Micro-particle injection experiments in ADITYA-U tokamak using an inductively driven pellet injector
S. Pahari, Rahulnath P.P., Aditya Nandan Savita, Pradeep Kumar Maurya, Saroj Kumar Jha, Neeraj Shiv, K. Raghavendra, H. Hemani, Belli Nagaraju, Sukantam Mahar, M. V. V. S. Rao, I.V.V. Suryaprasad, U.D. Malshe, J. Ghosh, Bharat Doshi, P. K. Chattopadhyay, R.L. Tanna, K.A. Jadeja, K.M. Patel, Rohit Kumar, Tanmay Macwan, Harshita Raj, Suman Aich, Kaushlender Singh, Suman Dolui, Devilal Kumawat, M.N. Makwana, K.S. Shah, S.P. Gupta, V Balakrishnan, C.N. Gupta, Swadesh Kumar Patnaik, Praveenlal Edappala, Minsha Shah, Bhavesh Kadia, Nandini Yadava, Kajal Shah, Gopal Shukla, M.B. Chowdhuri, R. Manchanda, N. Ramaiya, Manoj Kumar, Umesh Nagora, S. Varsha, S. K. Pathak, Kumudni Asudani, Paritosh Chaudhuri, P.N. Maya, Rajiv Goswami, Abhijit Sen, Y. C. Saxena, R. Pal, Shashank Chaturvedi
Abstract
Abstract A first-of-its-kind, inductively driven micro-particle (Pellet) accelerator and injector have been developed and operated successfully in ADITYA-U circular plasma operations, which may ably address the critical need for a suitable disruption control mechanism in ITER and future tokamak. The device combines the principles of electromagnetic induction, pulse power technology, impact, and fracture dynamics. It is designed to operate in a variety of environments, including atmospheric pressure and ultra-high vacuum. It can also accommodate a wide range of pellet quantities, sizes, and materials and can adjust the pellets’ velocities over a coarse and fine range. The device has a modular design such that the maximum velocity can be increased by increasing the number of modules. A cluster of lithium titanate/carbonate (Li 2 TiO 3 /Li 2 CO 3 ) impurity particles with variable particle sizes, weighing ∼50–200 mg are injected with velocities of the order of ∼200 m s −1 during the current plateau in ADITYA-U tokamak. This leads to a complete collapse of the plasma current within ∼5–6 ms of triggering the injector. The current quench time is dependent on the amount of impurity injected as well as the compound, with Li 2 TiO 3 injection causing a faster current quench than Li 2 CO 3 injection, as more power is radiated in the case of Li 2 TiO 3 . The increase in radiation due to the macro-particle injection starts in the plasma core, while the soft x-ray emission indicates that the entire plasma core collapses at once.