TJ-II:ECRH system calibration

2018 Spring

Proposal title

ECRH System Calibration

Name and affiliation of proponent

A. Cappa, J. Martinez (CIEMAT-LNF)

Details of contact person at LNF (if applicable)

Enter contact person here or N/A

Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)

The goal of this proposal is to check the calibration of the ECRH system transmission lines by performing reference shots for different off-axis positions. Plasma central temperature for typical ECRH densities ($<n_e>\approx 0.6\times 10^{19} m^{-3}$) and ECR heating powers (250 kW) will be taken as the main and more robust indicator of a correct system alignment. As in previous proposals, modulation experiments aiming to determine the location of the power deposition using ECE would also be desirable.

Three different launching positions will be tested with each launcher, on-axis and two off-axis positions. By setting equal power in both gyrotrons and having in principle the same theoretical polarization in both launched beams, the variation of the off-axis position should induced noticeable and comparable changes in the plasma temperature.

- Launching direction scan

• Plasma is created using only the beam under study
• TOTAL NUMBER OF USEFUL SHOTS=12 (6 per gyrotron, including on-axis launching reference discharges)
• 200 ms reproducible discharges with line density around 0.5 − 0.6.
• Power is set to 250 kW
• Launching directions at ρ= 0.00, 0.20, 0.42

- Fast Modulation Experiments

• Plasma target is created using one beam with 250 kW. The other beam is modulated.
• TOTAL NUMBER OF USEFUL SHOTS=16 (8 per modulated gyrotron, including on-axis launching reference discharge 250+50 kW without modulation)
• 200 ms reproducible discharges with line density ne around 0.5 − 0.6.
• Power in the non-modulated is set to 250 kW
• Power in the modulated gyrotron is set to 50 kW
• Launching directions: ρ = 0.00, 0.20, 0.42
• Modulation frequency: f = 6 kHz

If applicable, International or National funding project or entity

Enter funding here or N/A

Description of required resources

Required resources:

• Number of plasma discharges or days of operation:2 days taking into account that the experiments will be carried out at the beggining of the campaign.
• Essential diagnostic systems: Thomson Scattering, ECE, Microwave Interferometer, Rogowski.
• Type of plasmas (heating configuration): Standard (100_44_64)
• Specific requirements on wall conditioning if any:
• External users: need a local computer account for data access: yes/no
• Any external equipment to be integrated? Provide description and integration needs:

Preferred dates and degree of flexibility

Preferred dates: These experiments must be carried out at the very beggining of the campaign