Maria ELENA Angoletta for the RF team RF & longitudinal diagnostics: status, new features, observations & plans Maria ELENA Angoletta for the RF team Extended ECC 7 March 2019

In ELENA RF workpackage Outline RF system Status and typical operation New features in 2018 Observations Longitudinal diagnostics (processing*) Status, usage & examples Plans (≥ 2019) Conclusions [ * for the hardware: see Wolfgang’s talk after this one] In ELENA RF workpackage M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 1

1. RF system: status LLRF HLRF Implements in frontend all required features. Some features to be finalised / validated (ex: PAUSE, retrieval of Oasis signals during cycle). Integration (RF cycle editor) to be completed by ELENA/OP. LLRF + longitudinal diagnostics racks in ELENA hall, protected by transparent acrylic panels. HLRF New amplifier (PSB-style) installed in 2019 to minimise maintenance. No changes from the LLRF view (TBC slightly different transfer function?). Reduced HLRF max voltage (500 Vp until Nov 6 2018, 100 Vp after) M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 2

1. RF system: operation for pbars Injection/extraction synchro, phase+radial loops, multiple RF segments for ecooling. Bunched-beam cooling, bunch rotation (settings, not specific features). Single harmonic operation. Extracted beam at h = 1, 2 and 4 (top to bottom). Three RF segments & various harmonics tested. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 3

1. RF system: operation for H- ions Source synchronised to LLRF (no injection synchro enabled in LLRF) Beam phase + radial loops, extraction synchro Single harmonic operation. H- production cycle and extraction to GBAR. H- MD study cycle M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 4

2. RF system: new features in 2018 Frequency program: new (numerical) implementation Frequency program: averaging Btrain diagnostics Extraction synchro loop Wider cavity limits Reduced maximum voltage in HLRF system (new LLRF-HLRF power chain) Operation with RF segments The team finally developed and commissioned more new features than we expected! M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 5

2a. Frequency program: new implementation Deployed higher resolution frequency program (before startup 2018) to remove frequency “quantisation” effect due to low magnetic value. Exported to LEIR + PSB for uniformity approach (no quantisation there) End of 2017 run 2018 startup Limited numerical resolution. At low energy frequency program is quantized (~40 Hz) Sub-HZ resolution over whole Btrain range M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 6

2b. Frequency program: averaging Improved-resolution frequency program follows Btrain oscillations → ELENA OP required frequency program “smoothing”. User-selectable moving average (up to 20 ms) deployed (May 2018). Validated in MDs but not used operationally (loops seemed enough). NB: radial loop frequency contribution higher for long averaging! Freq. program synoptic with moving average Increased radial loop contribution when averaging. Radial loop frequency in [2700 Hz, - 800 Hz] for 12.5 ms averaging; in [1200 Hz, -400 Hz] for no averaging. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 7

2c. Btrain diagnostics Set of diagnostics requested by Btrain experts to evaluate Btrain stability/calibration. Feature available in frontend in July 2018, integrated in controls infrastructure in October 2018. Value Units Source of value Btrain from White Rabbit interface 10 nT DSP B Frequency contribution from Btrain Hz Number of particles obtained from LPU signal   Radial position from orbit system mm DSP C Frequency contribution from radial loop Number of particles obtained from TPU signal Btrain diagnostics published by LLRF in 2018 M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 8

2d. Extraction synchro loop Deployed in July 2018 (pbars and H-). Includes optimisation features (gain ramp etc) to provide smooth closure and operation. Beam: several user-selectable beam harmonics possible. Extraction reference: other harmonics implemented but depends on cabling. We will remain with h=1. Beam h Ref h Comments 1 Operational case for H- operation Antiprotons operation 2 Operational case for H- operation with 85 kV source before new cavity voltage limits 4 Harmonics used operationally Example of extraction synchro process M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 10

2e. Wider cavity limits Deployed in July 2018 to allow operation @h=1 with 85 kV H- source Smooth voltage change between ranges for cavity loops stability. Hardcoded. Will be changed to adapt to 100 Vp max HLRF configuration (→ next slide) Frequency range [kHz] Max voltage [Vp] 120 – 130 Raised linearly from 30 V @120 kHz to 65 V @130 kHz 130 – 140 Raised linearly from 65 V @130 kHz to 100 V @140 kHz 140 – 500 100 V 500 - 600 Raised linearly from 100 V @500 kHz to 500 V @600 kHz 600 - 2300 500 V Outside above ranges 0 V Wider cavity limits deployed in July 2018 M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 9

2f. Reduced maximum cavity voltage HLRF configuration + HLRF-LLRF power chain optimised (6/11/2018) to reduce noise injected into beam. Max voltage in HLRF reduced from 500 Vp to 100 Vp, Effect not (yet) fully appreciated: we’ll stay at 100 Vp max for now. ELENA LLRF-HLRF power chain to reduce noise injected to the beam M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 11

2g. Operation with RF segments First version of RF segments (same h/phase settings for all segments) in July 2018 → MATLAB script to setup segments-related settings. Final FESA classes for integration with the RF cycle editor on 2 Nov FESA classes for different h/phase settings in each RF segment deployed on 9 Nov. Antiproton cycle with three RF segments and the various harmonics tested. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 12

3. RF system: (some) observations Effect of gap opening on beam Non sinusoidal gap return for high cavity voltages Many more observations shown in Davide’s presentation: hot topic for ELENA’s performance!! M. E. Angoletta “ELENA LLRF STATUS” ECC 19 July 2018 13

3a. Effect of gap opening/cavity loops on beam Gap relay takes ~23 ms to open. Servoloops start as soon as gap opens. Closed loop: visible effect on the beam depending on delay from gap opening to voltage ramping. Feedforward control: no effect on the beam Important: open gap @last moment! → not self-bunching but result of cavity loops servoing to 0 V induced voltage/noise. Longitudinal structure visible via Tomoscope and Oasis signals for various opengap timing values. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 14

3b. Non-sinusoidal gap return for high voltages Bunch rotation (August 2018) requires voltage step. Implemented with ~high cavity voltage (100 Vp) Distortion observed in gap return Only for high voltages (≥~100 Vp) For closed loop as well as for feedforward control Reason not fully understood: power chain, HLRF ampli, other? Power chain + HLRF amplifier changed in November 2018 → investigation to be restarted. Closed loop control of cavity voltage. Stored traces: 40 V voltage program; coloured traces: 100 V voltage program. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 15

Outline RF system Longitudinal diagnostics (processing) Plans (≥ 2019) Status and typical operation New features in 2018 Observations Longitudinal diagnostics (processing) Status, usage & examples Plans (≥ 2019) Conclusions M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019

4. Longitudinal diagnostics: status & usage In summer 2018 longitudinal diagnostics deployed in LLRF boards. Bunched beam intensity from one (LPU,TPU) and two (LPU) harmonics. Intensity with two harmonic measured as for AD (downconverted data). Bunch length (two harmonics, LPU only). Same process as for AD, where data is calculated but not available to user. Intensity + bunch length available as Oasis signals: Easy correlation in Vscope window with other signals/phenomena Debunched-beam measurements (intensity, Δp/p from Schottky signals analysis of downconverted LPU signals) not available. FFT tests done with LLRF Oasis (downconverted) TPU data USAGE Intensity meas. extensively used to see efficiency improvements. Bunch length not used operationally in 2018. M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 16

4. Longitudinal diagnostics: examples Antiproton cycle (production) H- cycle (MD) First RF segment (from injection into ELENA to first cooling plateau) Acceleration and deceleration M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 17

5. Longitudinal diagnostics: observations Dependence of measurement on beam intensity Calibration Team priority for development/validation/ commissioning was given to LLRF in 2018 run! M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 18

5a. Dependence on beam intensity Intensity estimate: higher for long bunches, lower for short bunches (i.e. with higher peak density). Dependence visible more on TPU-derived signals than LPU-ones. Effect disappears for lower beam intensities Non-linearities (ex: saturation) somewhere in signal DAQ path?? → Must be understood!! Voltage changes generate synchrotron oscillations. Bunch length + height oscillations Visible more on TPU than on LPU (1 h type) intensity signals Same as before but radial steering added Bunch length + height oscillations + radial position oscillations generated Same oscillations visible on TPU intensity M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 19

5b. Measurements calibration Bunch-length calibration: not done. Intensity calibration: empirical calibration wrt. extracted beam measured in AD extraction line. Optimistic calibration! Possibly better calibration “from the bottom”, i.e. wrt. TRIC measurement (absolute calibration) in ELENA extraction line. Other options under evaluation. NB: intensity measured @specific points in cycle (AD-style) might be useful (ex: to be put in elogbook). Intensity measurements summary table for AD M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 20

Outline RF system Longitudinal diagnostics (processing) Plans (≥ 2019) Status and typical operation New features in 2018 Observations Longitudinal diagnostics (processing) Status, usage & examples Plans (≥ 2019) Conclusions M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019

Plans: LLRF Re-check with beam various observations from 2018 Re-commission cavity loops with new HLRF ampli. Deploy new cavity limits for 100 Vp operation [aim: 2019*] Re-commission/operate 2nd harmonic (shaping) loop [aim: 2019*] Support development of RF cycle editor by ELENA/OP [aim: 2019*] Validate/finalise additional features, ex: Longer Oasis timebase (currently 2.5 s/div, longer than for other signals) and Oasis data retrieval during cycle [aim: 2019*] PAUSE operation (low priority for ELENA?) Remote control of LLRF programmable amplifiers. H/w + s/w. [aim: 2019, if possible] * Assuming there is a ELENA ring run in 2019, timings, controls… M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 21

Plans: longitudinal diagnostics Move data processing to dedicated board (third board in LLRF) [aim: 2019*] Re-check with beam various observations from 2018 Implement remote control of LPU head ampli [low priority?] If required and financed [~10 kCHF] deploy ObsBox in ELENA, receiving data from LPU and/or TPU [planned in post-LS2 AD to replace current Schottky/intensity measurement system. → next slide ] * Assuming there is a ELENA ring run in 2019, timings, controls… M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 22

WP 26: Technical choices (cont’d) Layout & functionalities for new AD LLRF + intensity/Schottky system Bunched-beam intensity calculated in time by ObsBox [integration + baseline subtraction] → removed dependence on bunch shape. ObsBox: 128 GB memory on board → can store > 1000s of data @60 MHz Fiber optic data transfer LLRF to ObsBox (also timing events) FFT FESA classes based on BI ones

Conclusions ELENA LLRF frontend implements all functional requests. Integration to be completed, improvements will be deployed. Experience useful for post-LS2 AD LLRF (common approach). ELENA long. diagnostics implemented in LLRF boards. Will be moved to dedicated board in LLRF crate. ObsBox could be useful for ELENA (synergy with AD system) Several points/question marks to be analysed in future runs. Overall excellent progress & results. What’s next? We must know requests & machine plans to reserve & plan manpower (busy LS2!) M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019 23

SPARE SLIDES (… because you never know…) M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019

ELENA LLRF + long. diag. final layout M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019

Bunched beam intensity from 2 LPU harmonics 𝑵 𝑷 =𝒄𝒂𝒍∙ 𝑰 𝟎 𝒇 𝑹𝑬𝑽 M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019

Loops contribution Loops contribution for pbar cycle h = 1, 4, 4 (November 9th 2018) M. E. Angoletta “RF and longitudinal diagnostics” ECC 7 March 2019