My Research Interests :

Analytical Modeling & Computer Simulation of High Density High Temperature Plasmas in Ultra-Short Pulse Ultra-Intense Laser Plasma Interaction & High Power Solid State Lasers

              I joined the Laser Plasma Division, Center for Advanced Technology (CAT), Department of Atomic Energy, Govt. of India, Indore in 1994 as Scientific Officer-C . The work of the division has been related to the Indian initiative towards Inertial Confinement Fusion. Read a general article on the relevance of FUSION (ICF) published in INDIA TODAY, August 31' 1998 -> click here.

    I worked towards the development of High Power Nd:Glass Laser chain (100 Joule - 3 nanosecond per beam, four beams), where I worked on design, development & operation of various sub-systems. I, along with other colleagues developed Q-switched Nd:Glass–Nd:YLF Hybrid Laser Oscillator, Pulse Slicer, Spatial Filters, Laser Amplifiers, Frequency Conversion System and handled day to day operation & maintenance of laser chain for laser-plasma experiments. Coordinated the development of Laser Glass and Pockell Cells with Central Glass & Ceramic Research Institute, Calcutta and Laser Materials Division, CAT .  I had been associated with the High Power Laser Laboratory of Laser Plasma Division till May 1999 (refer to list of publications).

    To devote more time to my new found interest in Plasma, I switched to the analytical modeling & simulation of laser produced plasmas and shifted to the Laser Plasma Laboratory of the same division. Where, I focused on the study of "Relativistic Effects in Short Pulse Laser Plasma Interaction". I was awarded a Ph.D. by Indian Institute of Technology, Delhi on the same topic. I have setup a 3D-PIC (particle-in-cell) code "PICPSI-3D" for studying laser interaction with a preformed plasma, where I am studying laser based particle acceleration and related phenomena. Recently, I developed a 30 node computing cluster to develop parallel version of this code. I am also using 2D - hydrodynamic code "MULTI-2D" for hydrodynamic simulation of laser material interaction. At present I am continuing as Scientific Officer - E.

Academic Achievements :

 Projects / Certificates :

Computer Skills^* :

*  I have supervised one MCA and  two M.Sc. (Comp. Sc.) projects.  

Awards / Offices / Memberships :

References :

Current Research :

Laser fusion research has led to the progress of intense lasers and the physics of laser produced plasmas. The invention of chirped pulse amplification (CPA) technique has made it possible to realize the laser intensity > 10²⁰W/cm². Such ultra high power lasers with ultra short pulse can be produced not only in a big laser system, but also in a tabletop laser system called table-top-terawatt (T³) laser. This laser can be made to pass through a low-density plasma channel to ignite a compressed core. This scheme is called fast ignition and is being studied experimentally. Many scientists have shown interest in the physics and applications of matter irradiated by such ultra high intensity lasers. Experiments and particle-in-cell simulations have reported the generation of strong magnetic fields in the 100MG range. This magnetic field is an almost stationary field generated by the strong current of hot electrons. In addition, the ponderomotive pressure is about 10 Gbar at I_L =10¹⁹W/cm² and much higher than the plasma pressure. As a result, charged particle motions become complicated under the influence of strong magnetic fields, ponderomotive force and relativistic effects. The propagation of such ultra-short high-intensity laser pulse in under-dense plasma is of interest, both for the understanding of laser interactions in this new relativistically driven plasma regime and for applications such as laser wake field accelerators, X-ray lasers. Computer simulations have been taken up to study the interaction of ultra-short high-intensity laser pulse with under-dense plasma and over-dense plasma and to study the X-ray emission. Magnetic instability, fast ion acceleration and interaction with cluster are some other important phenomena of interest.

I took up experimental work on laser plasma interaction in 2001, where I participated in various experiments on laser plasma interaction using a 2 J-200 psec. laser system. Using this system we have studied the equation of state of some metals under high pressure. I have also been involved in experimental work on interaction of atomic clusters with an intense short pulse laser, where we studied the absorption and scattering of longer laser pulse (~25 psec, 2 J) with gas clusters and emission of x-rays and its correlation with cluster size.

My current research interest is the theory & simulation of laser plasma interaction in ultra-high intensity short pulse domain. I have developed analytical model using paraxial wave equation to study the propagation of a high intensity short pulse laser in underdense plasma and have studied the evolution of pulse, stimulated Compton scattering and non-resonant second harmonic generation. I have also studied the effect of a relativistic electron beam in underdense plasma where I have developed an analytical model using kinetic theory.

My thesis work on the theory of laser plasma interactions gave me in-depth understanding of various plasma processes. This helped me in enhancing my skills towards interpretation of experimental results and, I could take up simulation of laser plasma interaction. I have setup a 3D particle-in-cell code PICPSI-3D developed at L&PTD, BARC, Mumbai, India.  The code has been modified to suit our need and has been commissioned in our simulation laboratory to study the laser-plasma based acceleration schemes. Recently, we have commissioned a 30 node computing cluster, on which we are developing a parallel PIC code for laser-plasma interaction studies. The code is being run to study the two important domains of laser wake field acceleration i.e. SM-LWFA regime (keeping in view of existing laser power in our laboratory) and Bubble regime (keeping in view of augmentation in our laser power). I have also setup the 1D-PIC code LPIC++ developed at Max-Planck Institute, Germany.  

Publications

Journals: 7

Reports: 1

Conferences:  14

Journals:

1. Second Harmonic Generation in a Plasma Channel, A. Upadhyay and V. K. Tripathi, J. Plasma Physics, vol. 71, part 3, pp. 359–366, 2005

2. Equation of State Studies using a 10Hz Nd:YAG Laser Oscillator, M. Shukla, A. Upadhyay, V.K.Senecha, P. Khare, S. Bandopadhyay, V. N. Rai, C.P. Navathe, H. C. Pant, M. Khan & B. K. Godwal; Laser and Particle Beams,  vol. 21, 611, 2003.

3. Weibel Instability of Relativistic Electron Flows in a Plasma and its Coupling to Plasma Waves, A. Upadhyay, V. K. Tripathi and H. C. Pant, Plasma Phys. & Cont. Fusion, vol. 44, 2357-63, 2002.

4. Effect of Hot Electrons on Stimulated Compton scattering of a Laser in a Self Sustained Plasma Channel, A .Upadhyay, V. K. Tripathi and H. C. Pant, Physics of Plasmas, Vol. 9, No.5, May 2002.

5. Asymmetric Self-Focussing of a Laser Pulse in Plasma, A .Upadhyay, V.K. Tripathi, A. K. Sharma and H.C.Pant, J. of Plasmas Phys., vol. 68, part I, 75-80, 2002.

6. Pulse Front Sharpening of a Laser in Plasma., A. Upadhyay , V.K.Tripathi, H.C. Pant, Physics Scripta, Vol.63, 326-328, 2001.

7. Development of High Power Laser and Relevant Technology in India, A.S.Joshi, .P.Navathe, M.S.Ansari, M.P.Kamath, S.Bandyopadhyay, A. Upadhyay, A.P.Kulkarni, P.K.Tripathi, P.Khare, S.R.Patwa, J.D. Singh, N.Sreedhar, R.Chandra, M.N.Kumbhare and H. C. Pant, Fusion Engineering and Design, Vol. 44, 67-70, 1999.

Report:

1.      1-D Particle in Cell (PIC) Simulation of Relativistic Laser Plasma Interaction Using LPIC++,  A. Upadhyay, RRCAT Internal Report # CAT/2006-02, 2006.

International / National Conferences:

1. Scattering of Multi-Picosecond Laser Light from Argon Gas Cluster Plasma, H. Singhal, V. Arora, P. A. Naik, R. A. Khan, A. Upadhyay, S.R. Kumbhare and P.D. Gupta, Proc. Of Fourth DAE-BRNS National Laser Symposium, Jan. 10-13, 2005, Bhabha Atomic Research Center, Mumbai, India.

2. Design and Performance of High Power Laser for High Pressure Physics Experiments, H. C. Pant, M. Shukla, A. Upadhyay, V. N. Rai, V. K. Senecha, M. Khan and B. K. Godwal, International Conference on Frontiers of Plasma Physics and Technology, Dec. 9-14’ 2002, Banglore, India.

3. High Speed Time & Space Resolved Diagnostics of Laser Produced Plasma, M. Shukla, H. C. Pant, V. K. Senecha, A. Upadhyay, V. N. Rai and B. K. Godwal, International Conference on Frontiers of Plasma Physics and Technology, Dec. 9-14’ 2002, Banglore, India.

4. "Role of Decay Instability in Second Harmonic Emission from Laser Produced Plasmas" by A. Upadhayay, A. Kumar and V.K. Tripathi; 17th National Symposium on Plasma Science and Technology, Dec. 16-19, 2002 at Bharathiar Univ., Coimbatore.

5. Asymmetric Self-Distortion of a Short Laser Pulse in a Plasma, A. Upadhyay, V.K.Tripathi and H.C.Pant, XVI Plasma Science Society of India Symposium on Plasma Science and Technology, Nov. 2001, Center for Plasma Physics, Guwahati, India.

6. Pulse Front Sharpening of a laser in Plasma, A. Upadhyay, V.K.Tripathi, H.C. Pant, XV Plasma Science Society of India Symposium on Plasma Science and Technology, Dec. 2000, Saha Institute of Nuclear Physics, Calcutta, India.

7. Development of High Power Glass Laser for Plasma Studies, A. S. Joshi, M. P. Kamath, A. Upadhyay, P. K. Triapthi, A. P. Kulkarni, R. Pareekh and S. Gupta, National Seminar on High Power Lasers and their Applications, Feb. 1999, Cochin University, Cochin, India.

8. Development of Nd:Glass (Phosphate) for High Power Laser, A. Upadhyay, P. K. Tripathi, M. P. Kamath and A.S. Joshi, National Seminar on High Power Lasers and their Applications, Feb. 1999, Cochin University, Cochin.

9. Testing of Sol-Gel coated Anti-Reflection Coatings, R. Pareekh, A. P. Kulkarni, S. Gupta and A. Upadhyay, Proc. of National Laser Symposium 1998, Indian Institute of Technology, Kanpur, India.

10. On-Line Collimation of Relay Systems for the High Power Nd:Glass Laser, M.P. Kamath, A. Upadhyay, A. P. Kulkarni, P. K. Tripathi and A. S. Joshi, Proc. of National Laser Symposium 1998, Physical Research Laboratory, Ahmedabad, India.

11. Development of High Power Laser and Relevant Technology in India, Proc. of IAEA Technical Committee Meeting on Drivers and Ignition Facilities for Inertial Fusion, A.S.Joshi, .P.Navathe, M.S.Ansari, M.P.Kamath, S.Bandyopadhyay, A. Upadhyay, A.P.Kulkarni, P.K.Tripathi, P.Khare, S.R.Patwa, J.D. Singh, N.Sreedhar, R.Chandra, M.N.Kumbhare and H. C. Pant, March 1997, Osaka University, Osaka, Japan.

12. Nd:YLF::Nd:Glass(Phosphate) Hybrid Laser Oscillator for the High Power Glass Laser, M. P. Kamath, A.S.Joshi, A. P. Kulkarni, A. Upadhyay, P. K. Tripathi, S. R. Patwa, C. P. Navathe, M. S. Ansari, N. Sreedhar, R. Chandra and M.N. Kumbhare, Proc. of National Laser Symposium 1997, Center for Advanced Technology, Indore, India.

13. Measurement of Beam Profile of Nd:YLF Oscillator, A. Upadhyay and A. P. Kulkarni, Proc. of National Laser Symposium 1996, Bhabha Atomic Research Center, Mumbai, India