Highest RF peak power - 29th of May

Today we reached the highest peak power of RF. We measured 6.8 MW of RF. We hope to increase this soon to 10 MW by tuning all the parameters.

RF pulse from 2157A Klystron - 25th of May

In the figure you see the RF pulse (2998.5 MHz) produced by the 2157A Klystron. The modulator (ScandiNova AB) was operated at 165 kV, 4.9 us FWHM and 63 Hz. This is at full power level of 6.3 kW average power.

We have driven the input of the klystron at a low power (estimated at 2.5 W peak power, which is a tenth of the optimal power).

The output level measured by the RF diode detectors corresponds to 2.5 MW peak power. This corresponds to a small signal gain of +60 dB.

High Power RF Test - 23th of May

We have performed the first high power RF tests in May.

The RF setup is orginized in the following way:
- The output of the RF source, Phase-Locked Loop (PLL) Synchroniser, is fed to the 100-W continuous RF amplifier, MAL tld..
- Inside the PLL a RF switch is integrated at the output, so that we can produce a low power (13 dBm) RF pulse of tens of microsecond in duration.
- The MAL amplifier (type AM82-3S-45-50R) has a small signal gain of 41 dB and has a output maximum of 50.2 dBm.
- The output of the MAL amplifier is fed to the input of the Klystron Tube. The klystron tube has a small signal gain of 57 dB.
- At the output of the Klystron Tube the waveguide section (WR284) is mounted, which contains a circulator with load (Ferrite SC3-118), bi-directional coupler and RF pressure window (CPI VWX-1053) at the accelerator cavity.
- To the bi-directional coupler RF diode detectors (Agilent 423B) are connected to monitor the forward and reflected RF power.

In this test phase the RF pressure window is replaced by a reflection plate, so that all the RF power is dissipated in the RF load on the circulator.

In the control room we have placed all the measurement equipment: two puls generators to supply the trigger pulse for the modulator and RF switch inside the PLL Synchronizer. The signals are displayed on a oscilloscoop.

For the computer in the control room the modulator can be controlled and all the operating parameters can be monitored.

Upper: PLL Synchronizer, Lower: MAL RF Amplifier	N-type Coax cable connected to RF input of Klystron Tube.
Bi-directional coupler in waveguide section. RF diode detectors connected to forward and backward outputs.	Trigger signal generation and signal analyzing in control room.
Control computer in control room.	Red warning light indicates accelerator operation.

Assembly of Laser Transport System - 23th of Februari 2007

We have mounted the Laser Transport System to transport the high-power (2.5 W), femtosecond laser pulses (50 fs) from the laser laboratory to the accelerator laboratory. The laser beam is transported through vacuum pipes (10^-4 mbar) to remove all the influences of air (turbulances and dispersion).

The Laser Transport System consists of 4 boxes containing turning mirrors. Between the boxes vacuum tubes are mounted to transport the beam. The entrance and exit tubes are closed by vacuum windows (anti-reflection coated). Two complete laser beam lines can be hosted in the Laser Transport System. For the time being only one line will be used to transport the high-power fundamental beam (800 nm) from the femtosecond laser system.

Entrance of the Laser Transport System on the laser source optical table.	The first box (#1) is placed above the optical table and reflects the laser beams through the wall to the accelerator laboratory.
The three boxes in the accelerator room. The right most box is #2. Between box #3 and #4 the laser beam passes high above the walking area.	Layout of the mirrors in box #3. The laser beam is comming from the right. On the left the ion getter pump is located.
This is box #4.	Layout of the mirrors in box #4. The laser beam is coming from the right and reflected down.
The vacuum pipes from box #4 down to the laser table.	The exit of the Laser Transport System on the accelerator optical table.

Test assembly of Cavity Container with RF input coupler - Half Februari 2007

Last week we tested the assembly of the stainless steel container for the cavity together with the RF input coupler. Now, we can finish soon the RF waveguide section to prepare the RF test phase.

Secondly, we can also start the assembly of the vacuum components.

(a) Stainless Steel container with flange on one side and RF input coupler (copper) on the other side. The flange will host cooling water feedthroughs and vacuum pump connector.	(b) The RF waveguide (black) is connected to the RF input coupler. Between a RF window is placed to isolate the vacuum side (10-9 mbar) from the pressure side (2 bar SF6).
(c) This is the side on with the electron beam line will be constructed.

Repair of azimuthal orientation - 7th of Februari

During the assembly of the cavity on 20th of September 2006 in Eindhoven we discovered that there was an azimuthal mismatch between the cavity orientation and the flange of the stainless steel vacuum container (see foto 1 and 2).

The solution was to replace the fitting pin with a new one having an offset. Last week we installed this new pin. The last photo shows that the replacement was successful. Now both the cooling channel and all the bolts fit correctly.


1- Assembly in Eindhoven in September 2006
2- The mismatch between the cavity and SS container.

3- The new fitting pin.
4- Correct assembly.

25th Miller Conference on Radiation Chemistry

I am planning to participate in the Miller Conference on Radiation Chemistry in April this year.

Current status just before Christmas

A small overview of current status of the assembly of the electron accelerator setup.

Modulator and klystron assembly. Blue hat is lead shielding of klystron collector.	Cooling water machine to seperately cool the klystron tube, collector and magnet.
19"-inch cabinet with (top-to-bottom) three power supplies for klystron magnet, Ion getter pump power supply, PLL Synchronizer and RF amplifier .

Test assembly of RF waveguide section - 22th of December

Today I have finished the test assembly of the waveguide section between the klystron tube and the RF input coupler at the cavity side.

Below you see a small impression.

Total waveguide section	Circulator directly behind klystron tube
Bridging section	Section to Cavity with bi-directional coupler
RF input coupler with RF window	4-port Circulator

Modulator test 28th of November 2006

On this day we tested the modulator for the first time. The test was to check the pulses produced by the modulator without driving the klystron tube with RF power.

From the BNC output connectors the current and voltage pulses were obtained and recorded by an oscilloscope:



Note: The tension pulses are multiplied by a factor 2, because they were recorded using 50Ω termination, which causes the measured tension to be half of the proper value.