RF system

For basic concept of TARLA, a beam with 1 mA average current will be accelerated up to 40 MeV by four superconducting TESLA cavities inside two cryomodules. Each cavity is powered by a solid-state amplifier emitting radio frequency waves. Additionally the injector system will consist of two normal conducting RF structures (named buncher cavities). Figure shows the block scheme of TARLA RF system.

The Master Oscillator (MO) and phase reference system at TARLA provides several RF reference frequencies (10-3900) MHz to widely spread locations with low phase noise and phase drifts.

Buncher Cavities

The subharmonic buncher cavity (SHB) (260MHz) and fundamental buncher (FB) cavity (1.3GHz) are utilized to compress 600 ps FWHM-length bunches coming from the e-gun to 10 ps longitudinal (temporal) waist inside the first cell of the first superconducting (SC) cavity via ballistic bunching. The main parameters of buncher cavities are given in Table.

SHB

FB

Units

Frequency

260

1300

MHz

Gap Voltage

35

20

kV

Input Power

1067

320

Watt

Q

12000

13750

--

Tuning range

250

1500

kHz

Figures shows TARLA buncher cavities.

Amplifiers

Each superconducting TESLA cavity are driven by a 18 kW (saturated) solid state power amplifier on its own and amplifiers are controlled by RF controllers as shown in figure above( See: Block scheme of RF system). The RF-power is transferred to the RF cavities by waveguides and fed into the cavities by couplers.