PROTOCOL on Trial Start-Up to Test KTM Tokamak
On September 05, 2010 trial start-up of KTM Tokamak was carried out. The operations on preparation and performance of KTM Tokamak trial start-up are fulfilled within implementation of budget program 045 Creation of Kazakhstan Thermonuclear Material Studying Reactor Tokamak KTM.
Trial Start-Up Objective is working gas breakdown in vacuum chamber of KTM Tokamak and formation of plasma thread with current of 10-30 кА.
To obtain plasma thread the setting of the following Tokamak systems are performed:
The diagnostics of first order plasma physical parameters;
- Subsystem of data collection and registration;
- Preionization system of working gas;
- Power supply system of KTM magnetic windings;
- Vacuum pumping system of KTM chamber.
In the course of operations the following is carried out:
The conditions for stable operation of preionization system of working gas (argon) are found – pressure of working gas and induction of toroidal magnetic field;
- Zone in vacuum chamber with low level of scattered magnetic field is found;
- Realization of working gas breakdown and plasma current rise up to target level;
- Registration of basic physical parameters is performed.
The following systems are used for breakdown and formation of plasma thread:
- Preionization system for ionization of working gas;
- Power supply of electromagnetic winding of toroidal field;
- Condensing power supply of central solenoid and electromagnetic windings of poloidal field PF1, PF4;
- Magnetic diagnostics, CCD video camera and photoelectric multiplier (PEM) for diagnostics of physical parameters.
Working gas breakdown and plasma current are registered with the help of Rogowski coil, voltage sensing device and photomultiplier.
KTM subsystems, participating in the experiment on plasma obtaining are shown in Figure.
For pre-ionization formation by electron cyclotron resonance magnetron source is used with frequency of 2.45 GHz, microwave emissive power is - 900 W, emission is supplied through waveguide from low magnetic field, microwave emission impulse duration - 300 ms. Pre-ionization system is presented in Figure 2.
Light is seen through vacuum chamber window due to gas ionization.
To create eddy electric field, current is supplied in poloidal field winding by way of capacitors bank discharging of 22 mF capacity and voltage of 5 kV.
The main parameters upon which breakdown and plasma thread are formed: working gas pressure (argon) - 10-4 torr, voltage near the breakdown is – 8.4 V, magnetic field on axis of toroidal winding is – 0.043 tesla, plasma discharge duration is ~ 40 ms.
Figure 3 demonstrates video shooting moment of vacuum chamber from vertical branch pipe during plasma thread gaining (approx. 20-th millisecond since current injection into central solenoid coil).
1. Scenario is developed for trial start-up of Tokamak KTM. Physical parameters system adjustment is performed for first order plasma, as well as adjustment of data registration system, system of working gas pre-ionization, KTM electromagnetic winding feed system, vacuum chamber preparation system KTM.
2. Trial start-up of KTM is carried out and maximum plasma flux of 25 kA is obtained in accordance with Tokamak KTM trial start-up tasks.