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PV Name

Purpose

EGU

Limits

 

LLRF:IN20:RH:LOB_PDES

Desired Phase used by LOB local feedback, users, apps other than beam-based feedback  - may be used as readback by LEM

degrees; full range, not delta

 

 

LLRF:IN20:RH:LOB_P

Desired Phase for Beam-based feedback only

degrees; full range

none provided- to be calculated by beam-based feedback

 

LLRF:IN20:RH:L0B_PAVG

actual phase readback (avg of multiple channels): used by beam-based feedback, slc-aware readback arrys,

degrees; full range

none provided

 

 

 

 

 

 

LLRF:IN20:RH:L0B_ADES

Desired Amplitude used by LOB local feedback, users, apps other than beam-based feedback - may be used as readback by LEM

MeV;full range

HOPR, LOPR

 

LLRF:IN20:RH:L0B_A

Desired amplitude for beam-based feedback only

MeV;full range

HOPR, LOPR

 

LLRF:IN20:RH:L0B_AAVG

actual amplitude readback (avg of multiple channels): used by beam-based feedback, slc-aware readback arrys,

MeV;full range

HOPR, LOPR

 

 

 

 

 

 

LLRF:IN20:RH:G_L0_FB_CTL

When this PV is ON, beam-based feedback locks out users and other applications from setting L0B_A/P, or L0B_ADES/PDES.
Beam-based feedback is responsible for setting this PV ON when starting, setting it OFF when stopping.  When this PV is set OFF, the _ADES and _PDES PVs are set to supervisory mode and accept new values from users and applications other than beam-based feedback; _P and _A simply reflect the values of _ADES and _PDES.  Whe this PV is ON the _ADES and _PDES PVs are set to closed loop mode, and do not accept new values from users and applications. The _P and _A PVs accept values from beam-based feedback, and their values are reflected in _ADES, _PDES

 


 

 

 

 

 

 

NOTES

  • These PV names and usages are a template for L1S and the BC1 energy beam-based feedback
  • The _A, _ADES, _AAVG give the absolute energy gain of an on-crest electron (they will be calibrated by some external means, mostly using the beam); the units of ADES will be MeV
  • Phase _P, _PDES, _PAVG values give the absolute phase of the RF w.r.t. the beam (they are offset-corrected so that 0 means on-crest)

RESOLVED:

  • The local feedback loops will remain on during beam-based feedback and other user  or application inputs
  • The Beam-based feedback takes precidence over other applications and user inputs. when Beam-based feedback is on, other inputs are disabled
  • the L0B_A, L0B_P PVs will be an absolute value, not a delta.
  • Both amplitude and phase will be available as an actuator for the Beam-based feedback for DL1.  Only one of these will be used at a time

UNRESOLVED:

  •