1. 08/07/05Plasma Operations : Introduction P.J.Lomas 1 Plasma Operations: General Introduction Peter Lomas and Plasma Operations Group:- Jerzy Brzozowski, Peter de Vries, (Marco de Baar), Robert Felton, (Emmanuel Joffrin), Isabel Nunes, Fabio Piccolo, Filippe Sartori, Luca Zabeo

2. 08/07/05Plasma Operations Introduction P.J.Lomas 2 Contents Grad Shafranov equation Poloidal coils and power supplies Plasma Control Plasma Equilibria, Proteus, Maxfea, EFIT The Standard equilibria, The Pulse Schedule The control of Toroidal Field Gas fuelling Reprise

3. 08/07/05Plasma Operations Introduction P.J.Lomas 3 The Grad Shafranov Equation Force Balance Poloidal magnetic flux function, Poloidal current flux function, Together with Amperes Law gives Key to Plasma Engineering and Tokamak data interpretation See e.g John Wesson, Tokamaks, 2 nd ed. Oxford Science Publications Unit vector toroidal direction

4. 08/07/05Plasma Operations Introduction P.J.Lomas 4 For a theorist The JET coils and iron are just the boundary conditions for solving the equation For a Plasma Engineer The Grad Shafranov equation is just a tool which helps us exploit the power of JET machine for producing the plasmas we want, shape and position. Coils, or parts of coils are arranged in circuits with the various power supplies and these are controlled by the Plasma Position and Current Control system PPCC

5. 08/07/05Plasma Operations Introduction P.J.Lomas 5 Poloidal Field Circuits and Power Supplies + 4 Poloidal Divertor Circuits + - PVFA2 PVFA4 PVFA3 +- + - D1 D3 D4 D2 PVFA1 + - Shaping Circuit P4 Circuit P4 Imbalance Circuit PFX + - PFGC + - P1 External Circuit PFX Circuit  The functions of the individual circuits will be described in Plasma Ops I

6. 08/07/05Plasma Operations Introduction P.J.Lomas 6 These Circuits are controlled by Shape Controller PPCC-SC using the magnetic measurements and real time boundary reconstruction XLOC IpZpRpIpZpRp 9 PF Amplifiers Magnetic Diagnostics other parameters Calculate 9 PF Voltages PPCC Decoupling SL waveforms I PF Protection V 9  I PF I See lecture Plasma Control by Fernanda Rimini

7. 08/07/05Plasma Operations Introduction P.J.Lomas 7 With such a complex plant Protection is mandatory Protection Levels Limits and trips at power supplies Trips at the Coils Limit Avoidance in control Prepulse Checks (EiC) Schedule Validation Session Leader “good practice” Coil Protection System (CPS) Plasma Control (PPCC) Limit Actions Hardware Trips Power Supply Systems Software TripsFault Condition JET Operation Instruction JOI Pulse Termination Disruption?

8. 08/07/05Plasma Operations Introduction P.J.Lomas 8 Grad Shafranov Solvers, Plasma Equilibrium Design Control and Reconstruction DesignControlReconstruction MAXFEA PROTEUS XLOC EFIT Physics, Mapping

9. 08/07/05Plasma Operations Introduction P.J.Lomas 9 There are >69 commonly used equilibria (standard scenarios) E.g Triangularity scan V/SFE/LTV/SFE/HTV/SFE/VHTV/SFE/EHTITER-LIKE Triangularity variation 0.15-0.50 See Plasma Ops II

10. 08/07/05Plasma Operations Introduction P.J.Lomas 10 Often modifications are required:- Move outer strike Adjust top gap Done by editing GAP waveforms, see Plasma Control

11. 08/07/05Plasma Operations Introduction P.J.Lomas 11 A particular session might require a number of different pulses, PULSE-TYPES. These are prepared (in advance) to make up a PULSE-SCHEDULE using the Pulse Schedule Editor XPSEDIT. This tool gives the Session Leader control over Toroidal Field Poloidal Field Gas Real Time Control You will hear a lot more about this over the week

12. 08/07/05Plasma Operations Introduction P.J.Lomas 12 For example the large and complex power supplies driving the toroidal field can be driven from a single wave-form in the Pulse-Schedule Editor. This high level control is called LEVEL 1.

13. 08/07/05Plasma Operations Introduction P.J.Lomas 13 The JET gas introduction is another complex system:- 10 Gas Introduction Modules (GIMs) and one Tritium module. The plasma density needs to be processed, validated and routed the the Density Feedback and Valve controllers. interfer ometer bremsstrahlung process Real Time Signal Server GIM GIM waveform Dedicated pages in the pulse schedule, see Rob Felton’s talk SL density waveform PID RealTime Central Controller

14. 08/07/05Plasma Operations Introduction P.J.Lomas 14 This lecture is a very brief intoduction to:- Grad Shafranov equation Poloidal coils Plasma Control Protection Plasma Equilibria, Proteus, Maxfea, EFIT The Standard equilibria, The Pulse Schedule The control of Toroidal Field Gas fuelling You should now begin to understand how a JET pulse is put together. Any questions?