# Presentation: 022779

## HIF Research on the University of Maryland Electron Ring (UMER)

**HIF Research on the University of Maryland Electron Ring (UMER)**

**Research sponsored by US Department of Energy**

**Rami A. Kishek**
**on behalf of ****UMER**** collaboration**

## We Thank:

| University of Maryland Electron Ring (UMER) Team: |  |  |  |  |
| --- | --- | --- | --- | --- |
| Patrick O’Shea 
Martin Reiser
Irving Haber
Rami Kishek | Junior Scientists:
Santiago Bernal
Mark Walter
Yun Zou
Bryan Quinn
 | Graduate:
Yupeng Cui
Hui Li
John Harris
Yijie Huo
Gang Bai 
Kai Tian | Undergraduate:
D. Lamb
W-T. Lee
A. Gregory
M. Holloway
W. Tze |  |
| Terry F. Godlove
Don Feldman
Renee Feldman |  |  |  |  |
|  |  |  |  |  |
| Virtual National Lab for Heavy Ion Fusion (also provided WARP) | Alex Friedman
Dave Grote
Jean-Luc Vay | Christine Celata 
Steve Lund
John Barnard |  |  |
| NIU | Court Bohn | Ioannis Sideris |  |  |
| Others | Ingo Hoffman
Tom Wangler |  |  |  |

## Outline

- The University of Maryland Electron Ring
- Source Physics
- Transverse Physics
- Longitudinal Physics
- Future Directions

## HIF with electrons?  Scaling Laws

- 	1 keV	1 MeV	1 GeV	1 TeV

**UMER**

## Beam Dynamics Challenges for HIF

- Transverse:
- Halo Formation
- Emittance Growth
- Instabilities
- Longitudinal:
- Energy Spread
- Transverse-Longitudinal Coupling
- Compression
- Instabilities

## University of Maryland Electron Ring

*The most intense beam**	**in a strong focusing lattice*

- Variable-Parameter over a wide range
- Long Path
- Well-Diagnosed
- Low-Cost!

- UMER is designed to serve as a **research platform** for intense beam physics

- A “Tabletop” 	Accelerator Experiment

## Dimensionless Space Charge Intensity

- Matched Beam envelope equation (force balance):

- In UMER, force from space charge can be as much as 55 times the force from thermal pressure (emittance)!

**Dimensionless Space Charge Intensity**

**0 ******** ******** ******** 1**

## Scalings with Space Charge Intensity

**UMER Range**

**Scalings with Space Charge Intensity**

## UMER Schematic

**Extraction/**
**diagnostic **
**section**

**10 kV **
**Gun**

**UMER Schematic**

## UMER lattice

## Diagnostics Available

- Beam Position Monitors (17 BPMs)
- Phosphor Screens (18+ P-Screens)
- End Diagnostic Chamber:
- Energy Analyzer
- Pepper-pot Emittance (Phase Space) Monitor
- Slit-Wire Emittance (Phase Space) Monitor
- Faraday Cup

**Diagnostics Available**

## UMER is a Complex Machine

- Electron Gun

- Injection Line

- Ring Chambers

- Diagnostic
- Chamber

**UMER is a Complex Machine**

**> 150 Magnets**

**Assembly, Alignment**

**Power Supplies, Wiring**

**Diagnostics**

**Beam Control**

## UMER Photos (2002)

**Sep. 2002****4 Sections**

**July 2002****2 Sections**

**Dec. 2002****9 Sections**

## UMER Photos (2003)

**July 2003****12 Sections**

**Sep. 2003****13 Sections + Y**

## New Injection Y-Design

**Injector**

**Ring**

**IQF**

**RQ1**

**Mark Walter poster, Today (W)**

## Source Physics

## Simulation with WARP PIC-code

** **

**The Heavy Ion Fusion Virtual National Laboratory**

**WARP combines features of a plasma simulation ****and an accelerator code**

**Courtesy of Alex Friedman**

*D. P. Grote, et. al., Fus. Eng. & Des. 32-33, 193-200** *

## Intense Beams Can Carry Waves

**Experiment (100 mA) (top)**

**WARP Simulation (below)**

**Beam patterns sensitive to initial velocity distribution!**

**S. Bernal, ***et al.,*** NIM A ****519, **380-387** **(2004);** ****R.A. Kishek, ***et al.,*** Phys Plasmas ****10 (5), **2016 (2003).

## UMER Electron Gun

**UMER Electron Gun**

## Hollow Velocity Distribution

- _Construct New Distribution_:
- 	Uniform in Space
- 	**Velocity** is a Gaussian with non-zero mean, rotated about z axis, i.e. **hollow** in center.

## Hollow Velocity better fits experiment

**Simulated Pepper-Pot**

## Phase Space at Source Exit

**Phase Space at Source Exit**

**Irv Haber poster, Tomorrow (Th)**

## Transverse Physics

## First Experiments (during construction)

**1.0 cm**

**24 mA, ****10 keV**

**1.0 m**

**S. Bernal (PAC ’03)**

**First Experiments (during construction)**

**Rotated Beam**

**RMS Mismatched**

## Skew Quadrupole (Rotational) Errors

*Kishek, Barnard, and Grote, PAC 1999*

**Notes:**
Cross-moments, e.g. <xy> or <x’y> nonzero, so emittance not conserved
Can defined generalized emittances g, h which are conserved (see J.J. Barnard, et al., PAC’95)

## Injecting Rotated Beams  Halo

**Simulations**
**R. Kishek**
**Proc Halo ‘03**

**Experiment – ****	****(Bernal, Li)****shows similar features**

## Quadrupoles with Electronically Adjustable Skewness

**H. Li (PAC ’01)**

## Beam Rotation Correction

**24mA Beams (RC1-12)**

**Hui Li (& S. Bernal) poster, Today (W)**

## Computer Control & Tomography

**700 ********A pinhole beam**

**Note striations in beam and phase space:**
**	******** ****due to cathode grid**

**Hui Li (& S. Bernal) poster, Today (W)**

## New 5-Beamlet Experiment

***Bernal; Haber; Kishek***

## Particle Trajectories: x-x’ Phase Space

**Particle Trajectories: x-x’ Phase Space**

**Isotropic**

**Anisotropic**

**Notes:**
Self-similarity?

## Longitudinal Physics

## Long Solenoid Experiment (LSE)

**Notes:**
Fututre, measure the perturbations.on top of long grid pulse, add a cohere or incoherenet perturbation and study the energy spread change. Or thermailzation of the coherent flucturations.

## Experimental Study of BeamEnergy Spread: Energy Analyzer Design

**High resolution**
**  ****(< 1 eV for 10 keV beam)**
**ns temporal resolution**

**Yupeng Cui poster, Tomorrow (Th)**

**Notes:**
This shows the simulation of the performance of the energy analyzer using a computer code called Simion, which is an ion optics code. Here it shows the energy analyzer has resolution of 20 eV for a monoenergetic beam with divergence angle of 5o.

## Energy Spread Measurement Results

**Energy Spread Measurement Results**

**Yun Zou poster, Tomorrow (Th)**

## Laser-Generation of Perturbations

**Laser-Generation of Perturbations**

**Courtesy Yijie Huo**

## Photo & Thermal Emission Beam

- Current measurement with
- a fast (<ns) Bergoz current monitor

- Photoemission only (Cool cathode)

- Thermionic only, 100ns pulse

- Photoemission +Thermionic 5ns pulse

**Courtesy Yijie Huo**

## Propagation of Longitudinal Perturbation

- 20mA Thermal-Emission Current
- 20mA Photo-Emission Current

- Beginning

- End

**Courtesy Yijie Huo**

## Longitudinal Capture

- Beam End Evolution
- Focusing with Induction Gaps
- Multiple Pulses on beam

**John Harris poster, Today (W)**

## Spiral Generator for Gap Pulsers

***Patents Pending***

***MOSFET Switching***

***Output Transformer***

***Diode Ringing Suppression***

***Inversion of One Channel***

***Delay Line***

**John Harris poster, Today (W)**

## UMER Research Program

- Transverse:
- Quadrupole Rotations
- Halos
- 5-Beamlets
- Anisotropic Beams
- Chaotic Mixing
- Longitudinal:
- Electron Gun
- Beam Ends
- Perturbations & Waves
- Energy Spread

## Conclusions

- Scaled experiments are an efficient way to learn about long-path beam dynamics issues
- Many new results during construction
- Closure of the ring promises exciting results
- See our Posters (3 Wed / 3 Thu)

- Website:	_**http://www.ireap.umd.edu/umer**_
- Publications:	_**http://www.umer.umd.edu/**_