A.Saini, K.Ranjan, N.Solyak, S.Mishra, V.Yakovlev on the behalf of our team Feb. 8, 2011 Study of failure effects of elements in beam transport line & its compensation. 6/9/2016 1

Outline Layout of SC CW lattice Study and compensation of effects of RF element’ s failure :- Failure of first cavity in SSR0 section. Failure of last cavity in SSR0 section. Failure of last cavity in SSR2 section. Study and compensation of effects of focusing element’s failure:- Failure of first solenoid in SSR0 section. Failure of first solenoid in SSR1 section. 6/9/2016 2

Goals of work Study the effects of failure of focusing & accelerating elements in beam transport line. Retuning of the lattice to compensate the effects of failed elements. To minimize beam losses (below 1W/m) & achieving smooth beam propagation through linac ( Beam envelope, emittance growth, halo growth are calculated & compared for each case ). Lattice version is used for all calculations. \\tdserver1.fnal.gov\project\TD_SCRF\ProjectX\CW \650 MHz\Alex\v /9/2016 3

Initial Parameters Ensuring the surface field limit during retuning of amplitudes of rf cavities. - Maximum allowable surface magnetic field is 60 mT for spoke resonators (soft limitation in SSR sections). and 70 mT for elliptical cavities. Maximum field gradient ~ 10 T/ m in quad and <6 T/m in solenoids. 6/9/ Limitations & constraints Longitudinal emittance :  ∙mm mrad (changed to 0.275) Transverse emittance : 0.25 pi mm mrad. Initial Energy : 2.5 MeV * Tracewin code is used for all calculations ( )

Layout of Lattice 6/9/2016 5

Beam Envelope for ideal Lattice : No errors & failures  Calculation is performed with 10k macro-particles.  3 sigma Gaussian beam 6/9/2016 6

Emittance 6/9/ tt zz

Synchronous Phase Halo parameters 6/9/ HzHz HzHz HzHz

9 Case 1: Failure of First cavity in SSR0 section SSR0 period MEBT elements available for re-tuning  Field amplitude and phases are re-adjusted in RF Cavity.  Magnetic field gradients are changed in solenoids and quads …

Failure of First cavity in SSR0 section Failed cavity 6/9/ m 1.655m Gap between two successive RF element after failure of first cavity Gap between two successive RF elements

Beam Envelope 6/9/ Losses of Particles happen at these location

Emittance 6/9/

Compensation of Failed elements Solenoid Triplet RF Gaps SSR0 Cavity 6/9/  Matching section in MEBT & 3 following period in SSR0 section are used

Beam Envelope after retuning 6/9/

Emittance Before compensation After Compensation 6/9/

Halo Parameters Before compensation After Compensation 6/9/

Summary 6/9/ ParametersNo failure Failure of first Cavity SSR0 No Compensation Compensa tion At the end of Linac zz  ∙ mm mrad tt  ∙ mm mrad Final Energy MeV Losses (%)

6/9/ Case 2: Failure of Last cavity in SSR0 section

Failure of Last cavity in SSR0 section 6/9/ Failed cavity 1.135m Note: Failed cavity is used for matching between sections

Beam Envelope 6/9/ Losses of Particles happen at these locations

Compensation of last cavity in SSR0 section 6/9/ Failed cavity Gap between two successive RF element after failure of last cavity 1.745m

Beam Envelope after compensation 6/9/

Emittance Before compensation After Compensation 6/9/

Halo Parameters Before compensation After Compensation 6/9/

Summary 6/9/ ParametersNo failure Failure of last Cavity SSR0 No CompensationCompensation At the end of Linac  z (  ∙ mm mrad)  t (  ∙ mm mrad) Final Energy (MeV) Losses (%)

6/9/ Case 3: Failure of Last cavity in SSR2 section

Beam Envelope Failure of last cavity in SSR2 section 6/9/ Failed cavity

Beam Envelope 6/9/

Compensation of failure of last cavity in SSR2 section 6/9/

Beam Envelope 6/9/

Emittance Before compensation After Compensation 6/9/

Summary 6/9/ ParametersNo failure Failure of last Cavity SSR2 No CompensationCompensation At the end of Linac  z (  mm mrad)  t (  mm mrad) Final Energy, MeV Losses, % ---

6/9/ Case 4: Failure of first solenoid in SSR0 section

Beam Envelope Failure of first solenoid in SSR0 section 6/9/

Beam envelopes 6/9/

Compensation of Failure of first solenoid in SSR0 section 6/9/

Beam envelope 6/9/

Halo Parameters Before compensation After Compensation 6/9/

Beam Losses Before compensation After Compensation 6/9/

Emittance Before compensation After Compensation 6/9/

Summary 6/9/ ParametersNo failure Failure of first solenoid SSR0 No CompensationCompensation At the end of Linac  z (  mm mrad)  t (  mm mrad) Final Energy, MeV Losses %-

6/9/ Case 5: Failure of first solenoid in SSR1 section

Beam Envelope 6/9/

Beam Envelope before compensation 6/9/

Compensation of failure of first solenoid in SSR1 section 6/9/ Two solenoids - one upstream and one downstream are used for compensation

Beam Envelope after re-tuning 6/9/

Emittance Before compensation After Compensation 6/9/

Summary 6/9/ ParametersNo failure Failure of first solenoid SSR1 No Compensation Compensation At the end of Linac  z (pi mm mrad)  t (pi mm mrad) Final Energy, MeV Losses % ---

Conclusion Different scenario of failure of beamline elements are studied. In analysis the critical locations of failed elements are chosen to demonstrate strategy of tuning. It is possible to compensate the effects of failed elements by retuning neighboring elements ( RF cavity and Solenoids/Quads). 6/9/

Thank you 6/9/

SSR0 1 st cavity ViVfSynch Phase Initial Synch Phase Final elements Gap Gap SSR0_ SSR0_3 GradiGrad felements Quad Quad Quad Sol sol sol sol Sol5 6/9/

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