ADITYA is the first indigenously designed and built tokamak of the country. It was commissioned in 1989.
ADITYA, a medium size Tokamak, is being operated for over a decade. It has a major radius of 0.75m and minor radius of the plasma is 0.25 m. A maximum of 1.2 T toroidal magnetic field is generated with the help of 20 toroidal field coils spaced symmetrically in the toroidal direction. The major subsystems and parameters of the machine have been described elsewhere.
ADITYA is regularly being operated with the transformer-converter power system. ~100 msec 80 - 100 kA plasma discharges at toroidal field of 8.0 kG are being regularly studied. During this period experiments on edge plasma fluctuations, turbulence and other related works have been conducted. Standard diagnostics have been employed during these measurements. Figure below gives a view of ADITYA with the auxiliary heating systems attached to it.
ADITYA has been upgraded. Upgradation has been in different fronts. Vacuum system has been upgraded interms of more cleaning facilities. As found earlier, successful breakdown and startup require compensation of the error magnetic fields in the first few milliseconds. This is accomplished using the four fast feedback coils connected to give a radial magnetic field. Recent measurements of the magnetic fields due to the TR coils and BV coils also indicate the need for compensation of the error fields. The compensation also helped in improving the operating pressure range, which has the beneficial effect of reducing hard x-rays during the discharge. Plasma current feedback on the loop voltage and vertical field also is implemented.
Some more diagnostics have been integrated and made on-line. Some are in the design/fabrication phase. To increase the plasma energy content during the discharge, auxiliary heating systems have been integrated. A 20 - 40 MHz, 200 KW Ion Cyclotron Resonance Heating (ICRH) system has been integrated to ADITYA vacuum vessel and successfully operated in the last campaign. A 28 GHz, 200 KW gyrotron based electron cyclotron resonance heating (ECRH) system has also been successfully commissioned on ADITYA tokamak. Some neural network analysis to predict disruptions and density limit on ADITYA have also been performed.
Steady State Superconducting Tokamak
A steady state superconducting tokamak SST-1 is under design and
fabrication at the Institute for Plasma Research. The objectives of
SST-1 include studying the physics of the plasma processes in tokamak
under steady state conditions and learning technologies related to
the steady state operation of the tokamak. These studies are expected
to contribute to the tokamak physics database for very long pulse
operations. The SST-1 tokamak is a large
aspect ratio tokamak, configured to run double null
diverted plasmas with significant elongation (k)
and triangularity (d).
The specific objective of
the SST-1 project is to produce 1000 s elongated double null divertor
plasma.There are several conventional questions in
tokamak physics, which will be addressed again in steady state
scenario. Some of these are related to the energy, particle and
impurity confinement, the effect of impurities and edge localized
modes (ELM) in steady on energy confinement, the stability limits and
their dependence on current drive methods, the resistive tearing
activities in presence of RF fields, disruptions and vertical
displacement events (VDE), and thermal instability. In steady state
operations non-inductive current drive will sustain the plasma
current. Different aspects of current drive such as different current
drive methods and their combinations, current drive efficiency,
profile control and bootstrap current, will be studied. An efficient
divertor is required for the steady state operations with elongated
plasma. Various aspects of divertor operation such as steady state
heat and particle removal, erosion and particle recycling, radiative
divertors and pumped divertors will be studied. Advance tokamak
regimes are of prime interest in fusion research. These regimes are
characterized with high bN
and high bootstrap current, and are generally obtained in high
(H-mode) and very high (VH-mode) confinement modes in plasma with
high triangularity, elongation and large negative shear. Although
SST-1 is not optimized for advanced tokamak regimes, we propose to
attempt some experiments in this direction with in the limitations of
The choice of the parameters is dictated by
the technological and physics goals. NbTi
superconductor at 4.5K is used for the superconducting
magnets and maximum field at the conductor is restricted to 5.1 T.
Low aspect ratio machines are difficult to design using
superconducting coils due to space restrictions. Furthermore, higher
aspect ratios have the advantages such as high bootstrap current,
better confinement etc. We have, therefore, opted for large aspect
ratio (~5) in SST-1. Other Tokamaks have observed substantial
improvement in confinement (VH mode) and bNwith higher triangularity (d~0.4-0.8).
Elongation improves the current carrying capacity of the plasma. With
elongation in the range of k~1.6-2.0
improvement in bNhas been observed. We
have, therefore, chosen a range of k
and d similar to these ranges.
The double null configuration allows for the distribution of power
between larger number of divertor plates thus reducing the heat load
per plate. We have, therefore, selected double null configuration,
with a provision to go to single null operations in future.
The machine has a major
radius of 1.1 m, minor radius of 0.20 m, a toroidal field of 3.0 T at
plasma center and a plasma current of 220 kA. Elongated plasma with
elongation in the range of 1.7 to 1.9 and triangularity in the range
of 0.4 to 0.7 can be produced. Hydrogen gas will be used and plasma
discharge duration will be 1000 s. Auxiliary current drive will be
based mainly on 1.0 MW of Lower Hybrid current drive (LHCD) at 3.7
GHz. Auxiliary heating systems include 1 MW of Ion Cyclotron
Resonance Heating (ICRH) at 22 MHz to 91 MHz, 0.2 MW of Electron
Cyclotron Resonance heating (ECRH) at 84 GHz and a Neutral Beam
Injection (NBI) system with peak power of 0.8 MW (at 80 keV) with
variable beam energy in range of 10-80 keV.
Superconducting (SC) coils
for both toroidal field (TF) and Poloidal Field (PF) are to be
deployed in the SST-1 tokamak. An ultra high vacuum (UHV)
compatible vacuum vessel, placed in the bore of the TF coils, houses
the plasma facing components (PFC). A high vacuum cryostat encloses
all the SC coils and the vacuum vessel. Liquid Nitrogen (LN2)
cooled thermal shield between the vacuum vessel & SC coils as
well as between cryostat and the SC coils reduce the radiation heat
load on the SC coils. Normal conductor ohmic transformer system is
provided to initiate the plasma and sustain the current for initial
period. A pair of vertical field coils is provided for circular
plasma equilibrium at the startup stage of the plasma. A set of
saddle coils placed inside the vacuum vessel provide fast vertical
control of the plasma while PF coils are to be used for shape
control. Other subsystems include radio frequency (RF) systems for
pre-ionization, auxiliary current drive and heating, neutral beam
injection (NBI) system for supplementary heating, cryogenic systems
at liquid helium (LHe) and LN2 temperatures, chilled water
system for heat removal from various subsystems. A large number of
diagnostics for plasma and machine monitoring will be deployed along
with a distributed data acquisition and control system.
Basic Plasma Physics Experiments
A number of basic plasma physics experiments are operational in IPR. Some
of the major experiments are Large volume plasma device (LVPD),
Free-Electron Laser (FEL) Experiment, Non-neutral toroidal plasma, Dusty
plasma experiments, plasma nitriding studies, plasma immersed ion implantation, anode arc
studies, radio frequency experiments etc.
In the LVPD experiments, detailed studies are being carried out on
excitation and propagation of whistler waves. In the FEL experiment,
sheet relativistic electron beam is propagated through a fifty period
electromagnet wiggler and radiation in microwave ferquency range is
observed. Study of dicotron instability and electron cloud behavior in
toroidal magnetic field is done in non-neutral plasma experiment.
Excitation of dust acoustic waves, formation of coulomb crystal etc is
studied in dusty palsma experiments. Physics of plasma -surface
interaction and wave-particle interaction is studied in plasma nitriding
and rf experiments respectively.
The Facilitation Centre for
Industrial Plasma Technologies links the Institute for Plasma Research with
the industry. The knowledge
base in plasma sciences and associated technologies is exploited to generate
advanced plasma based technologies for material processing and environmental
was set up in 1997 to promote the commercial exploitation of IPR Plasma
technologies through development, incubation, demonstration, manufacturing
and transfer. The Centre has process
development and instrumentation laboratories,
material characterisation and
Advanced plasma process development
is realized by validation experiments, scale-up and setting up pilot plants.
A number of prototype reactors are available to develop a new idea rapidly
from concept to products. Incubation and demonstration
of a new technology is carried out in the jobshop to promote the industrial
acceptance of plasma based technologies and to generate techno-commercial
data relevant to entrepreneurs. The jobshop executes jobwork for surface
and material treatment on an industrial scale. The material characterization
facility, consisting of advanced instruments is open to users from industry,
research establishments and universities. Manufacturing of advanced plasma
reactors is another activity crucial to successful commercial transfer
FCIPT has a multi-disciplinary
team of scientists and engineers with expertise in
plasma physics, plasma chemistry, metallurgy, material sciences, power
electronics and instrumentation.
All the above activities under
a single roof provides an ideal environment for the Centre to offer a complete
package of industrial technologies and facilitation services to industries
interested in the adoption of indigenous technologies.