Enhancing Beam Availability with ALBA LLRF Upgrades

ALBA LLRF upgrades aim to improve beam availability by implementing auto-recovery processes and feed-forward loops for RF trip compensation. The upgrades involve detuning cavities, adjusting amplitudes and phases, and enabling tuning loops to ensure smooth power delivery to the beam. Despite challenges like disturbances induced by RF trips, the upgrades help maintain beam survival and minimize power losses.

• ALBA LLRF Upgrades
• Beam Availability
• Auto-recovery Process
• RF Trip Compensation
• Feed-forward Loops

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1. ALBA LLRF UPGRADES TO ALBA LLRF UPGRADES TO IMPROVE BEAM AVALIBYLITY IMPROVE BEAM AVALIBYLITY Emilio Morales USPAS Introduction to LLRF Winter 2017. Rohnert Park, CA

2. ALBA LLRF UPGRADES TO IMPROVE BEAM AVALIBYLITY ALBA LLRF UPGRADES TO IMPROVE BEAM AVALIBYLITY Introduction Designed to provide up to 3.6MV and to restore 540kW. RF interlocks: mainly due to internal arcs in RF amplifiers. Auto-recovery process implemented. Recover the plant with circulating beam. Observed: Disturbances induced to the beam due to RF trips may cause a partial o total beam dump.

3. CAVITY AUTORECOVERY WITH BEAM CAVITY AUTORECOVERY WITH BEAM RF Trip: Cavity absorbs power to the beam. LLRF: Detune the cavity around 500kHz. Amplitude and Phase loops disabled. LLRF Drive to minimum. Digital phase shifter. Auto recovery process: Plunger move to previous position. Tunning Loop enable Amplitude and Phase loops enable. Power increase smoothly.

4. FEED FEED- -FORWARD LOOPS FOR RF TRIP COMPENSATION FORWARD LOOPS FOR RF TRIP COMPENSATION Cav Volt - Beam Phase 460 160 Cav Volt - Beam Phase 450 460 160 155 Beam Phase (degrees) Effects observed after RF Trip beam survival: Cavity voltage reduced. More power delivered to the beam. Sync. Phase start to decrease and oscillates. The higher beam current and/or low RF voltage, the higher amplitude. 440 Cav Volt (kV) 450 155 Beam Phase (degrees) 4140 430 150 440 Cav Volt (kV) 420 430 150 145 420 410 145 410 400 0 0 0.5 0.5 1 1 1.5 1.5 2 2 2.5 2.5 3 3 3.5 3.5 4 t(ms) 400 4140 0 0 0.5 0.5 1 1 1.5 1.5 2 2 2.5 2.5 3 3 3.5 3.5 4 t(ms) Cav Dis - RvCav - Beam Power 35 Cav Dis BeamPower RvCav Cav Dis - RvCav - Beam Power 35 30 Cav Dis BeamPower RvCav 30 25 25 20 kW 20 15 kW 15 10 10 5 5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 t(ms) 0 0 0.5 1 1.5 2 2.5 3 3.5 4 t(ms)

5. FEED FEED- -FORWARD LOOPS FOR RF TRIP COMPENSATION FORWARD LOOPS FOR RF TRIP COMPENSATION Effects observed after RF Trip with partial beam lost: Cavity voltage reduced. Overshoot. Reverse power increase. Power delivered to the beam reduced. Extracting power from to beam. This extra power will be provided by the loop.

6. FEED FEED- -FORWARD LOOPS FOR RF TRIP COMPENSATION FORWARD LOOPS FOR RF TRIP COMPENSATION Main Parameters: Plants informed in < 100 ns Increase the drive following sinusoidal signal, but with opposite phase. Transient of 3ms with exponential curve. FPGA limitations: Math. Operations limited. Linear decay implemented. Simulations Interaction of the beam after RF trip with and w/o active compensation. Show that the it was not possible to completely remove the perturbation.

7. FEED FEED- -FORWARD LOOPS FOR RF TRIP COMPENSATION FORWARD LOOPS FOR RF TRIP COMPENSATION Experimental results 60mA, 1.5MV Fake interlock: 1.5MV 1.2MV No compensation: Beam Lost Measure the ripples FF loop enabled. Fake interlock repeated. Amplitude of FF loop increased to cancel the beam lost.

8. FEED FEED- -FORWARD LOOPS FOR RF TRIP COMPENSATION FORWARD LOOPS FOR RF TRIP COMPENSATION Next steps: Amplitude modulation of LLRF drive to phase modulation. The main advantage: the output of the amplifier would remain constant.

9. BEAM LOADING COMPENSATION BEAM LOADING COMPENSATION Feed-Forward loops to compensate bema loading effects. Following the same approach for the RF Trip compensation, algorithm developed.

10. ALBA LLRF UPGRADES TO ALBA LLRF UPGRADES TO IMPROVE BEAM AVALIBYLITY IMPROVE BEAM AVALIBYLITY Emilio Morales USPAS Introduction to LLRF Winter 2017. Rohnert Park, CA