Technology Developed

Plasma Sources

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

  1. 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.
  2. Developing a CEPS based electrodeless ECR plasma thruster that could be used for deep-space propulsion. Discussion on with ISRO for direct thrust measurements.
  3. 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.
  4. Initiating studies for developing high pressure discharges using CEPS for environment and biomedical applications beneficial to society.

Patent:

  • 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)

Important Reference:

  • 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 Sci. Technol., 25 (2), 025026, (2016); DOI: 10.1088/0963-0252/25/2/025026

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.

Patent:

A. Ganguli, R. D. Tarey R D, ‘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)

Important Reference:

  • 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 Sci. Technol., 26 (1), 015009, (2017); DOI: 10.1088/0963-0252/26/1/ 015009
  • R. D. Tarey, N. Arora, A. Ganguli, 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.

Important References:

  • 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, Plasma Sources Science and Technology, 28 (3), 035014 (8 pp), (2019) doi: 1088/1361-6595/ab0969.

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). It is being utilized for various environment and biomedical applications, which include Bactericidal activities, decreasing contact angle of bio-materials.

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

Schematic layout of the atmospheric plasma jet

Important Reference:

  • M. Khan, G. Vedaprakash, A. Ganguli, S. Kar, 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 Diagnostics

Particle Diagnostics

Standard Langmuir probes and electron and ion energy analyzers were developed and built for use in various experiments.

Typical Conventional Langmuir Probe schemes

A typical probe current (I) – probe bias voltage (V) characteristics of the Langmuir probe

Typical plasma parameters obtained from I – V characteristics of the Langmuir probe.

A typical Ion Energy Analyzer (IEA)

A typical IEA collector current characteristic

Typical beam energy estimated from the IEA

A typical Electron Energy Analyzer (EEA) (LHS, Top) layout (LHS, Middle) circuitry; (LHS, Bottom) A typical EEA collector current characteristic; (RHS) Typical beam energy estimation from the EEA.

Important References:

  • A. Ganguli, P A. Naidu and D. P. Tewari, “Studies on Microwave-Induced Plasma Production Using Helical Slow-Wave Structures”, IEEE Trans. Plasma Sci., 19 (2), 433, (1991); DOI: 10.1109/27.106843

  • Mukesh Pandey, “Design, Fabrication and Testing of ion energy analyzer for plasma diagnostics”, Master’s Thesis dissertation submitted to Indian Institute of Technology Delhi, India (1991)

  • Rajendra Kumar Jarwal, “Characterization of electron cyclotron resonance discharges produced by a slotted helical antenna in a mirror machine”, Doctoral Thesis submitted to Indian Institute of Technology Delhi, India (1995)

A novel RF compensated Langmuir probe (LP) was developed for LP diagnostics in helicon experiments. The probe was compensated for the fundamental and two harmonics. Similar probes were used for capacitively coupled discharges.

(a)Schematic of a compensated Langmuir Probe showing details of the probe when in use inside the plasma and (b) its configuration during tuning in the absence of plasma (c) RF equivalent circuit of the probe at the plane A-A in the presence of RF produced plasma and (d) at B-B in the absence of plasma during tuning;

(a) RF equivalent circuit of the structure given in LHS (b) at the plane BB. (b) Tuning of filters for 3 -stage CLP showing measured amplitude and phase of ZBB as a function of frequency for the tuned probe. (c) Comparison of I-V characteristics obtained from (i) Compensated LP (red dash-dotted line) and (ii) Uncompensated LP (black solid line) in a capacitively-coupled rf discharge system at a pressure of 60 mTorr and 10 Watt, RF power.

The highlight of this work is that the probe can be tuned in the absence of the plasma but remains tuned in the presence of plasma, when mounted onto a plasma discharge. This scheme is now being utilized in various labs across the world and the associated publication [given below] is a highly cited reference.

 Important Reference:

  • A. Ganguli, B. B. Sahu and R. D. Tarey, “A new structure for RF-compensated Langmuir probes with external filters tunable in the absence of plasma”, Plasma Sources Sci. and Technol., 17 (1), 015003 (2007); DOI: 1088/0963-0252/17/1/015003

A universal LP has been developed for operation in normal as well as RF environment.

Universal probes that can be used both in normal and rf environment (Top) A typical RF compensated Langmuir probe with the compensation done using the circuit in the aluminium box on the right of photograph. (Bottom) A typical normal Langmuir probe without the compensation box.

Important References:

  • A. Ganguli, B. B. Sahu and R. D. Tarey, “A new structure for RF-compensated Langmuir probes with external filters tunable in the absence of plasma”, Plasma Sources Sci. Technol., 17 (1), 015003, (2007); DOI: 1088/0963-0252/17/1/015003
  • A. Rawat, A. Ganguli, R. Narayanan, R. D. Tarey, “Correlation of stochastic and ohmic power absorption with observed RF harmonics and plasma parameters in capacitively coupled discharges”, Plasma Res. Exp., 2 (3), 035015, (2020); doi: 10.1088/2516-1067/abb56f

The Compact ECR Plasma Source (CEPS); Patent: IIT Delhi) has a very harsh ECR zone with high plasma density and high-energy ions. To conduct LP measurements inside the CEPS and measure ion energies close to it requires special designs of the LP and RFEA.

(Top LHS) A photographic view of the Special Langmuir Probe for harsh ECR measurement studies; (Top RHS) Photograph of the probe tip; (Bottom) A schematic of the Special Langmuir Probe.

Two photographic views of the Special Retarding Field Ion Energy Analyzer (RFEA) developed for harsh ECR measurement studies

Schematic layout of the RFEA

(a) Collector Current (Ic) – Discriminator Voltage (Vd) characteristics measured using the RFEA positioned just in front of a compact ECR Plasma Source (black, dashed-dot line) and slightly away from the source (red, solid line).

Important References:

  • 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 Sci. Technol., 29 (8), 085007, (2020); DOI: 10.1088/1361-6595/ab97a5

Plasma Wave Diagnostics

Plasma wave electric field and wavelength measurement at microwave frequencies: Wavelengths and electric fields of plasma waves generated by high power microwaves at 2.45 GHz were measured using interferometric techniques (using mixers) [Fig 1,2,3] and capacitively coupled high-frequency E-probes [Fig. 4,5].

[Fig. 1] A block diagram of the interferometric arrangement for wavelength measurements.

[Fig. 2] MIC based mixer for microwave interferometry

[Fig. 3] A typical wavelength interferogram. The envelopes of the dominant-long-waves (dlw) have been defined by the dashed curve. An enlarged view of a typical short-wave-burst (swb) is shown in the insert. The locations of the different peaks (cm) and the corresponding magnetic fields (in parentheses) have been marked.

Fig 4: (Top) A typical capacitive-coupled high frequency E-probe (Bottom) Two typical measured radial profiles of the radial electric field. The plot shows normalized |Er2| values versus radial position, r.

Important References:

  • A. Ganguli, M. K. Akhtar and R. D. Tarey, “Investigation of microwave plasmas produced in a mirror machine using ordinary-mode polarization”, Plasma Sources Sci. Technol., 8 (4), 519, (1999); DOI: 10.1088/0963-0252/8/4/301
  • A. Ganguli, M. K. Akhtar, R. D. Tarey and R. K. Jarwal, “Absorption of left-polarized microwaves in electron cyclotron resonance plasmas”, Phys. Lett. A, 250 (1-3), 137, (1998); DOI: 10.1016/S0375-9601(98)00833-0

Plasma wave magnetic field and wavelength measurement at radio wave frequencies: The RF wave magnetic field was sensed using a B-dot probe, built in-house. The wavelength was measured using a vector-voltmeter, with reference signal from RF power source. The signal from the B-dot probe was amplified and integrated to yield B.

(Top) Photograph of a compensated Langmuir probe [upper one] and a B-dot probe [lower one] (Bottom) A typical on-axis phase and amplitude plots from the B-dot probe

Important References:

  • A. Ganguli, B. B. Sahu and R. D. Tarey, “Investigation of absorption mechanisms in helicon discharges in conducting waveguides”, Plasma Sources Sci. Technol., 20 (1), 015021, (2011); DOI: 10.1088/0963-0252/20/1/015021

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. 

Patents:

  • 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)

Important References:

  • A. Rawat, A. Ganguli, R. Narayanan, R. D. Tarey, “A novel ex situ diagnostic technique for characterizing harmonics in radio frequency discharges”, Rev. Sci. Instrum., 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.

Patent:

  • 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)

Important References:

  • 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.

Instrumentation Developed

High Power Microwave Instrumentation

Various high power, passive components have been designed and fabricated for the high power microwave experiments using the Compact ECR Plasma Sources (CEPS: Patent: IIT Delhi) and the Large Volume Plasma System (LVPS; Patent: IIT Delhi). Components include: launcher section (for coupling magnetron to waveguide), rectangular to circular waveguide converters, waveguide triple stub tuner, E-plane and H-plane bends, quartz vacuum window, waveguide sections, etc. To reduce weight most components were fabricated from aluminum.

Photos of an assortment of some of the high power passive microwave components fabricated and developed in the lab: (Top left) E-bend; (Top Middle) Two-back-to-back H-bends; (Top RHS) rectangular-to-circular waveguide; (Middle, LHS) triple-stub-tuner; (Middle, Middle) waveguide launcher; (Middle, RHS) High power variable polarizer; (Bottom, LHS) High power Arbitrary Ratio Power Splitter; (Bottom, RHS) High power coaxial Triple Stub Tuner

Schematic of a typical high-power microwave vacuum seal

Important References:

  • Navneet Arora, “Characterization of the plasma in a large volume plasma system produced by compact electron cyclotron resonance sources”, Doctoral Thesis submitted to Indian Institute of Technology Delhi, India (2012)
  • Md. Kamran Akhtar, “Investigation of high-frequency guided-wave modes in microwave produced plasmas”, Doctoral Thesis submitted to Indian Institute of Technology Delhi, India (1996)
  • Rajendra Kumar Jarwal, “Characterization of electron cyclotron resonance discharges produced by a slotted helical antenna in a mirror machine”, Doctoral Thesis submitted to Indian Institute of Technology Delhi, India (1995)
  • 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)
  • R. Baskaran “High Density Electron Cyclotron Resonance Plasma production by slotted line antennas”, Ph.D. thesis, degree awarded by Indian Institute of Technology Delhi (1988)

An arbitrary ratio power splitter that can split the input CW microwaves at 2.45 GHz, 100 – 3kW power, into two arms was developed, tested and used in experiments. The test results were verified theoretically using scattering matrix formulation.

Photograph of the arbitrary ratio power splitter developed in the lab mounted on a microwave line

Schematic diagram of the arbitrary ratio power splitter

Photograph of the arbitrary ratio power splitter

Important References:

  • A. Ganguli and R. Baskaran, “New high‐power arbitrary ratio power splitter at microwave frequencies”, Rev. Scientific Instrum., 58 (6), 1123, (1987); DOI: 10.1063/1.1139569

The line uses indigenously developed coaxial triple stub tuner, along with low loss mica microwave-vacuum window for high power plasma applications with arbitrary impedance matching capability.

Photograph of the high power coaxial triple stub tuner

Cross sectional view of the high power coaxial triple stub tuner

Important References:

  • A. Ganguli, R. Baskaran, P. A. Naidu and G. V. R. Raju, “High power microwave line with arbitrary impedance matching capability for plasma applications”, Rev. Sci. Instrum., 60 (2), 244, (1989); DOI: 1063/1.1141072

A high power polarizer with capability to mix LCP and RCP in arbitrary ratio for the TE11 dominant mode of a circular guide was designed, fabricated and used in experiments.

A photograph of the circular polarizer with capability to mix LCP and RCP in arbitrary ratio for the TE11 dominant mode; a Teflon insert (not shown) is placed inside the polarizer for proper operation

Important References:

  • A. Ganguli, M. K. Akhtar, R. D. Tarey and R. K. Jarwal, “Absorption of left-polarized microwaves in electron cyclotron resonance plasmas”, Phys. Lett. A, 250 (1-3), 137, (1998); DOI: 1016/S0375-9601(98)00833-0
  • 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 Sci. Technol., 6 (2), 189, (1997); DOI: 10.1088/0963-0252/6/2/013

High Power RF Instrumentation

A novel technique for launching left or right polarized helicon or any other EM wave in plasma was developed. The method uses two loop antennas, oriented orthogonally and energized in quadrature phase. The separation between the loops controls the wavelength and their phasing, the polarization (left or right). Above all, the technique uses only one RF power supply.

A photograph of the phased-antenna

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

Important References:

  • A. Ganguli, B. B. Sahu and R. D. Tarey, “Investigation of absorption mechanisms in helicon discharges in conducting waveguides”, Plasma Sources Sci. Technol., 20 (1), 015021, (2011); DOI: 10.1088/0963-0252/20/1/015021

Electronic Instrumentation

Low Cost, Microwave Power Supply for Plasma Applications: In microwave ovens, low cost, 800-Watt magnetrons are operated in short pulses (with high peak power) to save cost of power supply. Since the magnetrons are very rugged, these can be used for plasma applications in CW mode (without exceeding the average power rating of the magnetrons), by designing an appropriate power supply with continuously variable power output. Such power supplies have been built in large numbers for the Compact ECR Plasma Sources (CEPS: Patent: IIT Delhi) and operated continuously for hours without isolators in large numbers for the Large Volume Plasma System (LVPS; Patent: IIT Delhi) and other experiments.

A stack of six Low Cost, 800 W magnetron power supply systems for plasma applications

Important References:

  • A. Ganguli, R. D. Tarey, N. Arora, R. Narayanan and K. Akhtar, “Development of compact electron cyclotron resonance plasma source”, 19th IEEE Pulsed Power Conference, June 2013; DOI: 1109/PPC. 2013.6627514
  • A. Ganguli, R. D. Tarey, N. Arora and R. Narayanan, “Development and studies on a compact electron cyclotron resonance plasma source”, Plasma Sources Sci. Technol., 25 (2), 025026, (2016); DOI: 10.1088/0963-0252/25/2/025026
  • 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 Sci. Technol., 26 (1), 015009, (2017); DOI: 10.1088/0963-0252/26/1/ 015009
  • R. D. Tarey, N. Arora, A. Ganguli, 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

LabVIEW Controlled Data Acquisition and LP Power Supply: A Data Acquisition Card (DAC) from National was configured on a LabVIEW platform to acquire Langmuir probe (LP) data. The LP power supply accepts a trigger from the DAC and produces an appropriate voltage ramp. The Start and Stop voltages for the scan, the duration of the ramp, the number of data points, etc. are all controlled from the LabVIEW program. The measured LP voltage and current are sampled and displayed.

(LHS) A photograph of the simultaneous sampling data acquisition card [NI 6143S] in conjunction with LP control module (RHS) The LABVIEW GUI pic for data control

Block diagram of the Langmuir Probe (LP) Power supply

Important References:

  • Navneet Arora, “Characterization of the plasma in a large volume plasma system produced by compact electron cyclotron resonance sources”, Doctoral Thesis submitted to Indian Institute of Technology Delhi, India (2012)

Software / Programs Developed

Generation of Bessel Functions: Algorithms and programs were developed for generating the Bessel functions Jn(z) and Yn(z) and their derivatives, where z is complex and n an integer.

The numerically computed numbers for the Bessel functions (Top) Jn(x) (n = 0); (Middle) Yn(x) (n = 0) and (Bottom) Jn(x) (n = 50) .

Important References:

  • A. Ganguli and R. Baskaran, “Generation of Bessel Functions with Complex Arguments and Integer Orders”, Int. J. Comp. Math., 21 (1), 43, (1987); DOI: 10.1080/00207168708803556

Interactive Graphics based Software for Langmuir Probe Data Analysis: A Fortran-cum-Windows based software was developed for undertaking interactive analysis of LP data as early as in 1995. Over time this software was replaced by faster MATLAB, GUI-based programs.

A GUI Interface, developed in-house, for an interactive Langmuir Probe analysis programme to estimate the plasma parameters for a typical Langmuir probe bias-probe current characteristics.

Important References:

  • A. Ganguli and R. D. Tarey, “An Interactive Graphics Based Software Package for Processing and Analyzing Langmuir Probe Data” IIT Delhi Internal Report (1995)

Guided wave modes: Programs were developed for computing high-frequency whistler (microwaves) and helicon (MHz) modes of plasma-loaded waveguides, their absorption.

(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) 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.

Important References:

  • A. Ganguli, M. K. Akhtar and R. D. Tarey, “Theory of high-frequency guided waves in a plasma-loaded waveguide”, Phys. 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”, Phys. Plasmas, 14 (10), 102107, (2007); DOI: 10.1063/1.2799161
  • A. Ganguli, B. B. Sahu and R. D. Tarey, “Helicon wave modes, their damping and absorption in lossy plasma loaded conducting waveguide”, Phys. Plasmas, 14 (11), 113503, (2007); DOI: 10.1063/1.2804702

Global Model: A two-zone global model was developed for determining plasma parameters in the ECR (source) region (CEPS) and the expansion chamber into which the plasma is ejected from the source. The calculations yield the flux and energy of ions exiting the source region from which the thrust imparted by the ions is determined.

(Top, LHS) (a) Schematic of the thruster model with the plasma source represented by Zone 1 and the expansion chamber representing Zone 2. (Top, RHS) Plasma parameters at different pressure in Zone-1 (blue squares) and a comparison with the experimental values (red circle) are shown here. Zone-2 represents actual size of MVPS with perfectly reflecting walls for the gas particles. Microwave power = 600 W. (a) plasma density; (b) electron temperature and (c) plasma potential; (Bottom, LHS) Zone 2 parameter for the same initial conditions; (Bottom, RHS) Simulated results in Zone 2 for (a) Ion energy; (b) ion velocity and (c) thrust produced by plasma in Zone-1 for same initial conditions.

Important References:

  • 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 Sci. Technol., 29 (8), 085007, (2020); DOI: 10.1088/1361-6595/ab97a5