Tokamak Plasma Experiments

There are two existing facilities in the institute to do experiments related to fusion plasma, namely Aditya tokamak and Superconducting Steadystate Tokamak-I (SST-I). Recent developments in ADITYA-U include realization of plasma parameters close to the design values, deployment of a novel electromagnetic high-speed pellet injectors for the first time, experimental studies related to runaway electron generation and losses, toroidal rotation studies and modulation of drift tearing MHD modes. Continued technology improvements on SST-1 yielded, for the first time, a record 15 days of plasma operation with maximum ohmic pulse current durations of 650 ms, a good 200 ms improvement over the one obtained last year.

Aditya Tokamak


After 25 years of successful operation of ADITYA tokamak (~ 30,000 discharges) in a circular poloidal ring limiter configuration, it has been upgraded to a tokamak named ADITYA Upgrade (ADITYA-U) to realize the shaped-plasma operations in an open diverter configurations. The upgradation was conceptualized in the year 2014 and the ADITYA tokamak had been dismantled to its base level in the year 2015. The ADITYA-U tokamak construction was completed in the year 2016 and the first plasma was achieved in December 2016.

The ADITYA-U tokamak is a medium-size air-core tokamak with a major radius of 0.75me and a minor radius (limiter radius) of 0.25 m and maximum toroidal magnetic field of 1.5 T. It has a toroidal belt limiters and two quarter poloidal limiters at two toroidal locations made up of graphite. The ADITYA-U is designed to produce circular plasmas with plasma current ~ 150 – 250 kA, plasma duration of ~ 250 – 350 ms with a chord average electron density in the range of 1 – 5 x 10^19 per meter cube and electron temperature ~ 300 eV – 1000 eV. In addition, it is designed to achieve shaped plasmas with plasma current ~ 100 – 150 kA, elongation (k) ~ 1.1 - 1.2 and triangularity ~ 0.45.


Parameter

Value

Major radius
75 cm
Minor radius
25 cm
Plasma current
180 kA
Coil type
Normal Conducting, water cooled
Toroidal magnetic field
1.5 Tesla (Max)
Central solenoid
Normal Conducting, water cooled
Plasma cross-section
Circular
Plasma duration
250-300 milli seconds
External Heating
ECRH, ICRH

Table The operational parameters of Aditya-U tokamak









Steadystate Superconducting Tokamak-1 (SST-1)

Steady-State Superconducting Tokamak (SST-1) is a medium size superconducting tokamak, which has been designed and built to study the physics of the plasma processes in tokamak under steady-state conditions. In recent times the experimental campaign has been extended to a record 15 days with 300 plasma shots, with plasma pulse durations upto 650 milliseconds, 30% higher than the best achieved ever before, and better reproducibility of plasma parameters. This became possible due to improvement of the initial magnetic field null inside the vacuum vessel, permitting higher gas fill pressures, in turn allowing plasma creation with a limited pulse of electron cyclotron heating at 42 GHz. The improved plasma density also permitted long-duration current drive using injected power at 3.7 GHz, which was not hitherto possible due to a low-quality plasma near the wave launcher. Also for the first time in SST-1, the three frequency ranges used for plasma heating (tens of MHz, few GHz, tens of GHz) were applied simultaneously. Improved cryo-insulation has permitted production of liquid Helium from the cryo-plant in addition to coil cooling, which will now allow cooling of current leads.

Parameter

Value

Major radius
110 cm
Minor radius
20 cm
Plasma current
220 kA (Max)
Coil type
Superconducting (4K)
Toroidal magnetic field
3 Tesla
Central solenoid
Copper conductor
Plasma cross-section
Elongated
Plasma duration
~650 milli seconds (as of March 2020) target ~ 1000sec
External current drive and heating
LHCD, ECRH, ICRH
Table The operational parameters of SST-1 Tokamak


A Small-Scale Spherical Tokamak (SSST) is under construction to study the plasma initiation and non-inductive current drive. This will help to realize a volumetric neutron source. The project is expected to go for plasma opertation in the 2nd Qtr. 2022.

  • ADITYA-U

     

     
  •  SST1
  • SSST