# Presentation: 264479

## Behavior of the TTF2 RF Gun with long pulses 

**Behavior of the TTF2 RF Gun with long pulses **
**and high repetition  rates** (TESLA note 2003-33)
- Jean-Paul Carneiro
- DESY Hamburg
- TESLA COLLABORATION MEETING
- DESY Zeuthen, 22 Jan 2004

## TTF2 RF GUN SCHEMATIC (ANSYS, F. Marhauser)

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**• ****14 water channels (1 in the back plane going twice around, 4 around the half cell, 7 around the full cell, 1 in the front plane and 1 in the iris making three loops around it)**
**• ****Max. water flow rate per channel:                            with          max. flow velocity and         channel cross section                             **
**• ****Total Maximum water flow rate :                                                                 with**

## TTF2 RF GUNAT PITZ 

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

## INSTALLATION

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**INSTALLATION**

- _ZEUTHEN_

- _HAMBURG_

**• ****We operated without interlock on the reflected power****	****	**** • OK**
**   ****coming from the RF gun**

**• ****We operated at PITZ the TTF2 RF gun with 27 kW of  mean power (10 Hz, 3 MW, 900 ****μs) which fulfils the TTF2 specifications **

**• ****The waveguides from the circulator to the RF gun window****	****	**** • In preparation**
**   ****was filled with SF6 in order to avoid sparks**

**• ****Water temp. : ****	****Set Point  58 C to 61 C****	****	****	**** • OK**
**	****	****Incoming 58 C to 48 C**
**	****	****Outgoing 58 C to 52 C**
**	****	****Stability  0.1 C****	****	****	**

**• ****Water flow : ****	****Estimated : ~1.5 l/s****	****	****	**** • Up to 3.6 l/s**
**	****	****(water flow meter being installed at PITZ)**

## PITZ WATER SYSTEM 

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**PITZ WATER SYSTEM **

## Up to 13.2 kW (10 Hz, 600 μs, 2.2 MW) 

**Up to 13.2 kW (10 Hz, 600 ****μs, 2.2 MW)**** **

**• ****At 10 Hz, 500 μs, 2.2 MW ****Δ****T=(53.7 C-51.9 C)=1.8 C**

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

## Up to 13.2 kW / Comparison with ANSYS simulations 

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**Up to 13.2 kW / Comparison with ANSYS simulations **

## Up to 20 kW (10 Hz, 900 μs, 2.2 MW) 

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**Up to 20 kW (10 Hz, 900 ****μs, 2.2 MW)**** **

**• ****Max Set Point Temp. of 64 C reached at ~ 20 kW. To go at higher mean power we decided to slightly remove the temp. probe in the iris. **

## Infrared camera observation of the RF Gun (10 Hz, 800 μs, 2.2 MW)

- Jean-Paul Carneiro

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**• ****Channels temp. stable  at ~ 45.5 C, iris at ~35 C, body and waveguide at ~30 C while going **
**   ****from P=2.2 kW to P=17.6 kW. **

## STABILIZATION OF THE TEMPERATURE  

- Jean-Paul Carneiro

**STABILIZATION OF THE TEMPERATURE  **

- Behavior of the TTF2 RF with long pulses and high repetition rates.

**• ****Stable operation going from 200 ****μs to 500 μs at 2.2 MW, 10 Hz reached in less than 5 mn.**
**• ****Should avoid getting more than 500 kW of reflected power.**
**• ****Easier to warm up the cavity rather than to cool it down.**

- Reflected Power 

- Temperature (SP) 

- _From 200 __μs to 500 __μs to 800 μs_
-  (2.2 MW, 10 Hz)

## DETUNING OF THE RF GUN WITH LONG RF PULSES

- Jean-Paul Carneiro

**DETUNING OF THE RF GUN WITH LONG RF PULSES**

- Behavior of the TTF2 RF with long pulses and high repetition rates.

- Reflected power

## ANSYS SIMULATION AT 27 kW OF MEAN POWER

- Jean-Paul Carneiro

**ANSYS SIMULATION AT 27 kW OF MEAN POWER**

- Behavior of the TTF2 RF with long pulses and high repetition rates.

- • We operated at PITZ the TTF2 RF gun at 10 Hz, 900 μs, 3.0 MW. Stable operation could be reached
-   for ~ 2/3 minutes then vacuum interlocks. More conditioning is still needed at this mean power.

- (Temp probe 1 cm in the iris hole)

## TOWARDS 50 HZ OPERATION (~130 kW MEAN POWER)

- Jean-Paul Carneiro

**TOWARDS 50 HZ OPERATION (~130 kW MEAN POWER)**

- Behavior of the TTF2 RF with long pulses and high repetition rates.

- • At 50 Hz operation, ANSYS predicts temperatures in the waveguide iris of ~170 C and stresses of ~130 MPa
-  which are not tolerable.
- • The operation of the RF Gun at 50 Hz would necessitate adding more cooling channels.
- • At 50 Hz, Cs2Te photocathode temp. is expected at 120 C which is OK.

## RESUME 

- Jean-Paul Carneiro

**RESUME **

- K. Floettman, O. Krebs, S. Schreiber,	**DESY Hamburg**
- J. Baehr, I. Bohnet, J.H. Han, M. Krasilnikov, D. Lipka, V. Miltchev, A. Oppelt,
- B. Petrossyan, F. Stephan, **DESY Zeuthen**
- M. v. Hartrott, F. Marhauser,** BESSY Berlin**

- Behavior of the TTF2 RF with long pulses and high repetition rates.

_**Aknowledgment**_

**• ****The TTF2 RF gun has been successfully tested at PITZ for 27 kW of mean power.**
**•**** ****More conditioning is needed at 27 kW of mean power to avoid vacuum interlocks.**
**• ****Compensation of the RF detuning should be tested.  **