogen Plasma: Detailed studies have been conducted on hydrogen plasma produced by CEPS and allowing it to flow into an expansion. The studies have relevance for semiconductor surface modification, negative hydrogen ion beam production, etc.
- A. Verma, P. Singh, R. Narayanan, D. Sahu, S. Kar, A. Ganguli and R. D. Tarey, “Investigations on argon and hydrogen plasmas produced by Compact ECR Plasma Source”, Plasma Research Express, 1 (3), 035012, (2019); DOI: 10.1088/2516-1067/ab3f90
High Pressure Discharges Using CEPS: Studies have been initiated for surface treatment, tribology and waste mitigation.
Low / Sub-Atmospheric Pressure
Novel method of harmonic detection using RF Dual-Directional Couplers: Using a dual directional coupler between the plasma load and the matching network, it is possible to measure the entire harmonic spectrum produced in RF discharges like capacitively coupled plasmas, for gaining insight into the nonlinear mechanisms generating the harmonics. A patent has been applied for this work.
A scheme for transformation of plasma impedance from the powered electrode (in contact with the rf plasma) of a capacitively-coupled rf discharge to the dual directional coupler (DDC2) plane Ã2.
The estimation of the harmonic power using this scheme (a) Plasma density ne measured using a compensated Langmuir probe and (b) RF harmonic power content (second, third and sixth harmonic) using DDC2 versus Argon gas pressure at fixed 10 W RF power.
The novelty of this scheme is that in spite of the DDC2 being placed in a region of strong standing wave formation, between the nonlinear plasma load and the matching network, the forward and reflected powers in the line can be estimated separately. This non-invasive scheme is thus able to provide a host of rf electrical parameters which define the electrical characteristics of the nonlinear plasma load.
- A. Ganguli, A. Rawat, R. D. Tarey and R. Narayanan, Non-invasive diagnostic for characterizing harmonics in a Radio Frequency discharge (Patent Filing Application No. 201911044619, 2019)
A. Rawat, A. Ganguli, R. Narayanan, R. D. Tarey, “A novel ex situ diagnostic technique for characterizing harmonics in radio frequency discharges”, Review of Scientific Instruments, 91 (9), 094705, (2020); DOI: 1063/5.0009015
- Arti Rawat, “Development of diagnostics for characterizing electron heating mechanisms in low-pressure rf discharges” Doctoral Thesis submitted to Indian Institute of Technology Delhi in June 2021
E probe for power density measurement in RF discharges: A novel J.E probe was developed for measuring absorbed power density in RF discharges at the fundamental and its harmonics. A patent has been applied for this work.
(a) A complete probe assembly drawing and (b) a photograph of probe head.
(a) A schematic and (b) photograph of the probe installed in the CCD system
The highlight of this work is that it has provided key insights into the nature of RF power absorption in rf-driven, capacitively coupled rf discharges (CCD). As CCD discharges are widely used in the industry, these studies will not only enable one to improve the models of the CCD discharge, but also identify methodologies to improve the efficiency of these systems for industrial purposes.
- A. Ganguli, A. Rawat, R. D. Tarey and R. Narayanan, “J.E probe to measure local plasma electron heating in RF discharges”, Patent Filing Application No. 202111003158, (2021)
- Arti Rawat, “Development of diagnostics for characterizing electron heating mechanisms in low-pressure rf discharges” Doctoral Thesis submitted to Indian Institute of Technology Delhi (2021)
- A. Rawat, A. Ganguli, R. Narayanan and R. D. Tarey, “A novel J.E probe for power density measurement in RF discharges”, Paper under preparation for Review of Scientific Instruments.
Radio frequency atmospheric plasmas using co-planar multi-structured electrodes: A co-planar multi-structure electrode antenna array was designed and fabricated in the lab on a glass-epoxy substrate to produce high pressure rf Dielectric Barrier Discharges (DBD) discharges at pressures ≈ few 100s Torr and rf power ≈ few 10s of Watt.
(Top) Schematic block diagram of experimental setup (Second row, LHS) Enlarged view inter-digited electrodes in micro-structured electrode (MSE) array (Second row, RHS) Coplanar micro-structured electrode plasma generation (Third row) Photograph of a typical rf plasma using MSE array
- Aamir Hussain and Sudeep K. Gupta, “Generation of radio frequency atmospheric pressure plasma using micro-structured electrodes”, Bachelor Thesis submitted to Indian Institute of Technology Delhi (2005)
Coaxial and Planar DC Discharge Systems: DC discharge sources in coaxial and planar electrode configurations have been developed for basic studies to study effect of boundaries and electrode asymmetry on the discharge dynamics.
(LHS) A schematic diagram of the coaxial electrode dc discharge system and external circuit connection; (RHS) A Typical discharge behavior in the coaxial dc syste (i) Id - Vd characteristics of the coaxial DC discharge at p ≈ 850 mTorr (ii) Hysteresis in the amplitudes of self-excited oscillations with increasing (Symbol: solid circle, Color: Black) and decreasing (Symbol: solid square, Color: Red) Id. The floating potential oscillations (Vf) were recorded as the discharge current was increased or decreased. A0 - A10 and B0 - B10 points are mentioned on the curve for increasing and decreasing Id. The 2nd NDR region is magnified in the inset in (i).
Experimental systems: (a) conducting boundary (CB) configuration (discharge is exposed to the whole ss chamber) and (b) small volume insulating boundary (SVIB) configuration [discharge is enclosed within glass tube (red dashed line) and mica sheets. Top and bottom mica (TM and BM, green dashed dotted dotted lines) are used to protect the discharge striking between the chamber and back side of electrodes]. (c) Large volume insulating boundary (LVIB) configuration [discharge is bounded by an insulating boundary all along the chamber walls using mica layers (dashed dotted dotted lines)].
- R. Kumar, R. Narayanan, R D Tarey and A. Ganguli, “Hysteresis Flip Effects on the DC Plasma Discharge Characteristics of a Co-Axial Electrode Geometry”, Proceedings (P2.56) of the 32nd International Conference on Phenomenon in Ionized Gases (ICPIG2015) held between July 26-31, 2015 at the Alexandru Ioan Cuza University in Iasi, Romania (2015); URL: https://www.plasma.uaic.ro/icpig2015/Content/Posters/P2.56.pdf
- P. K. Barnwal, S. Kar, R. Narayanan, A. Ganguli and R. D. Tarey, “Dependence of anode glow on surrounding geometry in a parallel plate glow discharge plasma”, Conference proceedings of 33rd International Conference on Phenomena in Ionized Gases, ICPIG 2017, July 9-14, 2017, Estoril Congress Centre, Estoril, Portugal, pg. 252 (2017); URL: http://icpig2017.tecnico.ulisboa.pt/wp-content/uploads/2017/06/ICPIG2017_proceedings.pdf
- P. K. Barnwal, S. Kar, R. Narayanan, R. D. Tarey and A. Ganguli, “Plasma boundary induced electron-to-ion sheath transition in planar DC Discharge”, Physics of Plasmas, 27 (1), 012110, (2020); doi: 10.1063/1.5108597.
- R. Kumar, R. Narayanan and A. Prasad, “Hysteresis in amplitudes of self-excited oscillations for co-axial electrode-geometry DC glow discharge plasma”, Physics of Plasmas, 21 (12), 123501, (2014); doi: 10.1063/1.4901578
Characterization of nonlinear effects in dc discharges: DC discharges depict a rich source of nonlinear behavior, such as Negative Differential Resistance (NDR), Anode Glows and its dynamical transitions, order-to-chaos-to-order transitions fluctuation, etc. These characteristics have been analyzed using time-series and non-linear dynamical tools.
(Top) Typical floating potential fluctuations obtained from a coaxial electrode dc discharge system with increasing and decreasing discharge current (Id); (Top, LHS) Id = 7.4, 14.5 and 16.4 mAa; (Top, Middle) Id = 17.7, 18.7, 20.4 and 22 mA (Top, RHS) Id = 24.1, 26 and 28 mA (Bottom, LHS) Return map for all regions (a, b for increasing current and c, d for decreasing current). The corresponding Id values for both increasing and decreasing cases are: (Symbol: solid circle, Color: Orange) = 7.4mA; (Symbol: open circle, Color: Red) = 14.5mA; (Symbol: open square, Color: Navy) = 16.5mA; (Symbol: solid square, Color: Wine) = 17.7mA; (Symbol: open triangle vertex left, Color: Black) = 18.7mA; (Symbol: open triangle vertex up, Color: Magenta) = 20.4mA; (Symbol: open triangle vertex down, Color: Blue) = 22mA; (Symbol: solid triangle vertex right, Color: Green) = 24.1mA; (Symbol: solid triangle vertex up, Color: Dark Cyan) = 26mA; (Symbol: solid triangle vertex down, Color: Dark Yellow) = 28.1mA. (Bottom, RHS) Id = 7.4, 14.5 and 16.4 mA 3d phase space plots of floating potential recorded for increasing Id: (a) period-2 region, Id = 7.4 mA, (b) chaotic region, Id = 14.5 mA, and (c) period-1 region, Id = 26.0 mA indicative of an order – to – chaos – to – order transition in the floating potential fluctuations.
- R. Kumar, R. Narayanan and A. Prasad, “Hysteresis in amplitudes of self-excited oscillations for co-axial electrode-geometry DC glow discharge plasma”, Phys. Plasmas, 21 (12), 123501, (2014); doi: 10.1063/1.4901578
Non-Thermal Atmospheric Plasma jet: Two nonthermal plasma jets have been developed recently at the Plasma Lab, IIT Delhi. One is a low frequency (AC) plasma jet whereas the other is by rf (27.12 MHz). These are being utilized for various environment and biomedical applications, which include Bactericidal activities, decreasing contact angle of bio-materials.
Non-thermal plasma jets developed at Plasma IIT Delhi, rf (27.12 MHz) plasma jet setup with the jet in the left side of the photo and the rf source on the right side of the photo
Typical applications for which the developed plasma jets are under investigations.
30kHZ AC Argon plasma jet treatment on E-coli bacteria (10-6 concentration)
Changes in hydrophilicity of the 3D printed Polylactic Acid (PLA): a biodegradable thermoplastic polymer: Water droplet contact angle decreased from (a) untreated PLA 80 ̊ (b) after CAP treatment for 6 min 18.5 ̊
- S. Kar, M. Khan, V. Gajula, A. Ganguli, D. Sahu, R. Narayanan, “Development of a novel electrical characterization technique to diagnose an rf atmospheric pressure plasma jet”, Poster presentation in 47th IEEE International Conference on Plasma Sciences (ICOPS-2020 [VIRTUAL]) and 2nd Asia-Pacific Conference on Plasma and Terahertz Science (APCOPTS-2020 [VIRTUAL]), online conference organized from Singapore from December 6-10, 2020. Paper-ID: TA6-S3-004; Programme Booklet: ICOPS 2020 Abstract e-booklet.pdf
Plasma Pyrolysis for waste mitigation: The lab is in the process of installing two plasma pyrolysis plants for waste management studies. One is already being set up adjacent to the Babarpur drain under East Delhi Municipal Corporation (EDMC) whereas the other is planned to be setup in IIT Delhi Campus as a Central Research Facility for undertaking research activities towards improving plant operation in terms of energy efficiency and environment management.
Plasma – Liquid Interaction: The lab has recently initiated work on plasma-liquid interactions at atmospheric pressure.
Theoretical and Simulation Studies
PIC and Molecular Dynamics Simulations: Fluid, Particle – In – Cell (PIC) and Molecular Dynamics simulation techniques are employed to unravel frontier problems of nonlinear and strongly coupled plasma medium and its interaction with intense laser radiation.
Some recent achievements in this regard are as follows:
- Novel scheme of laser energy absorption in magnetized plasma has been proposed .
- An unconventional mechanism of magnetic field generation in beam plasma system 
- Whistler wave and R&L wave excitation by a laser interacting with a strongly magnetized plasma has been illustrated. The electrostatic disturbances generated by the ponderomotive force of a finite laser pulse results in the absorption of the laser energy. 
- A. Vashistha, D. Mandal, A. Kumar, C. Shukla, and A. Das, “A new mechanism of direct coupling of laser energy to ions”, New J. Phys., 22 (6), 063023 (6 pp), (2019); doi : https://doi.org/10.1088/1367-2630/ab8cad
- A. Das, A. Kumar, C. Shukla, R. K. Bera, D. Verma, D. Mandal, A. Vashishta, B. Patel, Y. Hayashi, K. A. Tanaka, G. Chatterjee, A. D. Lad, G. R. Kumar and P. Kaw, “Boundary driven unconventional mechanism of macroscopic magnetic field generation in beam-plasma interaction”, Phys. Rev. Res., 2 (3), 033405 (6 pp), (2020); doi: 10.1103/PhysRevResearch.2.033405.
- L. P. Goswami, S. Maity, D. Mandal, A. Vashistha and A. Das, “Ponderomotive force driven mechanism for electrostatic wave excitation and energy absorption of Electromagnetic waves in overdense magnetized plasma”, (2021); arXiv:2104.09320v2
Modeling of electrodeless plasma thruster: Electric propulsion schemes exhibit higher fuel efficiency, although they yield much lower thrust than their chemical counterparts and hence are the natural choice for deep space missions. Among them the electrode-less thrusters, namely electron cyclotron resonance (ECR) thruster as well as helicon plasma thruster (e.g., VASIMR), have much longer lifetime than their electrode based counterparts. The lab has initiated investigations of the plasma dynamics in these electrodeless plasma thrusters using computer simulations. The work is being supported by ISRO.