# Presentation: 264487

## High-Brightness Electron Source: Expression of Intent

**Courtlandt L. Bohn**
**	****Northern Illinois University/Fermilab**
**14 May 2002**
- (Presented to Fermilab’s Accelerator Advisory Committee)

## Photoinjector Three (Pi3)

**A collaboration for the construction and operation of a high-brightness electron beam at Fermilab.**
**Advanced beam research and machine development.**
**The collaboration presently includes seven universities and three laboratories.   **
**An Expression of Intent submitted 02/11/02 to FNAL, ANL, LBNL, DOE, and NSF asking for encouragement to begin a design report.**

## Motivation

_**Fundamental beam and accelerator physics**_
**Wakefield & laser acceleration.**
**Bunch Compression.**
**Flat & Polarized Beams.**
**Emittance Reduction.**
**All of which will promotes growth and innovation through university training of accelerator physicists.**
_**Support for the new generation of linear colliders, FELs, and synchrotron radiation sources (~1 micron emittance and ~270 micron pulses)**_
**Demonstrate that injector specifications can be met.**
**Platform to study generation of required beams.**
**Develop expertise and infrastructure for LC efforts.**
_**Utilizes superconducting RF cavities and will foster Midwest and national development of the technology.**_

## Notional Layout of Photoinjector

_**Notional Layout of Photoinjector**_
- (as envisioned by DESY – cf. “Conceptual Design of the XFEL Photoinjector” by
- M. Ferrario, K. Floettmann, B. Grigoryan, T. Limberg, Ph. Piot)

_**Output Beam:**_
- for FEL; LC bunch charge is 3.2 nC

_**Energy:**_ 140 MeV  300 MeV

**Notes:**
Major components are: 
a drive laser that ejects electrons from the photocathode and delivers the requisite bunch train, 
 an electron gun that incorporates a 1.3 GHz copper RF cavity for rapid acceleration of the low-energy beam, 
 two cryomodules each housing eight TESLA SRF accelerating cavities
(4) a 3.9 GHz SRF accelerating section to improve the longitudinal phase-space of the beam prior to bunch compression, 
(5) an array of dipole magnets with which to compress the bunches, and 
(6) a section of electron-beam diagnostics.

## Major Components

**Drive laser (provides a flexible pulse structure and train) with a CsTe photocathode (high QE).**
**Emittance compensating solenoids.**
**A DESY donated 1.3 GHz, 8 cavity cryomodule (immediate acceleration reduces emittance growth due to space charge).**
**3****rd**** Harmonic superconducting RF section to correct non-linearities in longitudinal phase space.**
**Four-dipole compression stage.**
**Diagnostic & matching section.**
**A domestically developed cryomodule.**

## Laser and Gun Requirements(based on FEL requirements)

_**Laser and Gun Requirements**_(based on FEL requirements)

## Simulation Results: Transverse Parameters

_**Simulation Results: Transverse Parameters**_

## Simulation Results: Longitudinal Parameters

_**Simulation Results: Longitudinal Parameters**_

## Longitudinal Phase Space Before and After 3rd-Harmonic Section

## Phase Space After Bunch Compressor

- BEFORE

- AFTER

## Collaboration/Contributions

**Modeled on particle physics collaborations.**
**Envision the laboratories (Fermilab, Argonne, LBNL, DESY) taking responsibility for larger projects.**
**Infrastructure (Fermilab, ANL for chemistry)**
**RF Gun (ANL), High repetition RF Gun (LBNL)**
**Cryomodules (DESY, Pi3) **
**3****rd**** Harmonic (Fermilab/LBNL)**
**Compressor (Fermilab/ANL)**
**While the universities  (Chicago, Michigan, NIU, Northwestern, Pennsylvania, Rochester, UCLA ) .**
**Contribute personnel (e.g., students!) to laboratory-based projects**
**Take responsibility for smaller projects **
**Simulations**
**Laser **
**Diagnostics**

## Scope & Support

**Scope**
**Schedule: Approximately a 5 year construction project.**
**Cost:  A “ball-park” figure of ~$30M including M&S, labor **
**Collaboration working on (phased) schedule and cost**
**Funding prospects**
***Laboratory contributions***** *****will be crucial.***
**Requested significant DoEd funding (3M$ ******** 2 years = 6M$)**
**Expect continued state support through Illinois Consortium of Accelerator Research (ICAR).  Total grant now ~$2.5M/yr & would submit additional request.**
**Will submit university proposals to DOE & NSF which will increase university contributions. **

## A Staged Scenario

**Some observations:**
**Optimistic about DoEd support **
**Multi-laboratory interest**
**Funding agencies cautious, partially associated with LC technology choice, partially with resource limitations**
**Suggests an intermediate path compatible with LC choice **
**Reduced initial cost**
**Permits pursuit of beam physics**
**Does not foreclose on future options.**
**1****st**** Stage**
**Upgraded FNPL at new Fermilab site **
**Footprint & infrastructure consistent with eventual expansion to 1 ********m and 300 MeV**
**Current gun, additional Tesla cavities or cryomodule, 3****rd**** Harmonic cavity, new compressor**
**2****nd**** Stage (a year or two later)**
**Proposal for 1 ********m and 300 MeV will benefit from additional time and experience**
**Axially symmetric gun and second cryomodule**

## Conclusions

**Pi3 will greatly strengthen HEP and the laboratories: **
**A small scale program already proven successful.**
**A collaborative model to promote accelerator physics (will be opened to additional institutions).**
**Strengthens accelerator physics infrastructure.**
**Supports development of new technologies and machines.**

_**The collaboration has requested laboratory **_
_**assistance to develop a design report by the end of August.**_