# Presentation: 572382

## Self-stabilization of e-p Instability and Accumulation of a Superintense Circulating Beam

- V. Dudnikov*,
- BTG

## Superintense beam- circulating beam with intensity far above a space charge limit (with recalculated tune shift ΔQ>1)

*For uniform beam**:*
*Δ**Q*=-*Nr**p** R**ef* */ **πβ**2**γ** **3**Qa(a+b)*
*N= **Δ**Q **πβ**2**γ** **3** **Q** **a(a+b) / r**p**R**ef*
*For accelerators is typical **Δ**Q~0.1-0.3<1*

## Self-stabilization of e-p instability was observed in 1971. Circulating 100% space charge compensated proton beam with intensity, greater than the space charge limit (tune shift Q>5) was accumulated in 1971-73.

- G. Budker, G. Dimov, V. Dudnikov, V. E. Chupriyanov, V. G. Shamovsky, et. al.  in *Proceedings of the Xth International Conference on Particle Accelerators, Serpukhov,* Vol. 2, p. 287, 1977.
- G. Dimov, V. Chupriyanov, V. Shamovsky. *Sov. Phys., Tech. Phys.*, 16(10),1662,1971.
- G. Dimov, V. Chupriyanov. *Particle Accelerators,* 14, 155- 84, 1984.
- V. Dudnikov. Condition for Production of Circulating Proton Beam with Intensity Greater than Space Charge Limit,  *20th ICFA Advanced Beam Dynamics Workshop on High Intensity High Brightness Hadron Beams HB2002, FNAL, *8-12 April 2002;* **http://www-bd.fnal.gov/icfa/workshops/20*/
- V. Dudnikov. *PAC01 Chicago, *2001*(IEEE, Piscataway, NJ, 2001*).
- V. Dudnikov. *PAC05, Knoxville, *2005.
- F. Zimmermann. Review of Single Bunch Instabilities Driven by an Electron Cloud,** ***P**hys.** R**ev.** S**. **T**.** – A**ccelerators and Beams, *7, 124801, 2004.

##   Increase a beam density nb and ion density ni above a threshold level: 

-   Increase a beam density *n**b* and ion density *n**i* above a threshold level:
*(n**b** + n**i**)> ****2** /2**π**r**e** **a**2** *; *r**e **= e**2**/mc**2*.
-   In high current proton rings it is possible to reach this “Island of stability” by fast concentrated high current charge exchange injection without painting and enhanced generation of secondary plasma as it was demonstrated in small scale PSR at the BINP.

##    Outline

- e-p instability: historical remarks and references
- Small scale Proton Storage Rings
- Diagnostics
- Observations
- Damping of e-p instability
- Production of a stable space charge compensated super- intense circulating beam
- Applications

## Budker Institute of Nuclear Physicswww.inp.nsk.su

## First project of proton/antiproton collider VAPP, in the Novosibirsk INP (BINP), 1960

- Development of charge-exchange injection (and negative ion sources) for high brightness proton beam production. First observation and damping of e-p instability.
- Development of Proton/ Antiproton conversion.
- Development of electron cooling for high brightness proton and antiproton beam production.
- Production of space charge neutralized proton beam with intensity above space charge limit. Inductance Linac, Inertial Fusion, Neutron Generators.

## History of Charge Exchange Injection  (Graham Rees, ISIS , ICFA Workshop) 

- 1.   1951          Alvarez, LBL (H-) ;
-       1956          Moon, Birmingham Un. (H+2)
- 2.   1962-66     Budker, Dimov, Dudnikov, Novosibirsk ;
-                         first  achievements; discovery of e-p instability.IPM
- 3.   1968-70    Ron Martin, ANL ; 50 MeV injection at ZGS
- 4.   1972         Jim Simpson, ANL ; 50-200 MeV, 30 Hz booster
- 5.   1975-76   ** **Ron Martin et al, ANL ; 6 1012 ppp
- 6.   1977          Rauchas et al, ANL ; IPNS 50-500 MeV, 30 Hz
- 7.   1978          Hojvat et al, FNAL ; 0.2-8 GeV, 15 Hz booster
- 8.   1982          Barton et al, BNL ; 0.2-29 GeV, AGS
- 9.   1984          First very high intensity rings ; PSR and ISIS
- 10. 1980,85,88 IHEP, KEK booster, DESY III (HERA)
- 11. 1985-90     EHF, AHF and _KAON_ design studies. SSC
- 12. 1992          AGS 1.2 GeV booster injector
- 13. 1990's        ESS, JHF and SNS 4-5 MW sources

## History of Negative Ion 

- Sources Development (J.Peters)

- BDD, G.Budker, G.Dimov, V.Dudnikov
- Charge-Exchange Injection

## INP Novosibirsk, 1965, bunched beam 

- INP Novosibirsk, 1965, bunched beam

**first observation of an e****-**** driven instability? **
**coherent betatron oscillations & beam loss**
- with bunched proton beam; **threshold** ~1-1.5x1010,
- circumference 2.5 m, **stabilized by feedback**
- (G. Budker, G. Dimov, V. Dudnikov, 1965).
- F. Zimmermann review

- _Other __**INP PSR 1967**_:
**coasting**
**beam instability**** **
**suppressed by**
**increasing beam**
**current****;**
- fast accumulation of
- secondary plasma
- is essential for
- stabilization;
- 1.8x1012 in 6 m

- V. Dudnikov, PAC2001,
- PAC2005

## INP PSR for bunched beam accumulation by charge exchange injection (ionization loss~200eV)

- 1-   fist stripper;
- 2-   main stripper Pulsed supersonic jet;
- 3-   gas pumping;
- 4-   pickup integral;
- 5-   accelerating drift tube;
- 6-   gas luminescent profile
-       Monitor;
- 7-   Residual gas current monitor;
- 8-   residual gas IPM;
- 9-   BPM;
- 10- transformer Current monitor;
- 11- FC;
- 12- deflector for Suppression transverse instability by negative Feedback.

- Small Radius- High beam density. Revolution 5.3 MHz. 1MeV, 0.5 mA, 1 ms.

## General view of INP PSR  with charge exchange injection, 1965

- Magnet
- Vacuum chamber
- Beam line
- 5.   First stripping target
- 6.   Second stripping target

## Residual gas ionization beam current & profile monitors (ICM,IPM),1965

## Residual gas luminescent beam profile monitor INP,1965

- 1- magnetic pole;
- 2- proton beam;
- 3- moving collimator
- 4- light guide;
- 5-photomultiplier;
- 6-vacuum chamber

## Beam profiles evolution during accumulation

## Proton beam accumulation for different injection           current (0.1-0.5 mA), accumulated beam 300mA

- Injected beam

- Circulating beam,
- Low injection current

- Start saturation

- Strong saturation

## Transverse instability in the INP PSR, bunched beam (1965)

## Diagram of feedback system for e-p instability damping ( bunched beam)

## Transverse instability of bunched beam in INP PSR (1965) (& damping by FB system)

## Transverse instability of bunched beam with a high RF voltage

- 1-ring pickup, peak bunch
-    intensity ;
- 2-radial loss monitor.
- Beam was deflected after Instability loss.
- Two peaks structure of beam after instability loss.
- Only central part of the beam was lost

## Models of two-stream instability

- The beam- induces electron cloud build up and development of two-stream e-p instability is one of major concern for all projects with high beam intensity and brightness [1,2].
- In the discussing models of e-p instability, transverse beam oscillations is excited by relative coherent oscillation of beam particles (protons, ions, electrons) and compensating particles (electrons, ions) [3,4,5].
- For instability a bounce frequency of electron’s oscillation in potential of proton’s beam should be close to any mode of betatron frequency of beam in the laboratory frame.
- 1.        _[http://wwwslap.cern.ch/collective/electron-cloud/](http://wwwslap.cern.ch/collective/electron-cloud/)__. _
- 2.        _[http://conference.kek.jp/two-stream/](http://conference.kek.jp/two-stream/)__._
- 3.        G.I.Budker, Sov. Atomic Energy, 5, 9, (1956).
- B.V. Chirikov, Sov. Atomic.Energy,19(3), 239, (1965).
- Koshkarev, Zenkevich, Particle Accelerators, (1971).
- 6.        M.Giovannozzi, E.Metral, G.Metral, G.Rumolo,and F. Zimmerman , Phys.Rev.
-            ST-Accel. Beams, 6, 010101, (2003).

## Slide 22

## ISIS has much larger a and b, and low particle density. Bounce frequency is low . Only low modes of betatron oscillations are unstable. This lead to removing of electrons without beam loss.

- ISIS has much larger a and b, and low particle density. Bounce frequency is low . Only low modes of betatron oscillations are unstable. This lead to removing of electrons without beam loss.

## The oscillation tune of the electrons inside the proton beam (bounce frequency, plasma frequency), number of oscillation per turn:

- (Qe Ω)2 =4Nb rec2/*a(a+b)*L;
- (Qe)2 =2Nb reR /*a(a+b)*πβ2
- (Qe)2 =2(Nb +Ni) reR /*a(a+b)*πβ2
- Wavelength  λ=L/Qe<*a*  self- stabilization.
- R. A. Bosch, **Suppression of two-stream hose instabilities at wavelengths shorter than the beam’s transverse size, Phys.Rev. ST, 6 (2003).**

## PSR for beam accumulation with inductive acceleration

- 1-first stripper;
- 2-magnet pole n=0.6;
- 3-hollow copper torus
- with inductance current;
- 4-main stripper;
- 5-accelerating gap;
- 6-ring pickup;
- 7-BPMs;
- 8-Res.gas IPM;
- 9-vacuum chamber.
- FC; quartz screens;
- Retarding electron and
- ion collectors/
-  spectrometers .

## e-p instability with a low threshold in INP PSR, 1967

- 1-beam current, N>7e9p
- 2-beam potential, slow
- Accumulation of electrons
-  10 μs, and fast loss 1 μs.
- 3-retarding grid electron collector;
- 4,5-ion collector, ionizing
- Current Monitor;
-  6,7-ion Collectors Beam
- potential monitor;
- 8,9- negative mass Instability.
- Injection:
- Coasting beam, 1MeV, 0.1mA
- R=42 cm.

## PSR for Superintense Circulating p-Beam Production

- 1-striping gas target;
- 2-gas pulser;
- 3-FC;
- 4-Q screen;
- 5,6-moving targets;
- 7-ion collectors;
- 8-current monitor;
- 9-BPM;
- 10-Q pick ups;
- 11-magnetic BPM;
- 12-beam loss monitor;
- 13-detector of secondary particles        density;
- 14-inductor core;
- 15-gas pulsers;
- 16-gas leaks.

- Proton Energy -1 MeV; injection-up to 8 mA; bending radius-42 cm; magnetic field-3.5 kG;index-n=0.2-0.7; St. sections-106 cm;aperture-4x6 cm; revolution-1.86 MHz; circulating current up to 300 mA is up to 9 time greater than a space charge limit. A Stripping target is a gas jet.

## Tune diagram of betatron frequencies of the storage ring: 

- Tune diagram of betatron frequencies of the storage ring:
- 1-betatron frequency of low intensity beam νx=1.62; νz=0.85;
- Blue-trajectory of operation point with variation of correction current;
- Red- trajectory of operating point under the influence of the space charge.

## Instability of coasting beam in AG PSR, 1967

- 1- beam current
-     monitor;
- 2- vertical proton
-     loss monitor;
- 3- radial proton loss;
- 4- detected signal of
-     vertical BPM.
- 20 μs/div.

## e-p instability of coasting beam in the INP PSR (1967)

## Secondary Particles detector with repeller, INP,1967

## Mass Spectrum of Ions from the Beam

- Integral Signal (bottom), Differential Signal (top)

## Inductive BPM, INP,1967

## Spectrums of coasting beam e-p instability in BINP PSR  (magnetic BPM), very similar for LA PSR

## Beam accumulation with clearing voltage

- In beginning secondary plasma accumulation
-     suppressed by strong
-     transverse electric field.
- Vertical instability with zero mode oscillation
-      was observed
-      (Herward instability).

## Threshold intensity N (left)  and growth rate J (right) of instability as function of gas density n

- a- hydrogen; b- helium; c- air.

## Beam accumulation with space charge neutralization

## Self-stabilization of e-p instability was observed in 1971. Circulating 100% space charge compensated proton beam with intensity, greater than the space charge limit (tune shift Q>5) was accumulated in 1971-73.

- G. Budker, G. Dimov, V. Dudnikov, V. E. Chupriyanov, V. G. Shamovsky, et. al.  in *Proceedings of the Xth International Conference on Particle Accelerators, Serpukhov, *1977, Vol. 2, p. 287.
- G. Dimov, V. Chupriyanov, V. Shamovsky. *Sov. Phys., Tech. Phys.*, 16(10),1662, 1971.
- 3. 	G. Dimov, V. Chupriyanov. *Particle Accelerators,* 14, 155- 84, 1984.
- 4. 	V. Dudnikov. Condition for Production of Circulating Proton Beam with Intensity Greater than Space Charge Limit,  *20th ICFA Advanced Beam Dynamics Workshop on High Intensity High Brightness Hadron Beams HB2002, FNAL, *8-12 April 2002;* **http://www-bd.fnal.gov/icfa/workshops/20*/
- 5. 	V. Dudnikov. *PAC01 Chicago, *2001*(IEEE, Piscataway, NJ, 2001*).
- 6. 	V. Dudnikov. *PAC05, Knoxville, *2005.
- 7.	F. Zimmermann. Review of Single Bunch Instabilities Driven by an Electron Cloud,** ***P**hys.** R**ev.** S**. **T**.** – A**ccelerators and Beams, *7, 124801, 2004.

## INP PSR for Beam above a Space Charge Limit Ionization energy loss ~200 eV/turn, compensated by inductance field

## Small Scale Proton Storage Ring for Accumulation of Proton Beam with Intensity Greater than Space Charge Limit

## Self-stabilization of e-p instability and accumulation of proton beam with intensity above a space charge limit (with high injection current >5.5mA). Strong instability with low injection current <5.5 mA. 

- Self-stabilization of e-p instability and accumulation of proton beam with intensity above a space charge limit (with high injection current >5.5mA). Strong instability with low injection current <5.5 mA.
- For self-stabilization it is important to have a high injected current density          ( second threshold) and fast accumulation of secondary plasma.

## Proton beam accumulation with intensity greater than space charge limit. Dependence on injection current.

- Proton beam accumulation with intensity greater than space charge limit. Dependence on injection current.

- Np-number of accumulated protons;  Ij- injection current; ** Q-tune shift.

## Plasma generators for space charge compensation

- 1- circulating proton beam;
- 2- magnetic poles;
- 3- filaments, electron sources;
- 4- grounded fine mesh;
- 5- secondary emission plate with a negative potential.

- Electrons e emitted by filaments 3 are oscillating between negative plates 5 with a high secondary emission for electron multiplication.
- A beam density and plasma density must be high enough for self stabilization of   e-p instability (second threshold).
-  Secondary ion accumulation is important for self stabilization of e-p instability.

## Beam accumulation with a plasma generator on and off

- on

- off

- off

- on

## Space charge neutralized Superintense ion beams with intensity fare above space charge limit 

- Can be useful:
- In Inductance Linac with recirculation,
- For Inertial Fusion,
- For Neutron, Antiproton, Mu meson Generators
- For resonant reaction with internal targets
- For High Power Density Physics
- For FFAG accelerators
- For Inductive Synchrotrons
- Intensity limit don’t determined: *Δ**Q> 10-100 can be possible?*
- It is important to reproduce a Self-stabilization in Computer simulation

## It is important to repeat!

- It is very attractive to repeat an accumulation of Superintense ion beam with modern high current injectors. High current density beam should be stable without secondary ions.
- Now from RFQ it is possible to have H- beam with current ~100 mA and energy ~3 MeV.
- This can be enough for accumulation  ~ 1 kA of circulating proton beam in a small storage ring with R~1m.
- It is important to reproduce a Self-stabilization  and Superintense beam accumulation in Computer simulation

## Self-stabilization of e-p instability and accumulation of proton beam with intensity above a space charge limit (with high injection current); instability with low injection current

## A schematic a storage ring  for resonance reaction production by the interaction of a Superintense circulating ion beam with a thin internal target

*1- beam line for transport of injected H- beam: RFQ, cyclotron or DC accelerator; 2- injected H- beam  ; 3-bending magnets; 4-vacuum chamber  ; 5- generator of supersonic jet- stripping, reaction target; 6- supersonic jet, stripping-reaction target; 7- pump-recirculator of target jet; 8- cone of resonant gamma rays; 9- iron core for inductor for compensation of beam energy loss* *in first target; 10-circulating proton beam; 11- magnetic coil; 12- yoke of bending magnet; 13-16 electron cooling*

## Memo from: Bruno Zotterwww.aps.anl.gov/conferences/icfa/twoo-stream/

- Subject: Summary of my own conclusions of the workshop
- 1) Go on with your plans to coat the most sensitive locations in the PSR (Al stripper chamber, sections with ceramics and with high losses) with Ti nitride - make sure that the deposition technique avoids rapid flaking off;
- 2) If this is not sufficiently successful, install a transverse feedback system based on the wide-band split cylinder pickups - Dudnikov showed an example where a feedback seemed to work fine on e-p. If the oscillations are kept sufficiently small by it, there may be no need for high power;

## Slide 50

## Slide 51

## Instrumentation for observation and damping of e-p instability

- 1. Observation of plasma (electrons) generation and correlation with an instabilitydevelopment. Any insulated clearing electrodes could be used for detection of sufficient increase of the electron density. More sophisticated diagnostics (as from ANL) is used for this application in the LANL PSR. These electrodes in different location could be used for observation of distribution of the electron generation.
- 2. For determination an importance compensating particles it is possible to use acontrolled triggering a surface breakdown by high voltage pulse on the beam pipe wall or initiation **unipolar arc**. Any high voltage feedthrough could be used for triggering of controlled discharge. Could this break down initiate an instability?
- 3. For suppression of plasma production could be used an improving of surfaceproperties around the proton beam. Cleaning of the surface from a dust and insulating films for decrease a probability of the arc discharge triggering. Deposition of the films with a low secondary emission as TiN, NEG. Transparent mesh near the wall could be used for decrease an efficient secondary electron emission and suppression of the multipactor discharge. Biased electrodes could be used for suppressing of the multipactor discharge, as in a high voltage RF cavity.
- 4. Diagnostics of the circulating beam oscillation by fast **magnetic** beam position monitors (M**BPM). This signal can be used for feedback damping.**
- 5. Local beam loss monitor with fast time resolution. Fast scintillator, pin diodes.
- 6. Transverse beam instability is sensitive to the RF voltage. Increase of the RF voltage is increase a delay time for instability development and smaller part of the beam is involved in the unstable oscillation development.
- 7. Instability sensitive to sextuple and octupole  component of magnetic field, chromaticity (Landau Damping), ...

## References for first observation of e-p instability

- V.Dudnikov, “The intense proton beam accumulation in storage ring by charge- exchange injection method”, Ph.D.Thesis, Novosibirsk INP,1966.
- G. Budker, G. Dimov, V. Dudnikov, “Experiments on production of intense proton beam by charge exchange injection method” in Proceedings of International Symposium on Electron and Positron Storage Ring, France, Sakley,1966, rep. VIII, 6.1 (1966).
- G. Budker, G. Dimov, V. Dudnikov, “Experimental investigation of the intense proton beam accumulation in storage ring by charge- exchange injection method”, Soviet Atomic Energy, 22, 384 (1967).
- G.Budker, G.Dimov, V. Dudnikov, V. Shamovsky, “Experiments on electron compensation of proton beam in ring accelerator”, Proc.VI Intern. Conf. On High energy accelerators, 1967, MIT & HU,A-104, CEAL-2000, (1967).
- G.I.Dimov, V.G.Dudnikov, V.G.Shamovsky, ” Transverse instability of a proton beam due to coherent interaction with a plasma in a circular accelerator” Soviet Conference on Charge- particle accelerators”, Moscow,1968, translation from Russian, 1, 1973 108565 8.
- G. Dimov, V. Dudnikov, V. Shamovsky, “Investigation of the secondary charged   particles influence on the proton beam dynamic in betatron mode ”, Soviet Atomic  Energy, 29,353 (1969).
- H.A. Grunder and G.R. Lambertson, ‘Transverse Beam Instabilities at the Bevatron,’ Proc. 8th Int. Conference High Energy Acc., Geneva (1971).
- Yu.Belchenko, G.Budker, G.Dimov, V. Dudnikov, et al. X PAC,1977.
- O.Grobner, X PAC,1977.
- E. Colton, D. Nuffer, G. Swain, R.Macek, et al., Particle Accelerators, 23,133 (1988).

## Development of Charge Exchange Injection, observation and damping of e-p instability and Production of Superitense Beam

*V.Dudnikov. “Production of an intense proton beam in storage ring by a charge- exchange injection method”, Novosibirsk, Ph.D.Thesis,INP, 1966.*
- Development of a Charge- Exchange Injection; Accumulation of proton beam up to space charge limit; Observation and damping of synchrotron oscillation; Observation and damping of the coherent transverse instability of the bunched beam. Observation of the e-p instability of coasting beam in storage ring.
- G. Budker, G. Dimov, V. Dudnikov, “Experiments on production of intense proton beam by charge exchange injection method” in Proceedings of International Symposium on Electron and Positron Storage Ring, France,Sakley,1966, rep. VIII, 6.1 (1966).
- G. Budker, G. Dimov, V. Dudnikov, “Experimental investigation of the intense proton beam accumulation in storage ring by charge- exchange injection method”, Soviet Atomic Energy, 22, 384 (1967).
- G.Dimov, V.Dudnikov, “Determination of circulating proton current and current density distribution (residual gas ionization profile monotor)”, Instrum. Experimental Techniques, 5, 15 (1967).
*Dimov. “Charge- exchange injection of protons into accelerators and storage rings”, Novosibirsk, INP, 1968.*
- Development of a Charge- Exchange Injection; Accumulation of a proton beam up to the space charge limit; Observation and damping of synchrotron oscillations; Observation and damping of the coherent transverse instability of the bunched beam;.
*Shamovsky. “Investigation of the Interaction of the circulating proton beam with a residual gas”, Novosibirsk, INP, 1972. *
- Observation of transverse e-p coherent instability of the coasting beam in the storage ring, Observation of a transverse Herward’s instability, Damping of instabilities, Accumulation of a proton beam with a space charge limit.
- G. Dimov, V. Dudnikov, V. Shamovsky, “Transverse instability of the proton beam  induced by coherent interaction with plasma in cyclic accelerators”, Trudy Vsesousnogo soveschaniya po uskoritelyam, Moskva, 1968, v. 2, 258 (1969).
- G. Dimov, V. Dudnikov, V. Shamovsky, “Investigation of the secondary charged particles influence on the proton beam dynamic in betatron mode ”, Soviet Atomic Energy, 29,353 (1969).
- G.Budker, G.Dimov, V. Dudnikov, V. Shamovsky, “Experiments on electron compensation of proton beam in ring accelerator”, Proc.VI Intern. Conf. On High energy accelerators, 1967, MIT & HU,A-104, CEAL-2000, (1967).
-  *Chupriyanov. “Production of intense compensated proton beam in an accelerating ring”, Novosibirsk, INP, 1982.*
- Observation and damping transverse coherent e-p instability of coasting proton beam and production of the proton beam with an intensity up to 9.2 time above a space charge limit.
- G.Dimov, V.Chupriyanov, “Compensated proton beam production in an accelerating ring at a current above the space charge limit”, Particle accelerators, 14, 155- 184 (1984).
- G.Budker, G.Dimov, V.Dudnikov, et al. X PAC,1977.